HK1119311B - Method and system for achieving space and time diversity gain in wireless communication system - Google Patents

Description

Method and system for achieving space-time diversity gain in a wireless communication system

Technical Field

The present invention relates to wireless communication systems, and more particularly, to a method and system for achieving space-time diversity gain.

Background

In most current wireless communication systems, nodes in the network may be configured to operate based on a single signal receiving antenna and a single signal transmitting antenna. However, in many wireless communication systems today, the use of multiple transmit and/or receive antennas may improve the overall performance of the system. These multiple antenna configurations, also known as smart antenna techniques, may be used to reduce the negative effects of multipath and/or signal interference on signal reception. For example, currently applied CDMA-based systems, TDMA-based systems, WLAN systems, and OFDM-based systems (e.g., ieee802.11a/g/n) may benefit from the configuration of multiple transmit and/or receive antennas. It is estimated that smart antenna technology may be applied more and more widely to address the increasing system capacity demands as the base station infrastructure and mobile user terminals in cellular systems evolve. These needs stem in part from the transition of current voice communication services to the next generation of wireless multimedia services that provide voice, video, data.

The use of multiple transmit and/or receive antennas introduces diversity gain and array gain and suppresses interference caused during signal processing. These diversity gains improve system performance because they increase signal-to-noise ratio, improve robustness to signal interference, and/or provide more frequency reuse for higher capacity. In a communication system employing a multi-antenna receiver, M receive antennas may be used to cancel the effects of (M-1) interference. Accordingly, N signals can be simultaneously transmitted over the same bandwidth with N transmit antennas, and then the transmitted signals are divided into N signals by N antennas arranged at the receiver side. Systems using multiple transmit and multiple receive antennas are referred to as multiple-input multiple-output (MIMO) systems. One advantageous aspect in multi-antenna systems, particularly MIMO systems, is that the use of such transmission configurations significantly increases system capacity. For the case where the total transmit power is fixed, the capacity provided by the MIMO configuration may be proportional to the increased signal-to-noise ratio (SNR).

However, multi-antenna systems, due to their resulting increase in size, complexity, and power consumption, have limited their widespread use in wireless communication multi-antenna systems, particularly in wireless handheld devices. Providing a separate rf chain for each transmit and receive antenna is a factor that directly increases the cost of the multiple antenna system. Each radio frequency link includes a Low Noise Amplifier (LNA), a filter, a down converter, an analog-to-digital converter (a/D). In some existing single antenna wireless receivers, the individual rf links may account for 30% of the total receiver cost. It is therefore clear that as the number of transmitter and receiver antennas increases, the complexity, power consumption and overall cost of the system increases.

In the case of multiple antennas with only one radio frequency link, different propagation channels need to be decided or estimated. A simple method includes switching to a first receive antenna using a radio frequency switch and estimating a first propagation channel. After the first propagation channel is estimated, another receiving antenna is selected and its corresponding propagation channel is estimated. The method may be repeated until all channels are estimated. However, switching between receive antennas may disturb the modem of the receiver and may reduce throughput. Moreover, this approach requires more hardware and results in propagation channel estimation at different time intervals.

Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.

Disclosure of Invention

A method and/or system for achieving space-time diversity gain, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.

According to an aspect of the present invention, there is provided a method for diversity processing in a wireless communication system, comprising:

modifying a spreading code (generation code) of at least one pilot channel to measure a signal strength for each of a plurality of received multipath signals;

partially combining the plurality of received multipath signals based on the measured signal strengths.

Preferably, the method further comprises measuring signal to noise ratios (SNRs) of the plurality of received multipath signals.

Preferably, the method further comprises measuring signal strengths of the plurality of received multipath signals on a first pilot channel by nulling the spreading code.

Preferably, the method further comprises measuring signal strengths of the plurality of received multipath signals on a second pilot channel by assigning a non-zero value to the spreading code.

Preferably, the method further comprises combining portions of the plurality of received multipath signals having a signal to noise ratio above a certain threshold.

Preferably, the method further comprises combining the portions of the plurality of received multipath signals based on a maximum ratio combining algorithm.

Preferably, the method further comprises generating at least one of: multipath signal timing information, antenna indices, and maximum ratio combining weights for combined portions of the plurality of received multipath signals.

According to another aspect of the present invention, there is provided a machine-readable storage, having stored thereon, a computer program having at least one code section for implementing diversity gain in a communication network, the at least one code section being executable by a machine for causing the machine to:

modifying a spreading code of at least one pilot channel to measure a signal strength for each of a plurality of received multipath signals;

partially combining the plurality of received multipath signals based on the measured signal strengths.

Preferably, the machine-readable storage further comprises code for measuring signal-to-noise ratios of the plurality of received multipath signals.

Preferably, the machine-readable memory further comprises code for measuring signal strengths of the plurality of received multipath signals on the first pilot channel by nulling the spreading code on the first pilot channel.

Preferably, the machine-readable storage further comprises code for measuring signal strengths of the plurality of received multipath signals on a second pilot channel by assigning a non-zero value to the spreading code.

Preferably, the machine-readable storage further comprises code for combining portions of the plurality of received multipath signals having a signal to noise ratio above a certain threshold.

Preferably, the machine-readable memory further comprises code for combining the portions of the plurality of received multipath signals based on a maximum ratio combining algorithm.

Preferably, the machine-readable storage further comprises code for generating at least one of: multipath signal timing information, antenna indices, and maximum ratio combining weights for combined portions of the plurality of received multipath signals.

According to another aspect of the present invention, there is provided a system for achieving diversity gain in a communication network, the system comprising:

circuitry for modifying the generalized code of at least one pilot channel to measure signal strength for each of a plurality of received multipath signals;

circuitry to partially combine the plurality of received multipath signals based on the measured signal strengths.

Preferably, the system further comprises circuitry for measuring signal to noise ratios of the plurality of received multipath signals.

Preferably, the system further comprises circuitry for measuring the signal strength of the plurality of received multipath signals on a first pilot channel by nulling the spreading code.

Preferably, the system further comprises circuitry for measuring signal strengths of the plurality of received multipath signals on a second pilot channel by assigning a non-zero value to the spreading code.

Preferably, the system further comprises circuitry for combining portions of the plurality of received multipath signals having a signal to noise ratio above a certain threshold.

Preferably, the system further comprises circuitry for combining the portions of the plurality of received multipath signals based on a maximum ratio combining algorithm.

Preferably, the system further comprises circuitry to generate at least one of: multipath signal timing information, antenna indices, and maximum ratio combining weights for combined portions of the plurality of received multipath signals.

Various advantages, aspects and novel features of the invention, as well as details of an illustrated embodiment thereof, will be more fully described in the following description and drawings.

Drawings

FIG. 1A is a block diagram of a wireless communication system with 2 transmit antennas and M receive antennas with multiple radio frequency chains and receiver channel estimation, according to one embodiment of the present invention;

fig. 1B is a schematic diagram of a rake receiver (rake receiver) used in conjunction with one embodiment of the present invention;

fig. 2 is a schematic diagram of a finger structure for multipath diversity according to one embodiment of the present invention;

fig. 3 is a schematic diagram of an antenna and multipath diversity finger configuration according to one embodiment of the present invention;

FIG. 4 is a block diagram of a baseband processor for a MIMO system according to one embodiment of the present invention;

fig. 5 is a schematic structural diagram of a selection control unit for selecting a plurality of strongest signal paths according to an embodiment of the present invention;

FIG. 6 is a comparison of the performance of a wireless receiver in a first test case according to an embodiment of the present invention;

FIG. 7 is a diagram illustrating a comparison of the performance of a wireless receiver in a second test case according to an embodiment of the present invention;

FIG. 8 is a performance comparison diagram of a wireless receiver in a sixth test example in accordance with one embodiment of the present invention;

FIG. 9 is a graphical representation of a comparison of the performance of a wireless receiver in a sixth test case with a higher slot update rate, in accordance with one embodiment of the present invention;

FIG. 10 is a comparison of the performance of a wireless receiver in a third test example in accordance with one embodiment of the present invention;

fig. 11 is a diagram illustrating a comparison of the performance of a wireless receiver due to soft hand-off (SHO) according to an embodiment of the present invention.

Detailed Description

Various embodiments of the present invention relate to a method and system for achieving space-time diversity gain. The method of the present invention includes modifying the generalized code of at least one pilot channel to measure the strength of each of a plurality of received multipath signals. Based on the measured signal strengths, a portion of the plurality of received multipath signals may be combined. The signal strengths of the plurality of received multipath signals may be measured on the first pilot channel by nulling their generalized codes. The signal strengths of the plurality of received multipath signals may also be measured on the second pilot channel by assigning their generalized codes to non-zero values.

Fig. 1A is a block diagram of a wireless communication system with 2 transmit antennas and M receive antennas with multiple radio frequency chains and receiver channel estimation, according to one embodiment of the present invention. Ginseng radix (Panax ginseng C.A. Meyer)Referring to fig. 1A, the wireless communication system 100 includes, at a transmitting end, a Dedicated Physical Channel (DPCH) module 126, a plurality of mixers 128, 130, 132, a plurality of combiners 134 and 136, a first transmit antenna (tx 1)138, and an additional transmit antenna (tx 2) 140. At the receiving end, the wireless system 110 comprises a plurality of receiving antennas 106_1...MA Single Weight Generator (SWG)110, a plurality of Radio Frequency (RF) modules 114_1...PA plurality of Chip Matched Filters (CMFs) 116_1...PA baseband (BB) processor 126, a single weight generating baseband processor (SWGBB) 121. SWGBB 121 includes a channel estimator 122 and a Single Weight Generator (SWG) algorithm module 124.

The DPCH 126 is used to receive a plurality of input channels, e.g., a Dedicated Physical Control Channel (DPCCH) and a Dedicated Physical Data Channel (DPDCH). The DPCH 126 may control the power of the DPCCH and DPDCH simultaneously. The mixer 128 is used to mix the output of the DPCH 126 with spread and/or scrambled signals to produce spread complex-valued signals as inputs to mixers 130 and 132. Mixers 130 and 132 each use a weighting factor W₁And W₂The input complex-valued signals are weighted and outputs are generated to a plurality of combiners 134 and 136, respectively. Combiners 134 and 136 combine the outputs produced by mixers 130 and 132 with common pilot channel 1(CPICH1) and common pilot channel 2(CPICH2), respectively. Common pilot channels 1 and 2 have a fixed channel code assignment that is used to measure the phase amplitude signal strength of the channel. For example, the Single Weight Generator (SWG) algorithm module 124 may use the weight W₁And W₂And generates phase and/or amplitude adjustment values. Antennas 138 and 140 may receive the resulting output from combiners 134 and 136 and may transmit wireless signals.

Multiple receive antennas 106_1...MEach receiving antenna receives at least a portion of the transmitted signal. The SWG110 may comprise suitable logic, circuitry, and/or code that may enable determination of the input signals R to apply to each input signal R_1...MA plurality of weights. The SWG110 may be used to modify the reception from multiple receive antennas 106_1...MThe phase and amplitude of a portion of the received transmission signal and producing a plurality of output signals RF_1...P。

Radio frequency module 114_1...PComprising suitable logic, circuitry, and/or code that may enable processing of radio frequency signals. Radio frequency module 114_1...PSuch as filtering, amplification and analog-to-digital (a/D) conversion operations can be performed. Multiple transmit antennas 138 and 140 transmit the processed rf signals to the receive antenna 106_1...M. The single weight generator SWG110 may comprise suitable logic, circuitry, and/or code that may enable determination of the weights to be applied to each input signal. Single weight generator SWG110 may be used to modify the received signals from multiple receive antennas 106_1...MThe phase and amplitude of at least a part of the resulting signal and generating a plurality of output signals RF_1...P. Multiple RF receiving modules 114_1...PComprising suitable logic, circuitry and/or code that may enable RF coupling of received analog radio frequency signals_1...PAmplifies it and down-converts it to baseband. Multiple RF receiving modules 114_1...PEach of which includes an analog-to-digital (a/D) converter that digitizes the received analog baseband signal.

Multiple Chip Matched Filters (CMFs) 116_1...PComprises suitable logic, circuitry and/or code that may enable the RF receiver module 114 to be implemented_1...PThe output of which is filtered to produce in-phase (I) and quadrature (Q) components. With this in mind, in one embodiment of the invention, a plurality of Chip Matched Filters (CMFs) 116_1...PA pair of digital filters is included to filter the I and Q components within the bandwidth of the W-CDMA baseband (3.84 MHz). The outputs of the plurality of Chip Matched Filters (CMFs) will be passed to the baseband processor 126.

Baseband processor 126 may operate from a plurality of Chip Matched Filters (CMFs) 116_1...PReceiving in-phase and quadrature (I, Q) components and producing a plurality of baseband combined channel estimatesToThe baseband processor 126 may generate the original input spatial division multiplexed substream signal or symbol X₁To X_PMultiple estimated values ofToThe baseband processor 126 may use a BLAST (bell labs layered space time) algorithm to separate the different space-time channels, for example, by performing substream detection and substream cancellation. The capacity of transmission can be increased almost linearly using the algorithm of BLAST.

Multiple cluster path processor CPP118_1...PGenerating signals corresponding to multiple receive antennas 106_1...MBaseband combined channel estimateToThe channel estimator 122 may comprise suitable logic, circuitry, and/or code that may enable processing of the estimated values received from the baseband processor 126ToAnd produces a matrix H of processed estimated channels for use by a Single Weight Generator (SWG) algorithm module.

SWG algorithm module 124 may separately evaluate a plurality of amplitude values A₁Sum phase value phi₁These values are used by SWG110 to modify the received signals from multiple receive antennas 106_1...MThe phase and amplitude of a portion of the received transmission signal and producing a plurality of output signals RF_1...P。

Fig. 1B is a block diagram of a rake receiver used in conjunction with one embodiment of the present invention. Referring to fig. 1B, there is a rake receiver 150, a path searcher 152 and a channel estimator 154.

The rake receiver 150 includes a descrambler and despreader 156, an integration and dropping (MRC) module 158, and a Maximum Ratio Combining (MRC) module 160. The rake receiver 150 may be a radio frequency receiver designed to counter the effects of multipath fading using a plurality of sub-receivers. Each sub-receiver is delayed to match the individual multipath components. Each component may be decoded separately and then combined, resulting in a higher signal-to-noise ratio (or Eb/No) in a multipath environment.

In the rake receiver 150, one finger is assigned for each multipath to maximize the energy of the received signal. Each of the different multipath signals may be combined to form a composite signal having much better characteristics than the signal of a single path. The received signal may be split into multiple independent paths and combined with their corresponding channel estimates.

The descrambler and despreader 156 may comprise suitable logic, circuitry, and/or code that may be operable to multiply the scrambling code and the delayed version of the scrambling code by the received signal. The delay is determined by the path searcher 152 prior to descrambling. Each delay corresponds to a separate multipath that is combined by the rake receiver 150. The descrambler and despreader 156 despreads the descrambled data for each path by multiplying the descrambled data by a spreading code.

The integrate and ramp block 158 may comprise suitable logic, circuitry, and/or code that may enable integrating the despread data over a symbol period and generating a complex sample output for each Quadrature Phase Shift Keying (QPSK) symbol. This process may be performed for all paths combined by the rake receiver 150.

The MRC block 160 may comprise suitable logic, circuitry, and/or code that may enable combining the same symbols obtained via the different paths using corresponding channel information and a combining scheme such as Maximal Ratio Combining (MRC) and may generate an output signal.

The channel estimator 154 may comprise suitable logic, circuitry, and/or code that may enable estimating a phase and an amplitude of each identified channel. The channel phase and amplitude may be used to combine each path of the received signal.

The path searcher 152 may comprise suitable logic, circuitry, and/or code that may enable estimation of the delay of each path within the composite received signal. The received signal is delayed by a certain amount according to the value estimated by the path finder 152 and multiplied by the conjugate of the scrambling and spreading codes. For example, the descrambled and despread data may be combined in one symbol period.

In a W-CDMA downlink traffic channel, pilot symbols, e.g., 2 to 8 symbols and control symbols, may be transmitted in W-CDMA frame slots. For example, each W-CDMA frame has 15 slots, each frame is 10ms long. In the downlink of a W-CDMA system, the common pilot control channel (CPICH) will be transmitted at a higher power than the dedicated traffic channel. The CPICH may be received by all mobile terminals within a particular cell. For example, the CPICH may be transmitted with a constant Spreading Factor (SF)256 and a spreading code of all 1's. For example, there may be 10 symbols per slot and 150 symbols per CPICH frame. At the receiving end, CPICH symbols, which are pilot symbols, may be used for channel estimation.

Fig. 2 is a schematic diagram of a finger structure for multipath diversity according to one embodiment of the present invention. In fig. 2, a first common pilot channel (P-CPICH)201, a second common pilot channel (S-CPICH)203, a Dedicated Physical Channel (DPCH)205, a plurality of multiplexers 224 and 228, a received signal code power module (RSCP)230 are shown.

The P-CPICH 201 includes a receiver front end module 202, a descrambler 204, an accumulator 206, and an IIR filter 208. The S-CPICH 203 comprises a receiver front end 210, a descrambler 212, an accumulator 214, an IIR filter 216. DPCH 205 includes a receiver front end 218, a descrambler 220, an accumulator 222, and a channel compensation and decoding module 224.

The receiver front-end modules 202, 210, 218 may comprise suitable logic, circuitry, and/or code that may enable processing of RF signals received from the antenna 1. For example, the multiple receiver front ends 202, 210, 218 may perform filtering, amplification, and analog-to-digital (A/D) conversion operations. The receiver front-end modules 202, 210, 218 may amplify and down-convert the received analog RF signals to baseband. The receiver front-end modules 202, 210, 218 each include an analog-to-digital (a/D) converter for digitizing the received analog baseband signals.

The plurality of descramblers 204, 212, 220 may comprise suitable logic, circuitry, and/or code that may be operable to multiply the received signal by a scrambling code and a delayed scrambling code. The delay is determined by the path searcher 152 prior to descrambling. Each delay corresponds to a separate multipath that is combined by the rake receiver 150. The descramblers 204, 212, 220 may perform a despreading operation on the descrambled data by multiplying the descrambled data by a spreading code. Descramblers 212 and 220 may also multiply the received signal by a scrambling code and/or an orthogonal variable spreading code (OVSF).

The plurality of accumulators 206, 214, 222 may comprise suitable logic, circuitry, and/or code that may enable accumulation of the descrambled signals obtained from the descramblers 204, 212, 220, respectively. The plurality of IIR filters 208 and 216 may comprise suitable logic, circuitry, and/or code that may enable IIR filtering of the received signal paths from accumulators 206 and 214, respectively.

The P-chip 201 may process the first pilot signal to estimate the channel and perform a maximal ratio combining operation. The S-CHICH203 may process the second pilot signal once it is needed for demodulation. The DPCH 205 may process data based on channel information obtained from the P-CHICH 201 and the S-CHICH 203.

The multiplexer 224 may select one of the pilot signals (e.g., P-chip 201 or S-chip 203) with a pilot selection signal and generate an output to the channel compensation and decoding module 226. The channel compensation and decoding module 226 uses the pilot signal selected by the multiplexer 224. The channel compensation and decoding module 226 combines the same symbols obtained through the different paths using corresponding channel information and a combining scheme, such as Maximum Ratio Combining (MRC), and generates an output signal.

The multiplexer 228 may select one of the pilot signals (e.g., P-chip 201 or S-chip 203) with a pilot selection signal and generate an output to the RSCP module 230 accordingly. The RSCP module 230 may comprise suitable logic, circuitry, and/or code that may enable measurement of the received signal code power of a selected pilot signal.

The process of the present invention to achieve diversity gain can be used to combat multipath fading in a wireless cellular communication system because the quality of the signal can be improved without increasing the transmit power or losing bandwidth efficiency. In a single antenna W-CDMA handset, the attenuation of different multipath signals is independent of each other. The receiver may demodulate the same of several different multipath signals and combine the different multipath signals. The resulting combined signal is stronger than the single signal.

Fig. 3 is a schematic diagram of an antenna and multipath diversity finger configuration according to one embodiment of the present invention. In fig. 3, there is a common pilot channel 1(CPICH1)301, a common pilot channel 2(CPICH2)303, a Dedicated Physical Channel (DPCH)305, a plurality of multiplexers 324 and 332, and a plurality of received signal code power modules 328 and 330.

The CPICH1301 comprises a receiver front end module 302, a descrambler 304, an accumulator 306 and an IIR filter 308. The CPICH 2303 includes a receiver front end 310, a descrambler 312, an accumulator 314, and an IIR filter 316. DPCH 305 includes a receiver front end 318, a descrambler 320, an accumulator 322, and a channel compensation and decoding module 324.

The receiver front-end module 302 may comprise suitable logic, circuitry, and/or code that may enable processing of RF signals received from the antenna 1. The receiver front-end module 310 may comprise suitable logic, circuitry, and/or code that may enable processing of RF signals received from the antenna 2. The receiver front end 318 may comprise suitable logic, circuitry, and/or code that may enable processing of RF signals received from antennas 1 or 2. The multiplexer 332 may use the antenna selection signal to select a received signal from one of antenna 1 and antenna 2 and produce an output to the receiver front end module 318. The plurality of receiver front-end modules 302, 310, and 318 perform, for example, filtering, amplification, and analog-to-digital conversion operations. The multiple receiver front-end modules 302, 310, and 318 may be used to amplify and down-convert the received analog RF signal to baseband. Receiver front-end modules 302, 310, and 318 may include analog-to-digital converters (a/ds) to digitize received analog baseband signals.

The descramblers 304, 312, and 320 may comprise suitable logic, circuitry, and/or code that may enable multiplication of the received signal with a scrambling code and a delayed scrambling code. The delay may be determined by the path searcher 152 prior to descrambling. Each delay corresponds to a separate multipath that is combined by the searcher receiver 150. Descramblers 304, 312 and 320 may despread the descrambled data using the spreading code multiplied by the descrambled data. Descramblers 304, 312, and 320 may also multiply the received signal using scrambling code and/or Orthogonal Variable Spreading Factor (OVSF) codes.

Accumulators 306, 314, and 322 may comprise suitable logic, circuitry, and/or code that may enable accumulation of the descrambled signals obtained from descramblers 304, 312, and 320, respectively. The IIR filters 308 and 316 may comprise suitable logic, circuitry, and/or code that may enable IIR filtering of the signal paths derived from the accumulators 306 and 314 and may generate output signals to the RSCP modules 328 and 330, respectively.

The multiplexer 324 uses the pilot selection signal to select one of the pilot signals (e.g., CPICH1301 or CHICH 2303) and generates an output to the signal compensation and decoding module 326. The channel compensation and decoding module 326 may utilize the pilot signal selected by the multiplexer 326. Channel compensation and decoding module 326 may combine the same symbols from different paths using corresponding channel information and a combining scheme (e.g., maximum ratio combining, MRC) and generate an output signal.

The RSCP module 328 may comprise suitable logic, circuitry, and/or code that may be adapted to measure the received signal code power or signal-to-noise ratio (SNR) of a plurality of multipath signals received from the antenna 1 and may generate an output signal to the selection control unit. The RSCP module 330 may comprise suitable logic, circuitry, and/or code that may be adapted to measure received signal code power or signal-to-noise ratio (SNR) of a multipath signal received from the antenna 2 and generate an output signal to the selection control unit.

The generalized code of at least one pilot channel (e.g., CPICH1301 or CPICH 2303) may be modified, which may measure the strength of each of a plurality of received multipath signals. The strength of the multiple received multipath signals may be measured on a first pilot channel, such as the CPICH1301, by nulling its spreading code or scrambling code in the descrambler 304. The strength of the multiple received multipath signals may also be measured on a second pilot channel, such as the CPICH 2303, by assigning a non-zero value to its generalized code or scrambling code in the descrambler 312.

According to an embodiment of the present invention, the strongest multipath signals may be selected for demodulation, e.g., 6 of the 12 multipath signals may be selected based on the measured signal-to-noise ratio (SNR) of the multipath signals. The CPICH1301 and CPICH 2303 can be used simultaneously to monitor the signals obtained from both antennas (antenna 1 and antenna 2). The strongest signal paths may be processed by DPCH 305 based on their measured signal-to-noise ratios.

Fig. 4 is a schematic diagram of a baseband processor used in a MIMO system according to an embodiment of the present invention. In fig. 4, baseband processor 400 includes a Cluster Path Processor (CPP) module 432, a maximum ratio combining module 424, a despreading module 426, a diversity processor 428, a macrocell combiner module 430, a bit rate processing module 431, a convolutional decoding module 438, and a Turbo decoding module 440.

U.S. patent application No.11,173,854 (attorney docket No. 16218US02) provides a detailed description of signal clustering and is incorporated herein by reference in its entirety as part of this document.

CPP module 432 may includeA plurality of cluster processors for receiving and processing input signals, such as received from Chip Matched Filters (CMFs). In baseband receive processor 400, CPP 432a,.,. 432n in CPP module 432 may be partitioned into multiple processor pairs, each of which is used to track time (time-wise) and estimate the complex phase and amplitude of the elements in the cluster. One cluster is the aggregation of the received multipath signals, and the maximum time difference does not exceed 16 x 1/3.84⁶And second. In these cases, the need for two processors is that the transmit signal in the receive mode from the W-CDMA standard device is transmitted through two antennas, which require two processors. These receive modes include closed loop 1(CL1), closed loop 2(CL2), and STTD. CPP module 432 may determine an estimate of the overall transfer function of the channel and may be used to recover the channel at each base station.

CPP module 432 may generate a channel estimate of the actual time-varying impulse response of the channel based on each base stationAnd. CPP 432 may also be generated on a per base station basis with an antenna at the receiving end (e.g., antenna 106 in FIG. 1A)_1...M) Timing information T relating to the received signal. Corresponding lock indicator L₁And L₂May be generated by a cluster processor. The lock indicator may indicate which components of the corresponding estimate values are valid component values. In one embodiment of the invention, when the transmitted signal is transmitted with two antennas, the cluster path processor 432 a.... 432n may be configured to operate in pairs, where the two antennas may be located in the same base station or in different base stations. Channel estimation of the actual time-varying impulse response of the channel of each base stationAndand a lock indicator L₁And L₂And timing information T for each base station, may be passed to a single weight generator module (SWG) and a Maximum Ratio Combining (MRC) module 424 for further processing. Channel estimation valueAndlock indicator L₁And L₂And timing information T may be used by the SWG module to generate a Single Weight (SW) control signal for phase shifting of one or more signals received by the receive antenna.

The maximum ratio combining module 424 may comprise suitable logic, circuitry, and/or code that may be adapted to receive the timing reference signal T, and the channel estimate and lock indicator (h) from the corresponding cluster path processor module 432₁，L₁) And (h)₂，L₂) For processing signals received, for example, from a chip matched filter module (CMF). The maximal ratio combining module 424 may use channel estimate components indicating valid according to the corresponding lock indicator instead of using channel estimate components indicating invalid according to the corresponding lock indicator. The maximum ratio combining module 424 may provide a combining scheme or mechanism to implement a rake receiver in conjunction with the use of an adaptive antenna array to combat noise, fading, and/or co-channel interference.

The maximal ratio combining block 424 may comprise suitable logic, circuitry, and/or code that may enable summing together the various received path signals from the assigned RF channels to achieve the highest achievable signal-to-noise ratio, in accordance with one embodiment of the present invention. The highest achievable signal-to-noise ratio depends on the maximal ratio combiner. Where the maximal ratio combiner is a diversity combiner, all received multipath signals, each having a unique gain, are summed together. The gain of each multipath prior to summing is proportional to the received signal level of that multipath and inversely proportional to the multipath noise level. Each maximal ratio combining module may also use other signal combining techniques such as a selection combiner, a switched diversity combiner, an equal gain combiner, or an optimal combiner.

In one embodiment of the invention, the assignment of fingers within the maximal ratio combining module 424 is dependent on the channel estimate h obtained from the cluster path processing module 432₁And h₂. The proportionality constant used in the maximal ratio combining module 424 is dependent on the effective channel estimate from the constellation path processing module 432And

the Despreader (DS) module 426 may include a plurality of despreaders 426 a. Each despreader 426 a.. 426n may comprise suitable logic, circuitry, and/or code that may be operable to despread received signals, which may have been previously spread with an orthogonal spreading code in a transmitter. Prior to transmitting the information signal (referred to as "symbols"), the transmitter may have applied orthogonal spreading codes, resulting in a signal comprising a plurality of chips. The despreading module 426 may generate a local code, such as a Gold code or an Orthogonal Variable Spreading Factor (OVSF) code, that is applied to the received signal by a method that includes multiply and accumulate operations. After integration of a predetermined number of signal segments within which symbols are modulated is complete, processing gain may be achieved.

After despreading at the receiver, the original symbols can be extracted. WCDMA supports simultaneous transmission of multiple spread spectrum signals in a single RF signal using spreading codes among the spread spectrum signals, which are orthogonal and reduce Multiple Access Interference (MAI). The receiver may extract individual symbols from the transmitted multiple spread spectrum signals by applying a despreading code (equivalent to the code used to generate the spread spectrum signal). Similar to the CPP module 432 and the MRC module 424, a despreader module 426 may be assigned to each base station, while the MRC module 424 communicates with the despreader module 426 assigned to the same base station.

The diversity processor 428, including the plurality of diversity processor modules 428 a.,. 428n, may comprise suitable logic, circuitry, and/or code that may enable combining signals transmitted from multiple antennas in a diversity mode. The diversity mode includes OL, CL1, and CL 2. The diversity processor 428 may combine signals transmitted from multiple antennas at the same base station. Similar to the cluster path processor 432, the maximal ratio combining module 424 and the despreader module 426, the diversity processor 428 may be assigned to each base station, while the diversity processor 428 communicates with the despreading module 426 assigned to the same base station.

The macro cell combiner 430 may comprise suitable logic, circuitry, and/or code that may enable macro diversity. The macro diversity scheme may be used to combine two or more long-term lognormal signals (lognormal) that may be obtained through separate fading paths received from two or more different antennas located at different base stations. The micro diversity scheme may be used to combine two or more short-term Rayleigh (Rayleigh) signals obtained through separate fading paths received from two or more different antennas at a receiving station.

The bit rate processing block 431 may comprise suitable logic, circuitry, and/or code that may enable processing of data frames received from the macro cell merger 430. The processing may further include depuncturing (depuncturing) data within the received frames, deinterleaving, and further determining a rate at which the processed frames are transmitted in the output signal.

The convolutional decoder 438 may comprise suitable logic, circuitry, and/or code that may enable processing of the decoding of convolutional codes specified in the 3GPP specifications. The output of the convolutional decoder may be a digital signal comprising speech information suitable for processing by a speech processing unit. The Turbo decoder 440 may comprise suitable logic, circuitry, and/or code that may enable processing of decoding of convolutional codes as specified in the 3GPP specifications. The output of Turbo decoder 440 may be a digital signal having data information suitable for use by a video display processor.

The maximal ratio combining module 424 may use the channel estimate and lock indicator (h) for each base station₁，L₁)、(h₂，L₂) And timing information T to assign fingers to the received respective different path signals and to assign a proportional constant to each finger. Each of the received different path signals may be processed as a cluster of signals in a maximal ratio combining module 424. In one embodiment of the present invention, the maximum ratio combining module 424 may allocate a time T (n) to the nth grid element of the CPP 432, and a plurality of times T (n) depend on the time reference T. Given the time allocation and time offset toff, a particular CPP 432 module, namely 432n, may begin at [ T (n) -toff/2]Ending at [ T (n) + toff/2]Each different path signal is detected during the time interval.

The various path signals received in each of the CPP 432 sets constitute a signal cluster. For the value of n for a set of fingers, the relationship between the T (n) values of the processing elements of CPP 432 within the receiver satisfies that T (n +1) -T (n) is equal to a constant. Therefore, once T is determined, the timing relationship of the reception of each different path signal in the signal constellation can be determined. The time offset value toff may represent a duration of time that is at least as long as the time required to transmit the multiple segments in one symbol. For example, if the symbol includes 16 segments and the segment transmission rate of W-CDMA is 3.86X 106 segments/sec, then the time offset would be (16/3.84X 106) seconds, i.e., about 4 milliseconds.

Embodiments of the present invention are not limited to the case where the values of all n fingers T (n +1) -T (n) for a rake receiver are constant. However, each value T (n) depends on the time reference signal T.

The maximal ratio combining block 424 may scale and sum the received different path signals to generate a chip level output (chip level output), which is then transmitted to the despreading block 426. The despreader module 426 despreads the chip-level signal received from the maximum ratio combining module 424 to produce an estimate of the original transmitted signal. The diversity processor module 428 provides diversity processing and generates an output data estimate based on each base station. The macrocell combining module 430 implements macro diversity when received signals are transmitted by multiple base stations. Bit rate processing module 431 may perform processing tasks including depuncturing and de-interleaving of data frames conveyed within the received respective different path signals. The bit rate handler module 431 may determine the rate at which the processed data frames are transmitted to the convolutional decoder module 438 and/or the Turbo decoder module 440. The convolutional decoder module 438 convolutionally decodes the speech portion of the signal produced in the output of the bit rate processing module 431. The Turbo decoder module 440 Turbo decodes the data portion of the signal generated in the output of the bit rate processing module 431.

Fig. 5 is a block diagram of a selection control unit for selecting a plurality of strongest signals according to one embodiment of the present invention. The selection control unit 502 is shown in fig. 5.

The selection control unit 502 may comprise suitable logic, circuitry, and/or code that may enable receiving a plurality of multipath signals and corresponding RSCP measurements or SNR measurements therein. For example, for a rake receiver 150 with 6 fingers, the selection control unit 502 may receive 12 multipath signals and their corresponding RSCP measurements from 2 antennas (antenna 1 and antenna 2). The selection control unit 502 may select a portion of the received multipath signal based on the received RSCP measurement. For example, selection control unit 502 may generate the strongest 6 multipath signals among the 12 received multipath signals. Selection control unit 502 may also generate, for example, multipath timing, antenna indices, and corresponding MRC weights that result in multipath signals. The DPCH 305 may be selected for the 6 strongest paths in the 6 fingers.

To achieve more diversity gain, multiple antennas are used to provide more signal reception. For example, for a handheld device, two antennas may be used. In the case of using two antennas, the number of resolvable multipath signals can be doubled with respect to one antenna. By combining the multipath signals from the two antennas, full diversity gain can be achieved, which may require doubling the number of fingers already on the rake receiver for the other antenna. The order of diversity is determined by the total number of available multipath signals that can be selected, rather than the number of multipath signals that are selected. Full diversity gain can be derived from spatial or antenna and time or multipath signals. The order of the full diversity gain may be calculated as the product of the number of antennas times the number of multipath signals.

When there is no attenuation and the signal is only affected by gaussian additive white noise (AWGN), the performance measured in terms of Bit Error Rate (BER) can be represented by:

where Q (x) is a Q function of variable x, and α is a constant based on the number of diversity paths. BER may decrease exponentially as the signal-to-noise ratio (SNR) increases. In the case of rayleigh fading, the SNR may be an exponential random variable and equation (1) may be a conditional value based on the BER of the fading. Therefore, the average BER can be determined by averaging equation (1) as a density function of SNR,to be determined. Average BER with attenuation, expressed asCan be calculated according to the following equation:

averageMay decrease with increasing SNR. To improve performance, multiple multipath signals are combined, e.g., L multipath signals may be combined. The result is producedCan be calculated according to the following formula:

when the channels are also independent of each other,formula (3) can be represented by the following formula:

after diversity combining, the performance of the channel or the average BER may change depending on the inverse of the SNR raised to the power of lth. The power of the inverse of the SNR may be referred to as the order of diversity. For the case of iid rayleigh fading, the joint density function of the strongest m multipath signals of the L multipath signals can be calculated according to the following formula:

the BER after combining the strongest m multipath signals can be calculated according to the following equation:

from equation (6), the order of diversity is L, independent of m. For 1 ≦ m ≦ L, there will be a difference between selecting all multipath signals and selecting m multipath signals, which is defined as the SNR difference. From equations (4) and (6), the SNR difference can be calculated according to the following equation:

by combining the strongest 6 multipath signals, the present invention can lose, for example, 10log (12!/6! 6⁶)]dB is approximately equal to 0.9 dB. For example, there are 12 multipaths in totalIn the case of signals, selecting 6 fingers of a rake receiver for one antenna can achieve the same diversity gain as with two antennas with less than 1dB loss in SNR. If the number of multipath signals is less than 12, the loss is less. In each finger of the rake receiver 150, there are two pilot estimators that are not used simultaneously. According to one embodiment of the invention, the inactive one of the pilot estimators may be used to monitor the multipath signals from both antennas without adding any hardware complexity.

According to one embodiment of the invention, the selection control unit 502 may select a portion of the plurality of received multipath signals based on the received RSCP measurements. For example, selection control unit 502 may generate the 6 strongest multipath signals among the 12 received multipath signals, or select a portion of the multipath signals that exceeds a certain threshold among the multiple received multipath signals. The portion of the multipath signals selected by the selection control unit 502 may be combined by a Maximum Ratio Combining (MRC) algorithm. For example, the MRC module 424 combines the plurality of received multipath signals selected by the selection control unit 502. Selection control unit 502 may also generate information such as multipath timing, antenna indices, and corresponding MRC weights for the generated multipath signals.

Fig. 6 is a diagram illustrating comparison of performance of a wireless receiver in a first test example according to an embodiment of the present invention. In fig. 6, a graph 602 represents a comparison of the performance of a wireless receiver under the first test example (Case1) based on 3GPP TS 25.101. For example, there are 2 multipath signals, one multipath at 0dB and the second multipath at-10 dB. The update rate is 150 pilot signals and the Doppler (Doppler) frequency is 350 Hz.

The variation of the error probability with increasing SNR or (Ec/lor) can be shown with three different receiver structures. For the first receiver architecture employing a single antenna and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 1a-MRC 604. For the second receiver architecture with two antennas and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2as-MRC 606. In this receiver architecture, the strongest 6 multipath signals may be selected based on their measured signal-to-noise ratios, and the 6 fingers used to demodulate the strongest 6 multipath signals. For the third receiver architecture with two antennas and 12 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2a-MRC 608. In this case, each finger of the rake receiver demodulates one multipath signal.

For the second receiver architecture with two antennas and 6 fingers, the performance may be the same at any update rate as the third receiver architecture with two antennas and 12 fingers. For example, the gain of the second receiver structure with 2 antennas and 6 fingers is 3dB compared to the case of one antenna.

Fig. 7 is a diagram illustrating a comparison of the performance of a wireless receiver in the 2 nd test example according to an embodiment of the present invention. Referring to fig. 7, a graph 702 is shown representing a performance comparison of a wireless receiver under a second test Case (Case 2) based on 3GPP TS 25.101. For example, there may be 3 multipath signals, i.e., a first multipath at 0dB, a second multipath at 0dB, and a third multipath at 0 dB. The update rate is 150 pilot signals and the doppler frequency is 350 Hz.

The variation of the error probability with increasing SNR or (Ec/lor) can be shown with three different receiver structures. For the first receiver architecture employing a single antenna and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 1a-MRC 704. For the second receiver architecture with two antennas and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2as-MRC 706. In this receiver architecture, the strongest 6 multipath signals may be selected based on their measured signal-to-noise ratios, and the 6 fingers used to demodulate the strongest 6 multipath signals. For the third receiver architecture with two antennas and 12 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2a-MRC 708. In this case, each finger of the rake receiver demodulates one multipath signal.

For the second receiver architecture with two antennas and 6 fingers, the performance may be the same at any update rate as the third receiver architecture with two antennas and 12 fingers. For example, the gain of the second receiver structure with 2 antennas and 6 fingers is 3dB compared to the case of one antenna.

Fig. 8 is a diagram illustrating a comparison of the performance of a wireless receiver in test example 6 according to an embodiment of the present invention. Referring to fig. 8, a graph 802 is shown representing a comparison of the performance of a wireless receiver under test Case 6 (Case 6) based on 3GPP TS 25.101. For example, there may be 4 multipath signals, the first multipath being 0dB, the second multipath being-3 dB, the third multipath being-6 dB, and the fourth multipath being-9 dB. The update rate is 1 pilot signal and the doppler frequency is 420 Hz.

The variation of the error probability with increasing SNR or (Ec/lor) can be shown with three different receiver structures. For the first receiver architecture employing a single antenna and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 1a-MRC 804. For the second receiver architecture with two antennas and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2as-MRC 806. In this receiver architecture, the strongest 6 multipath signals may be selected based on their measured signal-to-noise ratios, and the 6 fingers used to demodulate the strongest 6 multipath signals. For the third receiver architecture with two antennas and 12 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2a-MRC 808. In this case, each finger of the rake receiver demodulates one multipath signal.

The performance of the second receiver architecture with two antennas and 6 fingers, updated at the pilot symbol rate, may be the same as the performance of the third receiver architecture with two antennas and 12 fingers. For example, the gain of the second receiver structure with 2 antennas and 6 fingers is 3dB compared to the case of one antenna.

Fig. 9 is a diagram illustrating a comparison of the performance of a wireless receiver in the 6 th test example according to an embodiment of the present invention. Referring to fig. 9, a graph 902 is shown representing a performance comparison of a wireless receiver under test Case 6 (Case 6) based on 3GPP TS 25.101. For example, there may be 4 multipath signals, the first multipath being 0dB, the second multipath being-3 dB, the third multipath being-6 dB, and the fourth multipath being-9 dB. The update rate is 10 pilot signals and the doppler frequency is 420 Hz.

The variation of the error probability with increasing SNR or (Ec/lor) can be shown with three different receiver structures. For the first receiver architecture employing a single antenna and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 1a-MRC 904. For the second receiver architecture with two antennas and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2as-MRC 906. In this receiver architecture, the strongest 6 multipath signals may be selected based on their measured signal-to-noise ratios, and the 6 fingers used to demodulate the strongest 6 multipath signals. For the third receiver architecture with two antennas and 12 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2a-MRC 908. In this case, each finger of the rake receiver demodulates one multipath signal.

The difference in performance between the second two antenna and 6 finger receiver architecture and the third two antenna and 12 finger receiver architecture is approximately 0.5dB for a slot rate of 10 pilot symbols and a doppler frequency of 420 Hz. The gain of the second receiver with two antennas and 6 fingers is about 3dB compared to the case with only one antenna. The second receiver configuration with two antennas and 6 rake will degrade performance as the moving speed increases and the update rate decreases.

Fig. 10 is a diagram illustrating a comparison of the performance of a wireless receiver in test example 3 according to an embodiment of the present invention. Referring to fig. 10, a graph 1002 is shown representing a performance comparison of a wireless receiver under 3 rd test Case (Case 3) based on 3GPP TS 25.101. For example, there may be 4 multipath signals, the first multipath being 0dB, the second multipath being-3 dB, the third multipath being-6 dB, and the fourth multipath being-9 dB. The update rate is 10 pilot signals and the doppler frequency is 420 Hz.

The variation of the error probability with increasing SNR or (Ec/lor) can be shown with three different receiver structures. For the first receiver architecture employing a single antenna and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 1a-MRC 1004. For the second receiver architecture with two antennas and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2as-MRC 1006. In this receiver architecture, the strongest 6 multipath signals may be selected based on their measured signal-to-noise ratios, and the 6 fingers used to demodulate the strongest 6 multipath signals. For the third receiver architecture with two antennas and 12 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2a-MRC 1008. In this case, each finger of the rake receiver demodulates one multipath signal.

The difference in performance between the second two antenna and 6 finger receiver architecture and the third two antenna and 12 finger receiver architecture is approximately 0.2dB for a slot rate of 10 pilot symbols and a doppler frequency of 420 Hz. The gain of the second receiver with two antennas and 6 fingers is about 2dB compared to the case with only one antenna. The second receiver configuration with two antennas and 6 rake will degrade performance as the moving speed increases and the update rate decreases.

Fig. 11 is a diagram illustrating a comparison of performance of a wireless receiver due to Soft Handoff (SHO) according to an embodiment of the present invention. Referring to fig. 11, a graph 1102 is shown representing a comparison of performance of a wireless receiver due to a 3GPP TS25.101 based soft handover. For example, there may be 6 multipath signals, the first multipath being 0dB, the second multipath being-3 dB, the third multipath being-6 dB, the fourth multipath being-9 dB, the fifth multipath being-12 dB, and the sixth multipath being-15 dB. For example, the update rate may be 10 pilot signals and the doppler frequency may be 350 Hz.

The variation of the error probability with increasing SNR or (Ec/lor) can be shown with three different receiver structures. For the first receiver architecture employing a single antenna and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 1a-MRC 1104. For the second receiver architecture with two antennas and 6 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2as-MRC 1106. In this receiver architecture, the strongest 6 multipath signals may be selected based on their measured signal-to-noise ratios, and the 6 fingers used to demodulate the strongest 6 multipath signals. For the third receiver architecture with two antennas and 12 fingers, the variation in error probability with increasing SNR or (Ec/lor) is denoted as 2a-MRC 1108. In this case, each finger of the rake receiver demodulates one multipath signal.

The difference in performance between the second two antenna and 6 finger receiver architecture and the third two antenna and 12 finger receiver architecture is approximately 0.65dB for a slot rate of 10 pilot symbols and a doppler frequency of 420 Hz. The gain of the second receiver with two antennas and 6 fingers is about 2dB compared to the case with only one antenna. The second receiver configuration with two antennas and 6 rake will degrade performance as the moving speed increases and the update rate decreases.

For test case1 and test case 2as shown in fig. 6 and 7, respectively, the performance of the second receiver structure with two antennas and 6 rake is similar to the performance of the third receiver structure with two antennas and 12 fingers at any update rate. In the 3 rd and 6 th test examples shown in fig. 8, 9, 10, the performance of the second receiver structure with two antennas and 6 fingers differs from the performance of the third receiver structure with two antennas and 12 fingers by 0.2-0.5 dB for example for a slot rate or 10 pilot symbols and a doppler frequency of 420 Hz. The gain of the second receiver architecture with two antennas and 6 fingers is about 2dB compared to the case with only one antenna. In a soft handoff embodiment, the performance of the second two antenna and 6 finger receiver architecture differs by 0.65dB from the performance of the third two antenna and 12 finger receiver architecture, for example, at a slot rate or 10 pilot symbols and a doppler frequency of 420 Hz.

According to one embodiment of the invention, the method and system for achieving space-time diversity gain of the present invention includes modifying the generalized code of at least one pilot channel (e.g., CPICH1301 or CPICH 2303) to measure the signal strength of a plurality of received multipath signals. The selection control unit 502 combines a portion of the plurality of received multipath signals based on the signal strengths measured by the plurality of RSCP modules 328 and 330. The signal strength of the multiple received multipath signals may be measured on a first pilot channel (e.g., CPICH1301) by nulling its generalized code or the scrambling code in the descrambling module 304. The strength of the multiple received multipath signals may also be measured by assigning a non-zero value to its spreading code or scrambling code in the descrambling module 212 on a second pilot channel (e.g., CPICH 2303).

The selection control module 502 may select a portion of the plurality of received multipath signals based on the received RSCP measurements. For example, the selection control unit may generate the 6 strongest multipath signals among the 12 received multipath signals or among the signals exceeding a certain threshold among the received multipath signals. The portion of the multipath signals selected by the selection control module 502 may be combined by a Maximum Ratio Combining (MRC) algorithm. Selection control unit 5020 may also generate MRC weights that generate multipath signals, such as multipath timing, antenna indices, and corresponding multipath signals.

Another embodiment of the present invention provides a machine-readable storage having stored thereon a computer program having at least one code section executable by a machine for causing the machine to perform the method for achieving space-time diversity gain described above.

Accordingly, the present invention may be realized in hardware, software, or a combination of hardware and software. The present invention can be realized in a centralized fashion in at least one computer system, or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. The method is implemented in a computer system using a processor and a memory unit.

The present invention can also be implemented by a computer program product, which comprises all the features enabling the implementation of the methods of the invention and which, when loaded in a computer system, is able to carry out these methods. The computer program in this document refers to: any expression, in any programming language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to other languages, codes or symbols; b) reproduced in a different format.

While the invention has been described with reference to several embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (9)

1. A method for diversity processing in a wireless communication system, the method comprising:

modifying a spreading code of at least one pilot channel to measure a signal strength for each of a plurality of received multipath signals;

partially combining the plurality of received multipath signals based on the measured signal strengths;

the method further includes employing a rake receiver architecture including two pilot estimators in each finger that are not used simultaneously, monitoring multipath signals from the antenna with the inactive one of the pilot estimators.

2. The method of claim 1, further comprising measuring signal-to-noise ratios of the plurality of received multipath signals.

3. The method of claim 1, further comprising measuring signal strengths of the plurality of received multipath signals on a first pilot channel by assigning zero values to the spreading code.

4. The method of claim 1, further comprising measuring signal strengths of the plurality of received multipath signals on a second pilot channel by assigning a non-zero value to the spreading code.

5. The method of claim 1, further comprising combining portions of the plurality of received multipath signals having a signal-to-noise ratio above a certain threshold.

6. A system for achieving diversity gain in a communication network, the system comprising:

circuitry for modifying the generalized code of at least one pilot channel to measure signal strength for each of a plurality of received multipath signals;

circuitry to partially combine the plurality of received multipath signals based on the measured signal strengths;

the system further includes a rake receiver architecture including two pilot estimators in each finger that are not used simultaneously, with the inactive one pilot estimator monitoring multipath signals from the antenna.

7. The system of claim 6, further comprising circuitry to measure signal-to-noise ratios of the plurality of received multipath signals.

8. The system of claim 6, further comprising circuitry for measuring signal strengths of the plurality of received multipath signals on a first pilot channel by assigning a value of zero to the spreading code.

9. The system of claim 6, further comprising circuitry for measuring signal strengths of the plurality of received multipath signals on a second pilot channel by assigning a non-zero value to the spreading code.