HK1157996A - System and method for frequency offsetting of information communicated in mimo based wireless networks - Google Patents

Abstract

A communications system includes a multiple-input/multiple-output architecture, which has a plurality of radio frequency chains. One of the plurality of radio frequency chains is configured to apply a first frequency offset to a base frequency of an output signal to generate a first transmitting frequency; and another of the plurality of radio frequency chains being configured to apply a second frequency offset to the base frequency to generate a second transmitting frequency.

Description

Frequency shifting system and method for communication information in a multiple-input/multiple-output based wireless network

Cross Reference to Related Applications

This application is based on and claims priority from U.S. provisional application No.61/015,514 filed on 12/20/2007, the entire contents of which are included herein for various purposes. This application is a continuation-in-part application of pending U.S. application No.11/399,536 filed on 7.4.2006 and claiming priority thereto, the entire contents of which are also included herein for various purposes.

Technical Field

The present invention relates to communication systems. More particularly, the present invention relates to a system and method for frequency shifting of communication information in a multiple-input/multiple-output based communication system.

Background

In a wireless communication system, efficient data transmission may be achieved using a multiple input/multiple output system ("MIMO" or "MIMO system"). Briefly, MIMO systems employ a single transmitter or multiple chained transmitters ("single chains" or "multiple chains") associated with multiple physical transmit antennas to simultaneously transmit multiple data streams ("signals") over a wireless channel. The multiple data streams are received by multiple receive antennas associated with a single receiver or multiple chained receivers ("single-chain" or "multi-chain").

The system realizes better space utilization of wireless channel bandwidth, correspondingly has higher throughput, and improves link reliability and spectrum efficiency. The MIMO channel contains the channel impulse response or channel coefficients when flat fading conditions occur between pairs of transmit and receive antennas. As is known in the art, MIMO systems can be modeled

y ═ Hx + n (equation 1)

Where x and y are the transmit and receive symbol vectors, respectively, n is the channel noise vector, and H is the channel matrix.

MIMO systems are most useful in indoor environments where rich multipath environments are provided by walls, ceilings and furniture, and thus the channel matrix takes into account multiple independent and orthogonal impulse responses or spatial signatures. In this environment, MIMO technology can transmit a plurality of parallel and independent data streams according to orthogonal elements of a channel matrix. MIMO systems deployed in highly dispersive environments produce high rank H matrices, which results in higher MIMO capacity even with low associated antennas.

The MIMO system developed for 4G (fourth generation mobile communication) IEEE 802.16e WiMAX system has two main central objectives for its optimization: (1) maximize/optimize spectral efficiency; and (2) dynamically achieve coverage gain or range improvements by reducing spectral efficiency.

For mobile phone dealers, spectrum is a precious and limited resource, with revenue determined primarily as a function of system capacity and throughput. Therefore, spectral efficiency is most important for networks where revenue is measured as a function of carrier bandwidth. A major part of business fees of mobile phone providers comes from monthly rental fees for each cellular base station.

Maintaining existing cellular base station coverage is also critical since any 4G wireless network requires ubiquitous service, but increased transmission channel bandwidth will reduce the link budget and thus make the cell size smaller. Mobile phone providers rely on MIMO technology and the ability to trade-off capacity to reach the cell edge to maintain current cell coverage.

Mobile phone providers are currently the largest economic force driving the development of MIMO systems and placing industry emphasis on spectral efficiency and dynamic range balancing, as well as innovative antenna systems for Base Station (BS) and group of stations (SS) equipment. Those mobile phone vendors in the WiMAX industry are familiar with a "matrix a" for coverage gain, where a single data stream is transmitted in parallel over two independent transmitter-antenna-receiver paths using Space Time Block Code (STBC) to encode the two streams so as to be orthogonal to each other, thereby improving the Signal-to-Noise Ratio (SNR) at the receiver, resulting in an increased cell radius. By extending the "matrix B" for increased capacity, the spatial multiplexing of MIMO is used to transmit independent data streams, and throughput is limited only by the rank of the H matrix and the local noise floor.

The same two central goals, driven by the mobile phone industry 4G system, are optimized for the MIMO system developed for IEEE 802.11n broadband local area network (WLAN) systems — maximizing spectral efficiency and capacity, and optimizing coverage. However, WLAN providers have overwhelming industry requirements for pattern size, power and cost, as these chipsets are now embedded in every portable Personal Computer (PC) that is sold, as well as all new mobile phones and Personal Digital Assistants (PDAs). Starting with the introduction of the first IEEE 802.11b wireless device less than a decade ago, WLAN solution providers gained tremendous revenue. As the WiFi standard evolves from an 11Mbps system based on IEEE 802.11b with 6Mbps goodput to a 54Mbps Orthogonal Frequency Division Multiplexing (OFDM) system based on IEEE 802.11a and IEEE 802.11g with goodput in the 25Mbps range, the WLAN scheme makes progress in capacity and range. In most home applications where MIMO technology works well, the introduction of IEEE 802.11n with MIMO shows a throughput up to 300Mbps peak and an effective throughput equivalent to 100 Mbps.

The same WLAN solution provider is working on cost reduction by integrating the chip and the radio frequency transmitter into one point sufficiently that a single chip can support all software functions and transmit and receive in a zero-IF (ZIF) architecture. The power reduction of these single chip solutions allows a limited mini-PCI power budget of about 3W, supports the 3x 3IEEE MIMO 802.11n protocol, has a relatively high power transmitter in the range of 17dBm per channel, and typical < 3dBi gain antennas for portable computers or access points to WLAN users up to 20 dBm. The same WLAN providers have reduced interest in spectral efficiency and allowed channel sizes to increase from 20MHz bandwidth to 40MHz bandwidth.

MIMO systems work best in indoor or high-scattering environments that produce high rank H matrices, resulting in higher MIMO capacity, while mobile telephone systems employing MIMO are deployed outdoors, typically in Line-Of-Sight (LoS) or Near LoS (NLoS) applications. High gain antennas between 10dBi-30dBi may be used for long distance point-to-point links. In this industry, it is not widely known that radio scattering (also referred to as multipath interference) is directly related to the beam width of an antenna, so that a high-gain narrow-beam antenna can realize less multipath interference as a low-gain wide-beam antenna. This less obvious fact is of logical significance, since high gain antennas have a narrow antenna beam width and therefore a small aperture capable of receiving strong radio signals. In effect, the narrow aperture received signal has traveled a similar distance, resulting in minimal multipath interference. Another way to understand this fact is to consider the reception of high energy Radio Frequency (RF) "pulses" generated by the transmitter and received by the receiving antenna. The pulse will pop off many obstacles as an impulse response to the receiving antenna. A receiving antenna with a narrow aperture directed directly at the source of the pulse will reject the pulse any longer delayed echoes that may have come from sources that are not in-line with the transmitter. Thus, outdoor high-gain directional point-to-point MIMO systems cannot rely on multipath dispersion or wireless scattering as a way to increase spatial H matrix rank; however, other ways including spatial separation and polarization diversity are possible.

Mobile phone providers have long relied on spatial separation to achieve independence of multipath reflections for antenna diversity receivers in outdoor environments. Many articles write about the problem of spatial separation of the receiving antennas. Generally, when the receiving antenna is mounted low and close to reflecting and scattering objects, very little separation in the range of half a wavelength or only a few inches is required to achieve channel multipath independence. However, as in most cases, when the receiving antennas are mounted at a tower or rooftop level, then a small separation does not significantly reduce the correlation of the multipath characteristics, and then a larger separation of orders of meters must be used to achieve independence of the wireless channels. Most antenna systems installed on rooftops, cell towers and other overhead structures separate diversity receive antennas by 2 meters or more to obtain path independence to achieve gain from antenna diversity. MIMO access systems may rely on the same antenna separation to improve overall throughput.

Polarization diversity can also be used to achieve independence of the wireless channels. Most IEEE 802.16e MIMO systems currently deployed use tilt diversity in each antenna, separating three or more antennas at 2 meter intervals, each of which can achieve beam steering gain and a high order channel matrix H. Unfortunately, because of existing lease agreements on antenna attachments, wireless backhaul networks cannot have multiple receiver antennas separated by two or more meters. These leasing protocols generally limit antennas to overall dimensions less than 1ft x 4ft (including the transceiver equipment itself).

Also for device manufacturers, mobile phone providers further limit point-to-point wireless equipment for backhaul purposes to overall dimensions less than 1ft x 1ft, which has become an industry "norm" for such equipment. This limitation effectively limits the allowed antenna gain, yet allows antenna diversity to be used to achieve independence of the MIMO paths and allows up to a 2x 2 matrix.

Antenna polarization diversity works well for LoS links where no obstructions are possible within the wireless Fresnel zone (Fresnel zone). In this case, the MIMO gain can be determined on-site so that the network planner can accurately determine the number of wireless links and their specified bandwidth achieved using a 1ft x 1ft transceiver.

For non-LoS or near LoS point-to-point links that experience time varying reflections, MIMO gain is not better characterized and may only be a fraction of the maximum possible throughput. For example, if the signal passes through wet green plants such as trees after rain, the 2x 2MIMO transmission formed using antenna polarization diversity will be a continuous polarization rotation. The presence of several trees in the fresnel zone typically results in a 10dB reduction in transmitter signal strength, even in light winds, which can change the propagation channel more quickly than a hardware algorithm that can process and update the channel matrix "H" to maintain full throughput. Therefore, it is difficult to de-quantize MIMO gain with network capacity for these types of links.

Taking into account the difficulty of quantifying capacity for 2 × 2MIMO point-to-point wireless links, adopting 3 × 3 or 4 × 4MIMO schemes will make this effort even more challenging. These higher MIMO schemes ideally transmit significantly higher capacity than non-MIMO schemes, however their effectiveness is governed by the specific location of the LoS and near-LoS path characteristics. No written procedures or guidelines specifying guaranteed/minimum MIMO gain for a given antenna separation; thus, installers and network planners do not have an accurate way to know what link capacity will be before deploying MIMO wireless equipment.

Finally, even in the best case of LoS and antenna isolation and independence, interference in the unlicensed band is always a problem. In many environments, interference in an unlicensed frequency band may be described as a general noise floor driven by tens, hundreds, or thousands of individual and geographically dispersed sources, with typically only a few sources playing a major role.

Most sources of interference may be in fixed locations-e.g., radiation from a microwave oven or DECT radio telephone, or even radiation from a pachinko machine. Some of the interference sources are mobile, such as Bluetooth (r) devices or portable computers. In general, for outdoor point-to-point networks, the noise floor may be static in nature, but may change abruptly when a mobile source is introduced near the point-to-point microwave link. These sources are not well handled by the channel specific MIMO radio link and are therefore affected by a single interference source on all MIMO paths.

Thus, there is a need for an improved MIMO system that provides greater bandwidth and higher reliability assurance. There is also a need for a MIMO system that requires limited antennas to allow availability in limited physical space.

Disclosure of Invention

The present invention meets these and other objectives. A communication system includes a multiple-input/multiple-output architecture including a plurality of radio frequency chains, wherein one of the plurality of radio frequency chains is configured to apply a frequency offset to a fundamental frequency of an output signal to generate a transmit frequency.

In one aspect, the present invention provides a communication system. The system includes a multiple-input/multiple-output (MIMO) structure that includes a plurality of radio frequency links. A first radio frequency link of the plurality of radio frequency links is configured to apply a first frequency offset to a fundamental frequency of an output signal to generate a first transmit frequency. A second radio frequency link of the plurality of radio frequency links is configured to apply a second frequency offset to the base frequency to generate a second transmit frequency. A first radio frequency link of the plurality of radio frequency links may be configured to apply a first frequency offset to a frequency of a first receive signal to generate the fundamental frequency, and a second radio frequency link of the plurality of radio frequency links may be configured to apply a second frequency offset to a frequency of a second receive signal to generate the fundamental frequency. The plurality of radio frequency chains may include at least one radio frequency chain dedicated to transmitting signals and at least one radio frequency chain dedicated to receiving signals. The communication system may further include a first local oscillator circuit cooperating with a first of the plurality of radio frequency chains to generate a first frequency offset, and a second local oscillator circuit cooperating with a second of the plurality of radio frequency chains to generate a second frequency offset. The system may further include a Zero Intermediate Frequency (ZIF) communication circuit that operates at a baseband frequency.

At least one of the plurality of radio frequency links may comprise one of time division duplex and frequency division duplex. At least one of the plurality of radio frequency chains may comprise a switch for switching between a receive mode and a transmit mode. A first radio frequency link and a second radio frequency link of the plurality of radio frequency links may include a heterodyne architecture to generate a first frequency offset and a second frequency offset. One of the first and second transmission frequencies may comprise a frequency in the industrial, scientific, and medical wireless bands. The system may operate as one of the group consisting of: IEEE 802.11 wireless devices, IEEE 802.16d worldwide interoperability for microwave access ("WiMAX"), 802.16e WiMAX; fourth generation mobile communications (4G), third generation partnership project ("3 GPP"), and wireless devices based on the third generation partnership project 2 ("3 GPP 2") standard.

The communication system may further include an antenna associated with at least one of the plurality of radio frequency chains, wherein the antenna comprises a first polarization. The system may include a first antenna associated with a first radio frequency link of the plurality of radio frequency links; and a second antenna associated with a second radio frequency link of the plurality of radio frequency links, wherein the first antenna comprises a first polarization and the second antenna comprises a second polarization, the first polarization being different from the second polarization. The system may include a first antenna associated with a first radio frequency link of the plurality of radio frequency links; and a second antenna associated with a second radio frequency link of the plurality of radio frequency links, wherein the first antenna and the second antenna each comprise a common polarization, wherein an offset frequency of one of the first and second radio frequency links is transmitted using beam steering.

In another aspect, the present invention provides a communication system comprising a multiple-input/multiple-output architecture including a plurality of radio frequency links. A first radio frequency link and a second radio frequency link of the plurality of radio frequency links comprise a first link group. The first linked set is configured to apply a first frequency offset to a fundamental frequency of the output signal to generate a first transmit frequency. A third radio frequency link and a fourth radio frequency link of the plurality of radio frequency links comprise a second set of links. The second concatenated group is configured to apply a second frequency offset to the fundamental frequency of the output signal to generate a second transmit frequency. The communication system may include an antenna comprising a first polarization associated with a first transmission frequency and a second polarization associated with a second transmission frequency. The first polarization and the second polarization are each selected from the group consisting of vertical polarization, horizontal polarization, and orthogonal polarization.

The communication system may further include a first antenna and a second antenna, each associated with one of the first linked-group and second linked-group phases, respectively, each antenna including an input for one of the first polarization and the second polarization, respectively. The first and second linked sets may further comprise local oscillator circuits for generating respective first and second frequency offsets, respectively.

In yet another aspect, the present invention provides a communication system comprising a multiple-input/multiple-output architecture including a plurality of radio frequency links. At least one of the radio frequency chains includes a plurality of filtering sub-modules. A first and a second of the filtering sub-modules are configured to apply respective first and second frequency offsets to a fundamental frequency of the output signal to generate respective first and second signals comprising first and second transmit frequencies, respectively. The communication system may comprise a combiner for combining the first signal and the second signal into a transmission signal. The first and second sub-modules include respective first and second local oscillator circuits therein for generating respective first and second frequency offsets, respectively. The first submodule may include a first local oscillator circuit and the second submodule may include a second local oscillator circuit, and the system may further include a common oscillator circuit cooperating with at least two of the plurality of radio frequency chains, the common oscillator circuit cooperating with the first local oscillator circuit and the second local oscillator circuit for generating the first frequency offset and the second frequency offset, respectively.

In yet another aspect, the present invention provides a communication system including a multiple-input/multiple-output architecture including a plurality of radio frequency links. A first radio frequency link of the plurality of radio frequency links is configured to apply a first frequency offset to a fundamental frequency of an output signal to generate a first transmit frequency. A second radio frequency link of the plurality of radio frequency links is configured to apply a second frequency offset to the base frequency to generate a second transmit frequency. The first and second transmit signals comprise respective first and second transmit frequencies, wherein at least two of the plurality of radio frequency chains are switchable to receive modes for receiving the first and second transmit signals, respectively. Each of at least two of the plurality of radio frequency chains comprises a respective first and second receive side filtering submodule for applying a first frequency offset to a first transmit frequency and a second frequency offset to a second transmit frequency to obtain a corresponding signal at the fundamental frequency. Each of the plurality of radio frequency chains includes only one receive antenna and each of the plurality of radio frequency chains includes only one transmit antenna.

One of the at least two of the plurality of radio frequency chains may comprise a transmit side filtering submodule and a first local oscillator circuit cooperating with the respective transmit side filtering submodule and the respective first receive side filtering submodule of the one of the at least two of the plurality of radio frequency chains. The second receive-side filtering sub-module may include a second local oscillator circuit for generating a second frequency offset. The first local oscillator circuit may further cooperate with a second receive-side filtering submodule of another of the at least two of the plurality of radio frequency chains. The communication system may further include a first frequency gain circuit for implementing a Maximum Ratio Combining (MRC) gain, the first frequency gain circuit cooperating with the first receive-side filtering submodule of one of the at least two of the plurality of radio frequency chains and the second receive-side filtering submodule of another of the at least two of the plurality of radio frequency chains.

In yet another aspect, the present invention provides a communication system. The system includes a Zero Intermediate Frequency (ZIF) circuit for generating a first output signal and a second output signal, the first output signal and the second output signal including a first frequency and a second frequency, respectively. The ZIF circuit includes a plurality of radio frequency links integrated in the ZIF circuit, a first radio frequency link of the plurality of radio frequency links configured to generate a first transmit frequency, and a second radio frequency link of the plurality of radio frequency links configured to generate a second transmit frequency. The communication system may include a common frequency synthesizer integrated in the ZIF circuit that cooperates with a first and second of the plurality of radio frequency chains to generate a first and second transmit frequency, respectively. The communication system may include first and second frequency synthesizers integrated in the ZIF circuit, the first and second frequency synthesizers cooperating with respective first and second ones of the plurality of radio frequency chains to generate respective first and second transmit frequencies.

In yet another aspect, the present invention provides a method of transmitting information using a communication system comprising a multiple-input/multiple-output (MIMO) architecture including a first radio frequency link and a second radio frequency link. The method comprises the following steps: a) receiving at least one output signal from the first radio frequency chain and at least one output signal from the second radio frequency chain, each output signal comprising a fundamental frequency; b) applying a first frequency offset to a fundamental frequency of at least one output signal received from the first radio frequency link to generate a first offset transmit signal; c) applying a second frequency offset to the fundamental frequency of at least one output signal from the first radio frequency link to generate a second offset transmit signal; and d) transmitting the first offset transmission signal and the second offset transmission signal. Step b) may further comprise the step of generating a first frequency offset using the first local oscillator circuit. Step c) may further comprise the step of generating a second frequency offset using a second local oscillator circuit. Step b) may further comprise the step of generating a first frequency offset using a first local oscillator circuit in combination with a common oscillator, and step c) may further comprise the step of generating a second frequency offset using a second local oscillator circuit in combination with a common oscillator. The method may further comprise the steps of: e) receiving at least one output signal from a third radio frequency link, the at least one output signal from the third radio frequency link comprising a base frequency; and f) transmitting at least one output signal from the third radio frequency link without applying a frequency offset.

In yet another aspect of the present invention, a method of transmitting information using a communication system including a multiple input/multiple output (MIMO) structure is provided. The architecture includes a first radio frequency link and a second radio frequency link. The method comprises the following steps: a) receiving a first offset transmission signal including a first frequency offset from the fundamental frequency, and a second offset transmission signal including a second frequency offset from the fundamental frequency; b) the first radio frequency link applying the first frequency offset to obtain a first signal at a controller fundamental frequency; and c) the second radio frequency link applies a second frequency offset to obtain a second signal at the fundamental frequency of the controller.

In yet another aspect, the present invention provides a method of transmitting information using a communication system including a multiple-input/multiple-output (MIMO) structure. The structure includes a first linked group including a first radio frequency link and a second radio frequency link, and a second linked group including a third radio frequency link and a fourth radio frequency link. The method comprises the following steps: a) receiving a first output signal from the first radio frequency link, a second output signal from the second radio frequency link, a third output signal from the third radio frequency link, and a fourth output signal from the fourth radio frequency link, each output signal including a fundamental frequency; b) applying a first frequency offset to the fundamental frequency of the first output signal to generate a first offset transmit signal; c) applying a first frequency offset to the fundamental frequency of the second output signal to generate a second offset transmit signal; d) applying a second frequency offset to the fundamental frequency of the third output signal to generate a third offset transmit signal; e) applying a second frequency offset to the fundamental frequency of the fourth output signal to generate a fourth offset transmit signal; and f) transmitting the first offset transmission signal, the second offset transmission signal, the third offset transmission signal and the fourth offset transmission signal, wherein the first and second transmission signals comprise a first transmission frequency and the third and fourth transmission signals comprise a second transmission frequency. Step f) may comprise transmitting the first offset transmit signal using a first antenna polarization and transmitting the second offset transmit signal using a second antenna polarization, wherein the first antenna polarization is different from the second antenna polarization. Step f) may further comprise transmitting the third offset transmit signal using a third antenna polarization and transmitting the fourth offset transmit signal using a fourth antenna polarization, wherein the third antenna polarization is different from the fourth antenna polarization. Steps b) and c) may each comprise the step of generating the first frequency offset using a first local oscillator circuit, and steps d) and e) may each comprise the step of generating the second frequency offset using a second local oscillator circuit.

In another aspect, the present invention provides a method of transmitting information using a communication system including a multiple input/multiple output (MIMO) structure. The structure comprises a plurality of radio frequency links, at least a first radio frequency link comprising a first transmit side filtering submodule and a second transmit side filtering submodule. The method comprises the following steps: a) receiving at least one output signal from the first radio frequency link, the at least one output signal comprising a base frequency; b) applying a first frequency offset to a fundamental frequency of the received output signal using the first transmit-side filtering submodule, thereby generating a first offset signal; c) applying a second frequency offset to the fundamental frequency of the received output signal using the second transmit-side filtering sub-module to generate a second offset signal; d) combining the first offset signal and the second offset signal into an offset transmit signal; and e) transmitting the offset transmission signal. Step b) may comprise the step of generating the first frequency offset using a first local oscillator circuit and step c) may comprise the step of generating the second frequency offset using a second local oscillator circuit. Step b) may comprise the step of using a first local oscillator circuit in combination with a common oscillator to generate the first frequency offset and step c) may comprise the step of using a second local oscillator circuit in combination with a common oscillator to generate the second frequency offset. Step a) may be performed using only one transmit antenna.

In yet another aspect, the present invention provides a method of transmitting information using a communication system that includes a multiple-input/multiple-output (MIMO) architecture that includes a first radio frequency link that includes a first receive-side filtering submodule and a second radio frequency link that includes a second receive-side filtering submodule. The method comprises the following steps: a) receiving a first offset transmission signal including a first frequency offset; b) receiving a second offset transmission signal including a second frequency offset; c) applying the first frequency offset to the received first offset transmit signal using the first receive-side filtering sub-module, thereby obtaining a first signal at a controller fundamental frequency; and d) applying the second frequency offset to the received second offset transmit signal using the second receive-side filtering submodule, thereby obtaining a second signal at the fundamental frequency of the controller. Step c) may comprise the step of generating the first frequency offset using a first local oscillator circuit and step d) may comprise the step of generating the second frequency offset using a second local oscillator circuit. Step c) may comprise the step of using a first local oscillator circuit in combination with a common oscillator to generate the first frequency offset and step d) may comprise the step of using a second local oscillator circuit in combination with a common oscillator to generate the second frequency offset. Step a) and step b) may be performed using only one receive antenna.

In yet another aspect, the present invention provides a communication system. The system includes a multiple-input/multiple-output (MIMO) structure including a plurality of radio frequency chains, at least two of the radio frequency chains applying a first frequency offset and a second frequency offset to a base frequency; and a controller system for selecting at least two transmission frequencies that minimize interference, the control system configured to determine the first frequency offset and the second frequency offset.

In yet another aspect, the present invention provides a method of transmitting information in a communication system comprising a multiple-input/multiple-output (MIMO) structure comprising a plurality of radio frequency chains, at least two of the radio frequency chains applying a first frequency offset and a second frequency offset to a base frequency. The method comprises the following steps: a) determining at least two transmission frequencies that minimize interference; and b) determining a first frequency offset and a second frequency offset to be applied to the fundamental frequency to provide at least two transmit frequencies.

Drawings

Fig. 1 is a schematic illustration of a portion of a communication network for wirelessly communicating information in accordance with one or more embodiments of the present invention.

Fig. 2 is a schematic diagram of the communication system of fig. 1 including a plurality of radio frequency chains applying independent frequency offsets to the base frequencies at the transmit side.

FIGS. 3a and 3b are schematic diagrams of filter circuits according to one or more embodiments of the invention;

fig. 4 is a schematic diagram of a communication system including a radio frequency link utilizing a base frequency at a transmit side and one or more radio frequency links applying independent frequency offsets to the base frequency at the transmit side in accordance with one or more embodiments of the present invention;

fig. 5 is a schematic diagram of a communication system including multiple single down-conversion or up-conversion radio frequency links applying independent frequency offsets to the base frequencies at the transmit side in accordance with one or more embodiments of the present invention;

fig. 6 is a schematic diagram of a communication system including a radio frequency link utilizing a base frequency at a transmit side and one or more single down-conversion or up-conversion radio frequency links applying independent frequency offsets to the base frequency at the transmit side in accordance with one or more embodiments of the present invention;

fig. 7 is a schematic diagram of a communication system including a plurality of linked radio frequency chains applying the same frequency offset to a base frequency at a transmit side in accordance with one or more embodiments of the present invention;

fig. 8 is a schematic diagram of a communication system including multiple radio frequency chains applying independent frequency offsets to base frequencies on a transmit side and combining transmit signals with a combiner in accordance with one or more embodiments of the invention;

fig. 9a is a schematic diagram of a communication system including a plurality of radio frequency chains configured to generate virtual antennas at a receiving side in accordance with one or more embodiments of the present invention;

FIG. 9b is a schematic diagram of another embodiment of the communication system of FIG. 9 a;

FIG. 9c is a schematic diagram of another embodiment of the communication system of FIG. 9 a;

FIG. 9d is a schematic diagram of a communication system in accordance with one or more embodiments of the present invention;

FIG. 10a is a schematic diagram of a ZIF circuit in accordance with one or more embodiments of the present invention;

FIG. 10b is a schematic diagram of the ZIF circuit of FIG. 10a in accordance with one or more embodiments of the present invention;

FIG. 10c is a schematic diagram of the RF link details of FIG. 10b in accordance with one or more embodiments of the present invention;

FIG. 10d is a schematic diagram of the RF link details of FIG. 10b in accordance with one or more embodiments of the present invention;

FIG. 10e is a schematic diagram of the ZIF circuit of FIG. 10a in accordance with one or more embodiments of the present invention;

FIG. 10f is a schematic illustration of the RF link details of FIG. 10e in accordance with one or more embodiments of the present invention;

FIG. 10g is a schematic diagram of the RF link details of FIG. 10e in accordance with one or more embodiments of the present invention;

FIG. 11 is a perspective view of a portion of a communication network in accordance with one or more embodiments of the present invention;

fig. 12 is a perspective view of a portion of the communication network of fig. 11 with a user communication device cooperating with the network.

Detailed Description

Fig. 1 shows a schematic diagram of a portion of a communication network for wirelessly communicating information in accordance with one or more embodiments of the invention. Fig. 2 is a schematic diagram of the communication system of fig. 1 including a plurality of radio frequency chains applying independent frequency offsets to the base frequencies at the transmit side.

The communication network 20 includes one or more communication systems 100, shown generally as system 100a and system 100b, in wireless communication with each other. However, the present invention is not particularly limited to wireless communication, but may also include any other communication methods and means now known or yet to be developed.

Each system 100 (e.g., systems 100a, 100b) may be part of a communication device, automation device, etc., disposed in a receiver, transmitter, transceiving circuitry or device, etc. For example, the system 100, i.e., the system 100a, may be integrated in a cellular phone (i.e., mobile phone) and the system 100b may be integrated in a base station. Thus, the systems 100 (i.e., 100a, 100b) are each capable of transmitting and receiving signals, as further taught herein.

System 100 is preferably configured to operate using a multiple-input/multiple-output architecture ("MIMO" or "MIMO system") to efficiently transmit data to another similar or compatible system and within network 20 or any other associated or suitable network. Communication may be effected in accordance with any suitable communication protocol known or yet to be developed. Thus, network 20 and/or system 100 may communicate using frequencies and protocols for any IEEE 802.11 protocol or standard, including but not limited to 802.11a, 802.11b, 802.11g, and/or 802.11n for use as a Wireless Local Area network ("WLAN"); 802.16d Worldwide Interoperability for Microwave Access ("WiMAX"), 802.16e WiMAX; 4G; wireless devices based on the third Generation Partnership Project ("3 GPP") or third Generation Partnership Project 2 ("3 GPP 2") standards, or any other system or protocol.

As shown in fig. 1 for simplicity, a first system 100 (e.g., system 100a) transmits multiple data streams over one or more transmit antennas in a channel 104 within an associated network 20 to one or more receive antennas of a suitable receiving system, such as a second system 100 (e.g., system 100 b). Thus, for simplicity, some figures depict only one system 100 to show both the transmit side and the receive side of the system 100.

However, channel 104 includes a plurality of radio frequency signals 102 (i.e., data streams) that one system 100 transmits to and/or receives from an appropriate communication system in a channel matrix H defined in Equation (Equation) 1. The channel 104 may include a bandwidth suitable for 802.16d and/or 802.16e protocols. Thus, channel 104 may have a bandwidth of 1.25MHz, 2.5MHz, 5MHz, 7.5MHz, 10MHz, and/or 20 MHz. The channel 104 may include a bandwidth suitable for the 802.11n protocol. Thus, the channel 104 may have a bandwidth of 5MHz, 10MHz, 20MHz, and/or 40 MHz. However, the bandwidth of the channel 104 is not limited to the foregoing and may include any suitable bandwidth.

The system 100 preferably includes a MIMO architecture, such as a chipset, the system 100 including a baseband media access controller 106, zero intermediate frequency communication circuitry ("ZIF circuitry") 108, and a plurality of receive and/or transmit radio frequency links 110 cooperating with one or more receive and/or transmit antennas 118. Readily available off-the-shelf components may be used in the system 100 for economic reasons and the ability to customize the solution for a particular user.

The MIMO architecture is defined by the number of transmitter-side and receiver-side radio frequency links that may connect one system 100 to another suitable system, such as the second system 100. Thus, a MIMO system having N transmitters and M receivers is an nxm MIMO system.

The baseband mac 106 may be any suitable controller that controls the access network 20, including at least one network-specific identifier. The baseband mac 106 communicates with and may be integrated with the ZIF circuit 108. Preferably, however, the baseband circuitry 106 is configured to be stand alone.

The ZIF circuit 108 may be configured as known in the art, however preferably includes circuitry that includes one or more embodiments and/or is compatible with one or more embodiments of the systems and methods described in U.S. serial No.11/399,536 filed on 7/4/2006, which is hereby incorporated by reference in its entirety for all purposes.

Either or both of the baseband media access controller 106 or the ZIF circuit 108 may be part of and/or associated with other devices, such as sets of digital signal processor elements known in the art with respect to high performance MIMO chipsets that provide greater processing power than off-the-shelf MIMO chipsets.

In accordance with one or more embodiments of the present invention, a controller of system 100 may provide and terminate data to be transmitted and may be configured to provide a single integrated function, including control of all functions of system 100.

The ZIF circuit 108 communicates with a plurality of radio frequency links 110 through one or more physical layer outputs and inputs 109, such that the ZIF circuit 108 may be used in applications of the industry standard 802.11 n. The example embodiments of fig. 1 and 2 show three links 110, however, any suitable number of at least two links may be used.

Preferably, to operate under the 802.11n protocol, the system 100 includes three links 110, and when used in a network operating under the 802.16d or 802.16e protocol, the system 100 includes four links 110. Each link 110 (i.e., link 110a, link 110b, and link 110c) preferably includes a filtering module 112, transmitter circuitry 114 for transmitting signals 102 over channel 104, and/or receiver circuitry 116 for receiving signals 102 over channel 104 (depending on whether system 100 is configured for transmit only, receive only, or both), and a switch 140 for switching between transmit and receive modes. Preferably, the link 110 is configured to have a transmit side and a receive side, making the link available for receiving and transmitting.

Although the system 100 is illustrated as a Time Division Duplexing ("TDD") system for a preferred operating device in a network operating according to the 802.11n protocol, those skilled in the art will recognize that the system 100 of the present invention may be readily configured as a Frequency Division Duplexing ("FDD") system for use in connection with networks operating under the WiMAX protocol. For example, those skilled in the art will recognize that the addition of one or more duplexers will allow system 100 to operate as an FDD system.

On the transmit side, each link 110 is preferably configured to receive a common output signal having a predetermined frequency from the physical layer of the MIMO structure, such as physical layer output 109. Each link 110 down-converts the signal and applies an independent adjustment to the frequency, i.e., applies a frequency offset, to generate and transmit a signal 102 that includes a frequency that includes an offset from the frequency of the ordinary output signal. Preferably, the transmission frequency of each link is different from at least one other transmission frequency from at least one other link.

On the receive side, each of the at least one links 110 is configured to receive a signal 102 containing a frequency with a frequency offset and upconvert the signal to a frequency usable by a controller (e.g., ZIF circuit 108) and then pass the signal to a physical layer (e.g., physical layer input 109) of the MIMO architecture. For example, the frequency after up-conversion may be the same as or different from the frequency of the ordinary output signal. However, for clarity, it is assumed that the frequency of the up-converted signal is the frequency of the ordinary output signal, i.e. the ordinary fundamental frequency.

The filtering module 112 may comprise any suitable filtering module, but preferably comprises a filtering module 112a, a filtering moduleBlock 112a includes a double conversion filtering process. Each filtering module 112a preferably includes a first mixer circuit 130 in communication with the output signal 200 of the ZIF circuit 108 through a physical layer output 109. The output signal 200 comprises a common fundamental frequency f₀Wherein the various receivers and transmitters of the system 100 are operable.

According to one or more embodiments of the invention, the output signal 200 may correspond to a frequency output of a ZIF circuit. Thus, for each link, at the same frequency, at the fundamental frequency (i.e., the first frequency f)₀) Provides respective output signals 200. However, the output signal 200 may also be or be associated with a baseband frequency generated by a baseband circuit and/or an intermediate frequency generated by an intermediate frequency output circuit.

Preferably, the fundamental frequency f₀May be any suitable frequency that may be used to transmit signals in the network 20. Thus, if the network 20 is a network using the protocol 802.11n, the first frequency f₀May be in the 2.4GHz band. Is higher than the first frequency f₀Low intermediate frequency f_IFAnd may be any suitable frequency that may be filtered. For example, if the first frequency f₀2.4GHz, the intermediate frequency f_IFMay be f₀-810 MHz-1.59 GHz, however intermediate frequency f_IFMay be at a frequency f greater than the first frequency₀Suitably low, any suitable frequency. Thus, advantageously, the bandwidth is effectively extended and a larger data transmission is ensured.

The first mixer circuit of each chain preferably takes the signal 200 from a common fundamental frequency f₀Down conversion to an intermediate frequency f_IFTo generate a second signal 202. Each intermediate frequency f_IFMay be different from any other intermediate frequency in the same link and/or system.

The first filter circuit 132 is in communication with the output of the first mixer circuit and filters the down-converted signal 202 into a filtered down-converted signal 204. The filter circuit 132 may include any suitable filter circuit or device capable of filtering noise, distortion, and other spurious phenomena from a signal, such as the down-converted signal 202 at any suitable frequency, and the filter circuit 132 may also include a SAW (surface acoustic wave) filter or other suitable filter, such as a hamming filter, a brick wall filter, a ceramic filter, and the like. The filter circuit 132 may also include a SAW filter switch bank 170 as further described herein.

The filtering module 112a preferably includes a second mixer circuit 134 in communication with the output of the first filter circuit 132. The second mixer circuit 134 is preferably configured to up-convert the filtered down-converted transmission signal 204 to a third frequency f₁I.e., the transmit frequency, to generate a filtered transmit signal 206. Filtered transmitted signal 206 includes transmitted signal 200 with noise, distortion, and other spurious signals removed or substantially reduced.

The first mixer circuit 130 and the second mixer circuit 134 provide a double conversion by shifting the first frequency f₀To convert the transmission signal 200 to an intermediate frequency f_IFTo filter and then to convert the intermediate frequency f_IFThe resulting filtered signal at is converted to a third, higher transmission frequency f₁To transmit. In this way the fundamental frequency is adjusted (independently of the adjustment of the other link), i.e. a frequency offset is applied to generate the signal for transmission. The signal comprises a frequency that includes an offset from the frequency of the ordinary output signal.

Here, the first frequency f₀And a third frequency f₁May be substantially the same (but preferably different), although the third frequency f₁May be greater than the intermediate frequency f_IFHigh and the first frequency f₀Any suitable frequencies, the same or different. At frequency f₀And frequency f₁The frequency difference between includes a frequency offset.

First frequency f₀And a third frequency f₁Depends on factors such as the nature and type of transmission scheme and protocol used, the transmission characteristics of the ZIF communication circuit 108 or other similar transmitter, receiver, transceiver or communication circuit/device used, and othersSimilar factors.

The filtered transmit signal 206 may be transmitted using the transmitter circuit 114 or any suitable transmitter or communication circuit or device. The output of the second mixer circuit 134 is preferably in communication with the transmitter circuit 114.

The transmitter circuit 114 may be configured to transmit the filtered transmit signal 206. Preferably, the transmitter circuit 114 includes a suitable band pass filter 136 that receives and appropriately filters the filtered transmit signal 206.

For example, for a WiFi signal, the band pass filter 136 may be used to filter or limit the frequency width of the filtered transmit signal 206 to a WiFi frequency band so as not to interfere with other signals. The resulting power level of the bandpass filtered signal is suitably amplified or boosted by a power amplifier 138 or other suitable power amplifier in communication with the bandpass filter 136.

Preferably, as a result of passing through the filtering module 112, the filtered transmit signal 206 is cleaner because, for example, it has a clean spectrum with little or no noise or distortion, so the power level of the signal can be raised to a higher level to increase the transmit power without the concomitant increase in noise and other spurious signals.

The amplified signal 206 from the power amplifier 138 may be passed to the transmitter/receiver diversity switch 140 for transmission through the physical antenna 118 using a suitable wireless transmission protocol, but the amplified signal may alternatively be transmitted over a suitable wired connection using a suitable wired protocol or standard. The transmitter circuitry 114 and accompanying transmit components may include other and/or alternative elements necessary to transmit wireless or wired signals, depending on, for example, the type of signal being transmitted, the communication medium and protocol, and other like factors.

The transmitter/receiver diversity switch 140 may alternatively include an operative connection with isolated receive and transmit antennas.

System 100 may be configured to receive wireless signal 102 through a receive antenna, which may be the same as or different from antenna 118. Signals received through the receive antennas are passed through a transmitter/receiver diversity switch 140 to the receiver circuitry 116.

The receiver circuit 116 is configured to receive signals for the system 100 and may include a suitable band pass filter 144 for receiving and appropriately filtering the received signals. For example, for WiFi signals, a band pass filter 144 may be used to filter or limit the frequency width of the received signal to the WiFi frequency band to remove out-of-band noise or other interfering signals.

The resulting bandpass filtered signal is suitably amplified by a suitable low noise amplifier 144 in communication with the bandpass filter 142. Receiver circuit 116 and accompanying receiver components may include other and/or alternative elements necessary to receive wireless or wired signals, depending on, for example, the type of signal received, the communication medium and protocol, and other like factors. The output of the receiver circuit 116 is a received signal 208. Since signal 208 (e.g., signal 102) is received from a similar system, the frequency of signal 208 is preferably the same as the transmitted signal, e.g., the frequency of signal 208 comprises the transmission frequency f₁。

The filtering module 112a includes a third mixer circuit 146, the third mixer circuit 146 having an input in communication with the output of the receiver circuit 116. Preferably, the third mixer circuit 146 is configured to be at the frequency f₁A received signal 208 is received. The third mixer circuit 146 may be configured to convert the frequency f₁Down-converting the received signal 208 to an intermediate frequency f_IFTo generate a down-converted received signal 210.

The filtering module 112a preferably includes a second filter circuit 148 in communication with the output of the third mixer circuit 146. The second filter circuit 148 is configured to filter the down-converted received signal 210 to generate an intermediate frequency f_IFFiltered down-converted received signal 212, intermediate frequency f_IFMay be intermediate to any other intermediate frequency in the same or different link or system 100Frequency.

The second filter circuit 148 may include a filter capable of filtering the intermediate frequency f_IFThe down-converted received signal 210 may be any suitable type of filter circuit or device that performs filtering of noise, distortion, and other spurious signals. The second filter circuit 148 may be configured substantially similarly to the first filter circuit 132.

The filtering module 112a preferably includes a fourth mixer circuit 150 in communication with the output of the second filter circuit 148. The fourth mixer circuit 150 is preferably configured to up-convert the filtered down-converted received signal 212 to the fundamental frequency f₀To generate filtered received signal 214. A ZIF circuit 108 or other similar transmitter, receiver, transceiver, or communication circuit/device communicates with the output of the fourth mixer circuit 150 through a physical layer input 109.

Filtered received signal 214 includes received signal 208 with noise, distortion, and other spurious signals removed or substantially reduced. The third mixer circuit 146 and the fourth mixer circuit 150 provide for the reception of the signal 208 from the transmission frequency f₁To a lower intermediate frequency f_IFTo filter and then convert the resulting filtered signal to a higher fundamental frequency f₀To be double converted for reception by the ZIF circuit 108. In this manner, the frequency offset is reversed to generate a signal comprising the frequency of the common output signal for use by the controller.

The filtering module 112 includes one or more local oscillator circuits 152 in communication with the first, second, third and fourth mixer circuits 130, 134, 146 and 150 to control the mixing frequencies of the plurality of mixer circuits.

However, the local oscillator circuit 152 may use any suitable frequency control signal or the like to control the mixing frequency of each or any combination of the first, second, third, and fourth mixer circuits 130, 134, 146, 150. Oscillator circuit 152 may include any suitable type of RF oscillator circuit or the like, including a suitable Phase Locked Loop ("PLL") oscillator circuit or the like. Where all local oscillators are associated with a common frequency controller 111 (i.e. a clock) to control the respective mixing frequencies.

Link 110b and link 110c are similarly configured by varying the oscillation to produce a transmit frequency f₂And f₃. In this way, the fundamental frequency is adjusted independently of the adjustment of the other link, i.e. a frequency offset is applied, to produce a signal having the respective frequency f₂And f₃For the transmitted signal. Wherein, the frequency f₀And frequency f₂Or f₃The frequency difference between includes a frequency offset. Similarly, links 110b and 110c are configured to receive frequency f₂And f₃And frequency-shifted in reverse to generate a fundamental frequency f comprising the common output signal₀For use by the controller.

Modifications and variations to the filtering module 112, the transmitting module 114, and/or the receiving module 116 may be made by those skilled in the art to improve gain, achieve particular filtering, and/or any other suitable purpose, which are contemplated by the present invention.

According to one embodiment of the invention, one oscillator circuit 152 (but not the other), i.e., the master oscillator circuit, may include or be associated with a frequency controller 111 (i.e., a clock) to control the respective mixing frequencies. The frequency controller 111 may be disposed in any one of the oscillator circuits 152, but not the other oscillator circuits, or an oscillator circuit in addition thereto may be associated with the ZIF circuit 108.

Each local oscillator may be configured to include a different oscillation frequency when cooperating with a respective link in system 100. In the exemplary embodiment of fig. 1 and 2, one link 110 generates the transmission frequency f₁The second link 110 may generate a third frequency f₂The link 110 may generate a third frequency f₃. Wherein each frequency f₁、f₂And f₃From fundamental frequency f₀Offset and the frequencies are different from each other.

Thus, for the example embodiments of fig. 1 and 2, a 3x 3MIMO system includes RF chains for adjusting the frequency of the signal 102 in the channel 104, respectively. The matrix of channels 104 is shown in equation 2 or more specifically in equation 3, where the superscript represents the shifted frequency.

(equation 2)

(equation 3)

Wherein the matrix coefficients are represented as h_TRWhere T is the transmit module on each link and R is the receive module on each link and is represented by a number. It should be understood that if the number of links present is n, the matrix may be adjusted appropriately.

Thus, h₂₂Including transmissions from one RF link 110 of the system 100 and received by a second RF link 110 of a second system 100. Preferably, the frequencies are chosen such that the cross product of one transmit chain with another receive chain having a different offset frequency is almost due to frequency independenceAnd (4) zero. For example, the frequency offset may be up to 60 Hz.

Preferably, the selected frequency is located in an adjacent channel, a second adjacent channel or other channel of a similar arrangement. Many modulation techniques used for MIMO systems involve high levels of out-of-band transmission that fall in adjacent and next adjacent channels. This transmission produces a high level of co-channel interference, as shown in the exemplary embodiment of fig. 2, from frequency f₀To f₁From f₁To f₀The use of these channels preferably includes a filtering module 112.

For channels that are not adjacent or next adjacent, no additional filtering is required. In this way, signal 206 may be generated without using downconversion or upconversion filtering to a new frequency in each link. Unlike the "integrated wireless transceiver" of U.S. serial No. 11/158,728, which is disclosed in U.S. patent Publication No. 2006/0292996, 28, p.a. pat Publication, 2006, which is incorporated herein by reference for all purposes, the present solution provides greater flexibility.

Alternatively, a frequency offset may also be generated using a baseband input with a double heterodyne structure, so that the resulting frequencies are different. As will be appreciated by those skilled in the art, standard high frequency wireless designs, which are typically high power high performance wireless designs, exhibit greater flexibility in application to several links.

The frequencies may be located in the same or different frequency bands, which may be licensed or unlicensed. In the unlicensed industrial, scientific, and medical ("ISM") radio band, system 100 may include additional controls for handling functions such as Dynamic Frequency Selection ("DFS"), and radar detection. For example, each receiver side of the filtering module 112 may include a means to detect radar pulses to meet FCC or international regulations for DFS. Preferably, these controls are configured to detect radar pulses on unlicensed band frequencies and to dynamically change channels when needed. In contrast, a standard MIMO system that does not contain a frequency offset includes only a single radar detector, since all MIMO operations are performed at a common frequency.

Further flexibility in the system 100 may be provided by selectively operating the local oscillator circuit 152 of the link when a common oscillator circuit is operatively connected to one or more other local oscillator circuits, in accordance with one or more embodiments of the present invention. Using switch 149, the local oscillator circuit can be bypassed and replaced by a normal oscillator circuit, thus generating the same frequency. Advantageously, system 100 can switch from a MIMO system to a standard system, if necessary.

In accordance with one or more embodiments of the invention, antenna 118 may include two separate antennas, a first antenna including inputs for vertical and horizontal polarization, and a second antenna including a single or two inputs. Wherein one frequency, frequency f₁Connected to the first antenna, the second and the third frequency, e.g. frequency f₂And frequency f₃Connected to a second antenna, in which the polarization may coincide with or be reversed with that of at least one of the receiving chains, and in which a third frequency, e.g. frequency f₃In accordance with the polarization of at least one other of the receive chains.

The antenna 118 may comprise two separate antennas with separate inputs for vertical and horizontal polarization, each with an input for circular polarization, used in the manner described above, each with an input for ordinary polarization to allow one frequency (frequency f) on the second antenna₁) Beam control of (2), and a second frequency (frequency f)₂) Non-beam steering. The antenna 118 may also comprise a common antenna with three inputs and common polarization to allow beam steering of one frequency but not the other.

Advantageously, the system 100 configured as a 3x 3MIMO system implements bandwidth expansion by a factor of 2, so that the guaranteed bandwidth is achieved for the link, roughly equivalent to the bandwidth of two 2x 2MIMO systems with a 1 x 1 single input/single output system.

Fig. 3a and 3b are schematic diagrams of filter circuits according to one or more embodiments of the invention. Filter circuit 132 and/or filter circuit 148 may include a SAW filter switch bank 170 to improve the link budget of system 100 caused by the applied frequency offset. The switch bank 170a may include a first SAW filter 172a and a second SAW filter 172b disposed parallel to each other. The plurality of switches 175 allow selection of one or the other of the filters 172 by routing signals to or from common inputs or outputs, respectively. Similarly, the switch group 170b may include first and second SAW filters 173a and 173b connected in parallel with each other, and third and fourth SAW filters 174a and 174b connected in parallel with each other. A plurality of switches 175 allow selection of one or the other filters 173 or 174 by routing signals to or from common inputs or outputs, respectively.

For example, channel 104 may be a 20MHz standard MIMO channel, containing typical thermal noise floor of-174 dBm/Hz or-101 dBm. Assuming that the MIMO streams will not self-interfere, using two MIMO streams with spatial diversity, the link budget, e.g., the sum of all gains and losses from the transmitter to the receiver, will be the same. The noise bandwidth will remain at 20MHz or-101 dBm.

With a single 40MHz channel, the throughput would be equal to the dual MIMO throughput for the 20MHz channel, however, there would be a 3dB loss in link budget because the wide noise floor of 40MHz would be at-98 dBm. Using two independent 20MHz channels, and a SAW filter circuit, the noise floor per MIMO stream will be at-101 dBm, ensuring that the link budget remains equal to a single 20MHz channel, but the noise floor uses a 40MHz spectrum.

Fig. 4 is a schematic diagram of a communication system including a radio frequency link utilizing a fundamental frequency at a transmit side and one or more radio frequency links applying independent frequency offsets to the fundamental frequency at the transmit side in accordance with one or more embodiments of the invention. System 100c is preferably configured to operate using a MIMO architecture to efficiently transmit data between another system 100c and/or other compatible and/or suitably configured systems. As such, system 100c may work in conjunction with other systems 100, such as systems 100a and/or 100b described herein, and include substantially similar structures as these systems. Accordingly, the description of system 100, i.e., 100a and/or 100b, is repeated herein. However, the system 100c is varied in certain respects.

Advantageously, the system 100c provides a cost-effective solution by simplifying the structure and reducing the number of components. The system 100c allows for independent adjustment of the frequency of one or more links while the frequency of one link is associated with the ZIF circuit. In a network employing the 802.11 protocol that uses three links, at least two of the links are independently adjusted to achieve the desired offset frequency, while the frequency of one link is substantially the same as the frequency of the output signal of the ZIF circuit 108. Thus, the system 100c does not have the link 110a including the filtering module 112, but includes a link 110d, the link 110d including a transmitting module 114 and a receiving module 116 in direct communication with the ZIF circuit 108, and a switch 140.

As disclosed, the ZIF circuit 108 generates the normal output signal 200 at a frequency sufficient for transmission. Thus, the first frequency f₀Can be matched with a third frequency f₁Equal and after suitable amplification may be transmitted as signal 102. Similarly, when received, the frequency f is matched by the receiving module 116₁The signal 102 at clears spurious emissions and passes it as signal 214 to the physical layer input 109 of the ZIF circuit 108. Accordingly, for the exemplary embodiment shown in fig. 4, the exemplary MIMO system is a 3x 3 system, where the matrix of the channel 104 is the same as equations 2 and 3. To prevent undesirable signal delays between link 110d and links 110b and 110c (i.e., the filtered links), ZIF circuit 108 preferably outputs signal 200 to link 100d in an appropriate amount so that signal 102 is regularly timed.

According to one embodiment of the invention, system 100c is configured such that one of local oscillator circuits 152 is a master oscillator circuit that allows link 110b and link 110c to output the same frequency when an appropriate switch 149 allows the master oscillator to effectively control the filtering modules of the other links. According to one embodiment of the invention, the link 110d may be omitted and the ZIF circuit 108 is in direct communication with the switch 140.

Fig. 5 is a schematic diagram of a communication system including a plurality of individual down-converted or up-converted radio frequency chains applying independent frequency offsets to the base frequencies at the transmit side in accordance with one or more embodiments of the present invention. System 100d is preferably configured to operate using a MIMO architecture to efficiently transmit data between another system 100d and/or other compatible and/or suitably configured systems. As such, system 100d may work in conjunction with other systems 100 (e.g., systems 100a and/or 100b), including substantially similar structures. Thus, the description of the system 100, i.e., 100a and/or 100b, is repeated herein. However, the system 100d is varied in certain respects.

Advantageously, the system 100d provides a simplified structure with a reduced number of components, a cost-effective solution. System 100d allows independent adjustment of the transmit frequency of one or more RF chains 110 with a single down-conversion or up-conversion. In a network using three links applying the 802.11 protocol, each link can be independently adjusted to obtain the desired channel matrix.

System 100d includes a plurality of links 110. Fig. 5 shows three links 110e, 110f and 110g used in the network 20 applying the 802.11 protocol. Of course, any suitable number of links may be used. Each of links 110 e-110 g is configured substantially similar to links 110 a-110 c. However, one or more of the links 110 e-110 f do not include a respective filtering module 112 with dual conversion, filtering module 112a, but instead include a respective filtering module 112, filtering module 112 e. For example, the filtering module 112e includes a mixer circuit 130 at the transmitting side, i.e., a mixer circuit 130e that down-converts the output signal 200 from the ZIF circuit 108.

As described herein, preferably at the normal frequency (i.e., the first frequency f)₀) Provides an output signal 200. The mixer circuit 130e converts the first frequency f₀Down-conversion to a suitable transmission frequency f₁And passes the signal 206 to the appropriate transmitter circuitry 114 to transmit the frequency via the antenna 118f₁The signal 102 is transmitted to and received by an effectively compatible system 100.

Each filtering module 112e further comprises a receiver-side mixer circuit 150, i.e. a mixer circuit 150e that upconverts the signal 208. As discussed herein, frequency f is received from effectively compatible system 100 via antenna 118₁And passes it to receiver circuitry 116. Receiver circuit 116 cleans signal 102 and passes cleaned signal 208 to mixer circuit 150e for up-conversion to first frequency f₀. The mixer circuit, in turn, passes the signal 214 to the ZIF circuit 108. The filtering module further includes a local oscillator circuit 152e that provides appropriate frequency control signals to the local mixer circuit 130e and the local mixer circuit 150 e. The filtering module 110f and the filtering module 110g are preferably similarly configured to operate at respective frequencies f₂And f₃Outputs a signal 102 and receives the same frequency. Accordingly, for the example embodiment shown in fig. 5, channel 104 is the same as that of equations 2 and 3. Accordingly, for the exemplary embodiment shown in fig. 5, the exemplary MIMO system is a 3x 3 system, where the matrix of the channel 104 is the same as equations 2 and 3.

According to one embodiment of the invention, system 100d is configured such that one of local oscillator circuits 152e is a master oscillator circuit that allows one or more of links 110f and links 110g to output the same frequency when a suitable switch (e.g., switch 149) allows the master oscillator to effectively control the filtering modules of the other links. Those skilled in the art will recognize that other means for frequency shifting and/or frequency shifting circuits may be employed and are contemplated within the scope of the present invention.

Fig. 6 is a schematic diagram of a communication system including a radio frequency link utilizing a base frequency at a transmit side and one or more individual down-converted or up-converted radio frequency links applying independent frequency offsets to the base frequency at the transmit side in accordance with one or more embodiments of the present invention. System 100e is preferably configured to operate using a MIMO architecture to efficiently transmit data between another system 100e and/or another compatible and/or suitably configured system. As such, system 100e may work in conjunction with other systems 100, such as system 100a, system 100b, system 100c, and/or system 100d, and include substantially similar structures. As such, the description of system 100, i.e., system 100a, system 100b, system 100c, and/or system 100d, is repeated herein. However, the system 100e is varied in certain respects.

Advantageously, the system 100e provides a simplified structure with a reduced number of components, a cost-effective solution. System 100d allows independent adjustment of the frequency of one or more RF chains 110 with a single down-conversion or up-conversion. In a network employing the 802.11 protocol that uses three links, at least two of the links may be independently adjusted to achieve the desired offset frequency, while the frequency of one link is substantially the same as the frequency of the output signal of the ZIF circuit 108.

System 100e includes a plurality of links 110. Fig. 6 shows three links 110h, 110i and 110j used in the network 20 operating in the 802.11 protocol. Of course, any suitable number of links may be used. The system 100e includes a link 110h configured substantially identical to the link 110d, wherein the link includes a transmit module 114 and a receive module 116 in direct communication with the ZIF circuit 108, and a switch 140 as described herein.

As disclosed, the ZIF circuit 108 generates a common output signal 200 at a frequency sufficient for transmission. Thus, the first frequency f₀Is equal to the third frequency f₁The signal may be transmitted as signal 102 after suitable amplification. Similarly, when received, the frequency f₁The signal 102 may be passed directly to the ZIF circuit 108 through the receive module 116. Links 110i and 110j may be configured substantially similar to one or more of links 110 e-links 110 g. However, the output signal from the ZIF circuit 108 to be down-converted is at the frequency f₁Here, i.e., the transmission frequency of link 110 h; the input signal to the ZIF circuit 108 is up-converted to frequency f₁. Thus, for the exemplary embodiment shown in fig. 6, the exemplary MIMO system is a 3x 3 system, where the matrix of the channel 104 is the same as equations 2 and 3. To prevent undesirable signal delays between link 110h and links 110i and 110j, ZIF circuit 108 preferably outputs signal 200 to link 100d in an appropriate amount so that signal 102 is regularly timed.

According to one embodiment of the invention, system 100d is configured such that one local oscillator circuit is a master oscillator circuit that allows all links to output the same frequency when appropriate switches place the master oscillator as a filtering module that is effective to control the other links. According to one embodiment of the invention, the link 100h may be omitted and the ZIF circuit 108 in direct communication with the switch 140.

Fig. 7 is a schematic diagram of a communication system including a plurality of radio frequency chains linked together that apply the same frequency offset to a base frequency on a transmit side in accordance with one or more embodiments of the present invention. System 100f is preferably configured to operate using a MIMO architecture for efficient data transfer between another system 100f and/or other compatible and/or suitably configured systems. Thus, the system 100f may work in conjunction with other systems 100 and include substantially similar structures. Thus, the description of system 100, i.e., system 100a, system 100b, system 100c, system 100d, and/or system 100e, is repeated herein. However, the system 100f is varied in certain respects.

Advantageously, the system 100f provides a robust structure. The system 100f allows independent adjustment of the frequencies of the RF links 110 linked together in a chain of multiple down-conversions or up-conversions. System 100e includes a plurality of links 110. Fig. 7 shows four links 110k, 110l, 110m and 110n operating in the network 20 and configuring a 2x 2MIMO system. Of course, any suitable number of links may be used. Each link in system 100e may be configured substantially similar to links 110 a-c. Unlike these links, however, two or more links in system 100e may be linked together to form group 119 using common oscillator circuits in the linked links. For example, the local oscillator circuit in link 110l may be inactive or omitted, and the local oscillator circuit 152k of link 110k may cooperate with link 110l to operate in link group 119 a. Similarly, links 110m and 110n may be linked in link group 119 b.

Thus, each set of linked links generates a common transmit frequency. In the example embodiment of FIG. 7, link 110k and link 110l generate frequency f₁Link 110m and link 110n generate frequency f₂. Thus, for the example embodiment of fig. 7, the matrix of channels 104 is shown in equation 4 or more clearly in equation 5, where the superscript represents the transmit frequency.

(equation 4)

(equation 5)

Wherein the matrix coefficients are represented as h_TRWhere T is the transmit module on each link and R is the receive module on each link, i.e., "1" for link 110k, "2" for link 110l, "3" for link 110m, and "4" for link 110 n. It should be understood that if the number of links present is n, the matrix may be adjusted appropriately.

In accordance with one or more embodiments of the present invention, in each linked group, the antennas associated with the links that are elements of the linked group may preferably be adjusted for polarization. In the example embodiment of fig. 7, antennas 118k and 118l are associated with linked-up link 110k and link 110l, respectively. Where antennas 118k and 118l include a polarization that is orthogonal to the other polarization to advantageously improve signal propagation.

Antennas 118, e.g., antennas 118k and/or 118l, may include a single antenna with independent inputs for vertical and horizontal polarization, a single antenna with independent inputs for dual tilt diversity, a single antenna with independent inputs for circular polarization, and/or a single antenna with independent inputs for normal polarization. Preferably, for each linked-up link, each transmitter side of the link is operatively connected to a dual-input, polarization diversity antenna, such that one link corresponds to one polarization and the second link corresponds to a second polarization.

On the receiver side, a similar antenna arrangement is made. Wherein for each linked-up link, each receiver side of the link is operatively connected to a dual-input, polarization diversity antenna such that one link corresponds to one polarization and the second link corresponds to a second polarization. Advantageously, the channel bandwidth is extended by a factor of 2 while the known antenna polarization techniques are reapplied to obtain a guaranteed bandwidth that is typically twice that of a 2x 2MIMO system.

According to one or more embodiments of the invention, antenna 118 may be configured as two independent antennas, where each antenna includes inputs for vertical and horizontal polarization, dual tilt polarization, circular polarization, and/or for ordinary polarization, to allow for one frequency, e.g., frequency f, on the first antenna₁And another frequency on the second antenna, e.g. frequency f₂Beam steering of (2).

According to one embodiment of the invention, antenna 118 may also be a common antenna including four inputs and common polarization to allow for a frequency, e.g., frequency f, on the first antenna₁And another frequency on the second antenna, e.g. frequency f₂Beam steering of (2).

Fig. 8 is a schematic diagram of a communication system including multiple radio frequency chains applying independent frequency offsets to the base frequencies on the transmit side and combining the transmit signals with a combiner in accordance with one or more embodiments of the present invention. System 100g is preferably configured to operate using a MIMO architecture for efficient data transfer between another system 100g and/or other compatible and/or suitably configured systems. Thus, system 100g may work in conjunction with other systems 100 and include substantially similar structures. Thus, the description of the system 100, i.e., 100a, 100b, 100c, 100d, and/or 100e, is repeated herein. Thus, system 100 may work in conjunction with other systems 100, such as systems 100a-100 f. However, the system 100g has variations in certain aspects.

Advantageously, system 100g provides a structure that limits the number of physical antennas. System 100g is operable to allow independent adjustment of the frequency of RF link 310 with multiple outputs and inputs. The system 100g includes a baseband media access controller 106, a ZIF circuit 108, and a plurality of receive and/or transmit chains 310 operating in conjunction with one or more receive and/or transmit antennas 118. Fig. 8 shows two links. Of course, any suitable number of links may be used.

Each link 310, i.e. links 310a and 310b, preferably comprises a filtering module 312, the filtering module 312 comprising a filtering submodule 311 on the transmitter side and a filtering submodule 313 on the receiver side; transmitter circuitry 114 for transmitting signals 102 over channel 104 and/or receiver circuitry 116 for receiving signals 102 over channel 104, depending on whether system 100g is configured for transmit only, receive only, or both, also includes a switch 140 for switching between transmit and receive modes.

On the transmit side, at least one link 310 is configured to down-convert the common output signal to a frequency different from at least one other frequency in the transmit signal 102, such as applying a frequency offset to one transmit data stream, as described herein. On the receive side, each at least one link 310 is configured to up-convert the frequency offset signal to a common frequency. Thus, the bandwidth is effectively extended and larger data transmission is ensured.

Each transmitter-side filtering submodule 311 preferably includes a plurality of initial mixer circuits 330, a plurality of filter circuits 332, a second mixer circuit 334 in communication with a respective local oscillator circuit 352x or 352y, and a combiner 353. Each mixer circuit 330 may be substantially the same as mixer circuit 130 described herein; filter circuit 332 may be substantially identical to filter circuit 132, and oscillator circuit 352 may be substantially identical to oscillator circuit 152; or each may be configured as any suitable component of the type known in the art.

As described herein, each mixer circuit 330 communicates with the output signal 200 of the ZIF circuit 108 through the physical layer 109. The output signal including a common first frequency f₀Wherein various receivers and transmitters of the system 100 may be operated. Preferably, each mixer circuit 330 of each chain will receive the first frequency f from the ZIF circuit 108₀Down-converting the signal 200 to an intermediate frequency f_IFI.e. the second frequency f_IFTo generate a second signal 202. InIntermediate frequency f_IFAs opposed to the same link, sub-module, and/or any other intermediate frequency in the system. Preferably, each initial mixer circuit 330 communicates with a respective filter circuit 332 via an output, the respective filter circuit 332 being substantially identical to the filter circuit 132. The filter circuit 332 filters the down-converted signal 202 into a filtered down-converted signal 204 that is received by the second mixer circuit 334.

Preferably, the system 100g includes a common oscillator circuit 351 in operative communication with a plurality of initial mixer circuits 330, and first and second local oscillators 352x and 352y in communication with a second mixer circuit 334. Each oscillator may be configured as any other known oscillator and as will be appreciated by those skilled in the art by multiple oscillators linked to a common frequency source, i.e., clock. Each second mixer circuit 334 is operatively connected to a different local oscillator circuit 352x or 352y, preferably configured to up-convert the filtered down-converted transmit signal 204 to a respective third frequency, i.e., transmit frequency, to generate the filtered transmit signal 206. Filtered transmitted signal 206 includes transmitted signal 200 with noise, distortion, and other spurious signals removed or substantially reduced. Wherein preferably each transmission signal comprises a transmission frequency different from one or more transmission frequencies in the same sub-module in the exemplary embodiment of fig. 8, and each link comprises a frequency f₁And f₂。

The respective initial and second mixer circuits 330 and 334 pass the first frequency f₀To convert the transmitted signal 200 to a lower third frequency f₁Or f₂To filter and then to convert the intermediate frequency f_IFThe resulting filtered signal at (a) is converted to a third, higher frequency for transmission to provide a double conversion. The individual transmit signals 206 are then combined in a combiner 353 into a filtered combined transmit signal 207. The combiner is in communication with a transmitter circuit 114, the transmitter circuit 114 configured to transmit a filtered transmit signal 207 through a transmitter/receiver diversity switch 140 via an antenna 118 to another system 100 in the network 20. Band-pass filter pair transmission signalAfter filtering by number 206, a combiner 353 may be provided.

System 100g may be configured to receive wireless device signals via the same or different receive antennas as antennas 118. Signals received through the receive antennas are passed through a transmitter/receiver diversity switch 140 to the receiver circuitry 116. The receiver circuit 116 is configured to receive signals for the system 100 and includes a suitable band pass filter 144 that receives and appropriately filters the received signals. The resulting bandpass filtered signal is suitably amplified by a suitable low noise amplifier 144 in communication with the bandpass filter 142. Receiver circuit 116 and accompanying receiver components may include additional and/or alternative elements required to receive wireless or wired signals, depending on, for example, the type of signal received, the communication medium and protocol, and other like factors. The output of the receiver circuit 116 is a received signal 209 at the transmit frequency.

Each receiver-side filtering submodule 313 preferably includes a plurality of initial mixer circuits 346 in communication with respective local oscillator circuits 352x or 352y, a plurality of filter circuits 348, as well as a second mixer circuit 350 and a splitter 355. Each mixer circuit 346 may be substantially identical to mixer circuit 146 described herein; filter circuit 348 may be substantially identical to filter circuit 148, and oscillator circuit 352 may be substantially identical to oscillator circuit 152; or each may be configured as any suitable component of the type known in the art. Submodule 313 includes a splitter 355, which splitter 355 suitably divides received signal 209 into signals having a frequency f₁And frequency f₂Of the received signal 208. Each signal 208 is provided to an initial receiver mixer circuit 346 having an input in communication with the output of the splitter. The separator may be located elsewhere where appropriate.

Preferably, the mixer circuit 346 is configured to transmit at a frequency f₁A received signal 208 is received. The third mixer circuit 346 may be configured to transmit a frequency f₁Down-converting the received signal 208 to an intermediate frequency f_IFTo generate a down-converted received signal 210. Submodule313 preferably includes a second filter circuit 348 in communication with an output of the mixer circuit 346. Each second filter circuit 348 is configured to filter the down-converted received signal 210 to generate an intermediate frequency f_IFFiltered down-converted received signal 212. The second filter circuit 348 may include a filter capable of filtering from the intermediate frequency f_IFThe down-converted received signal 210 may be any suitable type of filter circuit or device that filters noise, distortion, and other spurious signals. The second filter circuit 348 may be configured substantially similarly to the first filter circuit.

Sub-module 313 preferably includes a mixer circuit 150 in communication with the output of second filter circuit 148. The fourth mixer circuit 350 is preferably configured to up-convert the filtered down-converted received signal 212 to the fundamental frequency f₀To generate filtered received signal 214. The ZIF circuit 108 or other similar transmitter, receiver, transceiver, or communication circuit/device communicates with the output of the fourth mixer circuit 350 through the physical layer input 109.

Filtered received signal 214 includes received signal 208 with noise, distortion, and other spurious signals removed or substantially reduced. Third and fourth mixer circuits 346 and 350 for the transmission frequency f₁The received signal 208 is double converted to a lower intermediate frequency f_IFTo filter and then convert the resulting filtered signal to a higher fundamental frequency f₀To be received by the ZIF circuit 108 via a physical layer input. In this way, the frequency offset is reversed to generate a signal containing the fundamental frequency of the common output signal for use by the controller.

The exemplary embodiment of fig. 8 includes a 4 × 4MIMO structure in which a frequency offset is generated by using two local oscillators. In practice, system 100g provides two 2x 2MIMO systems, each connected to its own antenna, where each system operates at a different frequency and has a maximum ratio combining ("MRC") gain. Advantageously, only two physical antennas 118 are used. In this way, it may be possible to install the system 100g in a location having limited physical space, such as a vehicle having limited ceiling space.

According to one embodiment of the invention, system 100g includes polarization diversity antennas such that one linked-together link corresponds to one polarization and a second linked-together link corresponds to a second polarization. Wherein the minimum cross-polarization minimization of XPD (cross-polarization discrimination) between connecting two RF channels is from the frequency f₀To frequency f₁And vice versa, allowing two frequencies f₀And f₁Closer together. A similar antenna arrangement is made at the receiver and the linked-up links are connected to polarization diversity antennas. The polarizations of the corresponding pairs of signals 102 need to be aligned. Advantageously, the bandwidth expansion is made by a factor of 2, which is twice that of two 1 x 1 single input/single output systems. Thus, the channel 104 of the exemplary embodiment shown in fig. 8 is the same as equations 2 and 3.

Fig. 9a is a schematic diagram of a communication system including multiple radio frequency chains configured to generate a virtual antenna on the receiver side in accordance with one or more embodiments of the present invention. System 100h is preferably configured to operate using a MIMO architecture to efficiently transmit data between another system 100h and/or other compatible and/or suitably configured systems. As such, system 100h may work in conjunction with other systems 100 and include substantially similar structures. Thus, the description of system 100, i.e., 100a-100g, is repeated herein. Thus, system 100 may work in conjunction with other systems 100 (e.g., systems 100a-100 g). However, the system 100h is varied in certain respects.

Advantageously, system 100h is suitable for use with commercially available MIMO systems. Such a system limits the available physical layer transmit output from, for example, a ZIF circuit, but has a larger number of physical layer receive inputs. System 100h is operable to allow independent adjustment of the frequency of RF link 410 with a single physical layer output but multiple inputs. In this manner, one receive channel can be considered to be connected to a virtual antenna.

The system 100h includes a baseband mac 106, a ZIF circuit 108, and a plurality of receive and/or transmit chains 410 that may cooperate with one or more receive and/or transmit antennas 118. Fig. 9a shows two links. Of course, any suitable number of links may be used. Each link 410, i.e., links 410a and 410b, preferably includes a filtering module 412, the filtering module 412 including a transmitter-side filtering submodule 411 and a plurality of receiver-side filtering submodules 413; transmitter circuitry 114 for transmitting signal 102 over channel 104 and/or receiver circuitry 116 for receiving signal 102 over channel 104, depending on whether system 100h is configured for transmission only, reception, or both; and a switch 140 for switching between transmit and receive modes.

On the transmit side, at least one link 410 includes a transmit side filtering submodule 411, as described herein. The sub-module 411 is configured to receive a common output signal from the physical layer output, down-convert the common output signal, filter and amplify the signal, and transmit the signal through the physical antenna. In addition, at least the second link 410 is configured to receive a common output signal from the physical layer output, down-convert the common output signal to a different frequency than in the other link, i.e. apply a frequency offset, filter and amplify the signal, and transmit the signal through the physical antenna.

On the receiver side, each at least one link 410 includes a receiver-side filtering submodule 413. Sub-module 413 is configured to receive the transmit signal from the physical antenna, filter and amplify the signal, separate the filtered signal, and pass the signal to two or more branches of the sub-module. Each branch of the sub-module upconverts the upconverted signal to a common frequency before passing the signal to a respective physical layer input of the ZIF circuit. In this way, two or more upconverted signals may be obtained from a single physical antenna of a MIMO system, e.g., a MIMO system comprising a physical antenna and one or more virtual antennas.

The transmitter side filtering submodule 411 preferably comprises a first mixer circuit 430 in communication with a common oscillator circuit 451, a filter circuit 432, and a local oscillatorCircuit 452 is a second mixer circuit 434. The first mixer circuit 430 may be substantially the same as the mixer circuit 130 described herein; filter circuit 432 may be substantially identical to filter circuit 132, and general oscillator 451 and local oscillator 452 may be substantially identical to local oscillator circuit 152; or each component may be configured as any suitable component of the type known in the art. The first mixer circuit 430 is in communication with an output signal 200 from a physical layer output 409 of a ZIF circuit 108 as described herein, the ZIF circuit 108 including a common first frequency f as described herein₀Wherein the various receivers and transmitters of the system 100 are operable.

The first mixer circuit 430 is in operative communication with a common oscillator circuit, preferably for converting a common first frequency f from the ZIF circuit 108₀At 200 down-converting to an intermediate frequency f_IFI.e. the second frequency f_IFTo generate a second signal 202. The output of the first mixer circuit 430 is preferably in communication with a filter circuit 432 to pass the down-converted signal 202. The filter circuit 432 filters the signal 202 into a filtered down-converted signal 204 that is received by the second mixer circuit 434. The second mixer circuit 434 is operatively connected to the local oscillator circuit to preferably up-convert the filtered down-converted transmit signal 204 to a respective third frequency, i.e., the transmit frequency, to generate the filtered transmit signal 206.

Filtered transmitted signal 206 includes transmitted signal 200 with noise, distortion, and other spurious signals removed or substantially reduced. Wherein the transmission signal 204 preferably comprises a transmission frequency different from one or more transmission frequencies of other links. In the example embodiment of fig. 9a, the first link 410a comprises a transmission frequency f₁The second link 410b comprises a transmission frequency f₂。

Each of the first mixer circuit 430 and the second mixer circuit 434 provides a double conversion by converting the first frequency f₀To convert the transmission signal 200 into respective intermediate frequencies f_IFTo respective third frequencies f₁Or f₂To filter and then convert the resulting filtered signal for transmission. Intermediate frequency f_IFMay vary between links and sub-modules. In this way, the base frequency is adjusted independently of the adjustment of the other link, i.e. a frequency offset is applied, to generate a signal for transmission. The transmission signal comprises a frequency comprising an offset to the frequency of the ordinary output signal, wherein the frequency f₀And frequency f₁The difference includes a frequency offset.

The second mixer circuit 434 is in communication with the transmitter circuit 114, and the transmitter circuit 114 is configured to transmit the filtered transmit signal 206 through the transmitter/receiver diversity switch 140 to another system 100 in the network 20 via the physical antenna 118. In the example embodiment of fig. 9a, the ZIF circuit 108 includes a physical layer output 409a and a physical layer output 409b, but no other physical layer output is there.

System 100h may be configured to receive wireless signals 102 via a receive antenna, which may be the same or different from physical antenna 118. The signal received via the receive antenna is passed through a transmitter/receiver diversity switch 140 to the receiver circuit 116. The receiver circuit 116 is configured to receive signals for the system 100 and may include a suitable band pass filter 144 that receives and suitably filters the received signals. The resulting bandpass filtered signal is suitably amplified by a suitable low noise amplifier 144 in communication with the bandpass filter 142. Receiver circuitry 116 and accompanying receiver components may include additional and/or alternative elements as required to receive wireless or wired signals, depending on, for example, the type of signal received, the communication media and protocol, and other like factors. The output of the receiver circuit 116 is a received signal 209.

Each receiver-side filtering submodule 413 preferably comprises a plurality of initial mixer circuits 446, a plurality of filter circuits 448, a second mixer circuit 450 in communication with a common oscillator circuit 451 or any other suitable oscillator circuit, and a splitter 455. Each mixer circuit 446 may be substantially the same as mixer circuit 146 described herein; the filter circuit 448 may be substantially identical to the filter circuit 148, or each component may be configured as any suitable component of the type known in the art.

A separator 455, which may be arranged anywhere suitable, preferably divides the filtered received signal 209 into two or more received signals 208 of suitable frequencies, which are passed to the branches of the sub-modules based on the orthogonality of the received signals 209. In the example embodiment of fig. 9a, each link comprises a receiver-side sub-module 413, each having two or more branches, e.g. branch 413x and branch 413 y. Each signal 208 is provided to two or more branches including an initial receiver mixer circuit 446, a filter circuit 448, and a mixer circuit 450. In each branch, a mixer circuit 446 includes an input in communication with the output of the splitter.

Preferably, each initial mixer circuit 446 is preferably configured to communicate with a local oscillator circuit. In the example embodiment of fig. 9a, at least one mixer circuit 446 is preferably in communication with local oscillator 452x, and also in communication with mixer circuit 434, one or more other mixer circuits being in communication with local oscillator circuit 452. Each mixer circuit 446 is configured to receive a frequency f₁The received signal 208, and the received signal 208 is derived from the frequency f₁Down conversion to an intermediate frequency f_IFTo generate a down-converted received signal 210. Intermediate frequency f_IFMay vary between branches.

The filter circuit 448 is in communication with the output of the mixer circuit 346 and filters the down-converted received signal 210 to generate an intermediate frequency f_IFFiltered down-converted received signal 212. The filter circuit 348 may include a filter capable of filtering from the intermediate frequency f_IFAny suitable type of filter circuit or device that filters out noise, distortion, and other spurious signals from the down-converted received signal 210. The second mixer circuit 450 is in communication with the output of the filter circuit 448 and upconverts the filtered, down-converted received signal 212 to a frequency f₀To generate a filtered received signal 214 that is provided to the ZIF circuit 108 via the physical layer input 109 b. Filter elementReceived signal 214 of the wave includes received signal 208 with noise, distortion, and other spurious signals removed or substantially reduced.

In the example embodiment of fig. 9a, the initial mixer circuit 446 and the second mixer circuit 450 provide a slave frequency f of the filtered received signal 209 by dividing the filtered received signal 209 into one or more signals 208 that are passed to the branches of the sub-module₁To frequency f₀To be input to the ZIF circuit 108 through the physical layer input 109. In this way, the frequency offset is reversed to generate a signal for use by the controller that includes the frequency of the ordinary output signal.

The exemplary embodiment of fig. 9a includes a 2x 4MIMO configuration in which two local oscillator circuits are used to generate the frequency offset. In practice, system 100h provides two 2x 2MIMO systems, each connected to its own antenna, where each system operates at two different frequencies and has maximum ratio combining ("MRC") gain. Advantageously, there are only two physical antennas. By dividing the filtered received signal, one or more branches may be configured with virtual antennas 118 x. In this way, fewer physical antennas are required for installation in applications with limited physical space. Furthermore, advantageously, the number of receivers used is large despite the limited number of transmitters used.

Thus, for the example embodiment of fig. 9a, the matrix of channels 104 is shown in equation 6 or more clearly in equation 7, where the superscript represents the transmit frequency.

(etc.)Formula 6)

(equation 7)

Fig. 9b is a schematic diagram of an embodiment of the communication system of fig. 9 a. Wherein a plurality of common oscillator circuits are provided and operatively connected. Thus, system 100i does not contain a local oscillator circuit as does system 100h, and common oscillator circuit 451 operates with all mixer circuits of the transmit side filtering sub-module and one branch of the receiver side filtering sub-module. The common oscillator circuit 451 is further in communication with one or more branches of the receive side sub-modules of the other links 410. Similarly, one or more other common oscillator circuits 451 of the other link are in communication with respective branches of the receiver-side filtering sub-module, such that each branch of the receiver-side filtering sub-module is in communication with a different common oscillator circuit. Thus, for the example embodiment of fig. 9b, the matrix of channels 104 is shown in equation 6 or more clearly in equation 7, where the superscript represents the transmit frequency.

Fig. 9c is a schematic diagram of an embodiment of the communication system of fig. 9 a. The system 100j includes a receiver side sub-module 413 that utilizes one or more selectable frequency gain circuits 413z to obtain MRC gain. The circuit communicates with the physical layer input 109 to send a resulting signal for advantageous use by FM radio reception and detection. If no gain circuit is selected, no additional MRC gain is realized. Thus, for the example embodiment of fig. 9c, the matrix of channels 104 is shown in equation 8 or more clearly in equation 9, where the superscript represents the transmit frequency.

(equation 8)

(equation 9)

Fig. 9d is a schematic diagram of a communication system including multiple radio frequency chains configured to generate a virtual antenna on the receiver side in accordance with one or more embodiments of the invention. System 100k is preferably configured to operate using a MIMO architecture to efficiently transmit data between another system 100k and/or other compatible and/or suitably configured systems. Thus, the system 100i may work in conjunction with other systems 100 and include substantially similar structures. Thus, the description of system 100, i.e., 100a-100h, is repeated herein. Thus, system 100 may operate with other systems 100, such as systems 100a-100 h.

System 100i is substantially similar to system 100 h. However, the system 100i provides other combinations of filtered received signals 214 by combining the signal of one branch 413x of one receiver-side sub-module 413 and the signal of the other branch 413x of one receiver-side sub-module 413 using one or more selectable frequency gain circuits 413z for obtaining MRC gain. Which communicates with the physical layer input 109 to send the resulting signal. Without the selection gain circuit, no additional MRC gain would be achieved.

The exemplary embodiment of fig. 9d includes a 2x 3MIMO configuration in which two local oscillator circuits are used to generate the frequency offset. In practice, the system 100i connects only two physical antennas, but has a larger number of receiver-side physical inputs than antennas. By dividing the filtered received signal, one or more branches may be configured with virtual antennas 118 x. In this way, fewer physical antennas are required for installation in applications with limited physical space. Furthermore, advantageously, even if the number of transmitters used is limited, the number of receivers used is large.

In accordance with one or more embodiments of the invention, system 100 may include a baseband controller in which signal output 200 includes a different frequency than the common frequency f₀。

In accordance with one or more embodiments of the invention, the system 100 includes an RF converter in communication with a baseband controller. The RF converter preferably receives the MIMO baseband input and then converts it to an independently tunable RF output.

In accordance with one or more embodiments of the present invention, system 100 is independent of MIMO technology, whether it be 802.11n, 802.16d, 802.16e or other future possible wireless technologies that employ multiple-input/multiple-output (MIMO) technology for same frequency transmission as well as frequency translation (i.e., frequency offset), transmission.

In accordance with one or more embodiments of the present invention, system 100 may be used in a multimode or limited multimode fiber system as a way to improve throughput.

FIG. 10a is a schematic diagram of a ZIF circuit in accordance with one or more embodiments of the present invention. The ZIF circuit 508, such as the ZIF circuit 108, may be configured to generate an independently tunable ZIF output frequency to supply a communication system, such as the communication system 100. For clarity, the communication system is referred to as communication system 500 and includes any suitable communication system, and in particular any embodiment of communication system 100, e.g., 100a-100 h. The ZIF circuit 508 may be operated by a baseband media access controller, such as the baseband controller 106. The ZIF circuit 508 is preferably configured to include a plurality of independently tunable RF chains 510 operable by an antenna (e.g., antenna 118) to generate a RF signal including a plurality of frequencies f₁、f₂……f_NFor transmitting and receiving a plurality of signals 102 comprising matched frequencies f₁、f₂……f_NOf the signal of (1).

FIG. 10b is a schematic diagram of the ZIF circuit of FIG. 10a in accordance with one or more embodiments of the present invention. Therein, the communication system 500 includes three RF chains 510 and a frequency synthesizer 501 integrated in a ZIF circuit 508 to generate multiple frequencies. Preferably, the frequency synthesizer 501 is a common synthesizer used in all RF chains 510a of the ZIF circuit 508.

Fig. 10c is a schematic diagram of details of the RF link of fig. 10b in accordance with one or more embodiments of the present invention. The RF link 510 is configured as an RF link 510a, and for, for example, a 3x 3MIMO system, the RF link 510a includes an RF link 110i integrated on a ZIF circuit. The RF link 510a includes an In-phase and Quadrature-phase (IQ) input signal 600 and a frequency synthesizer 501 to apply a single frequency offset to mix the I/Q signal 600 to a predetermined frequency (e.g., frequency f)₁、f₂……f_N) The frequency synthesizer 501 may be any suitable synthesizer, depending on the RF output signal 606.

At the base band frequency of the I branch (e.g. frequency f)₀To) signal 600 is receivedTo low pass filter circuit 502a in communication with hybrid 504a, and similarly, signal 600 of the Q branch is passed to low pass filter circuit 502b in communication with hybrid 504 b. The various mixer circuits are in communication with a synthesizer 501, which synthesizer 501 preferably includes an RF oscillator circuit or the like, including a suitable Phase Locked Loop ("PLL") oscillator circuit or the like. The mixer circuit applies a frequency offset to the signal 600 to obtain a predetermined frequency, such as frequency f₁、f₂……f_NWhere each link of the ZIF circuit 508 includes one of these frequencies, but is different from the others, signal 606.

The respective RF output signals 606 of the I and Q branches are combined together and then passed to a transmitter circuit 514 comprising a bandpass filter and an amplifier. The transmitter circuit, in turn, passes the signal 606 to a switch 540, the switch 540 cooperating with the antenna 118. The signal 102 received from the antenna 118 is passed through a switch 540 to a receive circuit 516 comprising a band pass filter and an amplifier. Mixer circuit 504c and mixer circuit 504d cooperate with an amplifier to receive signal 608 from the amplifier. Signal 608 includes a predetermined frequency, such as frequency f₁、f₂……f_NOne of them. Mixer circuit 504c and mixer circuit 504d cooperate with synthesizer 501 to up-convert signal 608 to a signal 614 comprising a baseband frequency, e.g., frequency f for the I and Q branches₀. A pair of low pass filters 548a, 548b are operably connected to the amplifier and pass the signal 614 to each of the I and Q branches.

Advantageously, the RF link 510a includes a "true" ZIF because no intermediate frequencies are generated. Here, link 510a utilizes a single frequency synthesizer frequency offset to mix the I/Q signals into an RF output. Preferably, the synthesizer is configured to a desired RF output frequency, for example 5.4 GHz. Further, the synthesizer 501 preferably includes a common synthesizer used in each RF chain 510a of the ZIF circuit 508.

Fig. 10d is a schematic diagram of details of the RF link of fig. 10b in accordance with one or more embodiments of the present invention. The RF link 510 is configured as an RF link 510b, which RF link 510b includes a plurality integrated on a ZIF circuit for, e.g., a 3x 3MIMO system. On the transmit side, RF link 510b is configured substantially similar to RF link 510 a. However, link 510b is different in some respects. The RF link 510b includes a first mixer circuit 504a, a first mixer circuit 504b, and a second mixer circuit 506a to internally generate an intermediate frequency, which is then converted to an RF output signal 606. On the receive side, RF link 510b is configured substantially similar to RF link 510 a. However, link 510b is different in some respects. The RF chain 510b includes a second mixer circuit 506b that internally generates an intermediate frequency from the received signal 608, and first mixer circuits 504c, 504d that up-convert the frequency to a baseband input signal 614. Here, synthesizer 501 is configured as a fractional synthesizer 501a, which may be an 1/3-2/3 synthesizer (as shown), where the synthesizer operates at 3.6GHz and provides 1.8GHz and 3.6GHz outputs to mix and boost the RF signals from the IQ baseband to 3.6GHz (i.e., IF frequency) and then to 5.4 GHz.

FIG. 10e is a schematic diagram of the ZIF circuit of FIG. 10a, in accordance with one or more embodiments of the present invention. Therein, the communication system 500 includes three RF chains 510, each RF chain 510 including a separate frequency synthesizer 501b, wherein each chain is integrated in a ZIF circuit 508 to generate multiple frequencies. Preferably, the frequency synthesizer 501 is a common synthesizer used in all RF chains 510a of the ZIF circuit 508. Despite the fact that the RF link generates an intermediate frequency, this intermediate frequency is not detected, but the output appears to be a ZIF output because the internal IF is not visible outside the ZIF circuit.

Fig. 10f is a schematic diagram of details of the RF link of fig. 10e in accordance with one or more embodiments of the invention. The RF link 510 is configured as an RF link 510c, and for, for example, a 3x 3MIMO system, the RF link 510c includes a plurality integrated on a ZIF circuit. The RF link 510c is configured substantially similar to the RF link 510 a. However, link 510c is different in some respects. RF link 510c includes a single mixer circuit for each I and Q branch. However, each link 510c includes a separate synthesizer 501 configured as a separate frequency synthesizer 501b to apply a frequency offset to the I/Q signal 600 to obtain a predetermined frequency, such as frequency f₁、f₂……f_NSignal 606, where each link of ZIF circuit 508 includes one of these frequencies, but is different from each other.

Fig. 10g is a schematic diagram of details of the RF link of fig. 10e in accordance with one or more embodiments of the present invention. The RF link 510 is configured as an RF link 510d, the RF link 510d including a plurality integrated on a ZIF circuit for, e.g., a 3x 3MIMO system. The RF link 510d is configured substantially similar to the RF link 510 b. However, link 510d is different in some respects. The RF link 510d includes a first mixer circuit 504 and a second mixer circuit 506 to internally generate an intermediate frequency and then up-convert the frequency to an RF output signal 606. However, each link 510d includes an independent frequency synthesizer 501a to apply a frequency offset to the I/Q signal 600 to achieve a predetermined frequency, such as frequency f₁、f₂……f_NSignal 606, where each link of ZIF circuit 508 includes one of these frequencies, but is different from each other. Where the RF link 510c and the RF link 510d preferably use different synthesizers 501a for all wireless Tx/Rx links in the same ZIF circuit 508 to apply a frequency offset to the IQ signal to generate a signal at the IF frequency and then convert to a different RF frequency.

In accordance with one or more embodiments of the present invention, switching elements may be provided between each synthesizer 501b to allow one or more synthesizers to control the standard MIMO mode in which two or more links 510 operating independent links 510 operate on the same frequency. It should be appreciated that the ZIF circuit 508 can be configured in a number of different ways, such as using different synthesizer designs, different filtering approaches, using differential signals, and summing at RF instead of IF, which the present invention contemplates.

Fig. 11 is a perspective view of a portion of a communication network in accordance with one or more embodiments of the present invention. A portion of the network 20 includes physical points of field network elements 22 operatively disposed on a physical structure 24, such as a polished rod. Each point of the field network element includes any suitable communication system 100 described herein, preferably provided in an operable suitable physical embodiment known in the art to be closely weather-related.

Preferably, each communication system is in operable communication with another communication system 100 using MIMO technology having a plurality of frequencies, at least one of which includes an offset frequency, to serve as a network backhaul. For example, a communication system at first network element 22a may use a frequency comprising a first frequency f₁And a second frequency f₂To communicate with another communication system at second network element 22 b. Frequency f, as described herein₁Or f₂Includes a frequency offset to allow efficient communication using MIMO techniques. The second network element 22b not only communicates with the communication system of the first network element, but also uses a communication system comprising different frequencies f₃And f₄Is communicated with the communication system 100 of the third network element 22c, wherein one or more frequencies comprise a frequency offset to allow efficient communication using MIMO technology. Thus, by passing signal 102 from one network element to a subsequent network element, signal 102 may reach a junction point having a landline or backbone.

According to one or more embodiments of the invention, a cost-effective backhaul arrangement may be provided. Network elements 22, including any of systems 100, may communicate by transmitting different frequencies of the MIMO channel to different points in the field using different physical or virtual antennas. For example, network element 22a may be configured to operate by properly orienting the antenna nodes via frequency f₁Communicating with network element 22b and via frequency f₂Communicating with network element 22 c.

The channel matrix of system 100 to network element 22b may include only for frequency f₁By a single coefficient h₁₁And the matrix coefficient h₂₂Near zero, the matrix for channel 104 from system 100 to network element 22b may include only a single coefficient h near zero₁₁To aim atFrequency f₂Of the matrix coefficient h₂₂Is non-zero. Wherein system 100 comprises a low cost wireless device capable of supporting frequency specific wireless links to different systems using a single in/single out system.

Fig. 12 is a perspective view of a portion of the communication network of fig. 11 in which a user communication device may cooperate with the network. Advantageously, the MIMO architecture of system 100 incorporating frequency offsets is improved, bandwidth is effectively extended, and greater data transmission to mobile or stationary device users is guaranteed. Therein, a vehicle user 30a in the form of using the in-vehicle system 100 is configured as a mobile device user, while a user 30b using the cellular telephone based system 100 is configured as a stationary device user. For all communication devices, special vehicles, such as police cruisers, lack sufficient space, particularly on the roof. Thus, these users are only allowed to perform data services with a single antenna. Advantageously, using system 100, and in particular system 100h or system 100i, no additional physical antennas are needed because the system uses virtual antennas.

According to one or more embodiments of the invention, a user interface may be provided to the control system 100 by the control system. The interface and/or control system may be configured as a command line interface, a graphical user interface, a website-based graphical user interface, or a network management system linked together. The control system sets and monitors the status of the frequencies associated with each channel 104. Wherein the control system can select one or more frequencies in one or more systems 100 to minimize interference based on known or detected interference. For example, the control system may configure the operating systems 100 such that a first system 100 communicates with a second system 100 using channels in UNII2 (unlicensed national information infrastructure 2), and third and fourth systems 100 located near possible interference operate in channels in the ISM band.

Even so, there are very different ISM bands (e.g., 928MHz and 5.47GHz) that can be selected by the control system. For example, one channel may operate at 928MHz, which is selected to increase range and decrease attenuation via greenery, or a channel in the licensed band (2.5-2.7GHz) and a second channel in the unlicensed band to allow guaranteed service in the licensed band and additional bandwidth in the unlicensed band.

In a preferred embodiment, one or two MIMO streams are frequency translated such that the three streams are each adjacent to each other in one of the following frequency bands: 1)5.15-5.25 GHz; 2)5.25-5.35 GHz; 3)5.47-5.725 GHz; and 4)5.725-5.85 GHz. For example, a MIMO frequency shifter may use channels 100(5500MHz) and 108(5540MHz) to carry 2x 2MIMO streams. The 3x 3MIMO device may have used channels 100, 108 and 112 as continuous channels. However, the channel is not required to be continuous. In one example embodiment, the channel selected for each MIMO stream may be on the lowest interference channel, e.g., channels 60, 100, 120, and 140, which represent four independent 20MHz MIMO channels for a 4 x 4MIMO scheme. Since the employed radio can cover part of the 15 licensed bands (5150-. For example, the preferred embodiment of the present invention may use channels in the 4940 + 4990MHz band and the 5725 + 5850MHz band, where each channel may be a 5, 10, 20, or 40MHz stream from a 2 × 2MIMO wireless system. Similarly, a 3 × 3MIMO radio may frequency translate the MIMO streams such that one stream is a channel in the PSB, one stream is a channel in the ISM (5725) -5850MHz) band, and one stream is a channel in the ITS band. In the case of traffic transmission across multiple bands, both licensed and unlicensed, it is important to map the actual traffic or traffic types across these bands in such a way as to comply with the rules of the bands. For example, PSB and ITS bands are not used to carry wireless LAN traffic that is not used for general security (patrol/emergency) applications or smart transport applications, such as traffic video surveillance and flow control data.

In alternate embodiments, the present invention may include other possible channel mappings and applications. The Federal Communications Commission ("FCC") of the united states has recently adopted rules for allowing unauthorized use of television white space. These new rules allow White Space devices ("WSDs") to operate in the broadcast television spectrum, commonly referred to as television White Space, for performing broadband data services. The FCC proposed rules that "allow the use of these new and innovative types of unlicensed devices in unused spectrum to provide broadband data and other services to customers and enterprises". White space represents inactive television channels and therefore represents a very narrow channel of available frequency band of about 5MHz per "white space". The FCC has stated that "the [ white space ] device must include geolocation capabilities and provision of databases to access incumbent services such as full-power and low-power television stations (TV station) and cable system headends over the internet in addition to spectrum sensing technology. The database will tell the white space device what spectrum to use at that location. "based on this description, it is known that additional Dynamic Frequency Selection (" DFS ") rules are required to determine whether a channel can be selected, and the resulting channel group can be used. Thus, in an alternative embodiment of the invention, a MIMO frequency shifter enables existing MIMO devices to operate on multiple parallel data streams on separate channels in the frequency band. The resulting throughput may be three times that of legacy and available devices employing MIMO technology on a single white space channel.

In accordance with one or more embodiments of the invention, system 100 includes an antenna diversity switch and/or control system for one or more receiver-side transmit chains to select the strongest channel. For example, regardless of whether links 100 are linked, system 100 may be configured to allow beam steering of one or more antennas 118. As such, antenna 118, or any other suitable antenna, may include parallel radiating elements to achieve beam steering.

It will be appreciated by those skilled in the art that the present invention can be embodied in various specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalents are intended to be protected.

Claims (53)

1. A communication system, comprising:

a multiple-input/multiple-output fabric, the fabric including a plurality of radio frequency links;

a first radio frequency link of the plurality of radio frequency links is configured to apply a first frequency offset to a fundamental frequency of an output signal to generate a first transmit frequency; and

a second radio frequency link of the plurality of radio frequency links is configured to apply a second frequency offset to the base frequency to generate a second transmit frequency.

2. The communication system of claim 1, wherein a first radio frequency link of the plurality of radio frequency links is configured to apply the first frequency offset to a frequency of a first received signal to generate the fundamental frequency; a second radio frequency link of the plurality of radio frequency links is configured to apply the second frequency offset to a frequency of a second receive signal to generate the fundamental frequency.

3. The communication system of claim 1, wherein the plurality of radio frequency links comprises: at least one radio frequency link dedicated to transmitting signals and at least one radio frequency link dedicated to receiving signals.

4. The communication system of claim 1, further comprising a first local oscillator circuit cooperating with a first of the plurality of radio frequency chains to generate the first frequency offset.

5. The communication system of claim 4, further comprising a second local oscillator circuit cooperating with a second of the plurality of radio frequency chains to generate the second frequency offset.

6. The communication system of claim 1, further comprising a Zero Intermediate Frequency (ZIF) circuit operating at a baseband frequency.

7. The communication system of claim 1, wherein at least one of the plurality of radio frequency links comprises one of time division duplexing and frequency division duplexing.

8. The communication system of claim 1, wherein at least one of the plurality of radio frequency chains comprises a switch for switching between a receive mode and a transmit mode.

9. The communication system of claim 1, wherein a first radio frequency link and a second radio frequency link of the plurality of radio frequency links comprise a heterodyne architecture to generate the first frequency offset and the second frequency offset.

10. The communication system of claim 1, wherein one of the first and second transmission frequencies comprises a frequency in the industrial, scientific and medical radio band.

11. The communication system of claim 1, characterized in that the system operates as one of the group consisting of: IEEE 802.11 wireless devices, IEEE 802.16d worldwide interoperability for microwave access ("WiMAX"), 802.16e WiMAX; fourth generation mobile communications (4G), third generation partnership project ("3 GPP"), and wireless devices based on the third generation partnership project 2 ("3 GPP 2") standard.

12. The communication system of claim 1, further comprising an antenna associated with at least one of the plurality of radio frequency chains, wherein the antenna comprises the first polarization.

13. The communication system of claim 1, further comprising a first antenna associated with a first radio frequency link of the plurality of radio frequency links, and a second antenna associated with a second radio frequency link of the plurality of radio frequency links; wherein the first antenna comprises a first polarization and the second antenna comprises a second polarization, the first polarization being different from the second polarization.

14. The communication system of claim 1, further comprising a first antenna associated with a first radio frequency link of the plurality of radio frequency links, and a second antenna associated with a second radio frequency link of the plurality of radio frequency links; wherein the first antenna and the second antenna each comprise a common polarization in which an offset frequency of one of the first and second radio frequency chains is transmitted using beam steering.

15. A communication system, comprising:

a multiple-input/multiple-output fabric, the fabric including a plurality of radio frequency links;

a first radio frequency link and a second radio frequency link of the plurality of radio frequency links comprise a first linked group configured to apply a first frequency offset to a fundamental frequency of an output signal to generate a first transmit frequency; and

a third radio frequency link and a fourth radio frequency link of the plurality of radio frequency links include a second linked group configured to apply a second frequency offset to the fundamental frequency of the output signal to generate a second transmit frequency.

16. The communication system of claim 15, further comprising an antenna comprising a first polarization and a second polarization, the first polarization being associated with the first transmit frequency and the second polarization being associated with the second transmit frequency.

17. The communication system of claim 16, wherein the first polarization and the second polarization are each selected from the group consisting of vertical polarization, horizontal polarization, and orthogonal polarization.

18. The communication system of claim 15, further comprising a first antenna and a second antenna, each antenna associated with one of the first and second linked groups, respectively, each antenna comprising an input for one of the first and second polarizations, respectively.

19. The communication system of claim 15, wherein the first and second linked groups further comprise local oscillator circuits for generating respective first and second frequency offsets, respectively.

20. A communication system, comprising:

a multiple-input/multiple-output fabric, the fabric including a plurality of radio frequency links;

at least one of the radio frequency chains comprises a plurality of filtering sub-modules, a first and a second of the filtering sub-modules being configured to apply respective first and second frequency offsets to a fundamental frequency of the output signal to generate respective first and second signals comprising respective first and second transmit frequencies.

21. The communication system of claim 20, further comprising a combiner for combining the first signal and the second signal into a transmit signal.

22. The communication system of claim 20, wherein the first and second sub-modules comprise respective first and second local oscillator circuits for generating respective first and second frequency offsets, respectively.

23. The communication system of claim 20, wherein the first and second sub-modules include corresponding first and second local oscillator circuits, respectively, the system further comprising a common oscillator circuit cooperating with at least two of the plurality of radio frequency chains for generating the first and second frequency offsets, respectively.

24. A communication system, comprising:

a multiple-input/multiple-output fabric, the fabric including a plurality of radio frequency links;

a first radio frequency link of the plurality of radio frequency links is configured to apply a first frequency offset to a fundamental frequency of an output signal to generate a first transmit frequency; and

a second radio frequency link of the plurality of radio frequency links is configured to apply a second frequency offset to the base frequency to generate a second transmit frequency;

the first transmission signal comprises a first transmission frequency, and the second transmission signal comprises a second transmission frequency;

wherein at least two of the plurality of radio frequency chains are switchable to a receiving mode for receiving a first transmit signal and a second transmit signal, at least two of the plurality of radio frequency chains respectively comprising a respective first receive side filtering submodule and a second receive side filtering submodule respectively for applying a first frequency offset to a first transmit frequency and a second frequency offset to a second transmit frequency to obtain a respective signal at a fundamental frequency.

25. The communication system of claim 24, wherein each of the plurality of radio frequency chains comprises only one receive antenna.

26. The communication system of claim 24, wherein each of the plurality of radio frequency chains comprises only one transmit antenna.

27. The communication system of claim 24, wherein one of the at least two of the plurality of radio frequency chains further comprises a transmit side filtering submodule and a first local oscillator circuit that cooperates with the respective transmit side filtering submodule and the respective first receive side filtering submodule of the one of the at least two of the plurality of radio frequency chains.

28. The communication system of claim 27, wherein the second receive-side filtering sub-module comprises a second local oscillator circuit for generating the second frequency offset.

29. The communication system of claim 27, wherein the first local oscillator circuit further cooperates with a second receive-side filtering sub-module of another of the at least two of the plurality of radio frequency chains.

30. The communication system of claim 29, further comprising a first frequency gain circuit for implementing a Maximum Ratio Combining (MRC) gain, the first frequency gain circuit cooperating with the first receive side filtering sub-module of one of the at least two of the plurality of radio frequency chains and the second receive side filtering sub-module of another of the at least two of the plurality of radio frequency chains.

31. The communication system of claim 28, further comprising a first frequency gain circuit for implementing a Maximum Ratio Combining (MRC) gain, the first gain circuit cooperating with the first receive-side filtering sub-module of one of the at least two of the plurality of radio frequency chains and the second receive-side filtering sub-module of another of the at least two of the plurality of radio frequency chains.

32. A communication system, comprising:

a Zero Intermediate Frequency (ZIF) circuit for generating a first output signal and a second output signal, the first and second output signals including a first frequency and a second frequency, respectively, the ZIF circuit comprising:

a plurality of radio frequency links integrated in the ZIF circuit;

a first radio frequency link of the plurality of radio frequency links is configured to generate a first transmit frequency; and

a second radio frequency link of the plurality of radio frequency links is configured to generate a second transmit frequency.

33. The communication system of claim 32, further comprising a common frequency synthesizer integrated in the ZIF circuit, the common frequency synthesizer being operable with a first radio frequency link and a second radio frequency link of the plurality of radio frequency links to generate the first and second transmit frequencies, respectively.

34. The communication system of claim 32, further comprising first and second frequency synthesizers integrated in the ZIF circuit, the first and second frequency synthesizers cooperating with respective first and second ones of the plurality of radio frequency chains to generate respective first and second transmit frequencies.

35. A method of communicating information using a communication system comprising a multiple-input/multiple-output architecture including a first radio frequency link and a second radio frequency link, said method comprising the steps of:

a) receiving at least one output signal from the first radio frequency chain and at least one output signal from the second radio frequency chain, each output signal comprising a fundamental frequency;

b) applying a first frequency offset to a fundamental frequency of at least one output signal received from the first radio frequency link to generate a first offset transmit signal;

c) applying a second frequency offset to the fundamental frequency of at least one output signal from the first radio frequency link to generate a second offset transmit signal; and

d) transmitting the first offset transmission signal and the second offset transmission signal.

36. The method of communicating information of claim 35, wherein step b) further comprises the step of generating the first frequency offset using a first local oscillator circuit, and wherein step c) further comprises the step of generating the second frequency offset using a second local oscillator circuit.

37. The method of communicating information of claim 35, wherein step b) further comprises the step of using a first local oscillator circuit in conjunction with a common oscillator to generate the first frequency offset, and wherein step c) further comprises the step of using a second local oscillator circuit in conjunction with a common oscillator to generate the second frequency offset.

38. The method of transmitting information of claim 35, further comprising the steps of:

e) receiving at least one output signal from a third radio frequency link, the at least one output signal from the third radio frequency link comprising a base frequency; and

f) transmitting at least one output signal from the third radio frequency link without applying a frequency offset.

39. A method of communicating information using a communication system comprising a multiple-input/multiple-output architecture, the architecture comprising a first radio frequency link and a second radio frequency link, the method comprising the steps of:

a) receiving a first offset transmission signal including a first frequency offset from the fundamental frequency, and a second offset transmission signal including a second frequency offset from the fundamental frequency;

b) the first radio frequency link applies the first frequency offset to obtain a first signal at a controller fundamental frequency; and

c) the second radio frequency link applies the second frequency offset to obtain a second signal at the controller fundamental frequency.

^*Multiple input/multiple output reception is performed.

40. A method for communicating information using a communication system comprising a multiple-input/multiple-output architecture including a first linked set including a first radio frequency link and a second radio frequency link, and a second linked set including a third radio frequency link and a fourth radio frequency link, the method comprising the steps of:

a) receiving a first output signal from the first radio frequency link, a second output signal from the second radio frequency link, a third output signal from the third radio frequency link, and a fourth output signal from the fourth radio frequency link, each output signal comprising a fundamental frequency;

b) applying a first frequency offset to a fundamental frequency of the first output signal to generate a first offset transmit signal;

c) applying a first frequency offset to the fundamental frequency of the second output signal to generate a second offset transmit signal;

d) applying a second frequency offset to the fundamental frequency of the third output signal to generate a third offset transmit signal;

e) applying a second frequency offset to the fundamental frequency of the fourth output signal to generate a fourth offset transmit signal; and

f) transmitting the first offset transmission signal, the second offset transmission signal, the third offset transmission signal and the fourth offset transmission signal,

wherein the first and second transmit signals comprise a first transmit frequency and the third and fourth transmit signals comprise a second transmit frequency.

41. The method of communicating information of claim 40, wherein step f) further comprises transmitting the first offset transmit signal using a first antenna polarization and the second offset transmit signal using a second antenna polarization, wherein the first antenna polarization is different from the second antenna polarization.

42. The method of communicating information of claim 41, wherein step f) further comprises transmitting the third offset transmit signal using a third antenna polarization and transmitting the fourth offset transmit signal using a fourth antenna polarization, wherein the third antenna polarization is different from the fourth antenna polarization.

43. The method of transmitting information according to claim 40, wherein each of said steps b) and c) further comprises the step of generating said first frequency offset using a first local oscillator circuit, and wherein each of said steps d) and e) further comprises the step of generating said second frequency offset using a second local oscillator circuit.

44. A method of transmitting information using a communication system comprising a multiple-input/multiple-output architecture including a plurality of radio frequency links, at least a first radio frequency link including a first transmit side filtering submodule and a second transmit side filtering submodule, the method comprising the steps of:

a) receiving at least one output signal from the first radio frequency link, the at least one output signal comprising a fundamental frequency;

b) applying a first frequency offset to a fundamental frequency of a received output signal using the first transmit-side filtering sub-module to generate a first offset signal;

c) applying a second frequency offset to the fundamental frequency of the received output signal using the second transmit-side filtering sub-module to generate a second offset signal;

d) combining the first offset signal and the second offset signal into an offset transmit signal; and

e) and transmitting the offset transmission signal.

45. The method of transmitting information of claim 44 wherein step b) further comprises the step of using a first local oscillator circuit to generate said first frequency offset and wherein step c) further comprises the step of using a second local oscillator circuit to generate said second frequency offset.

46. The method of transmitting information of claim 44 wherein step b) further comprises the step of using a first local oscillator circuit in conjunction with a common oscillator to generate said first frequency offset and wherein step c) further comprises the step of using a second local oscillator circuit in conjunction with a common oscillator to generate said second frequency offset.

47. Method for transmitting information according to claim 44, characterized in that said step a) is performed by using only one transmitting antenna.

48. A method of transmitting information using a communication system comprising a multiple-input/multiple-output architecture, the architecture comprising a first radio frequency link and a second radio frequency link, the first radio frequency link comprising a first receive-side filtering submodule and the second radio frequency link comprising a second receive-side filtering submodule, the method comprising the steps of:

a) receiving a first offset transmission signal including a first frequency offset;

b) receiving a second offset transmission signal including a second frequency offset;

c) applying a first frequency offset to the received first offset transmit signal using the first receive-side filtering sub-module, thereby obtaining a first signal at a controller fundamental frequency; and

d) applying a second frequency offset to the received second offset transmit signal using the second receive-side filtering sub-module to obtain a second signal at the controller fundamental frequency.

49. The method of communicating information of claim 48, wherein step c) further comprises the step of using a first local oscillator circuit to generate the first frequency offset, and wherein step d) further comprises the step of using a second local oscillator circuit to generate the second frequency offset.

50. The method of claim 48, wherein said step c) further comprises the step of using a first local oscillator circuit in conjunction with a common oscillator to generate said first frequency offset, and wherein said step d) further comprises the step of using a second local oscillator circuit in conjunction with a common oscillator to generate said second frequency offset.

51. Method for transmitting information according to claim 48, characterized in that said steps a) and b) are performed by using only one receiving antenna.

52. A communication system, the system comprising:

a multiple-input/multiple-output structure comprising a plurality of radio frequency chains, at least two of the radio frequency chains applying a first frequency offset and a second frequency offset to a base frequency; and

a controller system for selecting at least two transmission frequencies that minimize interference, the control system configured to determine the first frequency offset and the second frequency offset.

53. A method of transmitting information in a communication system, the communication system comprising a multiple-input/multiple-output architecture, the architecture comprising a plurality of radio frequency chains, at least two of the radio frequency chains applying a first frequency offset and a second frequency offset to a base frequency, the method comprising the steps of:

a) determining at least two transmission frequencies that minimize interference; and

b) determining said first and second frequency offsets to be applied to the fundamental frequency to provide at least two transmit frequencies.