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Selected Areas in Communications, IEEE Journal on

Issue 11 • Date Nov. 2000

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Displaying Results 1 - 25 of 30
  • A reconfigurable 8 GOP ASIC architecture for high-speed data communications

    Publication Year: 2000 , Page(s): 2161 - 2171
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB)  

    A flexible and reconfigurable signal processing ASIC architecture has been developed, simulated, and synthesized. The proposed architecture compares favorably to classical DSP and FPGA solutions. It differs from general-purpose reconfigurable computing (RC) platforms by emphasizing high-speed application-specific computations over general-purpose flexibility. The proposed architecture can he used to realize any one of several functional blocks needed for the physical layer implementation of data communication systems operating at symbol rates in excess of 125 Msymbols/s. Multiple instances of a chip based on this architecture, each operating in a different mode, can be used to realize the entire physical layer of high-speed data communication systems. The architecture features the following modes (functions): real and complex FIR/IIR filtering, least mean square (LMS)-based adaptive filtering, discrete Fourier transforms (DFT), and direct digital frequency synthesis (DDFS) at up to 125 Msamples/s. All of the modes are mapped onto a common, regular data path with minimal configuration logic and routing. Multiple chips operating in the same mode can be cascaded to allow for larger blocks. View full abstract»

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  • Array gain and capacity for known random channels with multiple element arrays at both ends

    Publication Year: 2000 , Page(s): 2172 - 2178
    Cited by:  Papers (179)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    Two arrays with M and N elements are connected via a scattering medium giving uncorrelated antenna signals. The link array gain relative to the case of one element at each end is treated for the situation where the channels are known at the transmitter and receiver. It is shown that the maximum mean gain achieved through adaptive processing at both the transmitter and the receiver is less than the free space gain, and cannot be expressed as a product of separate gains. First, by finding the singular values of the transmission matrix, fundamental limitations concerning the maximum gain and the diversity orders are given, indicating that the gain is upper bounded by (/spl radic/M+/spl radic/N)/sup 2/ and the diversity order is MN. Next an iterative technique for reciprocal channels which maximizes power at each stage transmitting back and forth is described. The capacity or spectral efficiency of the random channel is described, and it is indicated how the capacity is upper bounded by N parallel channels of gain M(N View full abstract»

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  • Bit error probability for MDPSK and NCFSK over arbitrary Rician fading channels

    Publication Year: 2000 , Page(s): 2179 - 2189
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (373 KB)  

    In this paper, we analyze the bit error probability (BEP) of binary and quaternary differential phase shift keying (2/4 DPSK) and noncoherent frequency shift keying (NCFSK) with postdetection diversity combining in arbitrary Rician fading channels. The model is quite general in that it accommodates fading correlation and noise correlation between different diversity branches as well as between adjacent symbol intervals. We show that the relevant decision statistic can be expressed in a noncentral Gaussian quadratic form, and its moment generating function (MGF) is derived. Using the MGF and the saddle point technique, we give an efficient numerical quadrature scheme to compute the BEP. The most significant contribution of the paper, however, lies in the derivation of a closed-form cumulative distribution function (cdf) for the decision statistic. As a result, a closed-form BEP expression in the form of an infinite series of elementary functions is developed, which is general and unifies previous published BEP results for 2/4 DPSK and NCFSK for multichannel reception in Rician fading. Specialization to some important cases are discussed and, as a byproduct, a new and general finite-series expression for the BEP in arbitrarily correlated Rayleigh fading is obtained. The theory is applied to study 2/4 DPSK and NCFSK performance for independent and correlated Rician fading channels; and some interesting findings are presented. View full abstract»

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  • Performance of the 19-GHz high-speed wireless LAN system

    Publication Year: 2000 , Page(s): 2190 - 2197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (221 KB)  

    This paper describes a new high-speed wireless LAN system in the 19-GHz band. This system features a maximum throughput of 15.2 Mbit/s, which is faster than Ethernet's. To achieve high speed wireless data transmission, we propose the new global scheduling multiple access (GSMA). This system consists of a control module (CM) and some user modules (UMS). One CM can communicate with up to ten UMs. This GSMA, in which all data transmission is managed in the CM, has both short-length and long-length frames, and concatenates multiple packets, so that it performs well with light traffic and heavy traffic: with minimal delay. For high-speed transmission and easy construction, DQPSK/differential detection is used as a modulation/demodulation scheme, and both FEC and ARQ are adopted as the error control method. In addition, as a countermeasure to shadowing and multipath fading, the CM has an omnibeam antenna, and each UM uses a 12-sector antenna, and sector selection diversity is carried out at the UM. This wireless LAN system is based on the RCR STD-34A Japanese radio system standard. View full abstract»

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  • Unified error probability analysis for generalized selection combining in Nakagami fading channels

    Publication Year: 2000 , Page(s): 2198 - 2210
    Cited by:  Papers (76)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (459 KB)  

    We study generalized selection combining (GSC) schemes in independent Nakagami fading channels, where N diversity branches with the largest instantaneous signal-to-noise ratios (SNRs) are selected from the total of L (N/spl les/L) branches and then coherently or noncoherently combined. We propose two different techniques to derive the moment generating function (MGF) expressions for the GSC output SNR in generalized Nakagami fading channels, where there are distinct and noninteger fading severity parameters, as well as different average SNRs in different diversity branches. For arbitrary fading severity parameter m/sub k/, k=1, /spl middot//spl middot//spl middot/L, the MGF expression is given in a summation of N-dimensional definite integrals with the limits independent of SNR or channel parameters, and therefore can be evaluated very efficiently with numerical methods. Furthermore, for integer m/sub k/ closed-form MGF expressions are derived. Specializations of our results to Rayleigh channels and independent identically distributed (i.i.d.) Nakagami channels are presented, which are either new or equivalent to previously published results. Using the newly derived MGF expression, we provide a unified error probability analysis for many coherent and noncoherent modulation/detection schemes. View full abstract»

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  • A comparison of GSM receivers for fading multipath channels with adjacent and co-channel interference

    Publication Year: 2000 , Page(s): 2211 - 2219
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB)  

    We evaluate and compare several data detection schemes used in GSM systems. In particular, we compare the performance of decision feedback equalization (DFE) and nonlinear data directed estimation (NDDE) to that of maximum likelihood sequence estimation (MLSE). Establishing the performance of the basic NDDE detector is a first step in investigating the applicability of block transmission techniques to GSM systems. Our simulation results, obtained both for fading multipath channels and adjacent- and co-channel interference scenarios, suggest that the NDDE offers certain performance advantages over the DFE, and the performance of both detectors is comparable to that of the MLSE for the SNR region of interest in practical systems. Thus, they both represent viable alternatives to the MLSE detector. View full abstract»

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  • Wavelet-based estimation of the nonstationary mean signal in wireless systems

    Publication Year: 2000 , Page(s): 2220 - 2226
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (202 KB)  

    A new technique is described for estimating the nonstationary mean signal received at a mobile station in a Rayleigh fading environment. The estimate is based on samples taken at the midpoints between the local minima of the received envelope. The continuous wavelet transform is used to estimate the local minima. An estimate of the mean signal is obtained using a fixed number of local minima. This technique requires neither an estimate of the mobile speed nor an adaptive temporal averaging window in contrast to other estimators. Simulations show that the mean signal is estimated well in a nonstationary environment with variable mobile speed. View full abstract»

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  • Ordered statistics decoding of linear block codes on frequency nonselective multipath channels

    Publication Year: 2000 , Page(s): 2227 - 2239
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    This paper investigates the performance of ordered statistics decoding (OSD) of linear block codes with binary differential phase-shift-keying (2DPSK) transmission on frequency nonselective multipath channels. First, the wireless channel is modeled as a frequency nonselective, slow fading environment without intersymbol interference. Second, block interleaving is embedded to decorrelate the successive received symbols so that the performance of OSD, designed essentially for memoryless channels, is retained. Third, we derive the log-likelihood ratio of received symbols based on 2DPSK modulation. Fourth, we derive the statistics of received symbols and the statistics of received symbols after ordering. Further, we analyze the system error performance for sufficient degree of interleaving. Specifically, we derive the asymptotic bit error rate (BER) of OSD at high SNRs using the first-order approximation, finally, we conduct experiments at various channel characteristics and interleaving degrees for (128, 61, 22) extended BCH code and (24, 12, 8) extended Golay code. Results show that the error performance improves tremendously with increased interleaving degree. View full abstract»

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  • A Reed-Solomon coded DS-CDMA system using noncoherent M-ary orthogonal modulation over multipath fading channels

    Publication Year: 2000 , Page(s): 2240 - 2251
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB)  

    The performance of Reed-Solomon (RS) coded direct-sequence code division multiple-access (DS-CDMA) systems using noncoherent M-ary orthogonal modulation is investigated over multipath Rayleigh fading channels. Diversity reception techniques with equal gain combining (EGC) or selection combining (SC) are invoked and the related performance is evaluated for both uncoded and coded DS-CDMA systems. "Errors-and-erasures" decoding is considered, where the erasures are based on Viterbi's (1982) so-called ratio threshold test (RTT). The probability density functions (PDF) of the ratio associated with the RTT conditioned on both the correct detection and erroneous detection of the M-ary signals are derived. These PDFs are then used for computing the codeword decoding error probability of the RS coded DS-CDMA system using "errors-and-erasures" decoding. Furthermore, the performance of the "errors-and-erasures" decoding technique employing the RTT is compared to that of "error-correction-only" decoding refraining from using side-information over multipath Rayleigh fading channels. As expected, the numerical results show that when using "errors-and-erasures" decoding, RS codes of a given code rate can achieve a higher coding gain than without erasure information. View full abstract»

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  • Joint array combining and MLSE for single-user receivers in multipath Gaussian multiuser channels

    Publication Year: 2000 , Page(s): 2252 - 2259
    Cited by:  Papers (16)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    The well-known structure of an array combiner along with a maximum likelihood sequence estimator (MLSE) receiver is the basis for the derivation of a space-time processor presenting good properties in terms of co-channel and intersymbol interference rejection. The use of spatial diversity at the receiver front-end together with a scalar MLSE implies a joint design of the spatial combiner and the impulse response for the sequence detector. This is faced using the MMSE criterion under the constraint that the desired user signal power is not cancelled, yielding an impulse response for the sequence detector that is matched to the channel and combiner response. The procedure maximizes the signal-to-noise ratio at the input of the detector and exhibits excellent performance in realistic multipath channels. View full abstract»

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  • Using Walsh code selection to reduce the power variance of band-limited forward-link CDMA waveforms

    Publication Year: 2000 , Page(s): 2260 - 2269
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB)  

    This paper investigates the effects of Walsh code selection and baseband filtering on the statistical moments of the band-limited forward-link CDMA signal. A normalized moment, the "power variance," is proposed as a measure of the signal's sensitivity to nonlinear amplification. The estimation of the power variance for the case of a band-limited QPSK-modulated random waveform is presented as a baseline fur illustrating the effect of filtering on a sampled signal. The band-limited CDMA signal case illustrates the interaction between the Walsh codes and the wave-shaping filter, and quantifies the influence of "missing Hadamard basis functions. "Results verify the accuracy of the statistical models and illustrate the importance of Walsh code selection in the reduction of the power variance of a band-limited CDMA waveform. View full abstract»

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  • Performance of the deliberate clipping with adaptive symbol selection for strictly band-limited OFDM systems

    Publication Year: 2000 , Page(s): 2270 - 2277
    Cited by:  Papers (113)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (178 KB)  

    The performance of the strictly band-limited OFDM systems with deliberate clipping is examined in terms of the peak-to-average power ratio (PAPR) and the resultant bit error performance. The clipping is performed on the OFDM signals sampled at the Nyquist rate, followed by the ideal low-pass filter, Since the low-pass filter considerably enlarges the PAPR, there is a severe limitation in PAPR reduction capability. Thus, in order to achieve further reduction of the PAPR, the application of the adaptive symbol selection scheme is also considered. It is shown that the significant PAPR reduction with moderate complexity can be achieved by the combination of the clipping and the adaptive symbol selection. The price to be paid for PAPR reduction by this scheme is its performance degradation. The paper theoretically analyzes the bit error rate performance of the OFDM system with the Nyquist-rate clipping combined with the adaptive symbol selection, and considers the use of the forward error correction for compensation of the degradation. It is shown that even though the clipping scheme causes severe loss in required signal-to-noise ratio, the use of a powerful channel coding scheme such as turbo codes significantly alleviates the bit error rate performance degradation. View full abstract»

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  • Timing recovery for OFDM transmission

    Publication Year: 2000 , Page(s): 2278 - 2291
    Cited by:  Papers (110)  |  Patents (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB)  

    Orthogonal frequency division multiplexing (OFDM) is an effective modulation technique for high-rate and high-speed transmission over frequency selective fading channels. However, OFDM systems can be extremely sensitive and vulnerable to synchronization errors. In this paper, we present a scheme for performing timing recovery that includes symbol synchronization and sampling clock synchronization in OFDM systems. The scheme is based on pilot subcarriers. In the scheme, we use a path time delay estimation method to improve the accuracy of the correlation-based symbol synchronization methods, and use a delay-locked loop (DLL) to do the sampling clock synchronization. It is shown that by using this scheme, the mean square values of the symbol timing estimation error can be decreased by several orders of magnitude compared to the common correlation methods in both the AWGN and multipath fading channels. In addition, the scheme can track the symbol timing drift caused by the sampling clock frequency offsets. View full abstract»

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  • Adaptive redundant residue number system coded multicarrier modulation

    Publication Year: 2000 , Page(s): 2292 - 2301
    Cited by:  Papers (23)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    The novel class of nonbinary maximum minimum distance redundant residue number system (RRNS) codes is invoked in the context of adaptively RRNS coded, symbol-by-symbol adaptive multicarrier modulation, in order to combat the effects of frequency-selective fading inflicted by dispersive wide-band channels. The system's performance can be adjusted in order to maintain a given target bit error rate (BER) and bit per symbol (BPS) performance. The proposed adaptive RRNS scheme outperforms the convolutional constituent code based turbo coded benchmarker system for channel signal-to-noise ratios (SNR) in excess of about 15 dB at a target BER of 10/sup -4/. View full abstract»

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  • Noncoherent sequence detection in frequency nonselective slowly fading channels

    Publication Year: 2000 , Page(s): 2302 - 2311
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (262 KB)  

    A new class of noncoherent sequence detection (NSD) algorithms for combined demodulation and decoding of any coded linear and continuous phase modulations, transmitted over additive white Gaussian noise (AWGN) channels, has been previously presented. In this paper, this class is generalized to the case of frequency nonselective Rayleigh or Rice slowly fading channels, in the presence or absence of channel state information. Coded linear modulations, namely M-ary phase shift keying (M-PSK) and quadrature amplitude modulation (M-QAM), are considered. The proposed detection schemes have a performance which approaches that of coherent detectors, are very robust to phase and frequency instabilities, and compare favorably to other solutions previously proposed in the technical literature. View full abstract»

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  • A combined OFDM/SDMA approach

    Publication Year: 2000 , Page(s): 2312 - 2321
    Cited by:  Papers (96)  |  Patents (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (237 KB)  

    Two major technical challenges in the design of future broadband wireless networks are the impairments of the propagation channel and the need for spectral efficiency. To mitigate the channel impairments, orthogonal frequency division multiplexing (OFDM) can be used, which transforms a frequency-selective channel in a set of frequency-flat channels. On the other hand, to achieve higher spectral efficiency, space division multiple access (SDMA) can be used, which reuses bandwidth by multiplexing signals based on their spatial signature. In this paper, we present a combined OFDM/SDMA approach that couples the capabilities of the two techniques to tackle both challenges at once. We propose four algorithms, ranging from a low-complexity linear minimum mean squared error (MMSE) solution to the optimal maximum likelihood (ML) detector. By applying per-carrier successive interference cancellation (pcSIC), initially proposed for DS-CDMA, and introducing selective state insertion (SI), we achieve a good tradeoff between performance and complexity. A case study demonstrates that, compared to the MMSE approach, our pcSIC-SI-OFDM/SDMA algorithm obtains a performance gain of 10 dB for a BER of 10/sup -3/, while it is only three times more complex. On the other hand, it is two orders of magnitude less complex than the ML approach, for a performance penalty of only 2 dB. View full abstract»

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  • Iterative receivers for multiuser space-time coding systems

    Publication Year: 2000 , Page(s): 2322 - 2335
    Cited by:  Papers (69)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    Space-time coding (STC) techniques, which combine antenna array signal processing and channel coding techniques, are very promising approaches to substantial capacity increase in wireless channels. Multiuser detection techniques are powerful signal processing methodologies for interference suppression in CDMA systems. In this paper, by drawing analogies between a synchronous CDMA system and an STC multiuser system, we study the applications of some multiuser detection methods to STC multiuser systems. Specifically, we show that the so-called "turbo multiuser detection" technique, which performs soft interference cancellation and decoding iteratively, can be applied to STC multiuser systems in flat-fading channels. An iterative multiuser receiver and its projection-based variants are developed for both the space-time block coding (STBC) system and the space-time trellis coding (STTC) system. During iterations, extrinsic information is computed and exchanged between a soft multiuser demodulator and a bank of MAP decoders, to achieve successively refined estimates of the users' signals. Computer simulations demonstrate that the proposed iterative receiver techniques provide significant performance improvement over conventional noniterative methods in both single-user and multiuser STC systems. Furthermore, the performance of the proposed iterative multiuser receiver approaches that of the iterative single-user receiver in both STBC and STTC systems. View full abstract»

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  • An MLSE receiver using channel classification for Rayleigh fading channels

    Publication Year: 2000 , Page(s): 2336 - 2344
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (297 KB)  

    We propose a channel classification method that identifies the delay path profile of Rayleigh fading channels, which can be used in conjunction with conventional maximum-likelihood sequence estimation (MLSE) receivers. The proposed method determines the appropriate number of delay taps for the MLSE trellis, based on a decision variable obtained from multiple traffic bursts. By formulating the decision variable using the F-distribution, we derive exact expressions for misclassification probability. A new MLSE receiver structure that utilizes the channel classification method is described, and bit error rate (BER) simulation results are presented to demonstrate the performance improvement. The particular application which is discussed is the IS-136 TDMA standard. View full abstract»

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  • Analysis of an identifier splitting algorithm combined with polling (ISAP) for contention resolution in a wireless access network

    Publication Year: 2000 , Page(s): 2345 - 2355
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (267 KB)  

    A contention resolution scheme for an uplink contention channel in a wireless access network is presented. The scheme consists of a tree algorithm, namely the identifier splitting algorithm (ISA), combined with a polling scheme. Initially, ISA is used, but at a certain level of the tree, the scheme switches to polling of the stations. This scheme is further enhanced by skipping a few levels in the tree when starting the algorithm (both in a static and a dynamic way) and by allowing multiple instants simultaneously. An analytical model of the system and its variants leads to the evaluation of its performance, by means of the delay density function and the throughput characteristics. This model is used to investigate the influence of the packet arrival rate, the instant at which the ISA scheme switches to polling, the starting level of the ISA scheme, and the use of multiple instances on the mean delay, the delay quantiles, and the throughput. View full abstract»

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  • MMSE detection of multicarrier CDMA

    Publication Year: 2000 , Page(s): 2356 - 2362
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB)  

    Minimum mean-squared error (MMSE) detection of multicarrier code-division multiple-access (CDMA) signals is investigated. The theoretical performance of two different design strategies for MMSE detection are compared. In one case, the MMSE filters are designed separately for each carrier, while in the other case the optimization of the filters is done jointly. Naturally, the joint optimization produces a better receiver, but the difference in performance is shown to be substantial. The multicarrier CDMA performance is then compared to that of a single-carrier CDMA system on a frequency-selective fading channel. A mechanism is then developed to track the channel fading parameters for all the users' signals so that joint optimization of the receiver filters is possible in a time-varying channel. Simulation results show that the performance of this receiver is close to ideal theoretical results for moderate vehicle speeds. The performance begins to degrade when the normalized Doppler rate is higher than about 1%. View full abstract»

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  • A turbo-coded burst-by-burst adaptive wide-band speech transceiver

    Publication Year: 2000 , Page(s): 2363 - 2372
    Cited by:  Papers (4)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB)  

    Turbo-coded burst-by-burst adaptive orthogonal frequency division multiplex (AOFDM) wide-band speech transceivers are proposed. A constant throughput adaptive OFDM transceiver was designed and benchmarked against a time-variant rate scheme. The proposed joint adaptation of source-codec, channel-codec, and modulation regime results in attractive, robust, high-quality audio systems, capable of conveying near-unimpaired wide-band audio signals over fading dispersive channels for signal-to-noise ratios (SNR) in excess of about 5 dB. View full abstract»

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  • Improving the efficiency of circuit-switched satellite networks by means of dynamic bandwidth allocation capabilities

    Publication Year: 2000 , Page(s): 2373 - 2384
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    Current satellite systems operate according to circuit switching transfer modes. To improve flexibility and efficiency, several kinds of packet switching systems have been proposed. However, it appears that full packet switches are still too complex and expensive to be implemented on board the satellites in the near future. For the time being, dynamic bandwidth allocation capabilities (DBAC) provide a compromise solution when satellite systems are based on classical circuit switches, since the DBAC payload allows changing dynamically the capacity of each connection, without teardown and setup. We consider a DBAC satellite system, and define algorithms to allocate the bandwidth so as to provide deterministic and statistical QoS guarantees. Standard dual leaky buckets (DLBs) regulate the traffic sources. We define bandwidth-handling policies, design connection admission control rules, and evaluate the system performance analytically. Results show a significant increase in bandwidth utilization of our system, when compared to a plain circuit switching solution. View full abstract»

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  • A decomposition technique for efficient generation of correlated Nakagami fading channels

    Publication Year: 2000 , Page(s): 2385 - 2392
    Cited by:  Papers (58)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    Correlated Nakagami m-fading is commonly encountered in wireless communications. Its generation in a laboratory environment is therefore of theoretical and practical importance. However, no generic technique for this purpose is available in the literature. Correlated Rayleigh fading is easy to simulate since it has a simple relationship with a complex Gaussian process. Unfortunately, this is not the case for Nakagami fading. The difficulty lies in that the fading parameter can be a real number and there is no general theory linking a Nakagami vector to a finite set of correlated Gaussian vectors. In this paper, by introducing a direct-sum decomposition principle and determining the statistical mapping between the correlated Nakagami process and a set of Gaussian vectors for its generation, a simple general procedure is derived for the generation of correlated Nakagami channels with arbitrary parameters. A key parameter in the statistical mapping can be determined by using an iterative method. The validity of the new technique is examined through the generation of a correlated Nakagami sequence, as encountered in U.S. digital cellular, and a multibranch vector channel as encountered in diversity reception. View full abstract»

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  • Call admission control and resource management issues for real-time VBR traffic in ATM-satellite networks

    Publication Year: 2000 , Page(s): 2393 - 2403
    Cited by:  Papers (21)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    In this paper, a novel strategy for handling ATM connections of different natures, traffic profile, and QoS requirements in enhanced satellite systems is proposed. The conducted research starts from early studies on resource management in integrated terrestrial-satellite environments and focuses on a combined connection admission control/traffic resource management strategy for QoS provisioning to both real-time and non-real-time constant and variable bit rate sources. The resulting connection handling policy is dynamic, and effectively exploits the system bandwidth through the statistical multiplexing of traffic sources and a preemptive policy over the satellite air interface. The proposed strategy is suited for a generic integrated ATM-satellite system, although its effectiveness has been assessed on a multimedia satellite platform, based on the Ka-band payload and on-board processing. View full abstract»

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  • Performance evaluation of a reservation TDMA protocol for voice/data transmission in microcellular systems

    Publication Year: 2000 , Page(s): 2404 - 2416
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (322 KB)  

    This paper deals with a random reservation TDMA protocol able to support constant bit rate services as well as variable bit rate services. In particular, voice communications and data transmissions are considered. Voice terminals have a higher priority assigned than data terminals in accessing the shared channel. A suitable analytical approach is proposed in order to evaluate the data and voice subsystem performance. Comparisons to the well known PRMA scheme are also given in order to highlight the superior performance of the proposed approach in terms of maximum data load and overall throughput. View full abstract»

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Aims & Scope

IEEE Journal on Selected Areas in Communications focuses on all telecommunications, including telephone, telegraphy, facsimile, and point-to-point television, by electromagnetic propagation.

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Meet Our Editors

Editor-in-Chief
Muriel Médard
MIT