Shahbaz Khan

A comparison of MANETs and WMNs: commercial feasibility of community wireless networks and MANETs

In the past a lot of effort has been put into resolving some of the major challenges of AdHoc networks especially the added ones brought up by the mobility of nodes and the absence of infrastructure in MANETs. Unlike MANETs, Wireless Mesh Networks (WMNs) provide flexibility in terms of mobility i.e. Mesh clients can be stationary or mobile and can form a client mesh network among themselves and with mesh routers. WMNs make use of multiple radios and multiple channels per radio for increased capacity, higher throughput and low interference. We gave an overview of the work done on MANETs, experimental Community Wireless Networks (CWNs) and Industrial solutions for mesh networks. We highlighted the differences between WMNS and MANETs and how WMNs can overcome the limitations of MANETs. This paper also compares the feasibility and scope of forecasted applications for MANETs and WMNs. In the end, we gave a conclusion about the commercial viability of MANETs and the growing scope of applications proposed for WMNs.

Meshed high data rate personal area networks

Wireless mesh networks have proven to be of great potential in providing new and innovative applications in many areas in the last few years. WMNs can address some limitations and optimize the performance of existing standardized networks in terms of cost, reliability, simplified network configuration, extended coverage and so on. This article is a tutorial on the technical aspects of meshed personal area networks. The proposed solutions for meshing high data rate PANs (802.15.3) are discussed along with related issues where applicable. The article starts by giving an overview of the high data rate PAN standard (802.15.3) and its inherent limitations to operate in a mesh configuration. It discusses the main drivers behind meshing PANs and describes the architecture, operation in a mesh configuration, and the hidden node/exposed node issue, which is pronounced in mesh networks. The added functionality of routing in meshed PANs, optimizations due to multi-interface/multichannel communication, improved dynamic channel selection, transmitted power control procedures, and security aspects are also given in this article. The article concludes by summarizing the proposed approaches for meshing PANs.

Supplementary Interworking Architecture for Hybrid Data Networks (UMTS-WiMAX)

The future of wireless communications will mainly focus on user centricity and personalization. Multiple networks will be overlaid to provide supplemented connectivity to a user. Competitive options in the current communication technologies need to be carefully studied for designing an interworking solution. Extensive amount of work is done on interworking of UMTS (universal mobile telecommunications system) with WiFi (wireless fidelity). However, due to WiFis limited coverage it could not offer all benefits associated with interworking. With more recent technologies like WiMAX (worldwide interoperability for microwave access) in the market; which offers wireless broadband access with mobility support (IEEE 802.16e), and can be deployed for a wider coverage; we can interwork it with UMTS for enhancing its performance. In this paper, we present the interworking architecture of WiMAX with UMTS. We highlight a scenario where a UMTS operator can control access of a client within two networks (UMTS, WiMAX) and port packet-data to a supportive network in the last mile. We also discuss the commercial viability for this architecture

A resource allocation strategy for meshed high data rate WPANs

In order to extend the operating space of single hop High Data Rate (HDR) Wireless Personal Area Networks (WPANs), the meshed configuration can be used for multi-hop functionality. Since the superframe is shared between multiple WPAN piconets for communication, with higher device density, the superframe capacity usually proves to be a bottleneck. Furthermore, when the superframe capacity is shared in a distributed fashion, issues of fairness in time allocation arises. In this paper we propose a centralized scheme for resource allocation specifically in meshed WPANs and induce an element of fairness in time allocation. Simulation results prove the effectiveness of the proposed approach.

Capacity Analysis of High Data Rate Wireless Personal Area Networks

High data rate wireless personal area networks (WPANs) operate in a limited space with emphasis on supporting multimedia applications. The requirements for different types of voice and video codecs vary and therefore the resource allocation should be done accordingly. The efficient utilization of high data rate WPAN superframe is determined by the number of devices and the channel time allocated to them to support their respective applications. Since the MAC layer for high data rate WPANs is TDMA based, there is an upper limit on the practical data rate that can be supported considering fair utilization of the superframe. This paper discusses communication in a high data rate WPAN including various overheads imposed by different layers. It analyses the capacity of the superframe considering several application requirements at different transmitter data rates. The paper concludes by discussing some potential optimizations for fair utilization of the superframe and time allocation in WPANs.

Capacity Issues in Meshed High Data Rate WPANs

Some advantages of meshing Wireless Personal Area Networks (WPAN) are to increase the network coverage without high transmission power, self- configuration and self-healing, increased route redundancy and fewer retransmissions. This paper discusses the capacity issues when meshing high data rate WPANs i.e. IEEE 802.15.3, IEEE 802.15.3a and IEEE 802.15.3c. The capacity bottlenecks are discussed which arise in multihop communication with a shared superframe. The paper provides detailed analysis on the superframe capacity using different transmitter data rates and highlights the importance of frame aggregation to achieve higher throughput and low overhead. The paper concludes by discussing possible approaches to improve the capacity of meshed WPANs.

Centralised resource allocation policies for meshed high data rate wireless personal area networks

Multi-media applications with demanding throughput requirements often raise issues of capacity limitations in wireless networks. High data rate (HDR) wireless personal area networks (WPANs) can operate in a mesh configuration to extend from the legacy single-hop communication to multiple hops. Although the range of WPANs is increased in a mesh configuration, there are capacity constraints because the superframe time is shared by multiple piconet clusters instead of being dedicated for a single piconet cluster just like in the legacy single-hop case. Furthermore, the distributed superframe sharing can cause fairness issues because there is no mechanism to determine the requirement of each mesh piconet coordinator (MPNC) and monitor a fair allocation to each MPNC. Here, the authors propose a centralised resource allocation approach and define three resource allocation policies for meshed HDR WPANs. The proposed approach is augmented by a traffic estimation strategy to predict a suitable fraction of superframe time for each cluster. Simulation results prove the effectiveness of the proposed resource allocation policies and the fairness index is shown to increase upto 42% with the proposed approach in some cases.

Distributed Execution of an Inherently Sequential Network Simulator

Network simulators play a vital role in research and development of networks. Simulations are usually computationally intensive where distributed execution can improve performance significantly. However, due to the sequential nature of the communication process modeled by network simulators and limitations in access to source code it is not possible to completely isolate the sub-processes for distributed execution. An alternate solution in this case is to classify independent modules within a sequential simulation environment and execute the modules in parallel. This paper presents a similar mechanism for OPNET by enabling distributed execution of network simulation scenarios on a cluster of PCs using Sun Grid Engine. The proposed framework provides a demarcation between local configuration of software simulators and their remote execution. Such a demarcation gives a lead into future possibilities where computationally intensive tasks can be configured using devices with insufficient computational resources and executed remotely. Extensive experimental results in a Sun Grid Engine cluster environment using a variety of OPNET simulation scenarios show substantial efficiency in simulation run-time.

On-Demand Link Weight Routing Protocol with Cross-Layer Communication

Routing protocols face many challenges in Mobile Ad Hoc Networks (MANETs) due to the dynamic nature of wireless medium and unpredictable topological changes. This paper proposes On-Demand Link-Weight (ODLW) routing protocol. ODLW selects an optimum route on the basis of link reliability taking in consideration the link bandwidth, delay and node lifetime. The approach is based on Cross- Layer design where Physical Layer parameters are used as inputs for decision making at the routing layer. The simulation results show a significant improvement over AODV in terms of Network load, Route Discovery time and End-to-end delay.