CDMA multi-user receiver composed of de-correlating detectors with reduced noise enhancement effect

Proceedings of the 2006 International Conference on Wireless Communications and Mobile Computing

et al. 2006

For mobile systems higher than 3G, multi-rate data service is becoming an important issue. This paper proposes a multi-rate blockspreading CDMA system as an efficient scheme which is capable of intra-cell-interference free operation and inter-cell-interference reduction by a factor of reciprocal of the spreading factor. With a use of an accurate pilot transmission scheme, it is shown that a high frequency utilization efficiency can be achieved for various mixed data rate services.

Section: De-correlating Detectormentioning

confidence: 99%

A multi-rate CDMA system with block-spreading schemes for anti-interference and high frequency efficiency

Proceedings of the 2006 International Conference on Wireless Communications and Mobile Computing

et al. 2006

“…This important factor is examined in conjunction with noise amplification of DD by the preceding works of this paper [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…In these previous works, the relation between process gain L (spreading sequence length) and the number of active users K has been treated very little. This important factor is examined in conjunction with noise amplification of DD by the preceding works of this paper [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…This paper intends to improve the performance of multi-user receivers using LT techniques, without using coding methods such as the Turbo code. Assumed are in addition such factors that accurate pilot responses (signatures made of spreading sequences and channel gains) for all the users are given, a quasi-synchronization is maintained by controlling the transmit timing of each user, with a closed-loop control [20] and an enveloped spreading sequence which is made by surrounding the core sequence by guard sequences to avoid ISI [17][18][19] is used at the transmitter. In the operation of DD or MMSE, the performance degrades with the AWGN noise amplification (including interference noise for MMSE).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Sequential detection CDMA multi-user receiver

et al. 2005

Int. J. Commun. Syst.

SUMMARYThis paper proposes a sequential detection technique for a multi-user receiver that is constructed over a CDMA system. In this system, the transmitter transmits a symbol made by spreading the spectrum with an enveloped sequence protected by guard sequences, and a receiver de-modulates the core-sequence part of the received symbol with either a de-correlating detector or an MMSE detector. The advantage is that performance is improved without reducing the number of the active users. This sequential detection system estimates the best user signal from all of the soft outputs, which are obtained by solving a de-correlating system of equations. Once detected, the best user component is removed from the received symbol. The resultant symbol composed of the remaining user signals is then sequentially detected by repeating the method stated above. A computer simulation of this system reveals a remarkable improvement in the biterror rate performance compared to conventional systems.

“…Therefore, the available user population K is resultantly forced to limit, and the frequency utilization efficiency degrades. [2]- [4] This paper intends to increase bandwidth efficiency by detecting from the best user to worst user sequentially in solving a DD (or MMSE) system of linear equations.…”

Section: Introductionmentioning

confidence: 99%

Sequential detection CDMA multiuser receiver

SympoTIC '04. Joint 1st Workshop on Mobile Future &Amp; Symposium on Trends in Communications (IEEE Cat. No.04EX877)

et al.

Self Cite

This paper proposes c1 sequential detection multi-user receiver which is constructed over a CDMA system such that U transmitter transmits a symbol made bv spreading the spectmm with an enveloped sequence prorected by guard sequences, and a receiver de-modulates the core-sequence part of the received symbol with o de-correluting detector or an MMSE detectoc and has an advantage of increasing the number of the active users. This sequential detection uses such 0 method that the best user signal is estimated out of the so/r outputs, which are obtained by solving U de-correlating system of equations, and then detected, followed by removing the detected user componentporn the received symbol. All the user signuls may be sequentially detected by repenting the method stated above. The computer simulution reveals ~1 remarkuble improvement in bit error rate performance compared to conventional systems.