55,949 research outputs found
Comparison between the performance of conventional and selective RAKE receiver schemes
No full textIn this paper, we determine the effects of different diversity schemes on the behavior of a direct-sequence spread-spectrum RAKE receiver that operates with random sequences in a multipath fading channel with an arbitrary power-delay profile. Two different receiver architectures, the former employing the L instantaneously strongest paths out of the N-r resolved ones and the latter simply the L strongest on average paths out of the received N-r, are confronted in terms of symbol-error probability, when an M-level phase-shift keying system is assumed. The analytical approach devised for assessing such a comparison gives the symbol-error probability in terms of simple elementary integrals and immediately evidences the influence on system behavior of the number of resolved paths, bandwidth occupancy of the signal- and power-delay profiles with a remarkably moderate computational effort
Performance of a 3rd Generation Radio Link Control Protocol on a Multicarrier DS-CDMA System
No full textThis work investigates the behavior of a 3 rd Generation Radio Link Control Protocol on the forward link of a Multicarrier DS-CDMA architecture that employs Walsh and Quasi-Orthogonal channelization codes. Protocol performance is analytically assessed, determining the average delay suffered by a data unit transferred over the radio channel. For alternative allocation policies of Walsh and Quasi-Orthogonal codes, the effects on throughput of different transmission qualities and size of protocol data units are evaluated. system design
Multicarrier DS-CDMA performance with different assignment strategies of quasi-orthogonal codes
No full textAlternative code assignment policies for the forward link of a multicarrier DS-CDMA system employing the recently proposed quasi-orthogonal sequences are put forth in this paper. It is demonstrated how different allocation strategies of quasi-orthogonal codes alter the interference level suffered by active units; it is also shown how to shape the rate of interference growth as a function of the number of active users within the reference cell, by implementing some specific code allocation patterns. The performance, in terms of average bit error probability, achieved by various schemes is assessed in a frequency selective fading environment, and the advantages of different solutions highlighted. ©2002 IEEE
Goodput and delay analysis of a radio link control protocol operating over a multicarrier DS-CDMA architecture
No full textThis work proposes an analytical model to investigate the behavior of a Radio Link Control (RLC) protocol on the forward link of a mobile radio system and to relate its performance to transmission design. As a reference case, a multicarrier DS-CDMA architecture employing Walsh and Quasi-Orthogonal channelization codes, similar to the current cdma2000 system, is considered. Jointly modelling the features of the data link layer and of the underlying physical channels, it is possible to identify the interaction between transmission parameters and the RLC protocol behavior. The latter is assessed by analysis, determining the RLC protocol goodput and the average delivery time suffered by a data unit transferred over the radio channel, when two different coding approaches are. adopted: namely, rate compatible punctured convolutional codes and code combining
Allocation policies of quasi-orthogonal codes on the forward link of a multicarrier DS-CDMA system
No full textAlternative code assignment policies for the forward link of a multicarrier DS-CDMA system employing the recently proposed quasi-orthogonal sequences are put forth in this letter. It is demonstrated how different allocation strategies of quasi-orthogonal codes alter the interference level suffered by active units; it is also shown how to shape the rate of interference growth as a function of the number of active users within the reference cell, implementing some specific code allocation patterns. The performance achieved by various schemes is assessed in a frequency selective fading environment, in terms of average bit error probability
Rake reception with unequal power path signals
No full textThis letter analytically determines the effects of selective diversity on the performance of a Rake receiver in dense multi-path channels featuring an arbitrary power delay profile. The approach devised permits assessing the symbol-error probability of the Rake receiver with simple computations, and determining the influence on system behavior of different power delay profiles and number of resolved paths, as well as signal bandwidth
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