Tara Ali Yahiya

Resource allocation for real time services using cooperative game theory and a virtual token mechanism in LTE networks

In this paper a two level resource allocation scheme is proposed to enhance the Quality of Service (QoS) for multimedia services in LTE downlink system. It corresponds to a solution that combines cooperative game theory, a virtual token mechanism, and the EXP-RULE algorithm. By using cooperative game theory such as bankruptcy game and Shapley value, the proposed mechanism works by forming coalitions between flow classes to distribute bandwidth fairly. EXP-RULE algorithm has been modified to use a virtual token mechanism to improve its performance. By taking into account constraints such as Shapley value fairness and the virtual token robustness, the proposed mechanism can increase remarkably the performance for real time flows such as video and VoIP in downlink system. The performance evaluation is conducted in terms of system throughput, packet loss ratio (PLR), cell spectral efficiency and fairness index.

Performance Study of Multimedia Services Using Virtual Token Mechanism for Resource Allocation in LTE Networks

The LTE specification provides QoS of multimedia services with fast connectivity, high mobility and security. However, 3GPP specifications have not defined scheduling algorithms to support real time and non-real time application services. In this paper we propose a modified version of M-LWDF and EXP/PF scheduling algorithms based on token mechanism, which provide better performance to real time flows such as video and VoIP in downlink system. By taking the arrival rates of packets to queues into account, the proposed mechanism included in previous scheduling algorithms, can increase remarkably the bit-rate for multimedia services. Simulation results show that the proposed modified algorithms can achieve a throughput gain for real time services specially for video traffic. Performance evaluation is conducted in terms of system throughput and packet loss ratio (PLR).

Resource allocation using Shapley value in LTE networks

The LTE specification provides QoS of multimedia services with fast connectivity, high mobility and security. However, 3GPP specifications have not defined scheduling algorithms to support real time and non-real time application services. In this paper we propose a two level scheduling scheme composed by cooperative game concept and EXP-RULE scheduling algorithm. By using cooperative game theory such as bankruptcy game and Shapley value, the proposed mechanism works by forming coalition between flow classes to distribute the bandwidth fairly. To make a performance judgment, the proposed downlink scheduling scheme has been compared to other well known schedulers such as M-LWDF and PF. Simulation results show that the proposed scheme can improve the performance on the used metrics among services. The performance evaluation is conducted in terms of system throughput, packet loss ratio (PLR), cell spectral efficiency and fairness Index.

Interference mitigation by dynamic self-power control in femtocell scenarios in LTE networks

Efficient radio resource management and Quality of Service (QoS) guarantee are very important aspects in order to provide a good service in LTE Networks. Although the base station performs a smart scheduling scheme for resource allocation, the expected result could be affected due to interference, specially in femtocell scenarios. This article investigates the problem of interference in femtocell networks in LTE. The proposed method achieves inter-cell interference mitigation though a dynamic power self-control performed at each femtocell. In this paper we use the modulation and coding scheme (MCS) to obtain the optimum power value which assures a trade-off between Signal-to-Interference-plus-Noise-Ratio (SINR) and bit-rate efficiency. The main objective of our work is to optimize the sub-bands in order to decrease the interference and maintain the throughput at the same time. The performance evaluation is conducted in terms of throughput, Packet Loss Ratio (PLR) and SINR.

On the Integration of LTE and Mobile WiMAX Networks

Future generation networks will be seen as a new initiative to bring together all heterogeneous wireless and wired systems under the same framework, to provide connectivity anytime and anywhere using any available technology. Network convergence is therefore regarded as the next major challenge in the evolution of telecommunications technologies and the integration of computer and communications. We begin this article with an outline of the design tenets for an interworking architecture between both Long Term Evolution (LTE) and mobile WiMAX technologies. We then define the various functional entities and their interconnections needed for their interworking. Next, we discuss the end-to-end protocol layering in the interworking architecture, network selection and discovery, and IP address allocation. Finally, we describe in more detail the functional architecture and processes associated with security, QoS, and mobility management.

Policy-Based Threshold for Bandwidth Reservation in WiMax and WiFi Wireless Networks

A well designed resource allocation policy is important for network operators, especially in emerging networks with scarce resources such as wireless and mobile networks. Two promising wireless technologies nowadays are wireless metropolitan area network (WMAN) and wireless local area network (WLAN). The latter is already largely deployed whereas the former is more recently getting deployed as the wireless broadband access network. For better and cheaper wireless coverage extension, the integration of these two technologies seems to be a very good option. In this paper we analyze an admission control residing in the WiMax base station (BS) for resource allocation in the integrated WiFi-WiMax architecture. A mathematical model is introduced where the resource allocation is based on two thresholds corresponding to voice/data traffic from WiFi network and voice/data from WiMax network. The results of our analysis show clearly that a well designed resource allocation policy improves the usage of combined WiFi-WiMax network, therefore increasing the number of served users which will raise the operators profits.

LTE planning for Soft Frequency Reuse

Future 4G cellular systems will address the need of capacity increase for the support of diverse Internet services. This article deals with cell capacity issues and cell planning for LTE technology. The Soft Frequency Reuse (SFR) scheme is considered here as an interesting approach to efficiently utilize the bandwidth in LTE systems. With SFR, a cell is divided into two parts (the central part and the external part) using different reuse schemes. On the basis of a suitable path loss model, we have been able to characterize the Signal to Interference plus Noise Ratio (SINR) and the probability to use different transmission modes in a cell with SFR. This has allowed us to evaluate the capacity of a cell that can be achieved with SFR. Finally, a cell capacity optimization has been carried out by means of extensive numerical results in order to select both the radius of the cell-center region and the border-to-center power ratio of SFR.

Power adjustment mechanism using context information for interference mitigation in two-tier heterogeneous networks

This paper deals with the interference issue in a two-tier heterogeneous network. Although the co-channel spectrum allocation provides larger bandwidth for both macrocells and femtocells, the resulting cross-tier interference may prevent macrocell users to achieve the minimum required SINR. Therefore, in this work, we propose a centralized control strategy of downlink interference generated by femtocells to increase the performance requirement of macrocell users. Our mechanism presents two possible power control strategies for interference management which take benefit from some context information on femto and macrocell users positioning. System-level simulations show a better performance in terms of throughput for macrocell users while maintaining a targeted QoS for femtocell users.

A Utility-based Handover Decision Scheme for Heterogeneous Wireless Networks

With the massive deployment of sophisticated personal devices equipped with different access technologies for both wireless and cellular, mobile users should benefit from service continuity anytime anywhere. This paper seeks to bring seamless connectivity and performance continuity to the mobile users according to their needs and preferences. To this end, it focuses on handover decision that determines the need to initiate the handover and select the best access network. Handover decision in heteregeneous environments is a typical multi-objectives decision issue that requires efficient decision strategies. In this article, we propose an innovative handover decision scheme based on utility theory principles to deal effectively with the challenges revealed by the dynamic, probabilistic, and technological aspects of the multi-objectives decision problem. Our model is based on a single-criterion utility function that rates user satisfaction and captures sensitivity for each decision criterion. As well, an adaptive multi-criteria utility function is defined according to user preferences. Performance of the proposed handover decision strategy is evaluated via extensive simulation studies. Obtained results show that our strategy outperforms other handover decision schemes, which confirm the suitability and the efficiency of our solution.

Resource Management and Cell Planning in LTE Systems

Future 4G cellular systems will address the need for capacity increase for the support of diverse services. It is therefore of fundamental importance to design innovative 4G cellular systems able to support the increase in the traffic demand. This Chapter deals with LTE systems and the design of a new reuse scheme, called Soft Frequency Reuse (SFR), that is able to increase the cell capacity that is studied, considering the impact of different scheduling schemes and of different user mobility patterns. A consistent SFR scenario has been implemented in both Ns-3 and OMNeT++ environments. An analytical approach is proposed to evaluate the cell capacity with SFR that has been validated by means of Ns-3 simulations. Finally, OMNeT++ simulations have permitted to highlight the significant impact of the scheduling scheme and user mobility on cell capacity; different mobility patterns have been taken into account.