HK1175599A - Wireless network, method and system - Google Patents

Abstract

The present invention provides a wireless network, a method and a system, the wireless network comprising: means for receiving first communications from a first plurality of users utilizing a legacy Telecommunications Industry Association (TIA) Code Division Multiple Access (CDMA) standard, wherein each of the first communications includes voice data and has a pseudo noise (PN) code unique to its associated user; and means for receiving second communications from a second plurality of users utilizing a standard that is not TIA CDMA, wherein each of the second communications transmitted from the second plurality of users includes Internet Protocol (IP) data.

Description

Wireless network, method and system

The patent application of the invention is a divisional application of an invention patent application with the international application number of PCT/US2005/003028, the international application date of 27.1.2005, the application number of 200580003579.6 in the Chinese national phase and the name of 'a compensation multipath method'.

Cross Reference to Related Applications

The parent Application of the present invention (PCT/US 2005/003028) is a continuation of U.S. Application No.16/767,843 filed on 20/1/2004, U.S. Application No.16/767,843 is a continuation of U.S. Application No.16/767,843 filed on 3/7/2001, entitled "Method for Allowing Multi-user and Non-Orthogonal interaction of Code Channels", and U.S. Application No.09/898,514 is a continuation of U.S. Application No.09/898,514 filed on 19/7/2000, entitled "Method for Allowing Multi-user and Non-Orthogonal interaction of Code Channels", and U.S. Application No.09/898,514 is a priority of U.S. Application No.09/898,514 filed on 19/7/2000, entitled "Method for Allowing Multi-user and Non-Orthogonal interaction of Code Channels on the Link of CDMA System". The teachings of the above application are incorporated herein by reference.

Technical Field

The present invention relates to wireless communication services.

Background

Unprecedented growth in both form and demand for wireless communication services has emerged over the last two decades. Wireless voice communication services, including cellular telephones, Personal Communication Services (PCS), and other similar systems now provide nearly ubiquitous coverage. The infrastructure for such networks has also been built in the united states, europe and other industrial areas of the world where the most residents are located, often not just one, but rather, to provide multiple services of a residential choice.

The continued growth of the electronics and computer industries has contributed to the demand for access to the internet and services and the large number of services and features that they provide. This proliferation of computer-based devices, particularly portable devices, including laptop computers, hand-held Personal Digital Assistants (PDAs), internet-enabled cellular telephones, and similar devices, has resulted in a corresponding increase in demand for wireless data access.

Although cellular telephone and Personal Communication Services (PCS) networks have been widely used, these systems were not originally intended for carrying data traffic (traffic). Instead, these networks are designed to efficiently support continuous analog signals, in contrast to the explosion mode digital communication protocols required for internet communications. It is also desirable to consider that voice communication requires a communication channel bandwidth of approximately three kilohertz (kHz). However, what is generally acceptable for effective internet communications such as web browsing is a data transmission rate of at least 56 kilobits per second (kbps) or higher.

In addition, the nature of data traffic itself is different from the nature of voice communications. Sound requires a continuous full duplex connection; that is, it is expected that a user at one end of a connection may continuously transmit and receive to a user at the other end of the connection, while a user at the other end may also transmit and receive. However, in general, web access via the internet is of an explosive nature. Typically, a user of a remote client computer specifies, for example, a computer file address located on a web server. This request is then formatted as relatively short data information, typically less than 1000 bytes in length. The other end of the connection, such as a web server in the network, then responds with the requested data file, which may be from 10 kilobytes to several megabytes of text, image, video, audio data, or a combination thereof. Because of the inherent latency in the internet itself, users typically expect only a few seconds or more of delay before beginning to deliver the requested content to the user itself. And once the content begins to be delivered, the user may spend seconds or minutes viewing, reading the page content before specifying the next page to download.

Furthermore, the voice network is built to support the use of high mobility; that is, it maintains a voice user connection according to cellular and PCS networks while moving along a highway at a high speed in consideration of an extreme length supporting mobility having a high speed form. However, users of laptop computers are relatively stationary, such as being set up on a desk. Thus, the threshold considered for wireless voice networks in cell-to-cell or intra-cell high speed mobility is generally not required to support data access.

Disclosure of Invention

A wireless network, the wireless network comprising: means for receiving first communications from a first plurality of users utilizing conventional Telecommunications Industry Association (TIA) Code Division Multiple Access (CDMA) standards, wherein each of the first communications includes voice data and has a pseudo-noise (PN) code unique to its associated user; and means for receiving second communications from a second plurality of users utilizing non-TIA CDMA standards, wherein each of the second communications transmitted from the second plurality of users includes Internet Protocol (IP) data.

A method, the method comprising: receiving, by a wireless network, first communications from a first plurality of users utilizing conventional Telecommunications Industry Association (TIA) Code Division Multiple Access (CDMA) standards, wherein each of the first communications includes voice data and has a pseudo-noise (PN) code unique to its associated subscriber unit; and receiving, by the wireless network, second communications from a second plurality of users utilizing non-TIA CDMA standards, wherein each of the second communications transmitted from the second plurality of users includes Internet Protocol (IP) data.

A system, the system comprising: a first plurality of subscriber access units (SACs) that utilize a conventional Telecommunications Industry Association (TIA) Code Division Multiple Access (CDMA) standard to transmit first communications, wherein each of the first communications includes voice data and has a pseudo-noise (PN) code unique to its associated SAC; a second plurality of SACs that utilize non-TIA CDMA standards to transmit second communications, wherein each of the second communications transmitted from the second plurality of users includes Internet Protocol (IP) data; and a radio network node, the radio network node comprising: means for receiving the first communication from the first plurality of SACs utilizing the conventional standard TIA CDMA standard; and means for receiving the second communication from the second plurality of SACs utilizing the non-TIA CDMA standard.

It should be appreciated that retrofitting existing wireless infrastructure components may more efficiently reconcile wireless data. For additional functions to be implemented by new classes of users with high data transmission rates, but low mobility, it should be necessary to adapt backwards to the existing functions of users with low data transmission rates, high mobility. This would allow the same frequency allocation plane, base station antennas, construction location, and other existing voice network infrastructure perspectives to be utilized to provide new high speed data services.

It is particularly important to support as high a data transmission rate as possible on the reverse link of such networks to carry data on the reverse link, e.g., from the remote unit to the base station. Consider an existing digital cellular standard, such as IS-95 Code Division Multiple Access (CDMA), which specifies that different code sequences be used in the forward link in order to maintain minimum interference between channels. In particular, such systems utilize orthogonal codes on the forward link that define respective logical channels. However, optimal operation of such a system necessarily requires that all such codes must be time aligned to a particular boundary to maintain orthogonality at the receiver. Therefore, the transmission must be synchronized.

This is not a particular issue in the forward link direction, since all transmissions originate from the same location, i.e., from the base station receiving station location. However, current digital cellular Code Division Multiple Access (CDMA) standards do not attempt to utilize or require orthogonality in the reverse link. It is generally assumed that it is difficult to synchronize transmissions originating from remote units located at different distances from the base station. Instead, these systems typically utilize a chip-level scrambling code with a unique transition of this long pseudorandom code to resolve the respective reverse link channels. However, with this scrambling technique, the possibility of different user transmissions being orthogonal to each other is precluded.

Accordingly, embodiments of the present invention include a system that supports communication between a first cluster of users and a second cluster of users. The first group of users may be legacy users in a digital Code Division Multiple Access (CDMA) cellular telephone system that encode transmissions with a first common code. Such a first group of users may be uniquely identified by providing a unique code phase for each user. The second group of users, which may be users with high speed data services, encode transmissions with the same code and share one of the code phase offsets of the code. However, the users in each second cluster further encode their transmissions with an additional code that is unique to each user of the second cluster. This allows the transmissions of the second group of users to be orthogonal to each other while still maintaining the overall characteristics of appearing to be a single user for the first group.

The code assigned to the first group of users may be a pseudo random code of a common chip rate. The code assigned to the second cluster of terminals may generally be a set of unique orthogonal codes. The respective members of the first terminal cluster may be resolved using scrambling codes with unique phase offsets that select longer pseudorandom noise sequences.

In a preferred embodiment, it takes specific steps to ensure proper signaling operations between said second group of users or so-called "hub". In particular, the common code channel may be dedicated as a synchronization channel. For example, if the code structure is implemented in the reverse link direction, it allows the second cluster of terminals to maintain proper timing of transmissions.

In another embodiment, users of the second cluster may be allocated time slots for transmission and thus orthogonality is maintained through the use of time division multiple access. Also, the emphasis is that the set of users of the second cluster appear as a single user for the transmission of users of the first cluster.

Because of the orthogonal signaling, the principles of the present invention enable Code Division Multiple Access (CDMA) systems with exactly one antenna in a multipath environment to produce diversity decisions because the unique orthogonal codes can be seen at two or more different phases. In a preferred embodiment, the base station may generate diversity decisions for signals received at multiple phases from known field units in the second cluster in a multipath environment by selecting the "best" reverse link signal at one of the phases. The reverse link signals at the selected phase are orthogonally aligned with the reverse link signals of other field units in the selected cluster. The orthogonally aligned reverse link signals may be referred to herein as the orthogonal link, and the reverse link signals at phases that are not orthogonally aligned with other field unit signals in the second cluster may be referred to herein as non-forward links.

Because the forward links must be time aligned to maintain orthogonality between one user and the next, a timing control loop from the base station is utilized to maintain the reverse link signal at the selected phase in orthogonal alignment with the reverse link signals of other field units in the second cluster.

Existing Code Division Multiple Access (CDMA) systems define the non-orthogonality of reverse link channelization. This is performed by defining a unique pattern of spreading code transfer for each reverse link user. Orthogonal and non-orthogonal backward applicability may be achieved by orthogonal users sharing the same spreading code by the primary base station. When these user signals are received at other base stations, they are unlikely to be time aligned with each other, but they will all have unique code transitions that can be uniquely identified from their combination with orthogonal codes.

When the diversity selection is made and the code phase of the reverse link signal is shifted, there can be a significant code phase offset. With a conventional one-bit differential timing control loop, the orthogonality of the reverse link signal with respect to other field units may be too slow to be quickly achieved. Thus, when diversity selection occurs, re-alignment of the reverse link can be performed quickly using an overall timing adjustment command or information. The overall timing adjustment may be an absolute or relative value. In the case of the timing command, the field unit is informed of the generation of a coarse timing adjustment, and in the case of the timing information, the subscriber unit autonomously responds to the information in the timing information.

The threshold for timing control selection (i.e., dispersion selection) may be determined based on a threshold comprising at least one of:

1. the alternative path metric unit exceeds a threshold value for a specified period of time;

2. the secondary (i.e., unselected) path metric units exceed a threshold value for a specified period of time relative to the current path;

3. the primary (i.e., currently selected) path falls below an absolute unit of measure; or is

4. The secondary path exceeds an absolute unit of measure.

Wherein the unit of measure may be one or more of:

a. power;

b. signal to noise ratio (SNR);

c. a power change;

d. signal to noise ratio (SNR) variation

e. The relative proportions of the units of measure between the primary and secondary paths.

Drawings

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

Fig. 1 is a block diagram of a wireless communication system supporting orthogonal and non-orthogonal reverse links;

fig. 2 is a block diagram of circuitry used by the access terminal of fig. 1;

fig. 3 is a block diagram of the circuit of fig. 2, which also includes a code generator to operate on an orthogonal reverse link with other access terminals;

FIG. 4 is a block diagram of the environment in which the base station of FIG. 1 controls the timing of the orthogonal reverse link signals in the presence of multipath;

FIG. 5 is a block diagram of a Base Transceiver Station (BTS) of FIG. 1;

FIG. 6 is a timing diagram of a reverse link signal received at the base station receiving station of FIG. 4;

fig. 7 is a flow chart of a process performed by the base station receiving station and access terminal of fig. 4.

Detailed Description

Fig. 1 is a block diagram of a Code Division Multiple Access (CDMA) communication system 10 utilizing a signal coding structure in which a first logical channel class is assigned unique long codes with different code phase offsets, and a second logical channel class is provided utilizing a common long code and a common code phase offset in combination with an additional coding process utilizing a unique orthogonal code for each channel.

In the following description of the preferred embodiments, the shared channel resource of the described communication system 10 is a wireless or radio channel. It should be appreciated, however, that the techniques described herein may be applied to implement shared access to other forms of media, such as telephone connections, computer network connections, cable connections, and other physical media, for which access is recognized on a demand-driven basis.

The system 10 supports wireless communication for a first group of users 110 and a second group of users 210. The first group of users 110 are typically legacy users of cellular telephone equipment, such as wireless handsets 113-1, 113-2 and/or cellular handsets 113-h installed in automobiles. This first group of users 110 in principle uses the network in a voice mode whereby their communications are encoded into continuous transmissions. In the preferred embodiment, these users' transmissions are delivered from the subscriber units 113 over forward link 40 radio channels and reverse link 50 radio channels. Its signals are managed at a central location which includes the base station wires 118, the base station receiver stations (BTSs) 120, and the Base Station Controllers (BSCs) 123. The first group of users 110 thus typically engage in voice conversations using the mobile subscriber units 113, the Base Transceiver Stations (BTSs) 120, and the Base Station Controllers (BSCs) 123, connected to a telephone connection through the Public Switched Telephone Network (PSTN) 124.

The forward link 40 used by the first group of users 110 may be encoded according to known digital cellular standards, such as the Code Division Multiple Access (CDMA) standard defined in IS-95B, specified by the Telecommunications Industry Association (TIA). This forward link 40 includes a traffic channel 142 and at least one paging channel 141, as well as other logical channels 144. These forward link 40 legacy channels 141, 142, 144 are defined in a system that utilizes orthogonally coded channels. This first group of users 110 also encode their transmissions on the reverse link 50 in accordance with the IS-95B standard. It thus utilizes several logical channels in the reverse link 50 direction, including an access channel 151, a traffic channel 152, and other logical channels 154. In this reverse link 50, the first group of users 110 typically encode signals with a common long code using different code phase offsets. Such encoding of signals for conventional users 110 on the reverse link 50 is also well known in the art.

The communication system 10 also includes a second group of users 210. This second group of users 210 is generally users that require high-speed wireless data services. The system components include a plurality of remotely located Personal Computer (PC) devices 212-1, 212-2, …, 212-h and corresponding remote Subscriber Access Units (SAUs) 214-1, 214-2, …, 214-h and associated antennas 216-1, 216-2, …, 216-h. The central location includes a base station antenna 218 and a Base Station Processor (BSP) 220. The Base Station Processor (BSP) 220 provides connectivity from and to an internet gateway 222, which in turn provides access to data networks such as the internet 224 and a network file server 230 connected to the network 222. It should be appreciated that the Base Transceiver Station (BTS) 120 may be updated to operate in the same manner as the Base Station Processor (BSP) 220 and provide the same connectivity to and from the internet gateway 222. Thus, in some embodiments, the remote Subscriber Access Units (SAUs) 214 may communicate with the Base Station Processors (BSPs) 220 or the base receiver stations (BTSs) 120 in the forward link 40 and reverse link 50.

The Personal Computers (PCs) 212 may be implemented via bidirectional wireless network connections to transmit data to the web server 230 or receive data from the web server 230 over the forward link 40 and reverse link 50 used by the legacy user 110. It should be appreciated that in the illustrated point-to-multipoint multiple access wireless network system 10, the base station processor 220 is known to support communication with a plurality of different active subscriber access units 214 in the same manner as in a cellular telephone communications network.

In the present scenario, the assigned radio frequency used by the first cluster 110 is the same as the assigned radio frequency used by the second cluster 210. One aspect of the present invention specifically considers how to allow for a different coding structure used by the second cluster 210 while causing minimal interference to the first cluster 110.

PCs 212 are typically Internet enabled computing devices in the form of cellular telephones or Personal Digital Assistants (PDAs), such as laptop computers 212-l, handheld units 212-h, and the like. The PCs 212 are each connected to a respective Subscriber Access Unit (SAU) 214 by a suitable wired connection, for example in the form of an ethernet.

Subscriber Access Unit (SAU) 214 permits its associated Personal Computer (PC) 212 to connect to the network file server 230 through the Base Station Processor (BSP) 220, Internet Gateway (IG) 222, and network 224. In the reverse link direction, that is, on movement by the Personal Computer (PC) 212 towards the server 230 for data traffic, the Personal Computer (PC) 212 provides Internet Protocol (IP) layer packets to the Subscriber Access Unit (SAU) 214. The Subscriber Access Unit (SAU) 214 then encapsulates the wired frames (i.e., ethernet frames) with the appropriate radio connection frames and coding. The appropriately formatted wireless data packet then travels over one of the wireless channels comprising the reverse link 50 through the antennas 216 and 218. At the central base station location, the Base Station Processor (BSP) 220 then takes the radio link frame, reformats it into an internet communication protocol (IP) form, and hands it off to the Internet Gateway (IG) 222. The packets are then routed through any number and/or any form of transmission control/network communication protocol (TCP/IP) network, such as the internet 224, and to their final destination, such as a network file server 230.

Data may also be transmitted from the network file server 230 to the Personal Computer (PC) 212 in the forward link 40 direction. In this case, internet communication protocol (IP) packets originating at the file server 230 travel through the internet 224 and the Internet Gateway (IG) 222, and arrive at the Base Station Processor (BSP) 220. Appropriate wireless communication protocol frames and encodings are then added to the internet communication protocol (IP) packets. The packets then travel through the antennas 216 and 218 to reach the intended receiver Subscriber Access Unit (SAU) 214. The receiving Subscriber Access Unit (SAU) 214 decodes the wireless packet format and hands off the packets to the intended Personal Computer (PC) 212, which implements the Internet Protocol (IP) layer processing.

The known Personal Computer (PC) 212 and the file server 230 can thus be regarded as end points of a duplex connection at the Internet Protocol (IP) layer. Once a connection is established, a user at the Personal Computer (PC) 212 may transmit data to the file server 230 and receive data from the file server 230.

From the perspective of the second group of users 210, the reverse link 50 is actually comprised of a plurality of different types of logical and/or physical radio channels, including an access channel 251, a plurality of traffic channels 252-1, …, 252-t, and a maintenance channel 253. The reverse link access channel 251 is used by the Subscriber Access Units (SAUs) 214 to communicate information to the Base Station Processor (BSP) 220 for its granted traffic channel requests. The designated traffic channel 252 then carries payload data from the Subscriber Access Unit (SAU) 214 to the Base Station Processor (BSP) 220. It should be appreciated that it is known that an Internet Protocol (IP) layer connection may actually have more than one designated traffic channel 252. In addition, a maintenance channel 253 may carry information such as synchronization and power control information to further support the transmission of information throughout the reverse link 50.

Similarly, the second group of users 210 has a forward link 40 that includes a paging channel 251, a plurality of traffic channels 242-1, …, 242-t, and a maintenance channel 243. The paging channel 251 is used by the Base Station Processor (BSP) 220 to inform the Subscriber Access Unit (SAU) 214 of not only its allocated forward link traffic channel 252, but also the allocated traffic channel 252 in the reverse link direction for the Subscriber Access Unit (SAU) 214. In an alternative embodiment, the Base Station Processor (BSP) 220 does not delegate the assigned traffic channel 252 in the reverse link direction; for example, a slotted ALOHA technique may be used. Traffic channels 242-1, …, 242-t on the forward link 40 are then used to carry payload data information from the Base Station Processor (BSP) 220 to the Subscriber Access Unit (SAU) 214. Further, on the forward link 40, the maintenance channel 243 carries synchronization and power control information from the Base Station Processor (BSP) 220 to the Subscriber Access Units (SAUs) 214.

The sequence of signal processing operations is typically performed to encode the respective reverse link 50 logical channels 251, 252, and 253. In the reverse link direction, the transmitter is one of the Subscriber Access Units (SAUs) 214 and the receiver is the Base Station Processor (BSP) 220. The preferred embodiment of the present invention IS implemented in the context of a Code Division Multiple Access (CDMA) digital cellular telephone system where legacy users are also present in the reverse link 50, such as those operating in accordance with the IS-95B standard. In an IS-95B system, reverse link Code Division Multiple Access (CDMA) channel signals are identified by means of assigned non-orthogonal pseudo-random noise (PN) codes.

Attention is now directed to fig. 2, which will describe in detail the channel coding process for the first legacy user cluster 110. This first user class includes, for example, digital Code Division Multiple Access (CDMA) cellular telephone system users that encode signals according to the IS-95B standard as described above. The respective channels are thus identified by the modulation of the input digitized audio signal using a pseudo-random noise (PN) code sequence for each channel. Specifically, the channel encoding process will take an input digital signal 302 representing the information being transmitted. The quadrature modulator 304 provides in-phase (i) and quadrature (q) signal paths to a pair of multiplexers 306-i and 306-q. A short pseudo-random noise (PN) code generator 305 provides a short length (in this case 2) for spectral dispersion purposes^15-1Or 32767 bits). The short code is generally the same code for each logical channel of the first cluster 110.

A second code modulation step multiplexes the two signal paths with additional long pseudo-random noise (PN) codes applied to the in-phase (i) and quadrature-phase (q) signal paths. This is accomplished by the long code generator 307 and the long code multiplexers 308-i and 308-q. The long code provides a unique identification of each user on the reverse link 50. The long code may be a very long code, for example, only every 2^42-1Repeated at the bit. The long code is applied at the short code chip rate, e.g., one of the long codesBits are applied to each bit output by the short code modulation process, thus not creating additional spectral dispersion.

Individual users may be identified by applying different phase offsets of the pseudo random noise (PN) to each user. It should be appreciated that no other synchronization steps need be performed for the first group of users 110. In particular, these transmissions on the reverse link 50 are designed to be asynchronous and therefore do not need to be perfectly orthogonal.

Fig. 3 is a detailed diagram of the channel coding process for the second group of users 210. The second cluster 210, for example, includes wireless data users that perform signal encoding according to the optimal format for data transmission.

The respective channels are identified using input data modulated with a Pseudorandom Noise (PN) code sequence in the same manner as for the first group of users 110. However, it can be readily appreciated that the channels in the second cluster 210 are uniquely identified using a particular orthogonal code, such as Walsh Codes. Specifically, the channel coding process for this second group of users 210 takes the input digital signal 402 and applies a plurality of codes generated by a short Code generator 405, a Walsh Code generator 413, and a long Code generator 407.

As a first step, quadrature modulator 404 provides in-phase (i) and quadrature (q) signal paths to first multiplexer pairs 406-i and 406-q. The short pseudo-random noise (PN) code generator 405 provides a short length, in this case 2, for spectral dispersion purposes¹⁵The code of (2). The short code is the same as the short pseudo-random noise (PN) code used in each channel of the first cluster 110.

The second step of this process is to apply orthogonal codes, such as those generated by a Walsh Code generator 413. This is accomplished by the multiplexers 412-i and 412-q imprinting the orthogonal codes on each of the in-phase and orthogonal signal paths. The orthogonal code assigned to each logical channel is different and uniquely identifies these channels.

In the final step of this process, a second pseudo-random noise (PN) long code is applied to the in-phase (i) and quadrature phase difference (q) signal paths. The long code generator 407 thus forwards the long code to a respective one of the in-phase 408-i and quadrature 408-q multiplexers. This long code does not uniquely identify each user in the second cluster 210. Specifically, this code may be one of the very same long codes used in the first cluster that uniquely identifies the first cluster of users 110. Thus, for example, it is applied in the same manner as a short code chip rate code, so that one bit of the long code is applied to each bit output by the short code modulation process. In this approach, all users in the second cluster 210 will appear to the first cluster 110 as a single legacy user. In any event, the users of the second cluster 210 may be uniquely identified if they have been designated with unique orthogonal Fahrenheit codes.

As implemented in the preferred embodiment, additional information is fed back on the reverse link 50 to maintain orthogonality between different users in the second cluster 210. Specifically, maintenance channel 243 is thus included in the forward link 40. A maintenance channel or "center" channel 253 is also present in the reverse link 50 and provides synchronization information and/or other timing signals so that the remote unit 214 can transmit appropriate synchronization thereto. The maintenance channel may also be distinguished as a time slot. For details of the format of this reverse link maintenance channel, reference may be made to co-pending document U.S. patent Application Serial No.09/775,305, filed on 2/1/2001, entitled "MAINTENANCE LINK use ACTIVE/standby request CHANNELS," which is hereby incorporated by reference in its entirety.

It should be appreciated that the certain infrastructure may thus be shared by the second group of users 210 with the first group of users 110. For example, although shown as separate base station antennas in fig. 1, the antennas 218 and 118 may indeed be a shared antenna. Likewise, the position of the antennas may thus be the same. This allows the second group of users 210 to share equipment and physical construction locations already used by the legacy users 110. This greatly simplifies the wireless infrastructure development for the new second group of users 210, for example, without the need to establish new locations and new antenna points.

The Base Transceiver Station (BTS) 120 and Base Station Processor (BSP) 220 may combine (i.e., synchronize) the timing of the Base Transceiver Station (BTS) 120 and Base Station Processor (BSP) 220 by (i) communicating directly between each other via a communication link (not shown), (ii) responding to inputs from the Base Station Controller (BSC) 123, and (iii) communicating indirectly via the network 124, 224. Synchronization is useful for time aligning the reverse link 50 and ensuring proper switching of legacy and non-legacy users 110, 210 when moving from the Base Transceiver Station (BTS) 120 to the Base Station Processor (BSP) 220, or vice versa.

In addition, reverse link power control from the legacy users 113 and Subscriber Access Units (SAUs) 214 can be performed using different techniques. For example, both the Base Transceiver Station (BTS) 120 and the Base Station Processor (BSP) 220 may present power commands or information to the subscribers 110, 210. The Subscriber Access Units (SAUs) 214 and users 113 may, for example, (i) increase the power of their respective reverse link signals by a smaller amount if both the Base Transceiver Station (BTS) 120 and the Base Station Processor (BSP) 220 indicate that the increased power should be used and (ii) decrease the power of their reverse link signals by a larger amount (i.e., by more negative values) if both the Base Transceiver Station (BTS) 120 and the Base Station Processor (BSP) 220 indicate that the decreased power should be used. If one of them indicates to raise the power and the other indicates to lower the power, the affected Subscriber Access Unit (SAU) 214 in this example lowers its power. Alternative reverse link signal power control techniques may also be used.

Fig. 4 is a diagram of a multi-path (i.e., "multipath") environment 400 in which one of the users in the second cluster is in communication with the Base Transceiver Station (BTS) 120. In this example, the user utilizes a Subscriber Access Unit (SAU) 214-1, which is used in an automobile 401, to communicate in the reverse link with the Base Station Processor (BSP) 220 through the antenna tower 118. In this figure, the reverse link signal utilizes multiple paths 405, 405' (collectively 405) between the Subscriber Access Unit (SAU) 214-1 and the Base Station Processor (BSP) 220 as it is transmitted in a multipath environment 400. In this example, the multipath environment 400 is formed by a man-made structure 402 (i.e., a building) having electromagnetic properties that reflect Radio Frequencies (RF). The multipath 405 is also referred to as a reverse link primary path 405 and a reverse link secondary path 405'. Due to the two or more paths, the same number of reverse link signals 410, 410' (collectively 410) having a common long orthogonal code and a unique orthogonal code such as a walsh code (or other suitable, orthogonal code as described with reference to fig. 3) may be received at the Base Station Processor (BSP) 220.

Because the two reverse link signals 410, 410 'having the same unique orthogonal code are received at the Base Station Processor (BSP) 220, the Base Station Processor (BSP) 220 has an opportunity to implement diversity selection of the reverse link signals 410, 410'. The Base Station Processor (BSP) 220 may select, for example, the reverse link signal 410, 410' with the highest signal-to-noise ratio (SNR) to maximize the reverse link communication performance between the subscriber unit 214-1 and the Base Station Processor (BSP) 220. Other units of measure may also be used to select the "best" reverse link signal from the subscriber unit 214-1.

After selecting the "best" reverse link signal, the Base Station Processor (BSP) 220 determines an overall timing offset for the selected reverse link signal 410 based on the timing offsets for the reverse link signals from the other subscriber units 214-2, …, 214-h in the second cluster 210 (fig. 1) since the selected reverse link signal 410 should be orthogonally aligned. The Base Station Processor (BSP) 220 transmits the overall timing offset to the Subscriber Access Unit (SAU) 214-1 in the forward link 415 to align the selected reverse link signal 410 with the reverse link signals from the other subscriber units 214-2, …, 214-h. A fine timing offset is also transmitted in the forward link 415. The gross and fine timing offset feedback may also be transmitted to the subscriber unit 214-1 in the form of timing commands or timing reports.

In the case of timing reporting, the subscriber unit 214-1 autonomously shifts the phase of the long code (i.e., the orthogonal code common to the long codes used by the other subscriber units in the cluster) to orthogonally align with the long codes of the other subscriber units, thereby making the second group of users 210 appear to be a single user to the first group of users 110.

The Base Station Processor (BSP) 220 may also determine the power level of the selected reverse link signal and provide feedback of the power level to the subscriber unit 214-1 in the form of commands or reports. The Base Station Processor (BSP) 220 may also determine whether the signal-to-noise ratio (SNR) of the selected reverse link signal meets a quality threshold. The quality threshold may also comprise at least one of: (a) the unit of measure of the secondary path (or alternative or candidate) exceeds a threshold for a predetermined period of time, (b) the unit of measure of the secondary path exceeds a threshold for a predetermined period of time relative to the primary path, (c) the unit of measure of the primary path falls below an absolute unit of measure, and (d) the unit of measure of the secondary path exceeds an absolute unit of measure. The unit of measure may comprise at least one of: (a) power, (b) signal-to-noise ratio (SNR), (c) power variation, (d) signal-to-noise ratio (SNR) variation, (e) relative ratio of power, signal-to-noise ratio (SNR), or variation of two paths, (f) bit error rate, and (g) energy per chip divided by interference density (Ec/Io). An alternate path is then represented as a reverse link signal received by the Base Transceiver Station (BTS) receiver at a different phase from the reverse link signal at a phase that is orthogonally aligned with the reverse link signals of other field units in the same cluster.

The power level feedback may cause the subscriber unit 214-1 to adjust the power level of the encoded signal in response to the feedback. For example, the Base Transceiver Station (BTS) 120 may cause the timing of the reverse link signal to be shifted by utilizing the overall and fine timing offsets to cause phase shifting of long codes in the subscriber unit when (i) the signal-to-noise ratio (SNR) of the selected path does not meet the quality threshold, or (ii) the signal-to-noise ratio (SNR) of the non-selected path meets the quality threshold. The phase shift of the long code causes the "best" reverse link signal to be time aligned with the reverse link signals from other subscriber units utilizing the same long code.

Fig. 5 is a block diagram of the Base Station Processor (BSP) 220 and an example of a processing unit 505 and 520 that may be used by the Base Transceiver Station (BTS) 120 to determine the overall timing offset 417. The processing unit includes a receiver 505, an associator 510, a selector 515 and a quadrature timing controller 520.

In operation of the multipath environment 400, the Base Station Processor (BSP) 220 receives multipath reverse link signals 410, 410' from the antenna tower 118 at the receiver 505. The receiver 505 receives the multipath reverse link signal 410, 410', which contains the same common code and unique orthogonal codes, to be moved from the subscriber unit 214-1 to the Base Station Processor (BSP) 220 on the primary path 405 and at least one secondary path 405'.

The receiver 505 outputs the same number of reverse link signals (i.e., corresponding to the number of reverse link paths 405, 405' in the multi-path environment 400), each including the common code and unique orthogonal codes. After processing by the receiver 505, each of the received reverse signals 410, 410 'is transmitted to the correlator 510 and the quadrature timing controller 520 in the form of baseband signals 412, 412'. The correlator 510 correlates a unit of measure with the data of each received reverse link signal 410, 410'. The correlator 510 transmits the metric and reverse link signal data to the selector 515 to select the reverse link signal 410, 410' associated with the best metric. In other words, the reverse link signals 410, 410' that provide the best signals for reverse link communications will be selected to be orthogonally aligned with the reverse link signals from the other subscriber units 214-2, …, 214-h in the second cluster 210.

The selector 515 transmits information 517 corresponding to the selected reverse link signal to the orthogonal timing controller 520. Based on the information 517, the quadrature timing controller 520 processes the correlated (i.e., "best") reverse link signal and determines the gross and fine timing offsets 417 and 418. The controller 520 determines the offsets 417, 418 based on the selected reverse link signal timing for reverse link signals from other subscriber units 214-2, …, 214-h utilizing the same long code, as discussed with reference to fig. 3.

With continued reference to fig. 5, the gross and fine timing offsets 417 and 418 are communicated to a transmitter (Tx) 525. The transmitter (Tx) 525 transmits the overall and fine timing offsets 417 to the sum 418 to the Subscriber Access Unit (SAU) 214-1 on the forward link 415 as discussed with reference to fig. 4. It should be appreciated that the quadrature timing controller 520 may also propose the overall and fine timing offsets 417 and 418 to communicate to the subscriber unit 214-1 by first communicating the overall timing offset 417 and then determining the fine timing offset 418 by the quadrature timing controller 520 after the reverse link signals from the other subscriber units 214-2, …, 214-h have been transferred close enough in quadrature alignment with the reverse link signals.

Fig. 6 is a timing diagram 605 that depicts the timing of the reception of the plurality of reverse link signals 410, 410' from five field units a-E in the context of the multipath environment 400. The timing diagram 605 includes signals, indicated by vertical marks, for a group of five field units a-E (e.g., 214-1, 214-2, 214-3, 113-1, and 214-h) operating in a multipath environment. The field units a-C and E are non-legacy wireless devices that have the ability to make a common code overall phase offset for transmission in the reverse link, as well as the ability to include unique orthogonal codes in the transmission reverse link to distinguish the reverse link signal from other non-legacy subscriber units. The field unit D is a conventional wireless device that does not support unique orthogonal codes in the reverse link signal nor the overall phase offset of the common code.

When the reverse link signals of the non-legacy field units a-C and E are in orthogonal alignment, and thus appear as a single field unit, the timing of each reverse link facilitates alignment at a common alignment time 610 according to the unique orthogonal code. However, in a multipath scenario for a known field unit, where the majority of reverse link signals transmitted by the known field unit are received at the base station 120 and identified by the same unique orthogonal code (e.g., the walsh code described with reference to fig. 1), the base station 120 may select one of the majority of reverse links to align at the common alignment time 610.

For example, with continued reference to fig. 6, field unit a has the same reverse link signal received at both ends in time as the Base Station Processor (BSP) 220, as indicated by reference numerals 615 and 615'. In this embodiment, for the received field unit a reverse link signal represented by the reference numeral, the offset timing and signal metric are determined by the correlator 510 (fig. 5). Based on the signal metric units, the selector 515 determines which of the two reverse link signals 615, 615' will be aligned with the reverse link signals of the other field units in the same cluster (i.e., field units B, C and E) at the common alignment time 610. In the field unit a case of this example, the reverse link signal 615 closer to the common alignment time 610 will be selected for use by the Base Station Processor (BSP) 220 based on the signal metric. Accordingly, the Base Station Processor (BSP) 220 proposes an overall timing offset 417, which corresponds to the offset timing, to align the selected reverse link signal 615 at the common alignment time 610. Field unit a shifts the phase of the common long code to align with the reverse link signals of the field units B, C and E. Naturally, the other received reverse link signal 615' from the field unit a is shifted by the same amount due to the long quadrature code phase shift.

The field units B are aligned at a common alignment time 610 and are not located in a multipath environment as determined by the single reference label along their timing lines. Thus, the Base Station Processor (BSP) 220 does not need to determine whether the reverse link received non-aligned has a higher unit of measure or whether the Base Station Processor (BSP) 220 needs to feedback a decision on the timing offset to the field unit B.

Field unit C is another field unit located in multipath environment 400. In the case of field unit C, the selector 515 at the Base Station Processor (BSP) 220 determines whether the received reverse link signal 625 is aligned with other field unit reverse links having a smaller unit of measure than the non-aligned reverse link signal 625'. It should be appreciated that the non-aligned reverse link signal 625' can be a reverse link signal moving in the primary path or the secondary path. In either case, the Base Station Processor (BSP) 220 transmits an overall timing offset 417 for shifting the long code to align with the second reverse link signal 625' at the common alignment time 610. The other received reverse link signal 625 is thus shifted out of the orthogonal alignment.

The field unit D is a legacy field unit and its reverse link signal is not aligned with the non-legacy field units a-C and E. If the reverse link of other field units are aligned with the reverse link signal from field unit D, destructive interference may result because the field unit D does not include the unique orthogonal code, as is the case with non-legacy field units a-C and E.

In the case of field unit E, its reverse link signals are aligned at a common alignment time 610 without being affected by the multipath environment; therefore, no timing adjustment is required for this reverse link signal.

Fig. 7 is a flowchart illustrating the processes 700 and 765 performed by the Base Station Processor (BSP) 220 and the Subscriber Access Unit (SAU) 214-1, respectively, according to the previous description. In this embodiment, the Subscriber Access Unit (SAU) 214-1 processes 765 (step 745) and transmits a reverse link signal having a common long code and a unique orthogonal code to the Base Station Processor (BSP) 220 (step 750). In the multipath environment 400, a primary path 405 and a secondary path 405', which may be naturally occurring or artificially created, are the paths along which the reverse link signals 410, 410' travel to the Base Station Processor (BSP) 220.

The Base Station Processor (BSP) processing 700 begins (step 705) and receives the reverse link signals 410, 410' (step 710). The Base Station Processor (BSP) process 700 associates a unit of measure with each of the received reverse link signals 410, 410' (step 715). Based on the metric units, the Base Station Processor (BSP) process 700 selects the "best" reverse link signal from among the reverse link signals received in each of the primary and secondary paths 405, 405' from the Subscriber Access Unit (SAU) 214-1 (step 720).

The Base Station Processor (BSP) process 700 determines whether the selected reverse link signal is orthogonally aligned with the reverse link signals from other subscriber units using the common long code (see fig. 6) (step 725). If the best reverse link signal (720) from the Subscriber Access Unit (SAU) 214-1 is orthogonally aligned, the Base Station Processor (BSP) processing 700 ends (step 740) without sending timing adjustment information back to the Subscriber Access Unit (SAU) 214-1 or, in an alternative embodiment, a zero phase shift. If the best reverse link signal is not orthogonally aligned with the reverse link signals of other subscriber units utilizing the common long code, the Base Station Processor (BSP) processing 700 determines an overall time offset (step 730) and transmits the overall time offset (step 735) to the Subscriber Access Unit (SAU) 214-1.

The receipt 765 of the overall time offset 417 by the Subscriber Access Unit (SAU) 214-1 process will cause the Subscriber Access Unit (SAU) 214-1 to establish a common long code coarse phase adjustment in the reverse link signal (step 755). The Subscriber Access Unit (SAU) process 765 may terminate (step 760) or continue (not shown) to receive the overall or fine timing offset from the Base Transceiver Station (BTS) 120, as discussed with reference to fig. 5.

It should be understood that the processes described herein may be implemented in hardware, firmware, or software. Where implemented in software, the software may be stored on a computer readable medium such as Random Access Memory (RAM), Read Only Memory (ROM), compact disc read only memory (CD-ROM), magnetic or optical disk, or other computer readable medium. The software may be loaded from memory and executed by a processor, such as a general or special purpose processor, operating in the Base Station Processor (BSP) 220 and optionally in the Base Transceiver Station (BTS) 120. Similarly, processes implemented in software in the subscriber unit may also be stored on a computer readable medium and executed by an operating processor therein.

It should be appreciated that a single user in the second cluster 210 may use more than one unique orthogonal (fahrenheit) code. For example, the user may have a significant load to deliver to the Base Station Processor (BSP) 220, so the user may utilize two channels, each identified by a unique orthogonal code from which the user is based. Similarly, in another embodiment or network environment, the long code may be a short code, an orthogonal code, or other code that may use the same purpose as the long code described above.

In addition, it should be understood that the present invention may also be applied to other wireless networks. For example, in an 802.11 Wireless Local Area Network (WLAN), an Access Point (AP) performs the same processing described herein as the Base Transceiver Station (BTS), while a client station performs the same processing described herein as the field unit/subscriber access unit.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention encompassed by the appended claims.

Claims (6)

1. A wireless network, the wireless network comprising:

means for receiving first communications from a first plurality of users utilizing conventional Telecommunications Industry Association (TIA) Code Division Multiple Access (CDMA) standards, wherein each of the first communications includes voice data and has a pseudo-noise (PN) code unique to its associated user; and

means for receiving second communications from a second plurality of users utilizing non-TIA CDMA standards, wherein each of the second communications transmitted from the second plurality of users includes Internet Protocol (IP) data.

2. The wireless network of claim 1, wherein the second plurality of users transmit a maintenance channel when not transmitting IP data, and the maintenance channel transmissions of the second plurality of users have a common PN code.

3. A method, the method comprising:

receiving, by a wireless network, first communications from a first plurality of users utilizing conventional Telecommunications Industry Association (TIA) Code Division Multiple Access (CDMA) standards, wherein each of the first communications includes voice data and has a pseudo-noise (PN) code unique to its associated subscriber unit; and

receiving, by a wireless network, a second communication from a second plurality of users utilizing non-TIA CDMA standards, wherein each of the second communications transmitted from the second plurality of users includes Internet Protocol (IP) data.

4. The method of claim 3, wherein the second plurality of users transmit a maintenance channel when not transmitting IP data, and the maintenance channel transmissions of the second plurality of users have a common PN code.

5. A system, the system comprising:

a first plurality of subscriber access units (SACs) that utilize a conventional Telecommunications Industry Association (TIA) Code Division Multiple Access (CDMA) standard to transmit first communications, wherein each of the first communications includes voice data and has a pseudo-noise (PN) code unique to its associated SAC;

a second plurality of SACs that utilize non-TIA CDMA standards to transmit second communications, wherein each of the second communications transmitted from the second plurality of users includes Internet Protocol (IP) data; and

a radio network node, the radio network node comprising:

means for receiving the first communication from the first plurality of SACs utilizing the conventional standard TIA CDMA standard; and

means for receiving the second communication from the second plurality of SACs utilizing the non-TIA CDMA standard.

6. The system of claim 5, wherein the second plurality of SACs transmit a maintenance channel and the maintenance channel transmissions of the second plurality of SACs have a common PN code when IP data is not being transmitted.