Method and system for canceling multiple access interference in CDMA wireless communication system
First Claim
Patent Images
1. A coded division multiple access (CDMA) receiver, comprising:
- a plurality of antennas, the antennas receiving multiple users'"'"' signals of a first frequency, each user'"'"'s signal comprising a unique pilot signal;
a plurality of RF receivers, down-converting the multiple users'"'"' signals to baseband analog signals;
a plurality of analog-to-digital converters, converting the baseband analog signals to baseband composite digital signals;
a plurality of despreaders, each despreader correlating the baseband composite digital signals with pseudonoise of a desired user with a right timing tracking a corresponding multipath signal to generate a desired user'"'"'s multipath signal, which includes multiple access interference (MAI);
space process means, for each multipath, for weighting the desired user'"'"'s multipath signal and the MAI from all antennas, and then combining the weighted signals such that a signal-to-interference-plus-noise ratio (SINR) of the combined weighted signal is maximized to mitigate MAI;
first maximum ratio combiner (“
MRC”
), combining all weighted outputs from each multipath, each weighted output being weighted again by a complex conjugate of a channel gain derived from the desired user'"'"'s pilot signal to generate a maximal signal-to-noise ratio combined signal for the desired user;
first estimator, for each user, estimating a bit based on the maximal signal-to-noise ratio combined signal;
interference generator, for each user, generating other users'"'"' spreaded signals with their channel variation derived from their respective pilot signals;
cancellation means, subtracting other users'"'"' spreaded signals from the baseband composite digital signals to generate the desired user'"'"'s multipath signal;
second MRC, weighting multipath signals by their respective complex conjugate of the channel gain derived from the desired user'"'"'s pilot signal to generate maximal ratio combined signal for the desired user;
second estimator, for each user, estimating a user'"'"'s bit based on the maximal ratio combined signal.
2 Assignments
0 Petitions
Accused Products
Abstract
A receiver for the third-generation (“3G”) CDMA wireless system is disclosed. The receiver is adapted to mitigate the correlated interference by adaptive antenna process which will maximize the signal-to-interference-plus-noise ratio. After the mitigation of correlated interference from first step space process, the second step is to counter fading with MRC which is optimum after the mitigation of correlated interference. After these first two steps of interference mitigation by adaptive antennas and fading compensation through MRC, the decision signal for the first stage of MPIC will have the strongest desired part and least interference compared to any MPIC available. As can be appreciated, the first stage BER of the present receiver will be the lowest. Then, this low BER will result in a more accurate MAI regeneration, which will further cause a lower BER for the next stage and any subsequent stages. Therefore, the BER of the receiver of the present invention is more likely to converge to the BER of a single user, i.e. MAI-free, faster than those in the conventional systems. In other words, for a given BER requirement, the receiver of the present invention will take the least number of iterations to achieve.
46 Citations
3 Claims
-
1. A coded division multiple access (CDMA) receiver, comprising:
-
a plurality of antennas, the antennas receiving multiple users'"'"' signals of a first frequency, each user'"'"'s signal comprising a unique pilot signal;
a plurality of RF receivers, down-converting the multiple users'"'"' signals to baseband analog signals;
a plurality of analog-to-digital converters, converting the baseband analog signals to baseband composite digital signals;
a plurality of despreaders, each despreader correlating the baseband composite digital signals with pseudonoise of a desired user with a right timing tracking a corresponding multipath signal to generate a desired user'"'"'s multipath signal, which includes multiple access interference (MAI);
space process means, for each multipath, for weighting the desired user'"'"'s multipath signal and the MAI from all antennas, and then combining the weighted signals such that a signal-to-interference-plus-noise ratio (SINR) of the combined weighted signal is maximized to mitigate MAI;
first maximum ratio combiner (“
MRC”
), combining all weighted outputs from each multipath, each weighted output being weighted again by a complex conjugate of a channel gain derived from the desired user'"'"'s pilot signal to generate a maximal signal-to-noise ratio combined signal for the desired user;
first estimator, for each user, estimating a bit based on the maximal signal-to-noise ratio combined signal;
interference generator, for each user, generating other users'"'"' spreaded signals with their channel variation derived from their respective pilot signals;
cancellation means, subtracting other users'"'"' spreaded signals from the baseband composite digital signals to generate the desired user'"'"'s multipath signal;
second MRC, weighting multipath signals by their respective complex conjugate of the channel gain derived from the desired user'"'"'s pilot signal to generate maximal ratio combined signal for the desired user;
second estimator, for each user, estimating a user'"'"'s bit based on the maximal ratio combined signal.
-
-
2. In a code division multiple access (CDMA) wireless system with multiple users, a method of receiving a desired user'"'"'s signal by canceling multiple access interference (“
- MAI”
) from other users, each user'"'"'s signal propagating to an antenna through a plurality (“
L”
, “
L”
being a natural number) of different paths and resulting in multi-path components from each user on each antenna, the method comprising the steps of;(a) receiving composite RF signals from the multiple users simultaneously, at a plurality (“
M”
, “
M”
being a natural number) of spatially separated antennas;
(b) down-converting the composite RF signals to base-band signals and converting the base-band signals to digital signals;
(c) separating the digital signals at each antenna by multi-path components and by users;
(d) for each user, weighting and combining corresponding multi-path components from all “
M”
antennas such that a desired user'"'"'s signal-to-interference-plus-noise ratio is maximized to generate an adaptively filtered output;
(e) for each user, weighting the adaptively filtered output by a channel complex conjugate gain and combining all “
L”
adaptively filtered outputs to counter fading;
(f) estimating a first-stage bit for each user using the combined adaptively filtered outputs;
(g) generating MAI from other user'"'"'s bit estimations, channel gains, and spreading signals;
(h) subtracting MAI for each different path from the composite RF signals and coherently combining L×
M cleaned multi-path signals for the desired user; and
(i) estimating a desired user'"'"'s bit. - View Dependent Claims (3)
- MAI”
Specification
-
- Resources
Litigation Campaign Assessment
Thank you for your request. You will receive a custom alert email when the Litigation Campaign Assessment is available.
×
-
Current AssigneeChibo Capital, LLC
-
Original AssigneeEAnywhere Tech, Inc.
-
InventorsKong, Ning, Zhou, Xue-Song
-
Primary Examiner(s)Ha, Dac V.
-
Application NumberUS09/728,459Publication NumberTime in Patent Office1,600 DaysField of Search375/144, 375/148, 375/343, 375/346, 375/349, 375/350, 370/317, 370/320, 370/333, 370/334, 370/335, 370/342, 370/441, 370/479, 455/50.1, 455/52.3, 455/54.1, 455/63, 455/65, 455/67.3, 455133-135, 455/137, 455271-273, 455/278.1, 455/296, 455/303, 455/307US Class Current375/144CPC Class CodesH04B 1/7107 Subtractive interference ca...H04B 1/712 Weighting of fingers for co...H04B 7/0845 per branch equalization, e....H04B 7/0857 using maximum ratio combini...H04B 7/0897 using beamforming per multi...
