S. Verdu and S. Shamai (Shitz), "Spectral efficiency of CDMA with random spreading," IEEE Transactions on Information Theory, vol. 45, no. 2, pp. 622--640, Mar. 1999.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... 4) Cooperative MIMO Interference: Assuming knowledge of the interfering MIMO system parameters (for example, all channel matrices) and cooperative control of the interfering users, the interference treated above can be mitigated by employing a MIMO extension to the multiuser detector (MUD) [30], increasing the capacity of each MIMO user beyond that achievable with the spatial interference cancellation alone. A simple example is provided by a system of uninformed transmitter MIMO users, each utilizing transmitters communicating with a single receiver array fielding elements. It is ....

S. Verdu and S. Shamai (Shitz), "Spectral efficiency of CDMA with random spreading," IEEE Trans. Inform. Theory, vol. 45, pp. 622--640, Mar. 1999.

....(1) in the equivalent vector notation r = p i b i s i n (2) Note that n is a zero mean Gaussian random vector with E nn I N , where I N denotes the N Theta N identity matrix. The information theoretic capacity region of a single cell synchronous CDMA was derived in [4] see also [5]) An important measure of overall information capacity of a multiaccess channel is the sum capacity [4] Csum = 1 2 I N oe SPS (3) where S = s 1 ; s K ] is an N Theta K matrix with the users signature sequences as its columns and P = diagfp 1 ; Delta Delta Delta ; p K ....

S. Verd'u and S. Shamai. Spectral efficiency of CDMA with random spreading. IEEE Transactions on Information Theory, 45(2):622--640, March 1999.

.... CDMA channels can be found in [7, 8, 9, 10] In all of the above cases our final performance measures are simplified using large system approximations which involve modelling the signature sequences as random quantities and looking at the limit of large spreading gain and a large number of users [11, 12, 13]. Throughout the paper, the symbol error rate approximations are compared with simulated values to verify their accuracy. 2 Rayleigh Fading CDMA Channels The model for the received signal after down conversion and chip matched filtering is given by Pa 1 (m)b 1 (m)s 1 Pa k (m)b k (m)s ....

....fi s . We could attempt to determine the distribution of fi s based on knowledge of distributions of the signature sequences and channels however this is a very difficult problem. Alternatively we can call on some powerful new results which look at the behaviour of fi s when the system is large [13, 12, 16]. We have the following result which follows directly from [13, Theorem 3.1] Result 1 As N 1 with K = ffN and ff constant, and under some mild assumptions on the signature sequences (in addition to those given in Section 2) the random variable converges in probability to the ....

S. Verdu and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Trans. Inform. Theory, vol. 45, pp. 622--640, Mar. 1999.

.... of useful mathematical results can be applied (see [25, 26] In related work, large system analysis has previously been used to determine the signal to interference plus noise ratio (SIR) of linear CDMA receivers including the conventional SUMF, the decorrelator and the direct LMMSE receiver [27, 28]. As well, there also exist many other useful analytical techniques such as random matrix analysis, for more details see [29, 30] which can be useful in the analysis of multiuser receivers [31] This paper focuses on large system analysis. The main contribution in this paper is the use of ....

S. Verdu and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Transactions on Information Theory, vol. 45, pp. 622--640, March 1999.

....form as a function of the matrix K . The dependency of total capacity of that channel on the matrix K vanishes, if K is random (but still known at receiver side) with independent, identically distributed entries and Q Z tend to infinity with some fixed ratio S FZ which is called the load [5]. It is achieved for Gaussian input alphabet and will be denoted by ba(c d e W f W (the explicit formula, however, is not relevant for the development of this paper) IV. SEPARATION OF DETECTION AND DECODING In order to understand the result of Shamai and Verdu [3] consider now the problem of ....

Sergio Verdu and Shlomo Shamai (Shitz). Spectral efficiency of CDMA with random spreading. IEEE Transactions on Information Theory, 45(2):622--640, March 1999.

....large system SIR (SIR SUMF ) As the number of stages increases (m # #) #m converges to the LMMSE receiver s large system SIR (SIR LMMSE ) First, observe that at stage 0 we have # 0 = # 0 (#) # 1 (#) # P # 0 (#) P# # = SIR SUMF . 16) This is the SIR SUMF for equal power users [22, 23]. Let # m = P, #) and # m = P, # ) Then # m = lim ### = lim Provided 0 # and 0 we can move the limit inside the integral using the dominated convergence theorem to give Similarly we can show that with 0 # ....

S. Verdu and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Transactions on Information Theory, vol. 45, pp. 622--640, March 1999.

....under the usual assumption that the user information messages are uniformly distributed. From standard arguments [3, Ch. 8] we have that the transmitted signal bandwidth is L=T , where T is the (continuous time) duration of one channel use. Therefore, the system spectral efficiency is given by [4] = R k ; bit=s=Hz (3) We shall also define the system received energy per bit E b k=1 w k=1 R k and the system E b =N 0 , given by [4, 5] k 2 (4) The model (1) has been used extensively in order to derive in simple and concise form most MultiUser Detection (MUD) ....

....signal bandwidth is L=T , where T is the (continuous time) duration of one channel use. Therefore, the system spectral efficiency is given by [4] R k ; bit=s=Hz (3) We shall also define the system received energy per bit E b k=1 w k=1 R k and the system E b =N 0 , given by [4, 5] k 2 (4) The model (1) has been used extensively in order to derive in simple and concise form most MultiUser Detection (MUD) algorithms (see [1] and references therein) Moreover, several recent results on the performance analysis of MUD algorithms in the large system limit ....

[Article contains additional citation context not shown here]

S. Verdu and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Trans. on Inform. Theory, vol. 45, no. 2, pp. 622--640, March 1999.

....that the optimal joint multi user detection maximizes the sum capacity of the channel. I. INTRODUCTION Recently there has been a considerable interest in exploring the potentials of usage of multi user detection to provide the service to more users than processing gain of a CDMA system. In [1] it was demonstrated through the analysis of the spectral efficiency of various multiuser detection schemes in case of long random spreading that some multi user detection schemes can be feasible for the case of more users than the processing gain of the system. Some practical simulation results ....

....a fixed group size. Outline of the paper is as follows. In the Section II of this paper, bit error rates for the MSD receiver will be derived using Gaussian approximation of the multi user interference which is known to be valid for almost all long sequences after conventional matched filtering [1]. It will be shown in Section III that this MSD receiver is a version of the Space Altering Generalized Expectation Maximization Algorithm (SAGE) which ensures the increasing of the likelihood ratio in every iteration and convergence to at least local maximum of the likelihood function. Section IV ....

S.Verdu and S.Shamai (Shitz),"Spectral Efficiency of CDMA with Random Spreading", IEEE Trans. on Information Theory, vol. 45, pp. 622-640. 1999.

....in this paper is the case of imperfectly estimated channel gains in fading environments or the case of imperfect power control. The spectral efficiency loss incurred by this estimation error is analyzed in case of conventional decision feedback receiver. I. INTRODUCTION Two important results [1], 2] published in March 1999 in the Transactions on Information Theory stirred considerable interest in analyzing the performances of various receivers for large multiple access DS CDMA systems. Both results deal with random sequences where the number of users and processing gain increase to ....

....users is finite and signature sequences are pseudorandomly chosen. Using novel results from random matrix theory [3] the asymptotic approach in analyzing the performances of large system multiuser receivers is capable of producing analytically tractable and easily comparable results. Namely, in [1] asymptotic spectral efficiencies of linear and optimum receivers for synchronous CDMA systems with equal powers of users were derived. The spectral efficiencies of linear multiuser receivers were previously analyzed through simulations for finite systems in [4] Extending the results of [1] 5] ....

[Article contains additional citation context not shown here]

S.Verdu and S.Shamai (Shitz), "Spectral Efficiency of CDMA with Random Spreading", IEEE Trans. on Inform. Theory, vol. 45, pp. 622-640, March 1999.

....no fading. We also discuss and identify optimal power control laws for the conventional decision feedback receiver with and without power ordering. The power control law which equalizes single user capacities in the case of power ordering is also discussed. I. INTRODUCTION Two important results [1], 2] published in March 1999 in the Transactions on Information Theory stirred considerable interest in analyzing the performances of various receivers for large multiple access DS CDMA systems. Both results deal with random sequences where the number of users and processing gain increase to ....

....users is finite and signature sequences are pseudorandomly chosen. Using novel results from random matrix theory [3] the asymptotic approach in analyzing the performances of large system multiuser receivers is capable of producing analytically tractable and easily comparable results. Namely, in [1] the asymptotic spectral efficiencies of linear and optimum receivers for synchronous CDMA systems with equal user powers were derived. The spectral efficiencies of linear multiuser receivers were previously analyzed through simulations for finite systems in [4] Extending the results of [1] 5] ....

[Article contains additional citation context not shown here]

S.Verdu and S.Shamai (Shitz), "Spectral Efficiency of CDMA with Random Spreading", IEEE Trans. on Inform. Theory, vol. 45, pp. 622-640, March 1999.

No context found.

S. Verdu and S. Shamai (Shitz), "Spectral efficiency of CDMA with random spreading," IEEE Transactions on Information Theory, vol. 45, no. 2, pp. 622--640, Mar. 1999.

No context found.

S. Verdu and S. Shamai, "Spectral Efficiency of CDMA with Random Spreading ," IEEE Trans. on Information Theory, pp. 622--640, Mar. 1999.

No context found.

S. Verdu and S. Shamai. Spectral Efficiency of CDMA with Random Spreading . IEEE Trans. on Information Theory, pages 622--640, March 1999.

No context found.

S. Verdu and S. Shamai, "Spectral Efficiency of CDMA with Random Spreading," IEEE Trans. on IT, pp. 622--640, Mar. 1999.

No context found.

S. Verd'u and S. Shamai. Spectral efficiency of CDMA with random spreading. IEEE Transactions on Information Theory, 45(2):622--640, March 1999.

No context found.

S. Verdu and S. Shamai (Shitz), "Spectral efficiency of CDMA with random spreading," IEEE Trans. Inform. Theory, vol. 45, no. 2, pp. 622--640, Mar. 1999.

No context found.

S. Verd'u and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Transactions on Information Theory, vol. 45, pp. 622--640, Mar. 1999.

No context found.

S. Verdu, and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Trans. Inform. Theory, vol. 45, pp. 622-640, March 1999.

No context found.

S. Verdu and S. Shamai (Schitz), "Spectral efficiency of cdma with random spreading," IEEE Transactions on Information Theory, vol. 45, pp. 622-- 640, March 1999.

No context found.

Sergio Verdu and Shlomo Shamai (Shitz), "Spectral Efficiency of CDMA with Random Spreading," IEEE Transactions on Information Theory, vol. 45, no. 2, pp. 622--640, March 1999.

No context found.

S. Verdu and S. Shamai (Shitz), "Spectral efficiency of CDMA with random spreading," IEEE Transactions on Information Theory, vol. 45, no. 2, pp. 622--640, Mar. 1999.

No context found.

S. Verdu and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Trans. Inform. Theory, vol. 45, pp. 622--640, Mar. 1999.

No context found.

S. Verdu and S. Shamai, "Spectral efficiency of CDMA with random spreading," IEEE Transactions on Information Theory, vol. 45, pp. 622-- 640, March 1999.

No context found.

S. Verdu and S. Shamai. Spectral efficiency of CDMA with random spreading. IEEE Trans. Info. Theory, 45(2):622--640, March 1999.

No context found.

S. Verdu and S. Shamai (Shitz), "Spectral efficiency of CDMA with random spreading," IEEE Trans. Info. Theory, vol. 45, pp. 622--640, Mar. 1999.

First 50 documents

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC