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		<title><![CDATA[ Communications, IEEE Transactions on - new TOC ]]></title>
		<link>http://ieeexplore.ieee.org</link>
		<description>TOC Alert for Publication# 26 </description>
		<year>2009</year>
		<month>November </month>
		<day>23</day>
		<item>
			<title><![CDATA[IEEE Transactions on Communications - Cover page]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336831]]></link>
			<description><![CDATA[ ]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336831]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>C1</startPage>
			<endPage>C1</endPage>
			<fileSize>84</fileSize>
			<authors><![CDATA[]]></authors>
		</item>
		<item>
			<title><![CDATA[Policy allocation for transmission of embedded bit streams over noisy channels with feedback - [Transactions letters]]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336832]]></link>
			<description><![CDATA[An efficient policy allocation algorithm for the transmission of embedded bit streams over noisy channels with feedback is proposed. The transmission is based on the type- II hybrid ARQ/FEC protocol and uses a nested sequence C of channel codes to protect the packets. There are also constraints on the total bit budget and on the allowed number of retransmissions per packet. The allocation algorithm assigns different protection policies, each policy being a subset of C, to different packets to maximize the average number of correctly received source bits. We study the performance and the complexity of the proposed scheme through the transmission of images encoded by JPEG2000 over mobile channels with correlated Rayleigh fading. We demonstrate by simulations that the proposed multiplepolicy scheme provides significant improvements over a purely FEC scheme with no feedback and also the existing fixed-policy schemes. Our results show that feedback is particularly helpful for poor channel conditions and that the proposed scheme is very robust against changes in the channel signal-to-noise ratio (SNR) and the mobile speed.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336832]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3197</startPage>
			<endPage>3182</endPage>
			<fileSize>321</fileSize>
			<authors><![CDATA[Qiu, J.;Banihashemi, A.H.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Waterfall performance analysis of finite-length LDPC codes on symmetric channels]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336833]]></link>
			<description><![CDATA[An efficient method for analyzing the performance of finite-length low-density parity-check (LDPC) codes in the waterfall region, when transmission takes place on a memoryless binary-input output-symmetric channel is proposed. This method is based on studying the variations of the channel quality around its expected value when observed during the transmission of a finite-length codeword. We model these variations with a single parameter. This parameter is then viewed as a random variable and its probability distribution function is obtained. Assuming that a decoding failure is the result of an observed channel worse than the code¿s decoding threshold, the block error probability of finite-length LDPC codes under different decoding algorithms is estimated. Using an extrinsic information transfer chart analysis, the bit error probability is obtained from the block error probability. Different parameters can be used for modeling the channel variations. In this work, two of such parameters are studied. Through examples, it is shown that this method can closely predict the performance of LDPC codes of a few thousand bits or longer in the waterfall region.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336833]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3183</startPage>
			<endPage>3187</endPage>
			<fileSize>376</fileSize>
			<authors><![CDATA[Yazdani, R.;Ardakani, M.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Parallel lookahead algorithms for pruned interleavers]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336834]]></link>
			<description><![CDATA[In this letter, the design of efficient parallel pruned channel and turbo interleavers for Ultra Mobile Broadband (UMB) physical layer standard [1] is addressed. Channel interleaving is based on a bit-reversal algorithm in which addresses are mapped from linear order into bit-reversed order. Turbo interleaving is based on filling a 2D array row by row, interleaving each row independently using a linear congruential sequence (LCS), bit-reversing the order of the rows, and then reading the interleaved addresses column by column. To accommodate for flexible codeword lengths L, interleaving is done using a mother interleaver of length M = 2<sup>n</sup>, where n is the smallest integer such that L &#x02A7D; M, such that outlier interleaved addresses greater than L - 1 get pruned away. This pruning operation creates a serial bottleneck since the interleaved address of a linear address &#x003C7; is now a function of the interleaving operation as well as the number of pruned addresses up to &#x003C7;. A generic parallel lookahead pruned interleaving scheme that breaks this dependency is proposed. The efficiency of the proposed scheme is demonstrated in the context of both UMB interleavers. An iterative pruned bit-reversal algorithm that interleaves any address in O(log L) steps is presented. Moreover, an iterative pruned turbo interleaving algorithm based on LCSs that interleaves any address in O(log<sup>2</sup> L) steps is presented.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336834]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3188</startPage>
			<endPage>3194</endPage>
			<fileSize>298</fileSize>
			<authors><![CDATA[Mansour, M.M.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Noncoherent block-coded TAPSK]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336835]]></link>
			<description><![CDATA[In this letter, we propose three noncoherent blockcoded twisted amplitude and phase shift keying (NBC-TAPSK) schemes which are derived from noncoherent block-coded MPSK. We also propose a new noncoherent detector and a corresponding noncoherent distance for nonconstant-energy signals over the additive white Gaussian noise (AWGN) channel. At high data rates, NBC-8TAPSK has the best bit error performance among all noncoherent schemes.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336835]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3195</startPage>
			<endPage>3198</endPage>
			<fileSize>264</fileSize>
			<authors><![CDATA[Ruey-Yi Wei;Shi-Shan Gu;Tzu-Ching Sue;]]></authors>
		</item>
		<item>
			<title><![CDATA[On the statistics of signal-to-interference plus noise ratio in wireless communications]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336836]]></link>
			<description><![CDATA[This paper presents a unified analytical method for efficient computation of first and second order statistics of the signal-to-interference-plus-noise-ratio (SINR) in wireless communication systems. New exact expressions are derived for the moments of SINR and its autocorrelation function that are valid for arbitrary interfering signals. These are used to examine the accuracy of the commonly used approximations for the average SINR and to investigate effects of fast fading and interfering signals' temporal behavior on the autocorrelation properties of SINR.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336836]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3199</startPage>
			<endPage>3204</endPage>
			<fileSize>359</fileSize>
			<authors><![CDATA[Hamdi, K.A.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Performance of peak-to-average power ratio reduction in single- and multi-antenna OFDM via directed selected mapping]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336837]]></link>
			<description><![CDATA[Selected mapping (SLM) is a popular scheme for peak power reduction in orthogonal frequency-division multiplexing (OFDM) systems. In this letter, the performance of various versions of SLM, among them ordinary and directed SLM, in single- and multi-antenna point-to-point OFDM systems is assessed. Analytic expressions for the distribution of the PAR are derived. Numerical results cover that significant gains over conventional SLM can be achieved by directed SLM.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336837]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3205</startPage>
			<endPage>3208</endPage>
			<fileSize>521</fileSize>
			<authors><![CDATA[Fischer, R.F.H.;Siegl, C.;]]></authors>
		</item>
		<item>
			<title><![CDATA[On the pilot spacing constraints for continuous time-varying fading channels]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336838]]></link>
			<description><![CDATA[In common wireless systems pilot placing can be interpreted as a way to sample the channel with some degree of accuracy. In this letter we investigate the necessary conditions on the pilots spacing for time-varying fading to guarantee a specified average bit error rate. These constraints are evaluated in closed form for large SNR and small fading dynamics and specialized for varying fading correlation and coded/uncoded binary transmissions.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336838]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3209</startPage>
			<endPage>3213</endPage>
			<fileSize>301</fileSize>
			<authors><![CDATA[Savazzi, S.;Spagnolini, U.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Joint adaptive modulation and diversity combining with feedback error compensation]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336839]]></link>
			<description><![CDATA[This letter investigates the effect of feedback error on the performance of the joint adaptive modulation and diversity combining (AMDC) scheme which was previously studied with an assumption of error-free feedback channels. We also propose to utilize adaptive diversity to compensate for the performance degradation due to feedback error. We accurately quantify the performance of the joint AMDC scheme in the presence of feedback error, in terms of the average number of combined paths, the average spectral efficiency, and the average bit error rate. Selected numerical examples are presented and discussed to illustrate the effectiveness of the proposed feedback error compensation strategy with adaptive combining. It is observed that the proposed compensation strategy can offer considerable error performance improvement with little loss in processing power and spectral efficiency in comparison with the no compensation case.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336839]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3214</startPage>
			<endPage>3219</endPage>
			<fileSize>327</fileSize>
			<authors><![CDATA[Seyeong Choi;Hong-Chuan Yang;Alouini, M.-S.;Qaraqe, K.A.;]]></authors>
		</item>
		<item>
			<title><![CDATA[M-ary spreading-code-phase-shift-keying modulation for DSSS multiple access systems]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336840]]></link>
			<description><![CDATA[Code shift keying (CSK) was proposed to increase the transmission efficiency of DSSS systems, and to overcome the spreading gain versus data rate limitation. However, CSK modulation provides no multi-access capability, and degrades the flexibility of a spread spectrum system. In this work, a generalized M-ary DSSS modulation scheme, spreading code phase shift keying (SCPSK), is proposed to improve the system flexibility, and to provide the multi-access capability. This scheme involves switching the spreading code phase in accordance with the incoming data. The union bound of the symbol error probability, in an AWGN channel exposed to multi-user interference, are derived for performance evaluation. Furthermore, the performance of M-SCPSK in a multipath fading channel is investigated via simulation and compared with the conventional DSSS-BPSK scheme.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336840]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3220</startPage>
			<endPage>3224</endPage>
			<fileSize>337</fileSize>
			<authors><![CDATA[Yuh-Ren Tsai;]]></authors>
		</item>
		<item>
			<title><![CDATA[An ESPRIT-based approach for initial ranging in OFDMA systems]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336841]]></link>
			<description><![CDATA[In this letter, an initial ranging scheme for orthogonal frequency-division multiple-access systems is proposed by which users that intend to establish a communication link with the base station (BS) perform spreading in both the time and frequency domains and their synchronization parameters are estimated at the BS in closed-form using the ESPRIT algorithm. Compared to existing alternatives, the resulting scheme exhibits increased robustness against residual frequency offsets without involving computationally demanding peak search procedures.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336841]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3225</startPage>
			<endPage>3229</endPage>
			<fileSize>258</fileSize>
			<authors><![CDATA[Sanguinetti, L.;Morelli, M.;Poor, H.V.;]]></authors>
		</item>
		<item>
			<title><![CDATA[The trivariate and quadrivariate weibull fading distributions with arbitrary correlation and their applications to diversity reception]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336842]]></link>
			<description><![CDATA[The statistical characteristics of the trivariate and quadrivariate Weibull fading distribution with arbitrary correlation, non-identical fading parameters and average powers are analytically studied. Novel expressions for important joint statistics are derived using the Weibull power transformation. These expressions are used to evaluate the performance of selection combining (SC) and maximal ratio combining (MRC) diversity receivers in the presence of such fading channels.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336842]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3230</startPage>
			<endPage>3234</endPage>
			<fileSize>308</fileSize>
			<authors><![CDATA[Papadimitriou, Z.G.;Mathiopoulos, P.T.;Sagias, N.C.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Achieving full transmit diversity for PPM constellations with any number of antennas via double position and symbol permutations]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336843]]></link>
			<description><![CDATA[We present a general technique for constructing minimal-delay rate-1 Space-Time (ST) block codes for Pulse Position Modulations (PPM) with an arbitrary number of transmit antennas. We show that the novel idea of time-domain constellation extension as well as introducing joint position and symbol permutations achieves a full transmit diversity order while maintaining unipolar transmissions. This renders the proposed scheme suitable for low-cost Time-Hopping Ultra- Wideband (TH-UWB) systems as well as Free-Space Optical (FSO) communications with direct detection.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336843]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3235</startPage>
			<endPage>3238</endPage>
			<fileSize>273</fileSize>
			<authors><![CDATA[Abou-Rjeily, C.;Baba, Z.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Improving the performance of SM-MIMO/BICM-ID systems with LLR distribution matching]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336844]]></link>
			<description><![CDATA[In this paper, a distribution matching technique is proposed to process the extrinsic information produced by practical multiple-antenna detectors with iteratively demodulated, bit-interleaved coded modulation (BICM-ID). It is shown that significant gains may be achieved by appropriately processing the extrinsic information generated by practical multiple-antenna detectors before feeding it to the channel decoder. The validity of the proposed matching technique is shown via simulation results applied to Turbo-coded BICM-ID systems using (QRD)-M and list sphere detectors.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336844]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3239</startPage>
			<endPage>3243</endPage>
			<fileSize>432</fileSize>
			<authors><![CDATA[Jia, Q.;Kim, Y.;Seol, C.;Cheun, K.;]]></authors>
		</item>
		<item>
			<title><![CDATA[On the integrated cross-noise term in correlation detectors]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336845]]></link>
			<description><![CDATA[An integrated cross-noise component frequently arises in communications and in signal processing. One typical example is the autocorrelation receiver. Integrated cross-noise generally appears when a noisy signal is recovered (detected) using correlation techniques with a noisy signal as the reference. The statistics of the integrated cross-noise component are analyzed in general for both the cases of uncorrelated and correlated noise terms in the integrand. The exact 2nd order statistics of the integrated cross-noise are derived, and new improved expressions are derived for an approximate probability density function. Accurate computer simulations are performed to evaluate the actual probability density function of the integrated cross-noise component and these results are compared with the approximations. The convergence of the approximation to a Gaussian distribution is also discussed.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336845]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3244</startPage>
			<endPage>3248</endPage>
			<fileSize>325</fileSize>
			<authors><![CDATA[Niranjayan, S.;Beaulieu, N.C.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Comments on "exact error performance of square orthogonal space-time block coding with channel estimation"]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336846]]></link>
			<description><![CDATA[In a recent paper [1], Garg et al. present an expression for the exact decoding error probability (DEP) of square orthogonal space-time block codes (OSTBCs) with imperfect channel estimation. We show that their DEP expression is only asymptotically correct and point out how to obtain the exact result for arbitrary signal-to-noise ratio.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336846]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3249</startPage>
			<endPage>3251</endPage>
			<fileSize>200</fileSize>
			<authors><![CDATA[Jacobs, L.;Moeneclaey, M.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Improved linear group detection for combined spatial multiplexing/STBC systems]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336847]]></link>
			<description><![CDATA[Wireless architectures combining the use of spatial division multiplexing (SDM) and space-time block coding (STBC) have begun to appear in the latest communications standards. In recent years, different detection strategies for these schemes have been proposed which can be broadly categorised as groupbased or direct-detection techniques. While the former class aims at separating the different STBC streams and then apply conventional simple Alamouti decoding, the latter type directly estimates the transmitted symbols without fully exploiting the Alamouti structure. Previous publications have shown that directdetection outperform group-based detectors with the penalty of a higher computational complexity. This letter presents a unified view of the detection strategies for hybrid SDM/STBC systems and presents two new families of group-based detectors. It is shown that linear group detection, when properly implemented, attains the same performance as linear direct detectors at a significant lower complexity.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336847]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3252</startPage>
			<endPage>3257</endPage>
			<fileSize>283</fileSize>
			<authors><![CDATA[Riera-Palou, F.;Femenias, G.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Design of LDPC decoders for improved low error rate performance: quantization and algorithm choices]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336848]]></link>
			<description><![CDATA[Many classes of high-performance low-density parity-check (LDPC) codes are based on parity check matrices composed of permutation submatrices. We describe the design of a parallel-serial decoder architecture that can be used to map any LDPC code with such a structure to a hardware emulation platform. High-throughput emulation allows for the exploration of the low bit-error rate (BER) region and provides statistics of the error traces, which illuminate the causes of the error floors of the (2048, 1723) Reed-Solomon based LDPC (RS-LDPC) code and the (2209, 1978) array-based LDPC code. Two classes of error events are observed: oscillatory behavior and convergence to a class of non-codewords, termed absorbing sets. The influence of absorbing sets can be exacerbated by message quantization and decoder implementation. In particular, quantization and the log-tanh function approximation in sum-product decoders strongly affect which absorbing sets dominate in the errorfloor region. We show that conventional sum-product decoder implementations of the (2209, 1978) array-based LDPC code allow low-weight absorbing sets to have a strong effect, and, as a result, elevate the error floor. Dually-quantized sum-product decoders and approximate sum-product decoders alleviate the effects of low-weight absorbing sets, thereby lowering the error floor.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336848]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3258</startPage>
			<endPage>3268</endPage>
			<fileSize>841</fileSize>
			<authors><![CDATA[Zhang, Z.;Dolecek, L.;Nikolic, B.;Anantharam, V.;Wainwright, M.J.;]]></authors>
		</item>
		<item>
			<title><![CDATA[On the design of raptor codes for binary-input gaussian channels]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336849]]></link>
			<description><![CDATA[This paper studies the problem of Raptor-code design for binary-input AWGN (BIAWGN) channels using the mean-LLR-EXIT chart approach presented in [1]. We report that there exist situations where such a design approach may fail or fail to produce capacity-achieving codes, for certain ranges of channel SNR. Suggestions and discussions are provided pertaining to the design of Raptor codes for BIAWGN channels using the mean-LLR-EXIT chart.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336849]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3269</startPage>
			<endPage>3277</endPage>
			<fileSize>507</fileSize>
			<authors><![CDATA[Cheng, Z.;Castura, J.;Mao, Y.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Linear LLR approximation for iterative decoding on wireless channels]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336850]]></link>
			<description><![CDATA[On a fading channel with no channel state information at the receiver, true log-likelihood ratios (LLR) are complicated functions of the channel output. It is assumed in the literature that the power of the additive noise is known and the expected value of the fading gain is used in a linear function of the channel output to find approximate LLRs. This approach, however, is not optimal in the sense of bit error rate performance. In this paper, we introduce a measure of accuracy for the approximate LLRs based on their probability density function and we show that this measure provides a very convenient tool for finding good approximate LLRs. Assuming that the power of the additive noise is known, and using the proposed measure, we find a linear LLR approximation whose performance is extremely close to that of the true LLR calculation on an uncorrelated Rayleigh fading channel. These results are then extended to the case that the noise power is also unknown and a performance almost identical to the previous case is obtained.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336850]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3278</startPage>
			<endPage>3287</endPage>
			<fileSize>462</fileSize>
			<authors><![CDATA[Yazdani, R.;Ardakani, M.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Hybrid optical/RF channels: characterization and performance study using low density parity check codes]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336851]]></link>
			<description><![CDATA[A hybrid channel, consisting of a free space optical (FSO) link and a parallel radio frequency (RF) link, is considered. The FSO link carries most of the transmitted data while leaving only a small fraction of the data to be carried by the RF link. It is first shown that the capacity of the proposed hybrid structure is much higher than the capacity of a single FSO link. Next the performance of the hybrid channel is studied using a low density parity check code. A density evolution strategy for the hybrid channel is derived and a Gaussian approximation technique is presented. Using these techniques, the conditions for the convergence of the message passing algorithm in terms of minimum data carrying rate through the RF link are derived. Finally, numerical results showing the benefits of the hybrid channel under various channel conditions are presented.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336851]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3288</startPage>
			<endPage>3297</endPage>
			<fileSize>608</fileSize>
			<authors><![CDATA[Tapse, H.;Borah, D.K.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Partial iterative decoding for binary turbo codes via cross-entropy based bit selection]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336852]]></link>
			<description><![CDATA[Near-capacity performance of turbo codes is generally achieved with a large number of decoding iterations. Various iteration stopping rules introduced in the literature often induce performance loss. This paper proposes a novel partial decoding iteration scheme using a bit-level convergence test. We first establish decoding optimality of windowed partial iteration for non-converged bits given that convergence has been achieved on window boundaries. We next present two criteria for testing bit convergence based on cross-entropy, and propose a windowed partial iteration algorithm. The overall complexity and memory requirements of the new algorithm are evaluated and compared with known algorithms. Simulations reveal that the proposed scheme suffers essentially no performance loss compared to full iterations, while reducing the decoding complexity. We also briefly discuss possible extensions of the proposed scheme to general iterative receivers.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336852]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3298</startPage>
			<endPage>3306</endPage>
			<fileSize>479</fileSize>
			<authors><![CDATA[Wu, J.;Wang, Z.;Vojcic, B.R.;]]></authors>
		</item>
		<item>
			<title><![CDATA[The effects of channel estimation errors on a nonlinear precoder for multiple antenna downlink channels]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336853]]></link>
			<description><![CDATA[The effects of channel estimation errors on the performance of a system employing Tomlinson-Harashima precoding and the QR decomposition, operating over multiple antenna frequency-flat fading channels with decentralized receivers, is evaluated. The QR decomposition of the channel matrix is employed to arrive at an equivalent channel where successive interference cancellation at the transmitter can be used to remove the effect of the multiuser interference. However, in the case of imperfect channel estimation, it is not possible to remove the effect of the multiuser interference due to a mismatch between the precoder and the channel. Consequently, it is necessary to include the estimation error in deriving the probability of symbol error. We also provide simulations to corroborate the analytical results.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336853]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3307</startPage>
			<endPage>3315</endPage>
			<fileSize>508</fileSize>
			<authors><![CDATA[Amihood, P.;Masry, E.;Milstein, L.B.;Proakis, J.G.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Performance of BICM-SC and BICM-OFDM systems with diversity reception in non-gaussian noise and interference]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336854]]></link>
			<description><![CDATA[In this paper, we present a general mathematical framework for performance analysis of single¿carrier (SC) and orthogonal frequency division multiplexing (OFDM) systems employing popular bit¿interleaved coded modulation (BICM) and multiple receive antennas. The proposed analysis is applicable to BICM systems impaired by general types of fading (including Rayleigh, Ricean, Nakagami-m, Nakagami-q, and Weibull fading) and general types of noise and interference with finite moments such as additive white Gaussian noise (AWGN), additive correlated Gaussian noise, Gaussian mixture noise, co-channel interference, narrowband interference, and ultra-wideband interference. We present an approximate upper bound for the bit error rate (BER) and an accurate closed-form approximation for the asymptotic BER at high signal-to-noise ratios for Viterbi decoding with the standard Euclidean distance branch metric. For the standard rate-1/2 convolutional code the proposed approximate upper bound and the asymptotic approximation become tight at BERs of 10-6 and 10-12, respectively. However, if the code is punctured to higher rates (e.g. 2/3 or 3/4), the asymptotic approximation also becomes tight at a BER of 10-6. Exploiting the asymptotic BER approximation we show that the diversity gain of BICM systems only depends on the free distance of the code, the type of fading, and the number of receive antennas but not on the type of noise. In contrast their coding gain strongly depends on the noise moments. Our asymptotic analysis shows that as long as the standard Euclidean distance branch metric is used for Viterbi decoding, BICM systems optimized for AWGN are also optimum for any other type of noise and interference with finite moments.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336854]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3316</startPage>
			<endPage>3327</endPage>
			<fileSize>460</fileSize>
			<authors><![CDATA[Nasri, A.;Schober, R.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Jensen-cotes upper and lower bounds on the gaussian Q-function and related functions]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336855]]></link>
			<description><![CDATA[We present new families of lower and upper bounds on Q-functions. First, we consider the Craig form of the Gaussian Q-function Q(&#x003BE;) and shown that its integrand &#x003D5;(&#x003D5;; &#x003BE;) can be partitioned into a pair of complementary convex and concave segments. This property is then exploited in conjunction with the Jensen inequality and the Newton-Cotes' quadrature rule to produce a complete family of upper and lower bounds on Q(&#x003BE;), which can be made arbitrarily tight by finer segmentation. The basic idea is then utilized to derive families of upper and lower bounds also for the squared Gaussian Q-function Q/<sup>2</sup>(&#x003BE;), the 2D joint Gaussian Q-function Q(x, y, p), and the generalized Marcum Q-function Q<sub>M</sub>(x, y). The bounds are shown to be tighter than alternatives found in the literature, and in some cases the lower bounds provided find no equivalent in current literature. The generality of the principle is the elegant point of the method and the resulting Jensen-Cotes bounds are easy to implement and evaluate since only elementary transcendental functions are involved. As an example of application to the analysis of communication systems, we consider the bit error rates (BER's) of decode-and-forward (DF) cooperative relaying schemes with coherent and differential phase-shift keying (PSK) modulations, which have been shown to have an intricate dependence on the Gaussian Q-function, complicated by crossproducts, irrational functional arguments and multiple numerical integrations. In that example the bounds substantially reduce the complexity required to evaluate the expressions, retaining tightness despite multiple numerical integrations with infinite limits.i]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336855]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3328</startPage>
			<endPage>3338</endPage>
			<fileSize>1185</fileSize>
			<authors><![CDATA[De Abreu, G.T.F.;]]></authors>
		</item>
		<item>
			<title><![CDATA[On the average rate performance of hybrid-ARQ in quasi-static fading channels]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336856]]></link>
			<description><![CDATA[The problem of efficient communication over a scalar quasi-static fading channel is considered. The single-layer transmission (SLT) and multi-layer transmission (MLT) schemes do not require any knowledge of the channel state information (CSI) at the transmitter, but their performance is also limited. It is shown that using Hybrid-ARQ (HARQ) can significantly improve the average rate performance, provided that the rate assignment between different ARQ rounds is carefully chosen. The average rate performance of several HARQ schemes is optimized and compared. In addition, optimal power allocation among retransmissions is derived and shown to further increase the average rate. This power allocation gain is remarkable at low signal-to-noise ratio (SNR), but becomes negligible at high SNR. Comparison of two different types of limited feedback, sequential feedback (ARQ) and one-shot feedback (quantized CSI), is made from several perspectives. Although the optimization problem is formed with respect to the average rate, simulation results give a comprehensive comparison under different metrics, including average rate, outage probability, and the combination of both. Substantial performance improvement is observed with even one ARQ retransmission in all simulations. More importantly, this gain appears to be robust with respect to the fading distributions.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336856]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3339</startPage>
			<endPage>3352</endPage>
			<fileSize>610</fileSize>
			<authors><![CDATA[Shen, C.;Liu, T.;Fitz, M.P.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Asymptotic analysis of coherent and differential space-time codes in non¿gaussian noise and interference]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336857]]></link>
			<description><![CDATA[In this paper, we provide a unified framework for the asymptotic performance analysis of space-time codes (STCs) in correlated Ricean fading and non-Gaussian noise and interference. In particular, we derive simple and asymptotically tight expressions for the pairwise error probability (PEP) of coherent and differential STCs which are valid for any type of noise and interference with finite moments and detection with general Mahalonobis distance (MD) metrics including Euclidean distance (ED) and noise decorrelating (ND) metrics. These PEP expressions can be combined with truncated union bounds to obtain accurate asymptotic approximations for the bit, symbol, and frame error probabilities of STCs. We show that while the diversity gain of an STC is independent of the type of noise and the type of MD metric used, the coding gain is not and depends on certain moments of the noise and interference. We provide closed¿form expressions for these moments for several practically relevant types of noise and interference. We show that for correlated noise significant performance gains can be achieved with the ND metric compared to the ED metric. While noise correlations are beneficial at high signal-to-noise ratios if they can be exploited by the metric, they are harmful if this is not the case and the simple ED metric is employed. All our analytical findings are confirmed by simulations for various popular STCs and several different types of noise and interference.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336857]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3353</startPage>
			<endPage>3365</endPage>
			<fileSize>508</fileSize>
			<authors><![CDATA[Nezampour, A.;Schober, R.;Ma, Y.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Capacity of MIMO systems with asynchronous PAM]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336858]]></link>
			<description><![CDATA[Consider a multiple input multiple output (MIMO) system with pulse amplitude modulation (PAM), where each transmit antenna is allowed to choose a different transmission delay. (We refer to this system as a MIMO system with asynchronous PAM.) Such MIMO systems have been studied before for increasing diversity and avoiding unintentional beamforming. We quantify the capacity/outage capacity improvement due to asynchronism and the corresponding spectral leakage (if any) for MIMO point-to-point and MIMO broadcast channels. We show that under commonly used transmitter spectral mask constraints, the channel has unbounded degrees of freedom. Synchronous PAM exploits only a finite number of these degrees of freedom, and asynchronism helps to improve capacity. For most cases of interest, two distinct shifts attain most of the capacity improvement. These gains are robust to interference from adjacent carriers. Analysis of the spectrum of the asynchronous PAM suggests that optimal water-filling based schemes are useful for improving capacity only in directional links due to possible spectral leakage, while uniform power allocation leads to capacity improvement without any extra spectral leakage.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336858]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3366</startPage>
			<endPage>3375</endPage>
			<fileSize>576</fileSize>
			<authors><![CDATA[Barman, K.;Dabeer, O.;]]></authors>
		</item>
		<item>
			<title><![CDATA[A low-complexity generalized sphere decoding approach for underdetermined linear communication systems: performance and complexity evaluation]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336859]]></link>
			<description><![CDATA[For underdetermined linear systems, original sphere decoding (SD) algorithms fail due to zero diagonal elements in the upper-triangular matrix of the QR or Cholesky factorization of the underdetermined matrix. To solve this problem, this paper presents a low-complexity generalized sphere decoding (GSD) approach by transforming the original underdetermined problem into the full-column-rank one so that standard SD can be directly applied on the transformed problem. Since the introduced transformation maintains the dimension of the original problem for all M-QAM's, the proposed GSD approach provides significant reduction in complexity as compared to other GSD schemes, especially for M-QAM with large signaling constellation. Both performance and expected complexity are analyzed to provide the comprehensive relationships between the performance and complexity of the proposed GSD and its parameters. Illustrative simulation and analytical results are in good agreement in terms of both the performance and complexity and indicate that with the properly selected design parameters, the proposed GSD scheme can approach the optimum maximumlikelihood decoding (MLD) performance with low complexity for underdetermined linear communication systems including underdetermined MIMO systems, and the proposed expected complexity analysis can be used as reliable complexity estimation for practical implementation of the proposed algorithm and serve as reference for other GSD algorithms.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336859]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3376</startPage>
			<endPage>3388</endPage>
			<fileSize>758</fileSize>
			<authors><![CDATA[Ping Wang;Tho Le-Ngoc;]]></authors>
		</item>
		<item>
			<title><![CDATA[Improved channel allocation for multicarrier CDMA with adaptive frequency hopping and multiuser detection]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336860]]></link>
			<description><![CDATA[Multicarrier code-division multiple access (MCCDMA) system with adaptive frequency hopping (AFH) has attracted attention of researchers due to its excellent spectral efficiency. A suboptimal water-filling (WF) channel allocation algorithm was previously proposed for the reverse link of this system. To overcome the limitations of the WF algorithm in the presence of fading-induced near-far problem, a new allocation algorithm is proposed and demonstrated to improve performance when the conventional matched filter (MF) receiver is employed. Moreover, the allocation methods are extended to accommodate multiuser detectors (MUDs) at the receiver for MC-CDMA system with AFH. It is demonstrated that the combination of the improved allocation algorithm and the linear MUDs is very efficient in mitigating the fading and multi-access interference (MAI) for realistic mobile radio channels with correlated subcarriers, channel state information (CSI) mismatch, and imperfect power control. Numerical results show that the proposed adaptive transmission method has much greater system capacity than conventional non-adaptive MC direct-sequence (DS)-CDMA system.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336860]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3389</startPage>
			<endPage>3396</endPage>
			<fileSize>542</fileSize>
			<authors><![CDATA[Tao Jia;Duel-Hallen, A.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Cochannel interference avoidance MAC in wireless cellular networks]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336861]]></link>
			<description><![CDATA[Severe cochannel interference in wireless cellular networks significantly affects users at cell edges. We propose a cost-effective cochannel interference avoidance (CIA) medium access control (MAC) scheme to improve network performance. For CIA-MAC, base stations judged as severe interferers transmit randomly and the transmission is controlled by wireless channel states to optimize the overall network performance while maintaining proportional fairness among users. Conditions for triggering CIA-MAC are derived and two simple trigger mechanisms are obtained. The CIA-MAC scheme requires low signaling overhead and only minor changes to the existing mobile systems. Simulation results show that the proposed scheme, CIAMAC, significantly outperforms traditional approaches through the avoidance of severe cochannel interference as well as the exploitation of multiuser diversity through cross-layer design.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336861]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3897</startPage>
			<endPage>3405</endPage>
			<fileSize>675</fileSize>
			<authors><![CDATA[Miao, G.;Li, Y.(.;Himayat, N.;Talwar, S.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Energy-efficient resource allocation in wireless networks with quality-of-service constraints]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336862]]></link>
			<description><![CDATA[A game-theoretic model is proposed to study the cross-layer problem of joint power and rate control with quality of service (QoS) constraints in multiple-access networks. In the proposed game, each user seeks to choose its transmit power and rate in a distributed manner in order to maximize its own utility while satisfying its QoS requirements. The user¿s QoS constraints are specified in terms of the average source rate and an upper bound on the average delay where the delay includes both transmission and queuing delays. The utility function considered here measures energy efficiency and is particularly suitable for wireless networks with energy constraints. The Nash equilibrium solution for the proposed non-cooperative game is derived and a closed-form expression for the utility achieved at equilibrium is obtained. It is shown that the QoS requirements of a user translate into a "size" for the user which is an indication of the amount of network resources consumed by the user. Using this competitive multiuser framework, the tradeoffs among throughput, delay, network capacity and energy efficiency are studied. In addition, analytical expressions are given for users' delay profiles and the delay performance of the users at Nash equilibrium is quantified.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336862]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3406</startPage>
			<endPage>3414</endPage>
			<fileSize>491</fileSize>
			<authors><![CDATA[Meshkati, F.;Poor, H.V.;Schwartz, S.C.;Balan, R.V.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Performance analysis of MIMO free-space optical systems in gamma-gamma fading]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336863]]></link>
			<description><![CDATA[Atmospheric turbulence induced fading is one of the main impairments affecting free-space optics (FSO) communications. In recent years, Gamma-Gamma fading has become the dominant fading model for FSO links because of its excellent agreement with measurement data for a wide range of turbulence conditions. However, in contrast to RF communications, the analysis techniques for FSO are not well developed and prior work has mostly resorted to simulations and numerical integration for performance evaluation in Gamma-Gamma fading. In this paper, we express the pairwise error probabilities of single-input single- output (SISO) and multiple-input multiple-output (MIMO) FSO systems with intensity modulation and direct detection (IM/DD) as generalized infinite power series with respect to the signal- to-noise ratio. For numerical evaluation these power series are truncated to a finite number of terms and an upper bound for the associated approximation error is provided. The resulting finite power series enables fast and accurate numerical evaluation of the bit error rate of IM/DD FSO with on-off keying and pulse position modulation in SISO and MIMO Gamma-Gamma fading channels. Furthermore, we extend the well-known RF concepts of diversity and combining gain to FSO and Gamma-Gamma fading. In particular, we provide simple closed-form expressions for the diversity gain and the combining gain of MIMO FSO with repetition coding across lasers at the transmitter and equal gain combining or maximal ratio combining at the receiver.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336863]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3415</startPage>
			<endPage>3424</endPage>
			<fileSize>641</fileSize>
			<authors><![CDATA[Bayaki, E.;Schober, R.;Mallik, R.K.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Signal detection for optical communications through the turbulent atmosphere]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336864]]></link>
			<description><![CDATA[The probability of a miss in the detection of a signal in an optical communications system through the turbulent atmosphere using intensity modulation is studied. The turbulence of the atmosphere causes scintillation of the received signal intensity which is treated as a lognormal random process. The received background radiation and electronic noise in the receiver is treated as additive white Gaussian noise (AWGN). A Chernoff bound is derived for the lognormal sum distribution. An approximation for the lognormal sum distribution is investigated for its utility in calculating the probability of miss. For practical values of the signal-to-noise power ratio (SNR), a series solution for the characteristic function of the lognormal random variable is used to find the probability of miss. Simulation results agree with theoretical results. The method developed in this paper can be used by the system designer to choose the proper signal length and meet the system specifications for signal detection.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336864]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3425</startPage>
			<endPage>3432</endPage>
			<fileSize>450</fileSize>
			<authors><![CDATA[Brandenburg, J.C.;Liu, J.Q.;]]></authors>
		</item>
		<item>
			<title><![CDATA[A capacity analysis framework for the IEEE 802.11e contention-based infrastructure basic service set]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336865]]></link>
			<description><![CDATA[We propose a multimedia capacity analysis framework for the Enhanced Distributed Channel Access (EDCA) function of the IEEE 802.11e standard. Our analysis shows that the multimedia capacity of the EDCA function for each Access Category (AC) can accurately be estimated by appropriately weighing the service time predictions of a saturation model over different number of active stations. We propose a simple and generic cycle time model to derive the service time in saturation which we employ in the calculation of an accurate station- and AC-specific queue utilization ratio. Based on the estimated queue utilization ratio, we design a simple modelbased admission control scheme. We show that the proposed call admission control algorithm maintains satisfactory userperceived quality for coexisting voice and video connections in an infrastructure Basic Service Set (BSS) and does not present overor under-admission problems of previously proposed models in the literature.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336865]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3433</startPage>
			<endPage>3445</endPage>
			<fileSize>536</fileSize>
			<authors><![CDATA[Inan, I.;Keceli, F.;Ayanoglu, E.;]]></authors>
		</item>
		<item>
			<title><![CDATA[A low-jitter guaranteed-rate scheduling algorithm for packet-switched ip routers]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336866]]></link>
			<description><![CDATA[A Guaranteed-Rate scheduling algorithm for packet-switched IP routers with rate, delay and jitter guarantees is proposed. The algorithm can be used to schedule traffic with 100% throughput in Input-Queued IP routers with unity speedup. The traffic is scheduled according to transmission frames of duration F time-slots. An N x N doubly stochastic traffic rate matrix specifies a traffic rate between each pair of IO ports. The matrix is quantized and recursively decomposed into a sequence of F permutations. Each permutation is used to configure the crossbar switch for one time-slot without requiring additional scheduling. The recursive fair stochastic matrix decomposition is based upon the routing of a permutation through a binary rearrangeable network. In the resulting transmission schedule, the expected Inter-Departure Time (IDT) of a cell equals the Ideal IDT (IIDT), and the maximum IDT and service lag of a cell are bounded by an integer number of IIDTs. The delay and delay jitter experienced along an end-to-end path in a packet-switched IP/MPLS network are therefore small and bounded by an integer number of IIDTs, and the buffer sizes within the IP routers are small and bounded. The proposed algorithm can be used to schedule Guaranteed-Rate traffic in packet-switched IP/MPLS networks, to provide near-optimal queueing delays and essentially-zero delay jitter along end-toend paths when playback buffers are employed.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336866]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3446</startPage>
			<endPage>3459</endPage>
			<fileSize>907</fileSize>
			<authors><![CDATA[Szymanski, T.H.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Adaptive TORC detection for MC-CDMA wireless systems]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336867]]></link>
			<description><![CDATA[Multi carrier code-division multiple access (MCCDMA) is considered for beyond third generation wireless systems for its effectiveness in the presence of both multipath fading and interference. This paper analyzes MC-CDMA systems adopting an adaptive detection technique based on threshold orthogonality restoring combining (TORC). The mathematical framework here developed allows the evaluation of both the bit error probability and the bit error outage in downlink with perfect and imperfect channel state information and the derivation of the TORC threshold that optimizes the performance. The optimal threshold is analytically derived as a function of the number of subcarriers, the number of active users, and the mean signal-to-noise ratio. This enables an adaptive variation of the threshold following slow processes fluctuations. Numerical results show very good performance of TORC with optimal threshold comparing with others combining techniques with perfect and imperfect channel estimation. Results are shown both in uncorrelated Rayleigh fading as well as in time and frequency correlated fading channels.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336867]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3460</startPage>
			<endPage>3471</endPage>
			<fileSize>437</fileSize>
			<authors><![CDATA[Masini, B.M.;Conti, A.;]]></authors>
		</item>
		<item>
			<title><![CDATA[Fundamental capacity limits of cognitive radio in fading environments with imperfect channel information]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336868]]></link>
			<description><![CDATA[In this paper, we analyze the capacity gains of opportunistic spectrum-sharing channels in fading environments with imperfect channel information. In particular, we consider that a secondary user may access the spectrum allocated to a primary user as long as the interference power, inflicted at the primary¿s receiver as an effect of the transmission of the secondary user, remains below predefined power limits, average or peak, and investigate the capacity gains offered by this spectrum-sharing approach when only partial channel information of the link between the secondary¿s transmitter and primary's receiver is available to the secondary user. Considering average received-power constraint, we derive the ergodic and outage capacities along with their optimum power allocation policies for Rayleigh flat-fading channels, and provide closedform expressions for these capacity metrics. We further assume that the interference power inflicted on the primary¿s receiver should remain below a peak threshold. Introducing the concept of interference-outage, we derive lower bounds on the ergodic and outage capacities of the channel. In addition, we obtain closedform expressions for the expenditure-power required at the secondary transmitter to achieve the above-mentioned capacity metrics. Numerical simulations are conducted to corroborate our theoretical results.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336868]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3472</startPage>
			<endPage>3480</endPage>
			<fileSize>433</fileSize>
			<authors><![CDATA[Musavian, L.;Aïssa, S.;]]></authors>
		</item>
		<item>
			<title><![CDATA[A unified approach for generating cross-correlated and auto-correlated MIMO fading envelope processes]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336869]]></link>
			<description><![CDATA[Diversity techniques for various communication and MIMO systems exploit the spatial and temporal diversity attributes to mitigate the ill effects of the fading channels. To evaluate these techniques, a method to generate multiple correlated fading channels is crucial. We propose a unified approach capable of generating correlated flat-fading envelope processes with the desired auto-correlation functions, cross-correlation functions, and probability density functions (pdfs). The proposed approach utilizes the Gaussian vector autoregressive process and the inverse transform sampling techniques. Comparing to the past research focusing on generating fading channels of the same family, the novelty of the proposed approach is its capability to generate fading processes of heterogeneous pdfs. Three examples are demonstrated. In the first example, the autocorrelated Nakagami channel is generated. The second example is designed to generate correlated 2x2 MIMO Rayleigh channels. In the third example, the proposed approach generates three correlated channels having Nakagami, Rician, and Rayleigh pdfs. The settings of the first two examples are adopted from previously published results, which are intended to verify the effectiveness of our proposed approach to tackle previously known problems. The third example demonstrates the novelty of the proposed approach to generate correlated channels of heterogeneous pdfs.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336869]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3481</startPage>
			<endPage>3488</endPage>
			<fileSize>296</fileSize>
			<authors><![CDATA[Wei-Ho Chung;Hudson, R.E.;Kung Yao;]]></authors>
		</item>
		<item>
			<title><![CDATA[Generalized channel inversion methods for multiuser MIMO systems]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336870]]></link>
			<description><![CDATA[Block diagonalization (BD) is a well-known precoding method in multiuser multi-input multi-output (MIMO) broadcast channels. This scheme can be considered as a extension of the zero-forcing (ZF) channel inversion to the case where each receiver is equipped with multiple antennas. One of the limitation of the BD is that the sum rate does not grow linearly with the number of users and transmit antennas at low and medium signal-to-noise ratio regime, since the complete suppression of multi-user interference is achieved at the expense of noise enhancement. Also it performs poorly under imperfect channel state information. In this paper, we propose a generalized minimum mean-squared error (MMSE) channel inversion algorithm for users with multiple antennas to overcome the drawbacks of the BD for multiuser MIMO systems. We first introduce a generalized ZF channel inversion algorithm as a new approach of the conventional BD. Applying this idea to the MMSE channel inversion for identifying orthonormal basis vectors of the precoder, and employing the MMSE criterion for finding its combining matrix, the proposed scheme increases the signal-to-interference-plus-noise ratio at each user¿s receiver. Simulation results confirm that the proposed scheme exhibits a linear growth of the sum rate, as opposed to the BD scheme. For block fading channels with four transmit antennas, the proposed scheme provides a 3dB gain over the conventional BD scheme at 1 % frame error rate. Also, we present a modified precoding method for systems with channel estimation errors and show that the proposed algorithm is robust to channel estimation errors.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336870]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3489</startPage>
			<endPage>3499</endPage>
			<fileSize>545</fileSize>
			<authors><![CDATA[Hakjea Sung;Sang-Rim Lee;Inkyu Lee;]]></authors>
		</item>
		<item>
			<title><![CDATA[Maximum sum-rate of MIMO multiuser scheduling with linear receivers]]></title>
			<link><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336871]]></link>
			<description><![CDATA[We analyze scheduling algorithms for multiuser communication systems with users having multiple antennas and linear receivers. When there is no feedback of channel information, we consider a common round robin scheduling algorithm, and derive new exact and high signal-to-noise ratio (SNR) maximum sum-rate results for the maximum ratio combining (MRC) and minimum mean squared error (MMSE) receivers. We also present new analysis of MRC, zero forcing (ZF) and MMSE receivers in the low SNR regime. When there are limited feedback capabilities in the system, we consider a common practical scheduling scheme based on signal-tointerference- and-noise ratio (SINR) feedback at the transmitter. We derive new accurate approximations for the maximum sumrate, for the cases of MRC, ZF and MMSE receivers. We also derive maximum sum-rate scaling laws, which reveal that the maximum sum-rate of all three linear receivers converge to the same value for a large number of users, but at different rates.]]></description>
			<pubDate><![CDATA[Nov.  2009]]></pubDate>
			<guid><![CDATA[http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5336830&arnumber=5336871]]></guid>
			<volume>57</volume>
			<issue>11</issue>
			<startPage>3500</startPage>
			<endPage>3510</endPage>
			<fileSize>493</fileSize>
			<authors><![CDATA[Louie, R.H.Y.;Mckay, M.R.;Collings, I.B.;]]></authors>
		</item>
	</channel>
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