Dynamic channel allocation techniques using adaptive modulation and adaptive antennas

Blogh, J.S.; Cherriman, Peter; Hanzo, Lajos

doi:10.1109/vetecf.1999.797358

Cited by 6 publications

(11 citation statements)

References 22 publications

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“…In our previous investigations employing AAAs at the BS [23], we observed quite significant performance gains as a direct result of the interference rejection capabilities of the AAAs invoked. Since the CDMA-based network considered here has a frequency reuse of 1, the levels of cochannel interference are significantly higher than in [23], and hence, the adaptive antennas may be able to null the interference more effectively.…”

Section: Adaptive Antenna-assisted Network Performancementioning

confidence: 80%

“…In order to determine the number of users that may be supported with adequate call quality by the network, we have defined a conservative and lenient scenario that is formed from a combination of the performance metrics, as follows [23]:…”

Section: System Components and Performance Metricsmentioning

confidence: 99%

“…Since the CDMA-based network considered here has a frequency reuse of 1, the levels of cochannel interference are significantly higher than in [23], and hence, the adaptive antennas may be able to null the interference more effectively. On the other hand, the high number of interference sources may limit the achievable interference rejection.…”

Section: Adaptive Antenna-assisted Network Performancementioning

confidence: 99%

“…The adaptive beamforming algorithm used was the sample matrix inversion (SMI) algorithm [3]. Below, the specific adaptive beamforming implementation used for calculating the AAA weights in the CDMA-based network studied here is briefly highlighted as follows [23].…”

Section: Adaptive Antenna-assisted Network Performancementioning

confidence: 99%

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Adaptive Beamforming and Adaptive Modulation-Assisted Network Performance of Multiuser Detection-Aided FDD and TDD CDMA Systems

Blogh

Hanzo

2007

IEEE Trans. Veh. Technol.

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Abstract-The network performance of a frequency division duplex and time division duplex (TDD) code division multiple access (CDMA)-based system is investigated using system parameters similar to those of the Universal Mobile Telecommunication System. The new call blocking and call dropping probabilities, the probability of low-quality access, and the required average transmit power are quantified both with and without adaptive antenna arrays (AAAs), as well as when subjected to shadow fading. In some of the scenarios investigated, the system's user capacity is doubled with the advent of adaptive antennas. The employment of adaptive modulation techniques in conjunction with AAAs resulted in further significant network capacity gains. This is particularly so in the context of TDD CDMA, where the system's capacity becomes poor without adaptive antennas and adaptive modulation owing to the high base station (BS) to BS interference inflicted as a consequence of potentially using all time slots in both the uplink and downlink of the emerging wireless Internet.Index Terms-Adaptive beamforming, adaptive modulation, code division multiple access (CDMA) systems, Universal Mobile Telecommunication System Terrestrial Radio Access (UTRA), wireless network performance.

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Section: Adaptive Antenna-assisted Network Performancementioning

confidence: 80%

Section: System Components and Performance Metricsmentioning

confidence: 99%

Section: Adaptive Antenna-assisted Network Performancementioning

confidence: 99%

Section: Adaptive Antenna-assisted Network Performancementioning

confidence: 99%

See 2 more Smart Citations

Adaptive Beamforming and Adaptive Modulation-Assisted Network Performance of Multiuser Detection-Aided FDD and TDD CDMA Systems

Blogh

Hanzo

2007

IEEE Trans. Veh. Technol.

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“…The MC-DS-CDMA systems generally perform well and are efficiently used for quasi-synchronized channels [6]. It was reported that with the known instantaneous channel characteristics or transfer functions, the use of adaptive bit allocation algorithms could achieve significant performance improvements in terms of the transmitted power, channel throughput and bit-error-rate (BER) [7][8][9][10][11][12][13][14][15][16][17][18]. In general, a higher order modulation scheme is used to load more bits per symbol on subcarriers with large channel gains or signal-to-noise ratios (SNRs) for higher transmission throughput, and a low order modulation scheme is employed to allocate one or zero bit per symbol on the subcarriers in deep fade.…”

Section: Introductionmentioning

confidence: 99%

New adaptive bit allocation algorithms for multiuser OFDM/CDMA systems

Zhang

2007

Wireless Netw

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An adaptive bit allocation algorithm is proposed for multiuser transmission in OFDM/CDMA systems. The proposed scheme takes advantage of frequency diversity to dynamically allocate a suitable number of bits/per symbol on subcarriers of each user based on the transmitting objectives such as the required transmission rate and BER. A suboptimal solution to the problem of the bit allocation on subcarriers for each user is derived by minimizing the interference power from each user. Then an algorithm for adjusting the number of allocated bits is used to further reduce the interference without changing the total transmitted data rate. The performance obtained by minimizing the interference resulting from each user is studied in terms of BER, transmission data rate and the system capacity supporting multiple users. The theoretical analysis and simulation results show that the proposed algorithm substantially outperforms those reported previously.

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System Level Model for the Wireless Channel Unreliability in Mobile Cellular Networks

Rodriguez-Estrello

Cruz-Perez

Hernandez-Valdez

2006

2006 Proceedings of the First Mobile Computing and Wireless Communication International Conference

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In this paper, a new system level approach for the wireless channel unreliability modeling is proposed. Firstly, in order to characterize the call interruption process due to the wireless channel unreliability, the Gilbert-Elliot model is used to obtain the probability distribution of the interruption time. Then, it is shown that link unreliability can be adequately modeled by considering a Poissonian call interruption process. This allows simplifying system level mathematical analysis and easily identifying the factors that mainly influence the performance of mobile cellular networks. For the characterization of the interruption process in real cellular networks, it is enough to know some few system level statistics that can be easily obtained at base stations. Then, with the proposed call interruption modeling, an elegant teletraffic analysis for the performance evaluation of mobile cellular networks considering both wireless link unreliability and resource insufficiency is developed.

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Dynamic channel allocation techniques using adaptive modulation and adaptive antennas

Cited by 6 publications

References 22 publications

Adaptive Beamforming and Adaptive Modulation-Assisted Network Performance of Multiuser Detection-Aided FDD and TDD CDMA Systems

Adaptive Beamforming and Adaptive Modulation-Assisted Network Performance of Multiuser Detection-Aided FDD and TDD CDMA Systems

New adaptive bit allocation algorithms for multiuser OFDM/CDMA systems

System Level Model for the Wireless Channel Unreliability in Mobile Cellular Networks

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