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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...
VoIP offers cheap voice communication which instigated its quick market growth. IEEE 802.11 WLANs offer cheap wireless coverage which can be used to provide VoIP service in mobile devices. But call capacity of such networks is very low compared to wired networks. To increase voice capacity in WLANs incorporation of power capture, increased data rate, and use of multiple channels are of great importance...
The increase in multimedia usage places stringent requirements on wireless network performance in terms of lesser handoff delays. A VOIP client, for example, cannot tolerate a delay larger than 150 ms between the incoming voice packets to ensure a satisfactory interactive service to the user. Of the 150ms, only 50ms is allowed for handoff and the rest should accommodate the transmission delay of the...
Since channel scanning time in IEEE 802.11 handoff is dominant in total handoff delay time, attention has to be paid to the reduction of channel scanning time for effectively supporting delay sensitive applications such as voice over IP (VoIP). Therefore, this paper proposes a new channel scanning scheme that adaptively adopts full channel scanning before, and first satisfaction first reservation...
In this paper, we evaluate the impact of the wireless channel and physical layer parameters on the performance of VoIP traffic in IEEE 802.11g networks. The wireless channel is modeled using a finite state Markov chain based on an adaptive modulation and coding scheme. The transition probabilities encompass the effects of the time-varying wireless channel, such as the Doppler frequency and the operating...
IEEE 802.11e provides basic mechanisms for traffic differentiation in WLANs previously unavailable with the IEEE 802.11 standard. The enhanced distributed channel access (EDCA) is probably the most promising subset of such mechanisms, and it is already implemented in a huge number of Network Cards. In this paper we present an algorithm for the provisioning of QoS in EDCA WLANs. The algorithm is based...
This paper proposes a fast forward medium access control protocol (FFMAC) for quality-of-service (QoS) guarantee in multihop IEEE 802.11s wireless mesh networks with multiple channels. To the best of our knowledge, the proposed protocol is the first one which considers the multihop and multichannel issues simultaneously. It provides higher priority for real-time applications, while remaining the distributed...
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