Near-far effects in adaptive SDMA systems

Tangemann, M.

doi:10.1109/pimrc.1995.477371

Cited by 13 publications

(9 citation statements)

References 16 publications

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“…The DOA of incoming request is also uniformly distributed (0, 2π ]. Moreover, we assume that the received power levels for any mobile users sharing the same channel are equal due to power control, which avoids the near-far effect for SDMA system [20]. Using the spatial separation criteria from Section 3.2.2, i.e., angle separation and minimum interference energy, computer simulations are performed to determine the success probabilities, P s2 and P s3 , of creating three-fold SDMA, which are described in the following sections.…”

Section: Simulation Resultsmentioning

confidence: 99%

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Traffic Models and Blocking Probabilities for Two-Fold and Three-Fold SDMA Communication Systems

Huang

Doherty

2005

Wireless Pers Commun

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Spectrum efficiency is a constant challenge in the design of wireless networks. Space-division-multipleaccess (SDMA) is a promising approach to achieve higher spectral efficiency which reuses bandwidth via multiplexing signals based on their spatial signature. Several different studies have shown that SDMA can effectively improve system capacity in a mobile environment. In this paper, we present a new Markov chain traffic model for a duplicate-at-last (DL) approach [IEE Proceedings on Communication 146 (1999) 303] in two-fold and three-fold SDMA systems. Simplified blocking probability formulations for two-fold and three-fold SDMA are also derived. Simulations based on a common method of spatial separation check for channel allocation in SDMA are presented to evaluate the probability of successfully creating two-fold and three-fold SDMA channels. The simulation, as well as analytical, results indicate that the SDMA system can reduce the blocking probability of the calls and result in more traffic loading than a traditional cellular system. The results also show that our simplified approaches not only can reduce the computational complexity, but can also accurate approximate two-fold and three-fold SDMA performance.

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Section: Simulation Resultsmentioning

confidence: 99%

“…, 3L + 1.S(L) represents the success probability of channel allocation in L attempts for three-fold SDMA. S(L) is expressed mathematically asS(L) = P s3 + (1 − P s3 )P s3 + · · · + (1 − P s3 ) L−1 P s3 = 1 − (1 − P s3 ) L(23)A.2.2 Two-Dimensional Approximate ModelThe elements of the matrixD, in(20), are-If a = 0, b = 1, . .…”

mentioning

confidence: 99%

Traffic Models and Blocking Probabilities for Two-Fold and Three-Fold SDMA Communication Systems

Huang

Doherty

2005

Wireless Pers Commun

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“…This means that for each couple of sectors and , there will be a number of coefficients as follows: (5) where and indicate, respectively, the direction of arrival in sector and sector . As our partitioning scheme is a regular rectangular grid, for sake of simplicity for each sector, the direction of arrival can be identified with the four sides of the sector.…”

Section: ) Influence Of Movements Directionmentioning

confidence: 99%

“…Particularly, the conventional channel-assignment algorithms, both in case of call setup and handover, must be revised in order to ensure sufficient intracell cochannel interference rejection and to minimize the probability of an intracell handover. Furthermore, a new intracell handover strategy is required to manage the case when the angular separation between two mobile stations, which are sharing the same channel, becomes insufficient [5].…”

Section: Introductionmentioning

confidence: 99%

Smart channel-assignment algorithm for SDMA systems

Piolini¹,

Rolando

1999

IEEE Trans. Microwave Theory Techn.

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In order to exploit the potentialities of space-division multiple access in mobile cellular systems, the conventional radio resource management functions must be revised-especially the channel-assignment algorithms. In this paper, an algorithm designed to this purpose is presented and analyzed in reference scenarios and under various traffic load conditions, showing that a significant reduction of the intracell handover rate can be achieved. The proposed algorithm is not based solely on the current angular separation between mobiles, but also takes into account their potential future trajectory, predicted by means on the knowledge of the topography of the analyzed service area.Index Terms-Channel-assignment algorithm, intracell handover, SDMA.

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“…To overcome the near-far problem in SDMA systems, grouping into power classes according to the users' received power levels has been proposed in [6], where it is shown that the system capacity can be improved if classes are separately served. An extension of this idea for WCDMA systems was suggested in [7], where grouping the users who express the same signal-to-interference ratio (SIR) into different clusters was used to reduce the interference using adaptive power control.…”

Section: Introductionmentioning

confidence: 99%

WLC01-2: Resource Allocation and Scheduling for Multiuser MIMO Systems: A Beamforming-Based Strategy

2006

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A resource allocation policy using transmit Beamforming is proposed for the downlink of multiuser systems. Users to be selected for transmission in a given time slot are examined from groups of users to which the proposed algorithm determines the resources to be allocated in terms of antennas and power. The transmit beam-vectors are computed according to a zero-forcing criterion. Users are selected from different groups so as to achieve a desired balance between maximizing throughput and achieving a high degree of fairness among groups of users as well as between users within a group. Such grouping allows the proposed algorithm to make full usage of the resources and to dynamically allocate these while avoiding the complexity of the NP-complete resource reservation and users' scheduling. Computational complexity is reduced by first estimating the resources to be allocated to the groups of users and then distributing these fairly among the selected users in each group. Such an approach allows the base station to assign its antenna and power resources to groups of users for which transmission would alleviate the interference that would result in neighboring cells, or to direct the resources toward overloaded regions in the cell. Simulation results and comparisons show that the proposed dynamic resource allocation strategy achieves multiuser diversity and a high efficiency in terms controlling the tradeoff between throughput and fairness.

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Near-far effects in adaptive SDMA systems

Cited by 13 publications

References 16 publications

Traffic Models and Blocking Probabilities for Two-Fold and Three-Fold SDMA Communication Systems

Traffic Models and Blocking Probabilities for Two-Fold and Three-Fold SDMA Communication Systems

Smart channel-assignment algorithm for SDMA systems

WLC01-2: Resource Allocation and Scheduling for Multiuser MIMO Systems: A Beamforming-Based Strategy

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