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Due to the license-exempt nature of the cognitive radio (CR), multiple CR networks may operate (coexist) on the same channel. In this paper, we first discuss some techniques for self-coexistence of CR local and personal area networks, where the self-coexistence means the coexistence of homogeneous CR networks using the same PHY/MAC protocol. Then, we propose a self-coexistence etiquette for the ECMA...
This paper describes an approach to detect Quality of Service degradation due to packet congestion within wireless networks. The proposed approach can assist management systems to detect a degradation based on easy determinable packet metrics. Metrics like interface queue length, round trip times and retry ratio are evaluated regarding thresholds and detection performance. With a combination of metrics,...
802.11e HCCA (Hybrid coordination function Controlled Channel Access) exhibits good QoS provisioning for constant bit rate (CBR) video streams in a single collision domain. However, its performance degrades significantly for variable bit rate (VBR) video streams particularly in multi-collision domains. In addition, HCCA has the disadvantage of high complexity. In this paper, we introduce a deterministic...
The use of unlicensed bands, e.g., ISM (industrial, science and medical) bands is getting more and more attention nowadays due to the high scarcity and high costs of radio spectrum. Due to this, there is a high risk of interference, which degrades the performance and fails to support Quality of Service (QoS) for systems operating in these bands. Therefore, spectrum sharing between coexisting competing...
In this paper, we investigate the effect of interference on the performance of IEEE 802.11g wireless networks. We study different network configurations and evaluate their corresponding throughput performances with the aid of the ns2 simulator. We also provide recommendations for network deployment in order to minimize interference and improve the quality of service.
The use of wireless local area networks (WLANs), as well as the proliferation of the use of multimedia applications has grown fast in recent years. Some factors affect the quality of service(QoS) received by the user. The interference is an example. This work presents an empirical study of the QoS parameters of a VoIP application in the presence of an interference network, as well as the relevance...
A high-density wireless environment could not avoid cell/BSS (Basic Service Set) overlapping, which may cause Co-channel interference. Such interference makes it difficult to support QoS. It is desirable that BSSs can share a single frequency channel without interference and at the same time, QoS is supported. Additional functionalities particularly in MAC layer are required to achieve interference-free...
Backbone wireless mesh networking concept has been developed in order to provide higher bandwidth, better QoS (less delay and jitter) and larger coverage range compared with previous network types. These factors should be balanced in an appropriate way in order to satisfy mentioned goals. In this paper an optimization framework has been proposed in order to maximize throughput according to upper bound...
IEEE 802.11 wireless mesh networks emerge as an alternative to provide an infrastructure for last mile access networks in remote areas. The meshed topology provides good reliability, low cost, market coverage and scalability. However due to the shared nature of wireless medium, which limits the available network bandwidth, it is necessary to implement an effective load control scheme that enable the...
The cochannel overlapping basic service sets (OBSS) wireless interference is unavoidable in a high-density overlapping BSS environment. In order to provide interference-free environment and, at the same time, Quality of Services, centralized resources coordination functionalities particularly in Medium Access Control (MAC) layer are required. The proposed scheme, based on the context of 802.11 WiFi,...
IEEE P1900.4 is an emerging standard for optimized radio resource utilization where cognitive radio technologies are used for efficient spectrum utilization. In this paper, we design and implement a cognitive wireless network system based on open documents of IEEE P1900.4, and evaluate its performance using UDP streaming and HTTP download. Our experiments show interesting results that total network...
Optimization of IEEE 802.11e MAC protocol performance is done by modifying several parameters left open in the standard, like buffer size and acknowledgement policies. By using the developed event-driven simulator, results were extracted with single and multi-service. With only a single service, higher values for the goodput are obtained for video and background (BK) traffics in comparison with the...
In this paper, we provide a saturation throughput analysis of the IEEE 802.11 protocol at the data link layer by including the impact of both transmission channel and capture effects in Rayleigh fading environment. Impacts of both non-ideal channel and capture effects, specially in an environment of high interference, become important in terms of the actual observed throughput. As far as the 4-way...
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