TW201015928A - Optimal weights for MMSE space-time equalizer of multicode CDMA system - Google Patents

Abstract

Aspects of the invention provide an enhanced chip-level linear space-time equalizer 118 for multiple-input-multiple-output (MIMO) multi-code CDMA systems reusing same spreading codes in different transmit antennas 114. Reuse of the spreading codes at the transmitter 104, 204 creates an on-time inter-stream interference component (or cross-talk among distinct transmit antenna signals) which reuse the same spreading code as the desired signal in the soft metric sequence of the MIMO CDMA receiver after MMSE space-time equalization. The equalizer 118 has a MMSE weighting vector that takes the despreading effect into account.

Description

201015928 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a coded multiple proximity (ce > MA) communication system, and more particularly to a multi-input multiple-output (MIM) multiple code. Linear minimum mean square error (mmSE) spatial time equalizer for CDMA systems. [Prior Art] In a wireless communication system, a number of users share a channel within a common spectrum. In order to avoid conflicts caused by the simultaneous transmission of information by several users on the communication channel, some rules regarding the allocation of available channel capacity to the user are required. The rules for users to access communication channels have been reached by various forms of multi-directional proximity protocols. One form of agreement is called coded multiple proximity (CDMA). In addition to providing multi-directional proximity assignments to channels of limited capacity, an agreement may provide additional functionality. For example, an agreement can provide user isolation, limit user interference, and provide security (also known as low intercept probability) by increasing the difficulty of intercepting and decoding the unintended receiver. . In CDMA systems, each signal is isolated from the utterances of other users by the encoded signal. The information 彳§ number is specifically encoded into a transmission signal. The intended receiver that knows the user's code sequence can decode the transmitted signal to receive the information. The spectrum of the information signal is spread by the encoding such that the bandwidth of the encoded transmission signal is much larger than the original bandwidth of the information signal. To this end, CDMA# is a " Spreading " encoding. The energy of each user's signal is spread across the channel bandwidth, causing each user's signal to behave as a noise to other users. 145325.doc 201015928 As long as the decoding program can achieve a sufficient signal-to-noise ratio, the information in the signal can be restored (the isolation of the user's signal from the "noise' of other user signals). Other factors that affect the recovery of information about the user's signals are different situations for each user in this environment, such as fading, shadowing, and multipathing. Masking is caused by physical objects that interrupt the signal transmission path between the transmitter and the receiver, such as larger buildings. Multipath is signal distortion, which occurs because the signal spans multiple paths of different lengths and arrives at the receiver at different times. Multipathing is also known as the "time dispersion" of communication channels. The signals received in phase are enhanced with each other and produce a stronger signal at the receiver, while the signal received out of phase produces a weaker or fading signal. Multipath fading can also change over time. For example, in a mobile vehicle-borne device, the amount of multipath fading can change rapidly. To provide diversity and improved performance against harmful path effects, multiple transmit and receive antennas can be used. If the transmission path between the transmission and reception antennas is linearly independent (ie, the transmission on one path does not form a linear combination of the transmissions on other paths, to some extent it is generally true) When the number of antennas increases, the probability of correctly receiving the transmitted signal also increases. In general, as the number of transmit and receive antennas increases, diversity increases and performance improves. The use of multiple antennas at the transmitter and receiver in multiple input multiple output (mim〇) systems. If multiple antennas are available at the transmitter or receiver, techniques such as spatial multiplexing and code reuse can be used to increase peak traffic. Each channel used for transmission by code reuse is allocated up to Μ independent data streams, where Μ is the number of transmit antennas. Data streams sharing the same code 145325.doc 201015928 are differentiated based on their spatial characteristics, which requires a receiver with at least one antenna. In principle, the peak traffic using code reuse is twice the rate achievable by a single antenna. In a multi-code CDMA system, if the spatial time equalizer uses a minimum mean square error (MMSE) weighting vector that minimizes the mean square error of the wafer sequence, the same spreading code in the different transmission antennas Reuse will downgrade the equalization performance. Unlike multipath interference and background noise components, the CDMA despreader distorts the inter-stream interference components. This will degrade the performance of the prior art system. Therefore, there is a need in the art for an enhanced wafer level linear space time equalizer for a multiple input multiple output (MIMO) multiple code CDMA system in which the spread spectrum code can be reused in different transmit antennas. . SUMMARY OF THE INVENTION In one aspect, a CDMA receiver includes a spatial time equalizer operatively coupled to a receive antenna, wherein the spatial time equalizer applies a weight vector 'the spread vector is included as a spread spectrum The coefficient of a function of one of the factors. In another aspect, a CDMA receiver includes a space time equalizer having an equalization coefficient and a despreader, wherein the equalization coefficient is at least partially a function of a spreading factor. In another aspect, a method includes receiving a plurality of signals via a plurality of receive antennas, wherein the received signal from each receive antenna comprises a combination of one or more signals transmitted from a transmission device; A weighted vector having coefficients is used to process the signal to produce a plurality of bitstreams, the 145325.doc 201015928 medium and far coefficients being at least partially a function of the spreading code reuse. In a further aspect, the CDMA receiver includes an equalization component coupled to the receive antenna, wherein the equalization component applies a weighting vector comprising a coefficient of a function of a spreading factor; The solution spread spectrum component is operatively coupled to the equalization component, wherein the despread component divides the equalization metric sequence into a plurality of modulation symbol sequences. [Embodiment] The word "exemplary" is used herein to mean an example, instance, or description. Any embodiment described herein as "exemplary" is not necessarily interpreted as being better than other embodiments or Figure 1A is a diagram of a communication system 10 that supports a number of users and is capable of implementing at least some aspects and embodiments of the present invention. System 10 provides communication for a plurality of units 2a through 2g each serviced by a corresponding base station 4. The units are organized in such a way as to reach the expected area. For example, the coverage area can be defined as the area where the user of the terminal 6 can reach a specific service level (G〇s). The terminal 6 in the coverage area can be Fixed or active, and generally served by a primary base station. For each active terminal, transmissions from other base stations and terminals represent potential interference. As shown in Figure 1A, various terminals 6 are dispersed. Throughout the system, the terminal 6 includes a processing device 8. Examples of the processing device 8 include, but are not limited to, a processor, program logic, or representative data and instructions. Other base layer configurations. In other embodiments, the processors may include controller circuitry, processor circuitry, processors, general purpose single or multi-chip microprocessors, digital signal processors, embedded microprocessors, micro-controls 145325.doc 201015928 At any particular moment, each terminal 6 on the downlink and uplink communicates with at least one and possibly a plurality of base stations 4, depending, for example, on whether or not to adopt "soft handover" Whether the terminal is designed and operated to receive multiple transmissions from multiple base stations simultaneously or sequentially. The downlink represents the transmission from the base station to the terminal, and the uplink represents the terminal to the base station. In Fig. 1A, the base station 4a transmits data to the terminals 6a and 6j on the downlink, and the base station 4b transmits the data to the terminals 6b and 6j, and the base station 4c transmits the data to the terminal 6c and the like. In Figure 1A, the solid line with the arrow indicates the data transmission from the base station to the terminal. The dotted line with the arrow indicates that the terminal is receiving the pilot signal from the base station, but there is no data transmission. For the sake of brevity, the uplink communication is not shown in Figure 1A. The subject matter disclosed in U.S. Patent Application Serial No. 09/532,492 is entitled "HIGH EFFICIENCY, HIGH PERFORMANCE COMMUNICATIONS SYSTEM EMPLOYING MULTI- CARRIER MODULATION" (March 2000) A system for designing a system 10, which is disclosed in U.S. Patent Application Serial No. 08/963,386, entitled "METHOD AND APPARATUS FOR HIGH RATE PACKET DATA TRANSMISSION" The assignee of the present invention is incorporated herein by reference. System 10 can also be designed as a CDMA system that supports one or more CDMA standards, such as the IS-95 standard, the Wideband CDMA (W-CDMA) standard, other standards, or a combination thereof. In system 10, a number of terminals share a common resource, i.e., a total operating bandwidth W. In order to achieve the desired level of performance at a particular terminal, the interference from other transmissions needs to be reduced to an acceptable level. Similarly, in order to perform reliable transmission at a high data rate for a specific operating bandwidth, it is necessary to perform a specific carrier-to-interference plus interference ratio (C/I) level or higher. The total available resources are divided into small portions that are each assigned to a particular single unit to achieve interference reduction and required C/I achievement. ❿

For example, the total operating bandwidth w can be divided into equal operating bands (i.e., B = w/N), and each cell can be assigned to one of the 1^ bands. These bands are periodically reused to achieve higher spectral efficiency. For a 7-unit reuse mode such as the reuse mode supported by Fig. 8, unit 2a can be allocated a first band, and unit 2b can be assigned a second band or the like. Communication systems are typically designed to meet a number of system requirements, which may include, for example, 'quality of service (QOS), coverage, and performance requirements. Service quality is typically defined as each terminal in the coverage area is able to achieve a specified minimum average bit rate for a specified percentage of time. With the use of multiple antennas in both transmitters and receivers, recent developments in MIMO transmission technology have predicted large traffic gains in future wireless communication systems. The ΜΙΜΟ technology can be incorporated into various modulation and multi-directional proximity schemes, such as MIMO-CDMA, Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM), and the like. High-speed packet data channels in the 3G CDMA standard, such as High Speed Downlink Shared Channel (HS_DSCH) and Forward Link Packet Data Channel (F_PDCH), etc., typically use multi-channel coding, such as the Waish code. , it has a fixed spreading factor (SF) to transmit and receive a larger amount of information in the shorter frame interval. Depending on the data rate of the current packet, the base station (BS) can select a number of codes from the available channelization codes to supply the corresponding number of modulation symbols. When a MIMO-CDMA system supports multiple transport streams via multiple transmission antennas, the corresponding BS typically reuses the same channelized coding for different antennas. Unless otherwise designed in the MIMO-CDMA scenario, code reuse in the transmit antenna can cause severe damage to the mobile station (MS) space time equalizer.系统Multi-code CDMA system model Figure 1B is a block diagram of an embodiment of a multi-code CDMA system 1 including a transmitter portion 1 〇 2 and a receiver portion 〇 4. In the following discussion, the spread factor is expressed as . The transmitter portion 102 includes an encoder 106, a mapper 〇8, a demultiplexer 110, a plurality of spreaders 112', and a plurality of transmit antennas 114. The number of transmission antennas 114 is μ, and the number of orthogonal spreading frequencies assigned to each transmission antenna ι 14 is "/(«/< SF). Receiver portion 104 includes a plurality of receive antennas 116 'Minimum Mean Square Error (MMSE) spatial time equalizer 118, a plurality of despreaders 12A, multiplexer 122, demapper 124, and decoder 126. The number of receive antennas 116 is Ν ' and the number of despreaders ι2 分配 assigned to each receive antenna 116 is corresponding to the number of spreaders 112 assigned to each transmit antenna 114. It is generally understood by those skilled in the art that the spatial time equalizer 118 discussed herein can be applied to a general MIMO-CDMA system. Terminology encoders, decoders, rate matchers, interleavers, deinterlacers, mappers, demappers, spreaders, despreaders, and space time, etc. 145325.doc •10- 201015928 The chemist is intended to have its A general term in the general sense. In addition, the encoder. A device or method for encoding a signal (such as a bit stream) or a data from a form (such as a form suitable for transmission, storage, or processing). In general, the code can be constructed in software or hardware, constructed by -programs, algorithms, methods, or in circuits. The decoder can be a device that implements the reverse operation of the encoder, which cancels the encoding and fetches the original information.

Rate matching n can be a device or method that adjusts the rate or bit rate of the data stream to a pre-rate. For example, in a transmitter, the rate matcher can adjust the bit rate to match the capabilities of the transmitter. The rate matcher can perform the reverse process in a receiver. The wrong device can be a device that arranges data in a non-contiguous manner to increase performance or = the de-interlacer can implement the reverse operation of the interleaver and use 'column parent error data to make it easier to process. To collect 'group bits and convert them to a single modulation symbol (such as the opposite of implementing a mapper)

. A device or method of converting a symbol into a set of bits. The spreader can increase the bandwidth of the transmitted signal for the M bottle factor, so that it can be used as a general implementation. A device or square information bandwidth that exemplifies and reduces the bandwidth of the received signal. The frequency converter can reduce the bandwidth of the received signal to its spatial time equalizer. The ratio of the device or method time of a signal can be provided to the combination. For example, the spatial time equalizer can spatially compare and combine a received signal to recover the original signal. Referring to FIG. 1B, encoder 106 receives source bit sequence 128. Encoding, rate matching (ie, 'puncturing or repeating') and interleaving the source bit sequence 128' in each frame in encoder 1 且6 and mapping it to the modulated symbol sequence in mapper 108 (eg , four-phase shift keying (QPSK), 16-point quadrature amplitude modulation (16QAM), etc.). Then, the modulated symbol sequence is multiplexed into a stream from the group ’ in the demultiplexer u ’ where the mth group is transmitted via the wth transmission antenna 丨丨4. In the spreader U2, j streams in each group are expanded by j spreading codes, wherein the yth spreading code is equal to the seventh channelized coding (for example, orthogonal codes of the spreading factor, quasi-orthogonal codes) , or Huaxu code) and the product of the pseudo-random wrestling code of 38. The same set of j spreading codes are typically reused for each group, and each transmission antenna 114 typically uses the same transmission power, although the invention is not limited to these particular circumstances. After passing through the multi-dimensional multipath fading channel, the transmitted signal reaches the # receiving antennas 116, wherein the MMSE spatial time chip equalizer 118 corresponds to the one of the transmitting antennas ,14, and the received signals are divided into M groups. Equalize the soft metric sequence. Then, in the despreader 12A, the ^/a despreading code equal to the conjugate of the spreading codes divides each set of equalized soft metric sequences into ^ soft demodulating symbol sequences, each of which Corresponding to an orthogonal Huawei channel in the group. The resulting "ZM demodulation variable symbol sequence is multiplexed into a single stream in multiplexer 122 and demapped in demapper 124 into a sequence such as a log likelihood ratio (LLR) sequence. The sequence is deinterleaved in decoder 126 to match and decode the sequence to recover the original source bit sequence to decoded bit 130. 145325.doc • 12· 201015928 FIG. 2A is a block diagram of an embodiment of a mim〇 multi-code CDMA system 200 including a transmitter portion 202 and a receiver portion 2〇4. In the following discussion, the spreading factor is represented as a transmitter portion 202 comprising a plurality of encoders 206, a plurality of mappers 2〇8, a plurality of demultiplexers 210, a plurality of spreaders lu, and a plurality of transmit antennas 114. The number of transmission antennas 114 is slaved, and the number of spreading codes assigned to each of the transmission antennas 114 is. The receiver portion 204 includes a plurality of receiving antennas 丨丨6, a minimum mean square error (MMSE) spatial time equalizer 118, a plurality of despreaders 12A, a plurality of multiplexers 222, and a plurality of demappers 224. And a plurality of decoders 226 receive the number of antennas 116 as iV' and the number of despreaders 120 assigned to each of the receive antennas 116, which corresponds to the number of spreaders 112 assigned to each of the transmit antennas 114. Each encoder 206 receives a source bit sequence 128 for the encoder 206. The source bit sequence 128 in each frame is encoded, rate matched (ie, punctured or repeated) and interleaved in its corresponding encoder 2〇6, and mapped to modulation in its corresponding mapper 208. Symbol sequence (for example, QpSK, 16Q AM). In turn, the sequence of modulated symbols is demultiplexed into a set of streams in its corresponding demultiplexer 210, wherein the mth group is transmitted via the first transmit antenna. In the spreader 112, the streams in each group are expanded by a spreading code, wherein the yth spreading code is equal to the first channelized coding (eg, the orthogonal code of the spreading factor 5^, the quasi-positive The product of the code 'or Huaxun code' and the pseudo-random stirring code. Each set typically reuses the same set of j spreading codes' and each transmitting antenna 114 typically uses the same transmission power but 145325.doc • 13-201015928 The invention is not limited to these particular circumstances. After passing through the multi-dimensional multipath fading channel, the transmitted signal reaches the w receiving antennas 116, wherein the MMSE space time chip equalizer n8 corresponds to the one of the transmitting antennas 114, and the received signals are divided into M groups, etc. Soft metric sequence. Then, in the de-spreading unit 120, the //the despreading code equal to the commonality of the j spreading codes divides each set of equalized soft metric sequences into j soft demodulation symbol sequences 'each of which Corresponds to the one orthogonal huaxu channel in the group. Each of the resulting slave/demodulation variable symbol sequences is multiplexed into a single stream in its corresponding multiplexer 222 and mapped in its corresponding demapper 224 to a log likelihood ratio, such as Sequence of (LLR) sequences. Each of the μ sequences is deinterleaved, inverted rate matched, and decoded in its corresponding decoder 226 to restore the original source bit sequence to decoded bit 230. In an embodiment, after the mmse space time is equalized, the soft metric sequence of the ι, 2 μ 包括, 2 包括 includes five components: the expected letter $; one or more on-time inter-stream interference (or different transmission antennas) a string in the signal) 'which reuses the same spreading code as the expected signal; one or more of the quasi-parametric inter-stream interference 'which does not reuse the same spreading code as the expected signal' or multiple multipaths Interference (meaning, the total service unit signal component, which is not on time), and background noise (other unit interference, thermal noise, etc.). The punctual inter-stream + media. ^ Ding························································································ In the case of the spread code, it is discarded. The multipath interference and background noise are roughly suppressed by the SFSI. 145325.doc 14· 201015928 FIG. 2B is a block diagram of an embodiment of a spatial time equalizer 118. The spatial time equalizer 118 includes μ equalization memory banks 250 (memory m, where m = 0, 1, ..., Μ-1) corresponding to one of the transmission antennas 114. Each memory bank 250 contains N filters 252 (filter n, where n = 0, 1, ..., N-1) corresponding to the N receive antennas 116, and an adder 254. The filters 252 have filter coefficients vm,n opt, where m=0, 1, 2, ..., Μ-1, and n=0, 1, 2, ..., N-1, and each filter 252 produces a filtered output signal. Each bank 250 receives a signal from each of the N receive antennas 116 and processes the signal in a corresponding filter 252. Adder 254 adds the filtered output signals from each of filters 252 in each bank 250 to produce an equalized metric sequence 256. Focus on the equalization memory 0 250a, for the jth filter (in the memory bank, j = 〇, 1, ..., N-1, which has the filter coefficient Vh〇 〇 ρτ), the input of the filter j Connected to the jth receive antenna, and the output of filter j is coupled to the input of adder 254a. For example, the input of filter 〇 252a in equalization memory bank 250a having filter coefficients VH0, 0 OPT is coupled to receive antenna 〇 116a, and the output of filter 0 252a is coupled to the input of adder 254a. end. Similarly, the input of the filter N-1 252b having the filter coefficient VH 〇, Ν-ι PT is connected to the receiving antenna N-1 116b, and the output of the filter N-1 252b is connected to the input of the adder 254a. end. The outputs of the filters η (η = 0, 1, ..., N-1) in the block 〇 250a are added in an adder 254a to produce an equalized metric sequence, i.e., sequence 0 256a. 145325.doc -15- 201015928 Similarly, 'add each of the blocks m 250 (in this m=〇, 1, and N of the N filter waves 252) to produce μ The equalization metric sequence 256. The pilot signal is calculated as the channel coefficient 匕 and the noise common variance Rn as further described in Equation 8. The channel coefficient h and the noise common variance Rn are used to calculate the wave coefficient. V m, η OPT, where m = 〇, 1, 2, ..., Μ-1 and n = 0, 1, 2, ..., N-1. In another embodiment, in processor 8 The equalizer 118 is constructed as a software. Figure 3 is a flow diagram 300 illustrating the operation of one embodiment of a multi-code CDMA receiving system 1-4, 204. In one embodiment, the multi-code CDMA receiving system 104, 204 is in a contiguous manner. In loop operation, the loop begins at the "start" block and ends at the "end" block. In block 31, the equalizer 118 receives the pilot symbol sequence. In block 3 12, etc. The equalizer coefficients are calculated using the pilot symbols. In block 314, the receiving systems 1〇4, 2〇4 receive a signal via antenna 116. In block 316, The coefficients are normalized by the equalizer 118. The equalizer 118 processes the received signals to produce an equalized metric sequence 256. In block 318, the despreader 12 is processed, etc. The metric sequence 256 is generated to generate a demodulated variable symbol sequence. The presence of on-time inter-stream interference makes the conventional wafer-level MMSE equalizer less desirable because it does not take into account the despreading effect. In the application, 'control the traditional chip 145325.doc 201015928 MMSE weight in the non-optimal direction of the noise space, which makes the decoding performance degraded. In addition, the MMSE weight optimization solution in single-input single-output (SISO) multi-code CDMA The spread spectrum effect does not change the weight (or control direction), except for different scaling factors. Assuming that the demappers 124, 224 are more than soft demodulated, the decoding performance is not affected in sis 〇 multicode CDMA. In general, when the number of spreading codes used for each stream increases, the gap between the optimal MMSE weight (which takes into account the spread-spreading effect) and the non-optimal MMSE weight is reduced. This is because of the on-time flow. Interdiction The frequency gain will be roughly discounted by the number of spreading codes used, as discussed below. Linear MMSE equalizer weights for multi-code CDMA Traditional wafer-level MMSE weights in multi-code CDMA optimize traditional MMSE space The time chip equalizer corresponds to the slave transmit antennas 114' dividing the received signals into groups of equalized soft metric sequences. The multiplexers 122, 222, demappers 124, 224, and decoders 126, 226 are then used. The sequences are processed to produce decoded bits 130, 230, respectively. In the following discussion of the optimization of conventional wafer level MMSE weights, the span of multipath delay spread spectrum is Z wafer length, the span of the equalizer is five wafer lengths, and the receiver takes one user sample per wafer ( That is, the oversampling factor is household). In addition, An„, p(〇(/=〇, 1,..., I -1 ; n=0, 1,..., 1; w=0, 1,..., M_l; household =〇, 1,... And /Μ) is the channel coefficient between the state transmission antenna 114 and the "receiving antenna 116, which corresponds to the second chip delay and the first sample of the wafer. The mth transmission antenna 114 at the wafer time. The chip signal is represented by which Qiu Xin (4)|2] = 1 and 2

X is the average wafer energy per transmit antenna 114. 145325.doc -17· 201015928 Definition χ/»(^) = σ^ [xm(A:) xm(k + l)-"Xm(k + E + L-2)]T (1) is the wth The (five + u)-dimensional wafer vector of the transmission antenna 114 spans from the exponent ^ to the free + five + Z-2. Similarly, let (8) and %(8) be the received samples of the p-th sample of the A:th chip at the "receiving antenna} j 6 and its background noise component. In addition, define y" (kM3V. (A: )...Λπ W ...fan,. (none + five-1)...(* + five-1)]T (2) and n« (k)Ξ [»„,0 (k)- nnJ>_, (k )- nnfi {k + E-\)-· nnJ>_x (A: + £ - 1)]T (3) is the received sample vector of the fifth-dimensional receiving antenna at the receiving antenna 116 and the corresponding background noise Vector, then y〇W' = 'H〇,〇...ϊτ " ^Ο,ΑΖ-Ι + ' η〇W (4) yN—'(k\ ...Η _XA/-l(^) _ _ _ (Moxibustion) In Equation 4, '^, ^ denotes the 多 (£+ζ-ι) multipath channel matrix between the wth transmission antenna 114 and the "receiving antenna 116", and gives Set to do", m, 0 (9)

Uz-i)... Η

nine,/",. (厶-1)...ν„,〇(9) • . • • • ♦ 尸-1 (Z-1)...w〇) In addition, the vector of the received sample defined as the dimension of the dimension is defined as the total 145325 of the dimension. Doc -18- 201015928 Zhao background noise vector, define the noise covariance matrix of R" is ^, and define H〇,〇...Η (6) Η ^ [h〇h1 * · ]: •Hn,0 is iVPZxMCE + Zl) The overall multipath channel matrix. Then for the wth transmit antenna wafer stream with the target delay of D wafers, the optimal wafer level linear 1^18 £weighting vector can be minimized to become a .hW+R ,,]-1 ~σχ^Μ(£+Λ_1)+ί>| =<^XK( E+L-\)+D 1 Λ^(£+Λ-1)-1+r„ (7) As described above, calculating the channel matrix coefficients from a pilot signal by applying a matrix inversion lemma, Equation 7 can be rewritten as: ri ί M (£+/.-1)-1 " X+SNR . X ax^m(E^L-\)+D +R„ \ *'m,chtp J where the equalizer output chip SNR is (8)

SNR m^chip

E+L-\)+D 参M(£+L-iy) +Rw J*m(£+Ll )+£),/=〇hw(£+Li)+£) (9) In addition, equalization The output of the soft chip metric becomes xm(k + D) = yv^y(k)^ SNRmchin ϊ+gas-[Xw(A:" 讯]〇0) When ις·2=1)) When the Mth exhibition is exhausted (or the product of the Jth code and the common stirring code), the output soft symbol of the despreader 12 and the six 'A spread factor Λ becomes 〇)=7^2 (("_状+幻〇),乂=0,1,2, r 1 145325.doc 19- 201015928 where A* denotes the conjugate complex number of A. The demapper i24 re-determines and converts the round soft symbol to For the symbol index „, the coding index y, and the bit value of the transmission antenna index. The MMSE weighting vector of equation (7) is not optimal under the observation of the decoders 126 and 226, because it is not considered. Optimized in the case of the significant nature of the on-time inter-stream interference in the detuner 12〇. ΜΙΜΟ Multi-brown CDMA gold-enhanced wafer-level MMSE weighting vector The following discusses equalizing the received signal before despreading. MIm〇 multicode CDMA system. Space time equalizer application has a function of the spreading factor The weighted vector of the number. Considering that the transmitted wafer value 〜w is composed of ^/ orthogonal channel components, that is, = (12) where the phantom corresponds to the wafer component of the first spreading code of the wth transmission antenna 丨14 ( Where 呀^(幻丨2] = 1)), in equation (11), the SNR of the despreader output symbol metric <(") can be SNRi, symbol

SF κ

{E+L-\)+D

+ R h

m(E+L-])+D (13) Note that the orthogonal solution spread spectrum should be introduced relative to the SNR of the chip (S^gain factor and phase loss factor. However, in the code reuse MIM〇 multicode cdma system The actual SNR of the despreader output symbol becomes lower than that of equation (13) because the inter-time inter-channel interference appears to be different from multipath interference or background noise during the despreading process. The MMSE weighting vector of 'Equation (7) is not optimal for the decoders 126, 226 145325.doc -20 · 201015928, because the inter-flow interference is not considered in the despreader 120 The optimization is performed in the case of significant properties. Therefore, as discussed further below, the SNR of equation (13) is difficult to achieve in practice. See equations (4)-(6) and equations (10)-( 12), the soft demodulation variable symbolized by the weight vector for the wth transmission antenna stream and despread by the yth despreading code c*0) can be written as:

X^HE+L-\)*D (8)h咐+i_丨)+d

IVl ~iΣ · p*mtp^Q jSF丨 (

Rx^p(E+L-\)+D(n)^p(E+L-l)+D + Σ°Ά (8)\ +(") 9*p{E^L-\)+D (14)

The first and second items represent the signal and interference components, respectively. More specifically, in the equation (M), ^(4)(8) and ·) represent the expected symbol components after the spread spectrum, the on-time inter-channel interference components using the yth spreading code, and the multipath interference components. The on-time inter-stream interference component that does not use the y-th spread code disappears during the despreading process. Conversely, the on-time inter-stream interference component using the first spreading code has a magic spread gain due to the despreading frequency, = the expected signal component. The despreading operation does not change the covariance of the multipath interference shaping and background noise components (represented by y(8) in the equation (丨4)). Under the observation of the decoders 126, 226, the optimal river 卯 weight vector _ should be minimized by (4) (8) Π (ie, should be minimized relative to the target symbol), and thus it becomes

:W^h m(E+L^l)+〇 ^SF 2 h L· j σχ P(£+i-l)+0hp(£. + Σσ>Χ+κ«

q*p(E+L-\)+D 145325.doc (15) 201015928 By applying the matrix inversion lemma, the mmse weighted vector according to the spreading factor can be rewritten as m,opt :]ΙΨσΧ(

S+L-l)+D Σ p^mtp=0

SF • σ

:11 p(E+L-\)+Dnp(E+l-])+D q*P{E+L-\)+〇(16) The y-coded decoding of the Wth transmission antenna 114 The frequency converter output symbol SNR becomes SNRt°JU〇,=

SF m(£+Z,-l)+Z) ΛΪ·息 Σ

SF

X ^p(E+L-\)+D^p(E+L~\)+D Σσ>Χ 9^p(f+Z,-l)+£)

m(E^L-\)+D (17) Equations (13) and (17) are shown by the SF/J factor, and the variance of the quasi-time interference of equation (17) is greater than the variance of equation (13). Big. Thus the SNR achievable in equation (17) is lower than the expected Snr of equation (13) unless a separate 卯 code is assigned to the data transmission' and the transmission antennas 114 are fully re-used (ie, J =SF). In practice, the number of assigned and re-used codes is usually due to the spread of the spreading code depending on the data rate (eg, a smaller number of codes at lower data rates, and a larger number at higher data rates) Coding), control channel, presence of audio channel, etc., and less than SF. Equations (8) and (16) show that due to the difference in power factor SF/J of the on-time inter-flow interference component, the demapper 、24, 224 and the decoder 145325.doc •22· 201015928 126 226 In the soft symbol level used, the traditional wafer level optimization is not optimal. The traditional wafer level de-emphasis weighting vector underestimates the on-time inter-stream interference component because it does not take into account the despreading effect and therefore controls in a non-optimal direction. Thus, in an embodiment using the weighting vector of equation (8), the actual symbol SNR becomes even lower than equation (17), which is far from the upper limit of equation (13). When we reduce the number of spreading codes for multiple antenna reuse, the performance gap between the mim~cdma optimized MMSE weighting vector in equation (16) and the traditional weighting vector in equation (8) becomes larger. . In the enhanced wafer level equalizer 118, use the map! And the system model of Figure 2 wherein the multiple antennas j i 4 reuse the same spreading code, and all antennas 114 and encoding use approximately the same amount of transmission power. Referring to equations (8) and (16), the variation of the control direction of the weight vector is changed to just-time inter-stream interference. Thus, in sis 〇 multi-code CDMA systems where there is no inter-stream interference, conventional wafer-level MMSE weighting vectors and enhanced MMSE weighting vectors are controlled in the same direction (i.e., they are aligned in the signal space). However, the ratios of the weighted vectors may differ. The scaling factor is a function of SNR, and if the demappers 124, 224 are able to accurately rescale the input soft symbols for a fair evaluation, the conventional wafer level mmse weighting vector and the enhanced MMSE weighting vector have approximately the same decoding performance. . The generalization of the enhanced equalizer for arbitrary power and semaphore allocation in MIMO multi-code CDMA is the generation of enhanced 145325.doc -23- 201015928 wafer-level MMSE weighting vectors for ΜΙΜΟ multicode CDMA receivers 104, 204. In equations (i2)_(i7), it is assumed that all of the two transmission antennas 114 repeatedly use the same spreading code, and that the total transmission wafer energy of the second 2 is equally divided and assigned to the transmission antenna. And separate streams of the spread spectrum code. Equally, assume that each of the streams has wafer energy. In this section, arbitrary coding and power allocation scenarios take into account the existence of actual coded multiplexed pilot, control and audio channels, and unequal power allocation. For this purpose, 'will be defined as a chip assigned to the first transmission antenna U4 (w = 〇, 1, ..., M-1) and the jth code (; = 〇, 1, 1) of the spreading factor SF. Energy, which includes the sum of the wafer energies assigned to all possible subcode trees of the jth code (if they are being used in the wth antenna 114). If the first transmission antenna 114 does not use the yth code, then Ji is equal to 〇. As described above, the results of the enhanced wafer level MMSE weighted vector for multi-code CDMA are valid for special cases, where

Ei W = 0,1,...Λ/-l;y = 〇,l,...Jl m 1 0, m = -l;j = J,J + \,...SF -1 (18 And the transmission power is allocated to the data transmission. In one embodiment, the uncontrolled channel or pilot channel shares the transmitted power with the data stream. The total transmitted wafer energy of the mth transmission antenna 114 is represented by c, which includes all channels 'such as data, pilot, control channel, etc., and defines /w, m=〇) codes and the mth transmission stream. The good MMSE weight vector can be derived in the way of equation (15), which becomes Α/-Ι

m(E+L~\)+D Ρ up{E+L^\ )+D p{E+L^i + Σοχ+R” q*p(E+L-\)+D /»=〇, 1,...,A/-1 (19) 145325.doc -24 - 201015928 In addition, applying the matrix inversion lemma, the equivalent weight vector becomes w dan =

/ \ 1 X yjSF · EJm hm(£+x,_i)+i> · .E^hgf£+L_n+£)hpfg+L_n+D + [l + SNRi;Z'mbolj p*m,p=0 g *p(E+Ll)+D (20) where the first coded despreader output symbol SNR of the mth transmit antenna 114 becomes

(21) SF-EJmh /w(£"+Z<_l )+·0 A/—1ΣΞΙΡ·Ε>

p(E+L-\)+D np(E^L-\)+D

e/w(£+Z,-l)+D ρΦΐη,ρ-Ο q*p(E+L-\)+D A/-1

As shown in Figure 4, the analog error value of the block error rate (BLER) performance between the conventional equalizer (conventional EQ) and the enhanced equalizer (enhanced EQ) is compared for various wafer SNR values. c/iVo) 该 These simulations are performed for 4 transmission (or M=4) antennas 114 and 4 reception (or N=4) antennas 116. Coding, rate matching, interleaving, cluster mapping, and receiver counterparts are configured according to the 3GPP HSDPA HS-DSCH specification. In the HS-DSCH, the chip rate is 3.84 Mcps, the frame length (or block length) is 2 ms, which is 16, and for each antenna 114, the number of modulation symbols per spreading code per frame is 480. . In the simulation, fix the modulation cluster to QPSK. Therefore, the total number of coded bits transmitted by the spread spectrum code via the four antennas 114 in the frame is 3840 «/. The four transmit antennas 114 are set to use the same set of // spread spectrum codes, and the same amount of transfer wafer energy five c/M is equally divided and distributed to the J code channels of each antenna 114. 145325.doc -25- 201015928 For the sake of brevity, load channels (eg, common pilot channels, control channels, audio channels, etc.) are not mimicked in this simulation. Therefore, the overall Bs transfer wafer energy / 〇r is equal to the HS-DSCH wafer energy five c. The turbo code in the 3Gpp HSDpA specification is used for encoding, and the encoding rate is maintained at about 1/3 via the simulation. The carrier frequency is set to 2 GHz. The background noise component of the four receive antennas ιΐ6 is modeled by a spatially independent white Gaussian random process of power spectral density 沁. A wafer-isolated equalizer with fully synchronized and fully evaluated channel variance is used in the simulation = (ie, the oversampling factor is set to 1). When the multipath delay spans Z wafers 10, the spatial time is used. The equalizer time span and the target delay are determined to be several wafers and U-1 wafers. Figure 4 shows the 3 km/h vehicle Α model described in the standard SCM keyway level (6 paths, 2 degree BS angular spread, 35 degree Ms angular spread, 1 〇 wavelength bs antenna spacing, 〇·5 wavelength Single-code reusable BLER performance in MS antenna spacing). The corresponding information rate is set to state kbps, and the number of elements is 3 840. In the single coding case, as illustrated in Fig. 4, at the block error rate (BLER) of ΗΓ2, there is a gain of about this.观测 Observed that the number of * codes increases, the gain of the self-enhanced equalizer decreases: when the number of codes is close to the shape, the power balance between the on-time inter-flow interference component and the multi-interference (10) and the β-phase component becomes Closer to the power balance of the conventional equalizer of (8). Thus, the improvement for _ coding is smaller than the improvement for single coding. The conventional wafer level MMSE weighting vector (8) provides a smaller signal to noise ratio than the MIM 〇 multicode CDMA enhancement 145325.doc 26 201015928 MMSE weighting vector (16) that reuses the same encoding in different transmission antennas. As we can see in the comparison between (8) and (i6), the two weight vectors are still controlled in different directions even after compensating for the scaling factor. In the example towel, on-time interflow interference is a key component. Therefore, it is preferable to consider the enhanced SMMSE weighting vector for the despreading effect. Those skilled in the art will appreciate that any of a variety of different techniques and methods can be used to represent such information and signals. For example, the materials, instructions, commands, signals, signals, bits, symbols, and wafers referred to in all of the above descriptions may be referenced by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein can be constructed as electronic hardware, computer software, or a combination of both. In order to clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above in terms of their respective functionalities as a hardware or software. It will depend on the particular application and design constraints for the overall system. The skilled artisan can construct the described functionality in a different manner for each particular application, but such construction decisions should not be construed as causing a departure from the scope of the invention. A general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device designed to perform the functions described herein, Discrete gate or transistor logic, discrete hardware components, or any combination thereof, to construct or perform various illustrative logic blocks, modules 145325.doc -27- 201015928 and circuits described in connection with the embodiments disclosed herein. A general purpose processor can be a microprocessor, a conventional processor, a microcontroller state machine, or the like. A processor can also be constructed to calculate: a combination of 'a Dsp and a microprocessor, a plurality of micro-portions, an R-Dsp core', or a plurality of microprocessors, or any other combination The steps of the methods or algorithms described in the embodiments disclosed herein may be embodied directly in the hardware, in a processed software module, or in a combination of the two. Software module can reside

Flash memory, (4) Memory front (10)), can hold H = 1 body (: _), electronic erasable program only read (ROM), scratchpad, hard disk, removable disc, memory (a M), or any other known in the art: = in storage media. Coupling a storage medium to, for example, the processor causes the processor to read information for the second entity and to insert information into the storage medium. In the alternative, the storage medium may be integrated in the processing. The participating storage medium may reside in the removable storage area. 2. In the alternative, the processor and the storage medium may reside as a user. In the machine. : Modules may include, but are not limited to, any of the following: software components, such as software object oriented software components, category groups: and: components, processes, methods, functions, Attributes, Procedures, Library, Data Structures, Telecommunications, Data, and Resources provide a prior description of the disclosed embodiments to enable any practitioner skilled in the art to make or use the present invention 145325.doc -28 - 201015928. Various modifications to the embodiments are obvious to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but in the broadest scope of the principles and novel features disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a diagram of a communication system supporting a number of users and capable of implementing at least some aspects and embodiments of the present invention; FIG. 1B is a block diagram of one embodiment of a multi-code CDMA system; 2A is a block diagram of another embodiment of a multi-code CDMA system; FIG. 2B is a block diagram of one embodiment of an MMSE space time equalizer; FIG. 3 is a flow chart illustrating operation of one embodiment of a multi-code CDMA system; and

Figure 4 is a graph of block error rates for various wafer-to-signal noise ratio (SNR) values for an embodiment of the present invention using a one-code reuse and a 3 km/h vehicle A multipath channel model. [Main component symbol description] 2A-2G 32 One 7L 4A-4G Base station 6A-6J Terminal 8 Processor 10 Communication system 145325.doc 201015928 100 ΜΙΜΟMulticode CDMA system 102 Transmitter part 104 Receiver part 106 Encoder 108 Mapper 110 Demultiplexer 112 Spreader 114 Transmission Antenna 116 Receive Antenna 116a Receive Antenna 116b Receive Antenna 118 Minimum Mean Square Error Space Time Equalizer 120 Despreader 122 Multiplexer 124 Demapper 126 Decoder 128 source bit sequence 130 decoded bit 200 ΜΙΜΟ multicode CDMA system 202 transmitter portion 204 receiver portion 206 encoding 208 mapper 210 demultiplexer 145325.doc - 30 - 201015928 multiplexer demapper decoder Decoded bit equalization memory equalization memory filter, filter filter adder 222 224 226 230 250 250a 252 252a 252 252b 254 254a adder 256 equalization metric sequence 256a equalization metric sequence

-31 - 145325.doc

Claims (1)

201015928, VII. Patent application scope: 1. A CDMA receiver for equalizing at least one signal in a communication system, the CDMA receiver comprising: a plurality of receiving antennas for receiving the at least one signal; And a first equalizer operatively coupled to the plurality of receive antennas, wherein the equalizer applies a weight vector comprising a spread spectrum factor and a plurality of transmit antennas transmitting the at least one signal One of the energy coefficients is a function of a plurality of coefficients. 2. The receiver of claim 1, wherein the equalizer generates a complex array equalization metric sequence corresponding to the plurality of transmit antennas. 3. The receiver of claim 2, wherein the at least one signal repeatedly uses at least one spreading code from the plurality of output antennas; and further comprising a plurality of despreaders operatively coupled to the equalizers' The plurality of despreaders divide each of the set of metric sequences into a plurality of modulated symbol sequences. 4. The receiver of claim 3, wherein the equalizer is a minimum mean square error • (MMSE) equalizer. 5. The receiver of claim 4, wherein the MMSE equalizer comprises a plurality of filters corresponding to the plurality of receive antennas, and is operatively coupled to the plurality of receive antennas - each filter generating -. The filtered output is used to generate the equalized metric sequence. 6. The receiver of claim 1, wherein the weight vector is a minimum mean square error (MMSE) weight vector. 7. The receiver of claim 1, wherein the receiver comprises a single 145325.doc 201015928 CDMA receiver. 8. The receiver of claim 1, wherein the receiver comprises a multi-depletion CDMA receiver. 9. The receiver of claim 1 wherein the energy is configured as an unequal energy configuration. 10. The receiver of claim 9, wherein the plurality of coefficients are also obtained by considering the repeated use of the spreading code. 11. A method for equalizing a plurality of signals in a communication system', the method comprising: receiving the plurality of signals using a plurality of receiving antennas; processing the plurality of signals with a weight vector having a plurality of The coefficients are used to generate a plurality of bitstreams, wherein the plurality of coefficients are a function of a) a spreading factor and b) an energy configuration between a plurality of transmission antennas transmitting the plurality of signals. 12. The method of claim 1 further comprising generating a complex array equalization metric sequence corresponding to the plurality of transmission antennas. 13. The method of claim 12, wherein at least one of the plurality of signals reuses at least one spreading code from the plurality of transmission antennas. 14. The method of claim 13, further comprising despreading each of the set of quantized sequences into a plurality of modulated symbol sequences. 15. The method of claim 11, wherein the weighting vector is a minimum mean square error (MMSE) weighting vector. 16. The method of claim 2, wherein the energy is configured as an unequal energy configuration. 145325.doc 201015928. The method of claim 16, wherein the plurality of coefficients are also obtained by considering spreading of the spread code. 18. A connector for equating at least a signal in a communication system, comprising: a receiving component for receiving the at least one signal; and a processing component for processing the at least one signal, wherein The processing member is operatively connected to the receiving member and the processing member is used - A weighting vector comprising a plurality of coefficients of a spreading factor and a function of one of an energy configuration between a plurality of transmission antennas transmitting the at least one syndrome. 19. The receiver of claim 18, further comprising an equalization means for equalizing to generate a complex array equalization metric sequence corresponding to the plurality of transmission antennas. 2. The receiver of claim 19, wherein the at least one signal repeatedly uses at least one spreading code from the plurality of transmission antennas; and θ further comprises a spreading component 'where the spreading component equalizes each group of measurements The sequence is divided into a plurality of modulated symbol sequences. 21. The receiver of claim 20, wherein the equalization means is a minimum mean square error (MMSE) equalizer. 22. The receiver of claim 21, wherein the job equalizer includes a plurality of filters corresponding to the plurality of receive antennas, and is operatively coupled to the plurality of receive antennas, each of the fabrics generating - The filtered output is used to generate the equalized metric sequence. For example, the receiver of claim 18, wherein the weighting vector is a minimum mean square error I45325.doc 201015928 difference (MMSE) weight vector. 24. The receiver of claim 18, wherein the receiver comprises a single code CDMA receiver. 25. The receiver of claim 18, wherein the receiver comprises a multi-code CDMA receiver. 26. The receiver of claim 18, wherein the energy is configured as an unequal energy configuration. 27. The receiver of claim 19, wherein the plurality of coefficients are also obtained by considering the repeated use of the spreading code. 145325.doc