Cédric Gueguen

Scheduling in OFDM Wireless Networks without Tradeoff between Fairness and Throughput

Providing multimedia services in wireless networks requires maximizing the system throughput without sacrificing fairness. Previous works focus on system capacity optimization but fail to jointly ensure adequate fairness. This paper proposes a new MAC scheduling scheme which dynamically takes in consideration the QoS experienced by the mobiles and the transmission conditions in an extended cross-layer design. Based on a weighted opportunistic algorithm, our resource allocation takes a maximum advantage of multiuser diversity optimizing fairness and system throughput. This provides an efficient support of multimedia services in OFDM wireless networks. Performance evaluation shows that the proposed scheduling widely outperforms the best existing wireless OFDM based scheduling schemes.

Compensated Proportional Fair Scheduling in Multiuser OFDM Wireless Networks

In wireless networks, providing a fair bandwidth allocation without too much reducing the system throughput is very challenging. Path loss attenuations induce unequal spectral efficiencies and in terms unequal throughtput for mobiles with different geographical positions. In the litterature, Proportional Fair (PF) is acknowledged as the reference scheduler in multiuser OFDM wireless networks. Opportunistically considering the channel state, PF is adapted to the wireless environment fighting the multipath fading negative effects. PF takes advantage of multiuser diversity and globally maximizes the throughput. Additionally, PF scheduling currently makes the best tradeoff between fairness and throughput maximization. However, severe fairness deficiencies appear when the mobiles experience unequal path loss. In this paper, we propose to solve this fairness issue with a modified PF scheme that introduces distance compensation factors. Simulation results show that this well-balanced resource allocation outperforms other existing scheduling schemes and jointly provides both high system throughput and high fairness.

An Efficient and Fair Scheduling Scheme for Multiuser OFDM Wireless Networks

This paper proposes a new MAC scheduling scheme for efficient support of multimedia services in multiuser OFDM wireless networks, both in the uplink and in the downlink. This scheme is based on a system of weights that dynamically accounts for the experienced QoS and the transmission conditions in an extended higher layers/MAC/PHY cross layer design. This approach solves the crucial issue of wireless multiple access schemes: ensuring fairness without sacrificing the throughput offered by the scarce bandwidth resource. Performance evaluation shows that the proposed scheduling outperforms existing wireless OFDM based scheduling schemes and demonstrates that choosing between high fairness and high system throughput is not required.

Inter-cellular scheduler for 5G wireless networks

Enhancing the Quality of Experience (QoE) in wireless networks is a crucial issue. Many acknowledged works focus on intra-cellular scheduling. They have shown that when the channel impairment is taken into consideration by the opportunistic scheduling approaches, it allows to reach higher throughputs and, for the most efficient ones, a higher fairness. However, if some of these works provide results near to optimum considering a single cell, high QoE cannot be guaranteed for scenarios where the cells are overloaded. In this article, we propose a new inter-cellular scheduler able to help the overloaded cells thanks to a dynamic cell bandwidth allocation. Our resource allocation technique is based on an adequate emergency parameter called Mean Cell Packet Delay Outage Ratio (MCPDOR). Performance evaluation shows that the proposed scheduler widely outperforms existing solutions in various scenarios. A variant of our solution that does not consider MCPDOR is also proposed and evaluated.

Comparison study of resource allocation strategies for OFDM multimedia networks

Advanced MAC scheduling schemes provide efficient support of multimedia services in multiuser OFDM wireless networks. Designed in a cross layer approach, they opportunistically consider the channel state and are well adapted to the wireless multipath fading environment. These schedulers take advantage of time, frequency, and multiuser diversity. Thereby they maximize the global system throughput while ensuring the highest possible level of fairness. However their performances heavily depend on the bandwidth granularity (i.e., the number of elementary resource units) that is used in the resource allocation process. This paper presents and compares the main OFDM scheduling techniques. In particular it studies the influence of bandwidth granularity on the resource allocation strategies performances. The paper reveals that though bandwidth granularity has never been considered in former studies, it is of major importance for determining the application range of advanced OFDM scheduling techniques.

Weighted fair opportunistic scheduling for multimedia QoS support in multiuser OFDM wireless networks

Efficient support of multimedia services in next generation wireless networks requires advanced scheduling schemes that achieve both system capacity maximization and full QoS differentiation. This paper proposes a new MAC scheduling scheme for multiuser OFDM wireless networks. Designed in an opportunistic cross-layer approach, this scheme uses a system of weights that dynamically adjusts the priority of the flows considering the transmission conditions and the QoS that they currently experience. This results in a very efficient management of the bandwidth. Performance evaluation shows that the proposed scheduling outperforms existing wireless OFDM based scheduling schemes providing full QoS differentiation, high fairness and system throughput maximization.

Adaptive and Generic Scheduling Scheme for LTE/LTE-A Mobile Networks

Abstract Schedulers for multi-carrier wireless networks are a central element of cellular systems and are subject to extensive research. However, state-of-the-art schedulers are hardly implementable in a real system such as long term evolution advanced (LTE-A), which imposes additional constraints on how resources are allocated. To address this problem, we first propose adaptive and generic scheduling scheme (AGSS) a generic resource allocation procedure that enables the implementation of state-of-the-art scheduling policies for building a LTE scheduler. In a second step, we propose our own scheduling policy called opportunistic PDOR aware (OPA) that both optimizes the use of the radio spectrum and provides the quality of service actually expected by applications. We show how to implement this policy using our generic scheduling scheme. We then compare the performance of AGSS to the classic scheme in a LTE environment when used with a given policy. We show that the proposed scheme outperforms the classic scheme whatever the policy. We also establish that OPA offers the best performances in terms of capacity and quality of service compared to state-of-the-art policies.

Dynamic Frame Aggregation Scheduler for Multimedia applications in IEEE 802.11n Networks

Providing Quality of Service (QoS) to real time applications over Wireless Local Area Networks (WLANs) is becoming a very challenging task due to the diversity of multimedia applications. Concurrently, there are numerous WLANs devices that are rising recently. Mainly, we focus on IEEE 802.11n since it was designed to support a high data transmission rate (toward 600 Mbps) based on frame aggregation schemes. The aggregation mechanism accumulates many frames before transmitting them into a single larger frame, thus reducing overhead and increasing efficiency and throughput. Yet, this scheme cannot provide QoS satisfaction for delay sensitive application even if it supports higher throughputs. Indeed, aggregation headers cause supplementary delays particularly when aggregating unfrequent packets with small sizes. To overcome this limitation, we propose in this paper a new Dynamic Frame Aggregation (DFA) scheduler to provide QoS satisfaction to real time services. To achieve this goal, we defined new scheduling parameters such as QoS delays to avoid accumulation of non-scheduled packets. Hence, the DFA scheduler serves packets and dynamically adjusts the aggregated frame size based on these QoS delays. Conducted simulations illustrate the performance of our proposed DFA scheduler in term of satisfying QoS, throughput, loss and delay requirements of voice and video traffics.

Dynamic Tradeoff between Energy and Throughput in Wireless 5G Networks

Even though system energy and spectral efficiency are major issues in wireless network, reaching these objectives conjointly seems very difficult and requires the usage of tradeoffs. Moreover, depending on the context, the importance of either varies. In underloaded context, guaranteeing high Quality of Service (QoS) is easily achievable due to large surplus of available radio resources and focus should be put on energy rather than system throughput. On the contrary, in an overloaded context, the lack of available radio resources required that resources allocation algorithms focus on system capacity in order to preserve QoS. Since the major issue of the network is to satisfy users, in this specific case, energy consumption must become lesser important. Many specialized solutions have been proposed that focus either on energy saving or on throughput maximization. They provide high performances, respectively, on their specific network traffic load context, previously described, but are not optimized outside. Other solutions that proposed static tradeoffs provide average performances but can not be fully efficient in all scenarios. In this paper, we propose a Dynamic Tradeoff between energy and throughput efficiency that adapts the scheduler priorities to the network context and particularly to the traffic load. Considering the context, the scheduler is able to adjust its behavior in order to maintain high QoS while reducing as much energy as possible. Performance evaluation will show that the proposed solution succeeds to minimize energy consumption better than energy focused scheduler in underloaded context while being able to reach the same spectral efficiency as throughput oriented scheduler in highly loaded context.

Autonomous and dynamic inter-cell interference coordination techniques for future wireless networks

Inter-Cell Interference Coordination (ICIC) techniques are proposed as solutions to alleviate the negative impact of interference on system performance, while enhancing the provided Quality of Service (QoS). Typically, the available bandwidth is divided into inner and edge sub-bands. Users are also classified into interior and edge users. The available resources in each zone are exclusively allocated to users belonging to this zone. Mobile users classification is usually based on a threshold that can be either a given mean SINR value or a given distance. However, ICIC approaches based on these static parameters cannot efficiently manage non-homogeneous distribution of users. In this paper, we introduce a dynamic handoff algorithm that aims to adapt static ICIC schemes to uneven distribution of users. Our new solution dynamically computes the classification of active users into interior and edge users, based on a heuristic load balancing algorithm. In our proposal, each cell autonomously reconfigures its bandwidth allocation constraints without modifying bandwidth repartition across the cellular network. This makes the solution well adapted to the non-uniform repartition of users at the multi-cell scale. Simulation results show that the proposed scheme improves bandwidth usage, reduces packet delay, and increases user satisfaction compared to state-of-the-art ICIC techniques.