WO2004045103A1 - Reduced complexity mmse multiuser detection for a multirate cdma link - Google Patents
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- WO2004045103A1 WO2004045103A1 PCT/US2003/034378 US0334378W WO2004045103A1 WO 2004045103 A1 WO2004045103 A1 WO 2004045103A1 US 0334378 W US0334378 W US 0334378W WO 2004045103 A1 WO2004045103 A1 WO 2004045103A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
- H04B1/7105—Joint detection techniques, e.g. linear detectors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
- H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
- H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
- H04B2201/70703—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation using multiple or variable rates
Definitions
- An aspect of this invention relates to multirate code-division multiple access (CDMA) detection systems.
- CDMA code-division multiple access
- multiuser detection has been developed for wireless communication.
- information e.g., code, timing, channel
- information e.g., code, timing, channel
- MMSE minimum mean square error
- MMSE multiuser detection a linear transformation that minimizes the mean square error may be applied to the outputs of the conventional detector for each user of a single rate system in order to decouple the co-channel l interfering users.
- the computation of the standard MMSE linear transformation may involve a matrix inversion, where the order of the matrix is proportional to the number of users. As the order of the matrix increases, the computation of the inverse matrix becomes more difficult.
- a high-rate data user operating at M times the data rate of a low-rate user appears to a conventional MMSE detector as M low-rate users, causing a significant increase in the order of the matrix and resulting computation complexity.
- an MMSE linear transformation may be applied every low-rate symbol interval to the conventional detector outputs of all symbols from all users that occur in the low-rate user symbol interval.
- FIG. 1 shows a block diagram of an embodiment of a multiuser detector.
- FIG. 2 shows a representation of input signals in a multiuser detector.
- FIG. 3A shows a flow chart of the operation of an embodiment of a symbol-level detector.
- FIG. 3B shows a timing diagram of a received signal that may be detected by the symbol-level detector.
- FIG. 4A shows a representation of an exemplary multirate system.
- FIG. 4B shows a block diagram of an embodiment of a multiuser detector.
- FIG. 5 shows a flow chart of the operation of an embodiment of a multiuser detector.
- FIG. 6A shows a representation of another embodiment of a multirate system.
- FIG. 6B shows a block diagram of another e bodiment of a multiuser detector.
- FIG. 7 shows a flow chart of the operation of an embodiment of a multiuser detector
- FIG. 8 shows a block diagram of a wireless device including a multiuser detector.
- Figure 1 shows a detector 10 for detecting data in a received signal 16 of a multirate DS-CDMA communication system.
- Channels in the received signal 16 may be de-spread with the channels' code waveforms via the conventional detector 18, (bank of correlators, i.e., matched filters).
- the detector 10 uses MMSE processing 12 over a reduced observation interval 14 to detect one or more data users 17 within the received signal 16.
- the received signal 16 may include data users having a range of user rates. For example, in a system having two user rates, the high-rate users may be detected in the presence of low-rate users or the low-rate users themselves may be detected.
- the MMSE processing 12 may be conducted at both the symbol level 12a and the chip level 12b.
- symbol-level MMSE processing the soft symbol outputs of the conventional detector 18 are passed to the MMSE processor 12a.
- chip-level MMSE processing the received signal is passed directly to the chip-level MMSE processor 12b.
- the detector 10 may detect signals that include spreading codes that are selected because of a property that enables a reduction in complexity of multiuser detection.
- spreading codes are used in 2 nd and 3 rd generation CDMA downlink systems and their property can be described as follows for a two user-rate system. Given that we have a system with low-rate users characterized by spreading factor
- OVSF Orthogonal Variable Spreading Factor
- any node of the tree 20 has been assigned to a user, none of the nodes underneath can be utilized. Thus, user code assignments are grouped in the smallest possible sub-tree structure.
- the orthogonal Walsh spreading codes that are currently being used on the IS-95 CDMA and cdma2000 downlinks are essentially equivalent to the above codes.
- the codes described here also have the property of being orthogonal. However, in the presence of multipath, the orthogonality property may be partially lost, since the code words between multipath components are not time-aligned. In addition, orthogonality may not available between downlink signals of different cells. [0023] Eq. la defines the downlink spreading codes of length
- the quantity of user rates in the system may be generalized to an arbitrary number of possible rates.
- An embodiment describes the limited case in which the detector detects a received signal that includes two user
- the receiver methods described here may include multi-antenna space-time adaptive processing (STAP) and forward error correction (FEC) coding.
- STAP space-time adaptive processing
- FEC forward error correction
- the receiver algorithms described here can be preceded by a front-end STAP processing (i.e., the linear transformation can be applied after the STAP combining of the different antenna received signal streams) .
- the receiver algorithms may also be used in conjunction with FEC coding such that the linear transformations discussed here provide improved soft values for the coded symbol stream, which are then fed into the FEC decoder to recover the information bits.
- the receiver methods described here may be used in conjunction with interference cancellation methods.
- the inputs to the algorithms described here can include the output of an interference cancellation algorithm where the received signal (in the case of chip-level processing) or the conventional detector outputs (in the case of symbol-level processing) are first "cleaned" of some of the interfering signals, i.e., the interference is estimated and subtracted out.
- interference may also be estimated and subtracted out at the outputs of the receiver algorithms described here.
- Figure 3A shows one aspect of a symbol-level detector
- the symbol-level detector 30 includes three stages to detect high-rate and low-rate users.
- the first stage is a high rate detector 32 that is applied at the high symbol rate to the received signal to process the low-rate users as well as the high-rate users. Because of the spreading code properties described earlier, multiple low-rate users collapse into a single "effective" high-rate user in the high-rate processing interval.
- the high rate detector 32 generates soft outputs for the actual high-rate users and the effective high-rate users.
- the high rate detector 32 may be any linear filter including a bank of correlators, and a matched filter bank, (i.e., the conventional detector for each user) .
- the second stage 34 applies a high-rate linear MMSE transformation to the high-rate outputs of the first stage to produce new soft outputs for the high-rate users and the effective high-rate users, where these outputs will be decoupled to an extent from one another.
- the linear MMSE transformation serves to minimize the mean square error between the actual transmitted symbols and the output of the transformation.
- the third stage 36 then applies a linear MMSE transformation
- One of the second and third stages 34 and 36 may also be any linear detector. The functions of the second stage 34 and the third stage 36 may be interchanged in different embodiments.
- Figure 3B shows a timing diagram of a received signal that may be detected by a symbol-level detector 30.
- the exemplary received signal shows a 3 user synchronous system, where the code waveforms of two of the users 37a and 37b have a spreading factor of 4, and the code word of the third user 39 has a spreading factor of 2, (i.e., the third user has twice the data rate of the first two users) .
- time of the low-rate users 37a and 37b is T 0 and the symbol
- time of the high rate user 39 is T 0 / 2 .
- the received signal can be written as:
- T ⁇ is the ideal observation interval needed for
- observation interval is T 0 /2 , for the first interval:
- a linear transformation can be applied separately for
- each T 0 /2 interval to reduce the MAI and recover the data.
- the complexity savings may be substantial.
- opting for the high-rate one-shot decorrelator described above reduces the interfering symbols in the observation interval (as well as the dimensionality of the correlation matrix, R) by -l for each high-rate user.
- R the dimensionality of the correlation matrix
- r [r[lf r[2] r • • • r[2 mH_mL f Eq. 7 where r[j] is a vector of the received signal chip samples in
- a H) [j] and d- H) [j] are the amplitude
- G[j] is the code matrix of order 2'"" x (K H + 2) , with each column containing a different code
- n[j] contains the noise samples over the 'th
- the low-rate users can be modeled as a single effective high-rate user, (which follows from Eq. lc) .
- the output of the matched-filter (i.e., correlator) outputs for all users for the 'th interval can be expressed as
- the effective high-rate user (representing the collapsed low-rate users), and the other-cell user.
- Equation 8 and 9 can be modified to define the code matrix G[j] .
- the code matrix is
- W[j] p in Eq. 10 will be a scalar.
- this method of handling multipath also applies to any asynchronous user signals, (e.g., other-cell users) , where the corresponding code words are simply shifted vertically in its code matrix column according to its relative delay.
- N+l is the number of taps
- h Int (n, ⁇ p ) are the chip-spaced
- interpolation filter taps sampled (from the underlying sample-spaced interpolation filter) at appropriate sample
- chip-spaced code words can be considered to be the linear sum of several chip-spaced "virtual" paths, delayed and weighted to approximate the underlying non-chip-spaced code word samples.
- the system model described in this section directly extends to a larger observation window, by modifying the code matrix, G[j] and the data vector, x[j] in Eq. 8. For example,
- the received signal can now be expressed as:
- G[j](-1) , G[j](0) , and G[j](+1) contain the code waveforms corresponding to the observation window intervals previous to the desired symbol interval, equal to the desired symbol interval, and successive to the desired symbol interval, respectively. Note that the code vectors in the columns of G[j](-1) and G[j](+1) do not necessarily extend over a whole
- Figures 4A and 4B show an aspect of another detector 50.
- Figure 4A shows a representation of an exemplary multirate system in which two low rate users 40a-40b are collapsed into an effective high rate user 41.
- the system also includes one actual high rate user 42.
- the exemplary system is limited to three users merely to improve the clarity of the description of the detector 50.
- the detector 50 is not limited to any number of low-rate users and high- rate users.
- the low rate users 40a-40b each may have a spreading factor of 4, while the actual high rate user 42 has a spreading factor of 2.
- the symbol time of each of the low rate users 40a-40b is T 0
- the symbol time of the high rate user 42 is T 0 /2.
- Figure 4B shows an aspect of the detector 50.
- a high-rate user may be detected by applying a form of the MMSE criterion to the j'th high-rate subinterval, (i.e., a "high-rate" MMSE detector) . Both symbol level processing and chip level processing may be applied for detecting users.
- the detector may include a high rate detector 52 to generate soft outputs from the received signal.
- An MMSE detector 54 operates as the second stage and a linear detector 56 as the third stage. The MMSE detector 54 applies a linear transformation to the soft outputs for a single high-rate symbol interval to decouple the actual and effective- high rate users, deriving improved soft symbol outputs for each high rate user.
- Each of the actual high rate user outputs of the MMSE detector 54 represent soft outputs of the detected data corresponding to actual high rate user.
- the effective high rate user outputs of the MMSE detector 54 represent a combination of the underlying collapsed low-rate users.
- the detector 50 may not include the high rate detector 52. Instead, the MMSE detector 54 applies the MMSE linear transformation directly to the input signal.
- An MMSE linear transformation may be applied to the conventional detector soft symbol outputs in order to derive improved soft symbol outputs for each user.
- the MMSE linear transformation for each subinterval, L[j] , to apply is
- 2 E
- E
- (x'(I - R'L') - n'GL')((I - R)x - LG'n ] E
- Tr(x) refers to the trace (of a matrix) .
- Implicit in the above equation is the assumption that all entries of x[j] are uncorrelated, (i.e., the data of all users are uncorrelated with each other) . This assumption leads to the diagonal character of the matrix P£j] . This
- Eqs . 12 and 16 can be rewritten as:
- RD] x[j](0)x
- 4 ) (0) H' . H KL ,, + ⁇ for / 2, 3,..., 2"' i ⁇ m "-l:
- xUK-l ⁇ LJKO ⁇ xLJK+l are the first elements of the vectors implicitly defined in Eq. 12, and which contain the effective high-rate user data, (for the collapsed low-rate users) for the previous, current, and successive high-rate symbol subintervals, respectively.
- a MMSE linear transformation may be applied directly to the received signal, without the front-end conventional detector.
- the linear transformation, v[j] is derived
- Figure 5 shows a flow chart of the operation of detector 50.
- a signal that is modulated by a spreading code such as in a CDMA system is received.
- the signal includes actual high-rate users and low-rate users.
- the signal is decoded using the high symbol rate for the low-rate users as well as the high-rate users.
- the low-rate users are collapsed (i.e. modeled as) into one or more effective high- rate users.
- soft outputs may be detected for the actual high-rate users and the effective high-rate users, (for the case of symbol-level processing) .
- an MMSE linear transformation is applied to the soft outputs for a high-rate symbol interval to decouple the actual and effective high rate users generating soft outputs.
- the resulting decoupled actual high rate user soft outputs represent the detected data of the corresponding actual high rate users.
- the decoupled effective high rate user soft outputs represent a combination of the underlying collapsed low-rate users.
- a linear transformation may be applied over successive intervals of the effective high-rate user soft outputs to decouple the low-rate users embedded in the effective high-rate user soft outputs.
- an MMSE linear transformation 66 would be applied directly to the received signal, bypassing the initial detector 64.
- Another embodiment uses techniques for recovering the low-rate users from the soft outputs of the high-rate front- end conventional correlator (matched-filter) detector for all users. Instead of one MMSE processing window over the entire low-rate symbol interval, (1) the MMSE processing is done over several separate smaller windows, (2) and used to obtain an MMSE estimate for the low-rate user for each processing sub-interval, (3) these estimates are combined for the low-rate user in some way. In other words, we can take the 2"' L ⁇ '"" outputs from the high-rate MMSE processing for the low-rate users and combine them in some way to get an estimate of the low-rate user. The outputs from the high- rate MMSE processing for the low-rate users follow from the minimization of the cost function
- each of the high-rate MMSE outputs for the low- rate user derived above part of the low-rate symbol is recovered, i.e., we partly recover an effective high-rate user that represents some combination of the underlying collapsed low-rate users. As described below, these outputs can be combined in some way to decouple and detect the low- rate users. Using this approach allows us to apply MMSE solutions in smaller subintervals, which reduces complexity, while still recovering the low-rate users.
- the output of the high-rate MMSE detector derived above for the effective high-rate user in the j'th subinterval can be written as:
- B e is a diagonal matrix of size2"' i ⁇ '" w x 2'" L ⁇ '" H and is implicitly
- y is of length (2"' L ⁇ '" + 2)K , (assuming
- R e is a (2"' L ⁇ '" H +2)K x 2'" L ⁇ '"" correlation matrix, which contain the
- R_ e is the correlation
- Eq. 40 simply expresses Eq. 28 and Eq. 29 in a more compact form. As we saw in Eq. 28, we can express the effective high-rate user outputs as :
- T' e contain the high-rate MMSE solutions for the
- L can be chosen to minimize Ex e -(LR e )-'Ly
- Figure 6A shows a representation of another multirate system in which two low rate users 70a-70b are collapsed into an effective high rate user 71.
- the system also includes one actual high rate user 72.
- the low rate users 30a-70b each may have a spreading factor of 4, while the actual high rate user 72 has a spreading factor of 2.
- the symbol time of each of the low rate users 70a-70b is T 0
- the symbol time of the actual high rate user 72 is T 0 /2.
- the detector 80 includes a high rate detector 82 similar in operation and function to high rate detectors 32 and 52. Similarly, the high rate detector 82 generates soft outputs for the actual high-rate users and the effective high-rate users.
- the detector 80 includes a linear detector 84 as the second stage and an MMSE detector 86 as the third stage.
- the linear detector 84 may post-multiply the soft outputs of the high rate detector 82 (over the whole low-rate symbol interval) to generate transformed effective high-rate user soft outputs and transformed actual high-rate user soft outputs.
- the multiple low-rate users appear as multiple decoupled high- rate symbols while still being coupled to the actual high rate users.
- the MMSE detector 86 may apply a linear transformation to the soft outputs of the second stage linear detector over one high-rate interval to decouple a low rate user (i.e. transformed effective high-rate symbol) from the actual high rate users.
- a low rate user i.e. transformed effective high-rate symbol
- the detector 80 will not include the high-rate detector 82. Instead, the preprocessing decoupling transformation 84 is applied directly to the input received signal.
- the transformed outputs decouple the
- the preprocessing enables the detection to consist of a single high-rate MMSE transform, with no post-processing combining necessary.
- This embodiment describes MMSE detection, as we have done elsewhere in the report. Other linear transformations can be applied as well to the post-transformed pseudo-high- rate intervals to recover the low-rate users.
- Note that the approach described here requires that the code words for each user repeat (to within a sign change) every high-rate interval, a property that is satisfied by the spreading codes introduced earlier. This will generally not be the case in commercial systems since the transmissions from different cells are mixed with unique very long codes spanning many symbols. (One cell can be processed by first stripping off the long code.) As such, the other-cell user will not be discussed in this section.
- K K H +1
- the first row of the matrix X can be expressed as follows:
- H ⁇ (defined earlier) , is a 2" ⁇ '" H xK L matrix with K L
- ⁇ ⁇ ⁇ ] [ ⁇ ⁇ m(-i) r x T ul( ) r ⁇ ⁇ [j](+i) r f Eq. 63
- the off- diagonal elements are all zero except for the following:
- each group of high-rate intervals making up a specific low-rate interval is transformed separately.
- first transform 3 low-rate symbols worth of high-rate outputs are transformed, one low-rate interval at a time, before implementing the high-rate MMSE approach described here to detect a low-rate user.
- An advantage of this approach is that it doesn't depend on the signal-to-noise levels of the users.
- a disadvantage is that performance will not be as good as the MMSE approach described in this section, since
- Figure 7 shows a flow chart of the operation of the detector 80.
- Blocks 90-94 of the operation are similar to the operation of the detector 50 described in blocks 60-64 of Figure 5.
- a decoupling linear transformation is applied to the high rate soft outputs to generate transformed effective high-rate user soft outputs and transformed actual high-rate user soft outputs that remain coupled.
- an MMSE linear transformation is applied to the transformed outputs to decouple the low-rate users from the actual high rate users.
- each of the high-rate MMSE outputs (i.e., for each sub-interval) for the low-rate user derived above, part of the low-rate symbol is recovered, i.e., we partly recover an effective high-rate user that represents some combination of the underlying collapsed low-rate users.
- these outputs can be combined in some way as to decouple and detect the low-rate users. Using this approach allows us to apply MMSE solutions in smaller subintervals, which reduces complexity, while still recovering the low- rate users .
- each vector v e [j] r is of length 3*2'"" +2ds .
- the matrix V ⁇ ' has dimensions 2"' L ⁇ "' » x(2'" L +2(2'"" +ds)) .
- x_ e contains the data of
- G e is the code matrix, (with dimensions
- V e 'G_ e x conjugate e represents the middle term
- L can be chosen to minimize E,x.-(LG.)T I Lr
- the approach described here requires that the code words for each user repeat (to within a sign change) every high-rate interval, a property that is satisfied by the spreading codes introduced earlier. This will generally not be the case in commercial systems for the other-cell users since the transmissions from different cells are mixed with unique very long codes spanning many symbols. (One cell can be processed by first stripping off the long code.) As such, we will not include the other-cell user in this section. For systems where the other-cell users' code-words did repeat every high-rate interval (to within a sign change) , then they could easily be included in the processing. Note that even if only intra-cell signals are processed, this low complexity method will provide better performance than a standard MMSE chip equalizer.
- the received signal samples for the 2"' ⁇ " '" W high-rate intervals can be rearranged as follows, (assuming a single symbol window, i.e., no edge effects):
- G does not depend on the interval number, j, because of the assumption, (stated above) , that all the code words repeat (to within a sign change) every high-rate interval. Note also that the vectors r[j] and r[j ⁇ l] will overlap if there is
- the first row of the matrix X can be expressed as follows :
- the vector P xd ⁇ is a vector of all zeros except
- the received signal chips are transformed one low-rate interval separately at a time.
- a processing window larger than one symbol i.e., for taking edge effects into account
- This transformation is meant to decouple in some way low-rate user j from the other low-rate users in the
- Step 5 An alternative to computing the derivative in Step 5 is to utilize numerical optimization techniques to iterate to the optimal h j solution. Therefore, Step 5 would now
- FIG. 8 shows a wireless device 100 for communicating information.
- the wireless device 100 may include a transceiver 102 coupled to an antenna 103 to communicate information with other wireless devices.
- a baseband device 106 may implement call processing, system control, and the man-machine interface.
- the baseband device 106 may include a multi-user multi-rate detector 104 to detect a conditioned input signal generated by the transceiver 102.
- the multi-user multi-rate detector 104 operates in accordance with one or more aspects of the detector described in this specification.
- the baseband device 106 may also include an audio codec to interface to one or more input/output (I/O) devices 106 such as keyboards, speakers, and microphones.
- I/O input/output
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Application Number | Priority Date | Filing Date | Title |
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EP03776600A EP1561289B1 (en) | 2002-11-08 | 2003-10-29 | Reduced complexity MMSE multiuser detection for a multirate CDMA link |
CN200380101478.3A CN1706110B (en) | 2002-11-08 | 2003-10-29 | Reduced complexity MMSE multiuser detection for a multirate CDMA link |
AU2003284364A AU2003284364A1 (en) | 2002-11-08 | 2003-10-29 | Reduced complexity mmse multiuser detection for a multirate cdma link |
DE60327939T DE60327939D1 (en) | 2002-11-08 | 2003-10-29 | MMSE Multiuser Detection with Reduced Complexity for Multirate CDMA Transmission |
AT03776600T ATE433620T1 (en) | 2002-11-08 | 2003-10-29 | MMSE MULTI-USER DETECTION WITH REDUCED COMPLEXITY FOR MULTIRATE CDMA TRANSMISSION |
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US10/291,189 US7333466B2 (en) | 2002-11-08 | 2002-11-08 | Reduced complexity MMSE multiuser detection for a multirate CDMA link |
US10/291,189 | 2002-11-08 |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7061891B1 (en) | 2001-02-02 | 2006-06-13 | Science Applications International Corporation | Method and system for a remote downlink transmitter for increasing the capacity and downlink capability of a multiple access interference limited spread-spectrum wireless network |
US7209515B2 (en) * | 2001-03-30 | 2007-04-24 | Science Applications International Corporation | Multistage reception of code division multiple access transmissions |
US7006461B2 (en) * | 2001-09-17 | 2006-02-28 | Science Applications International Corporation | Method and system for a channel selective repeater with capacity enhancement in a spread-spectrum wireless network |
US7075973B2 (en) * | 2003-03-03 | 2006-07-11 | Interdigital Technology Corporation | Multiuser detection of differing data rate signals |
US7313168B2 (en) * | 2003-03-06 | 2007-12-25 | Nokia Corporation | Method and apparatus for receiving a CDMA signal |
US7856071B2 (en) * | 2005-07-26 | 2010-12-21 | Alcatel-Lucent Usa Inc. | Multi-path acquisition in the presence of very high data rate users |
US8275023B2 (en) * | 2006-02-13 | 2012-09-25 | Telefonaktiebolaget Lm Ericsson (Publ) | Method and apparatus for shared parameter estimation in a generalized rake receiver |
KR100838519B1 (en) * | 2006-11-27 | 2008-06-17 | 전자부품연구원 | Joint Detection-Decoding Receiver of DS-CDMA System |
US8494098B2 (en) | 2009-05-04 | 2013-07-23 | Qualcomm Incorporated | Method and system for inter-cell interference cancellation |
US8615030B2 (en) * | 2009-05-04 | 2013-12-24 | Qualcomm Incorporated | Method and system for multi-user detection using two-stage processing |
US8494029B2 (en) * | 2009-05-04 | 2013-07-23 | Qualcomm Incorporated | Method and system for multi-user detection in the presence of multiple spreading factors |
US8451963B2 (en) * | 2009-06-09 | 2013-05-28 | Qualcomm Incorporated | Method and system for interference cancellation |
CN103152797B (en) * | 2013-01-28 | 2016-05-25 | 北京傲天动联技术股份有限公司 | A kind of low-rate users connection control method |
CN105262531B (en) * | 2015-10-27 | 2018-08-24 | 杭州电子科技大学 | User has the coding/decoding method of the extensive antenna system of double antenna |
CN111610498B (en) * | 2020-06-22 | 2023-04-07 | 成都航空职业技术学院 | Space-time adaptive signal processing method with high-degree-of-freedom decoupling |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5544156A (en) * | 1994-04-29 | 1996-08-06 | Telefonaktiebolaget Lm Ericsson | Direct sequence CDMA coherent uplink detector |
FI100569B (en) * | 1995-05-08 | 1997-12-31 | Nokia Telecommunications Oy | Method and apparatus for variable rate coding and detection in a multipurpose mobile communication system |
CN1053313C (en) | 1997-04-21 | 2000-06-07 | 北京信威通信技术有限公司 | Time division duplex synchronous code partition multi-address radio communication system |
US6208684B1 (en) | 1998-09-18 | 2001-03-27 | Dspc Technologies Ltd. | Cyclic adaptive receivers for DS-CDMA signals |
KR100283379B1 (en) * | 1998-11-16 | 2001-03-02 | 정선종 | Parallel Multistage Interference Cancellation |
KR100277697B1 (en) * | 1998-12-02 | 2001-01-15 | 정선종 | Adaptive Receiver Using Constrained Mean Square Error Minimization |
US6426973B1 (en) * | 1999-04-29 | 2002-07-30 | The Board Of Trustees Of The University Of Illinois | Differential minimum mean squared error communication signal compensation method |
CN1178071C (en) | 1999-06-29 | 2004-12-01 | 张世平 | Mobile telephone type transmitter for automatic location tracking |
JP3370955B2 (en) * | 1999-07-19 | 2003-01-27 | 株式会社日立国際電気 | CDMA base station device |
US6680902B1 (en) * | 2000-01-20 | 2004-01-20 | Nortel Networks Limited | Spreading code selection process for equalization in CDMA communications systems |
DE10003734A1 (en) * | 2000-01-28 | 2001-08-02 | Bosch Gmbh Robert | Detection method and device |
JP4744725B2 (en) * | 2001-05-25 | 2011-08-10 | 三菱電機株式会社 | Interference canceller |
JP2003143045A (en) * | 2001-11-02 | 2003-05-16 | Fujitsu Ltd | Signal processing apparatus using algorithm for minimizing mean square error |
-
2002
- 2002-11-08 US US10/291,189 patent/US7333466B2/en active Active
-
2003
- 2003-10-29 AU AU2003284364A patent/AU2003284364A1/en not_active Abandoned
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Non-Patent Citations (2)
Title |
---|
CHEN J ET AL: "ANALYSIS OF DECORRELATOR-BASED RECEIVERS FOR MULTIRATE DS/CDMA COMMUNICATIONS", IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, IEEE INC. NEW YORK, US, vol. 48, no. 6, November 1999 (1999-11-01), pages 1966 - 1983, XP000928389, ISSN: 0018-9545 * |
SAQUIB M ET AL: "DECORRELATING DETECTORS FOR A DUAL SYNCHRONOUS DS/CDMA SYSTEM", WIRELESS PERSONAL COMMUNICATIONS, KLUWER ACADEMIC PUBLISHERS, NL, VOL. 9, NR. 3, PAGE(S) 197-214, ISSN: 0929-6212, XP000791291 * |
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AU2003284364A1 (en) | 2004-06-03 |
CN1706110A (en) | 2005-12-07 |
EP1561289A1 (en) | 2005-08-10 |
CN1706110B (en) | 2013-03-27 |
ATE433620T1 (en) | 2009-06-15 |
EP1561289B1 (en) | 2009-06-10 |
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