Traffic Sensitive and Traffic Load Aware Path Selection Algorithm For MMR WIMAX Networks

The recent developments in the broadband wireless access (BWA) communication systems have introduced several major changes to the existing systems. Legacy IEEE 802.16j is one such amendment to the existing IEEE 802.16 WiMAX family. The key modification introduced by 802.16j system is the concept of relay station (RS), which may be used to enhance the system coverage or to make system throughput optimal. The end terminals, subscriber stations (SS) are unchanged in the standard. The overall change pertinent to the system has raised many unresolved issues related to RS and multi-hop relay base station (MR-BS). The selection of path from a SS to MR-BS via a RS is also one of the issues, need to be addressed. The path selection of a SS in both uplink and downlink directions is left open in the standard. It is very significant to satisfy the traffics of stringent quality of service (QoS) requirements and to appropriately manage the resources of a cell under different circumstances. This paper proposes a path selection algorithm to achieve the aforementioned qualities in the network. The path selection metrics include traffic load of the transparent relay station and traffic sensitivity factor of the SS. An extensive simulation work discusses the performance evaluation of the proposed work using QualNet simulator

Multilevel Downlink Relay Queue Aware And Loss Recovery Scheduling For Media Transmission In Wireless Cellular Networks

In this document, we study the result of multi hop relaying on the throughput of the downstream channel in cellular networks. In particular, we contrast the throughput of the multi hop method through that of the conventional cellular system, representing the feasible throughput development by the multi hop relaying under transitive transmission considerations. We moreover propose a hybrid control plan for the multi hop communicate, in which we activist the use of in cooperation, the straight transmission and the transitive multi hop relaying. Our study illustrates that the majority of the throughput gain can be obtained with the related of a transitive relaying scheme. Important throughput improvement could be moreover obtained by operating the simultaneous relaying transmission in conjunction with the non simultaneous transmission. We also disagree here that the multi hop relaying technology can be developed for mitigating injustice in qualityof- service (QoS), which arrive due to the location-dependent signal quality. Our outcomes demonstrate that the multi hop system can provide more even QoS over the cell district. The multi hop cellular system design can also be used as a selfconfiguring network mechanism that efficiently contains variability of traffic distribution. We have studied the throughput development for the consistent, as well as for the non uniform traffic distribution, and we conclude that the utilization of transitive relaying in cellular networks would be relatively robust to alter in the actual traffic distribution

Rate Optimal design of a Wireless Backhaul Network using TV White Space

The penetration of wireless broadband services in remote areas has primarily been limited due to the lack of economic incentives that service providers encounter in sparsely populated areas. Besides, wireless backhaul links like satellite and microwave are either expensive or require strict line of sight communication making them unattractive. TV white space channels with their desirable radio propagation characteristics can provide an excellent alternative for engineering backhaul networks in areas that lack abundant infrastructure. Specifically, TV white space channels can provide "free wireless backhaul pipes" to transport aggregated traffic from broadband sources to fiber access points. In this paper, we investigate the feasibility of multi-hop wireless backhaul in the available white space channels by using noncontiguous Orthogonal Frequency Division Multiple Access (NC-OFDMA) transmissions between fixed backhaul towers. Specifically, we consider joint power control, scheduling and routing strategies to maximize the minimum rate across broadband towers in the network. Depending on the population density and traffic demands of the location under consideration, we discuss the suitable choice of cell size for the backhaul network. Using the example of available TV white space channels in Wichita, Kansas (a small city located in central USA), we provide illustrative numerical examples for designing such wireless backhaul network

Improving relay based cellular networks performance in highly user congested and emergency situations

PhDRelay based cellular networks (RBCNs) are the technologies that incorporate multi-hop communication into traditional cellular networks. A RBCN can potentially support higher data rates, more stable radio coverage and more dynamic services. In reality, RBCNs still suffer from performance degradation in terms of high user congestion, base station failure and overloading in emergency situations. The focus of this thesis is to explore the potential to improve IEEE802.16j supported RBCN performance in user congestion and emergency situations using adjustments to the RF layer (by antenna adjustments or extensions using multi-hop) and cooperative adjustment algorithms, e.g. based on controlling frequency allocation centrally and using distributed approaches. The first part of this thesis designs and validates network reconfiguration algorithms for RBCN, including a cooperative antenna power control algorithm and a heuristic antenna tilting algorithm. The second part of this thesis investigates centralized and distributed dynamic frequency allocation for higher RBCN frequency efficiency, network resilience, and computation simplicity. It is demonstrated that these benefits mitigate user congestion and base station failure problems significantly. Additionally, interweaving coordinated dynamic frequency allocation and antenna tilting is investigated in order to obtain the benefits of both actions. The third part of this thesis incorporates Delay Tolerate Networking (DTN) technology into RBCN to let users self-organize to connect to functional base station through multi-hops supported by other users. Through the use of DTN, RBCN coverage and performance are improved. This thesis explores the augmentation of DTN routing protocols to let more un-covered users connect to base stations and improve network load balancin

Capacity modeling for admission control in WiMAX networks

WiMAX networks support QoS reservation of resources by allowing a new flow to apply for admittance in the system. Thus, there is a need for an accurate estimation of the available capacity to be shared by incoming connections. Admission control algorithm must ensure that, when a new QoS resource reservation is accepted, reservations already present in the system continue having their QoS guarantees honored. Its efficiency is then expressed in terms of accuracy and computational complexity which is the focus of the work in this thesis. Different approaches are presented to compute the aggregated allocated capacity in WiMAX networks and, based on their limitations, the E-Diophantine solution has been proposed. The mathematical foundations for the designed approach are provided along with the performance improvements to be expected, both in accuracy and computational terms, as compared to three alternatives of increasing complexity. The different solutions considered are validated and evaluated with OPNET’s WiMAX simulator in a realistic scenario. Finally, the multi-hop relay case is analyzed: a capacity model description is provided together with a conjectured reuse of the admission control algorithm designed