Masood Maqbool

Analytical evaluation of various frequency reuse schemes in cellular OFDMA networks

In this paper, we present an analytical solution to carry out performance analysis of various frequency reuse schemes in an OFDMA based cellular network. We study the performance in downlink in terms of signal to interference (SIR) ratio and cellular capacity. Analytical models are proposed for integer frequency reuse (IFR), fractional frequency reuse (FFR) and two level power control (TLPC) schemes. These models are based on a fluid model originally proposed for CDMA networks. The modeling key of this approach is to consider the discrete base stations entities as a continuum. To validate our approach, Monte Carlo simulations are carried out. Results of validation study show that results obtained through our analytical method are in conformity with those obtained through simulations. However, compared to time consuming simulations, our model is very time efficient. We also present a comparison between above three frequency reuse scheme.

Analytical performance evaluation of various frequency reuse and scheduling schemes in cellular OFDMA networks

In this paper, we present an analytical solution to carry out performance analysis of various frequency reuse schemes in an OFDMA based cellular network. We study the performance in downlink in terms of signal to interference (SIR) ratio and total cell data rate. The latter is analyzed while keeping in view three different scheduling schemes: equal data rate, equal bandwidth and opportunist. Analytical models are proposed for integer frequency reuse (IFR), fractional frequency reuse (FFR) and two level power control (TLPC) schemes. These models are based on a fluid model that was originally being proposed for CDMA networks. The modeling key of this approach is to consider the discrete base station entities as a continuum. To validate our approach, Monte Carlo simulations are carried out. Validation study shows that results obtained through our analytical method are in conformity with those obtained through simulations. A comparison between the above-mentioned frequency reuse schemes and scheduling policies is also presented. We also propose an optimal tuning of involved parameters (inner cell radius and power ratios).

Comparison of Various Frequency Reuse Patterns for WiMAX Networks with Adaptive Beamforming

In this paper, we evaluate the performance of a WiMAX network in different frequency reuse scenarios with and without adaptive beamforming technique. We study the possibility of deploying reuse 1 networks. Radio quality in terms of SINR and outage probability on one hand, and throughput on the other hand, are the parameters considered for this analysis. Extensive Monte Carlo simulations, based on effective SINR computation using abstraction model mean instantaneous capacity (MIC), have been performed in downlink. The simulation results show that some frequency reuse schemes with a very good global throughput performance result however into significant user outage. The improvement in performance due to adaptive beamforming is evaluated. The frequency reuse patterns satisfying the two parameters (outage and throughput) in the best possible way are being suggested (based on simulation results) for WiMAX networks.

An Efficient Analytical Model for the Dimensioning of WiMAX Networks

This paper tackles the challenging task of developing a simple and accurate analytical model for performance evaluation of WiMAX networks. The need for accurate and fast-computing tools is of primary importance to face complex and exhaustive dimensioning issues for this promising access technology. In this paper, we present a generic Markovian model developed for three usual scheduling policies (slot sharing fairness, throughput fairness and opportunistic scheduling) that provides closed-form expressions for all the required performance parameters at a click speed. This model is compared in depth with realistic simulations that show its accuracy and robustness regarding the different modeling assumptions. Finally, the speed of our analytical tool allows us to carry on dimensioning studies that require several thousands of evaluations, which would not be tractable with any simulation tool.

An efficient analytical model for WiMAX networks with multiple traffic profiles

In this paper, we present a simple and accurate analytical model for performance evaluation of WiMAX networks with multiple traffic profiles. This very promising access technology has been designed to support numerous kinds of applications having different traffic characteristics. The need for accurate and fast-computing tools is thus of primary importance to face complex dimensioning issues that integrate this traffic profile diversity. Our product-form queueing model provides closed-form expressions giving all the required performance parameters for each traffic profile at a click speed. The model is compared with extensive simulations that show its accuracy and robustness. Finally, the speed of our analytical tool allows us to carry on a preliminary performance study.

An efficient analytical model for the dimensioning of WiMAX networks supporting multi-profile best effort traffic

This paper tackles the challenging task of developing a simple and accurate analytical model for performance evaluation of WiMAX networks. The need for accurate and fast-computing tools is of primary importance to face complex and exhaustive dimensioning issues for this promising access technology. In this paper, we present a generic Markovian model developed for three usual scheduling policies (slot sharing fairness, throughput fairness and opportunistic scheduling) that provides closed-form expressions for all the required performance parameters instantaneously. We also present and evaluate the performance of a fourth policy, called throttling policy, that limits the maximum user throughput and makes use of the Maximum Sustained Traffic Rate (MSTR) parameter foreseen by the standard. At last, we extend these studies to multi-profile traffic patterns. The proposed models are compared in depth with realistic simulations that show their accuracy and robustness regarding the different modeling assumptions. Finally, the speed of our analytical tools allows us to carry on dimensioning studies that require several thousands of evaluations, which would not be tractable with any simulation tool.

An analytical model for WiMAX networks with multiple traffic profiles and throttling policy

In this paper, we present a simple and accurate analytical model for performance evaluation of WiMAX networks with multiple traffic profiles. This very promising access technology has been designed to support numerous kinds of applications having different traffic characteristics. One of the QoS parameters considered by the standard for traffic classes is the maximum sustained traffic rate (MSTR), which is an upper bound for user throughput. Taking into account MSTR implies the implementation of a throttling scheduling policy that regulates the user peak rate. Our models take into account this policy and provides closed-form expressions giving all the required performance parameters for each traffic profile at a click speed. The model is compared with extensive simulations that show its accuracy and robustness.

A semi-analytical method to model effective SINR spatial distribution in WiMAX networks

The stationary probabilities of different modulation and coding schemes (MCS) are required for dimensioning an OFDMA based network. In this paper, we introduce a semi-analytical approach to find out these stationary probabilities for a WiMAX network in downlink (DL) with users served by the best base station (BS). Using Monte Carlo simulations, we find the spatial distributions of effective signal to interference-plus-noise ratio (SINReff) for different values of shadowing standard deviation (σSH). With the help of distribution fit, we show that generalized extreme value (GEV) distribution provides a good fit for different frequency reuse schemes. Furthermore, by applying curve fitting, we demonstrate that the parameters of GEV distributions, as a function of (σSH) values, can be expressed using polynomials. These polynomial can then be used off-line (in place of time consuming simulations) to find out GEV cumulative distribution function (CDF), and hence the stationary probabilities of MCS, for any desired value of (σSH). We further show that these polynomials can be used for other cell configurations with acceptable deviation and significant time saving.

Effect of Distributed Subcarrier Permutation on Adaptive Beamforming in WiMAX Networks

In this paper, we investigate the performance of adaptive beamforming while using subcarrier permutation PUSC in WiMAX cellular network. In the literature, it has been shown that frequency reuse 1 is possible for beamforming capable WiMAX networks but with partial resource utilization or base station coordination. In this paper, we show however that using distributed subcarrier permutation (PUSC) offers sufficient diversity to allow full resource utilization without the need of coordination. We study an IEEE 802.16e cellular network employing adaptive beamforming per PUSC Major Group. Performance is evaluated in terms of radio quality parameters and system throughput. Results are based on Monte Carlo simulations performed in downlink. The simulation results show that even with reuse 1 and full load conditions, outage probability can be reduced to an acceptable value.

Achieving Frequency Reuse 1 in WiMAX Networks with Beamforming

In this chapter, we examine the performance of adaptive beamforming in connection with three different subcarrier permutation schemes (PUSC, FUSC and AMC) in WiMAX cellular network with frequency reuse 1. Performance is evaluated in terms of radio quality parameters and system throughput. We show that organization of pilot subcarriers in PUSC Major groups has a pronounced effect on system performance while considering adaptive beamforming. Adaptive beamforming per PUSC group offers full resource utilization without need of coordination among base stations. Though FUSC is also a type of distributed subcarrier permutation, its performance in terms of outage probability is somewhat less than that of PUSC. We also show that because of lack of diversity, adjacent subcarrier permutation AMC has the least performance as far as outage probability is concerned. Results in this chapter are based on Monte Carlo simulations performed in downlink.