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The increase in number of users in Wireless Mesh Networks (WMNs) setups consequently represents an upsurge in numbers of services. Services such as internet, e-commerce, audio streaming, Voice over Internet Protocol (VoIP), Video on Demand (VoD), file and printer sharing among others will be clogged and ran over WMNs. This further leads to poor Quality of Service (QoS). Quick and timely discovery...
Wireless networks are required to guarantee the Quality of Service (QoS), including throughput, fairness, delay, etc. IEEE802.11 MAC protocol employs a typical backoff mechanism, Binary Exponential Backoff (BEB) algorithm, to avoid collisions when multiple users try to access the shared wireless channel. Many works on QoS guaranteeing point out that the BEB algorithm introduces the unfairness and...
In wireless Media Access Control (MAC) environment, management of channel access and controlling of packet transmission is done via shared channel in a distributed way. MAC protocols objectives for Wireless Network is to maximize channel utilization and minimizing channel access delay. It is MAC protocol's responsibility to provide best possible utilization of provided bandwidth while fulfilling the...
Real-time applications over wireless networks often suffers from jitter, delay and packet loss. The traditional techniques for error control are FEC (Forward Error Correction) and ARQ (Automatic Repeat Request). In this paper a hybrid FEC/ARQ mechanisms with limiting the slots number between the loss of the last retransmission of the original block n and the reception of block n + φ is analyzed in...
We consider a multihop wireless network with multiple users. The channels may experience fading. The power is consumed only during transmission and is a general monotonically increasing function of rate. We provide low complexity algorithms for joint routing, scheduling and power control which ensure stability of the queues, certain minimum rates and/or upper bound on the end-to-end, mean delays.
The Voice over IP (VoIP) service demands high priority over other services and applications. Some constrains are associated with this real-time service, such as delay and throughput which need to be addressed before delivering to the customer. The mobility in IP networks is a demand that facilitates IP applications and services, especially in wireless networks. This paper demonstrates the performance...
Beyond 3G or 4G or Fourth generation wireless networks is an era of heterogeneous networks where a large number of wireless networks having different quality of service and features are present simultaneously. To provide ubiquitous access to end users in such environment, vertical handoff mechanism is deployed where an active call or session is transferred from one access point to another depending...
VoIP (Voice over Internet Protocol) popularity is increasing due to its various benefits therefore it is a popular technology used in Wireless networks. Hence, Quality of Service in terms of its specific parameters has to be satisfied. VoIP Performance is generally limited to specific factors such as MOS, R-Factor, Jitter, Delay which will be described in this paper. We then investigate and compare...
Wireless networks are becoming a combination of more and more diverse and complicated networks. Handoff is a process to maintain data session continuity where mobile node changes from one base station coverage area to another base station area. Mobile maintains its existing connections via vertical handoff. In wireless environment single node mobility is known as host mobility and group of nodes moving...
This paper proposes a methodical approach to improve the Quality of Service (QoS) evaluation in wireless and mobile networks. The approach uses the fuzzy logic tools and techniques to map the traditional QoS parameters into a unified value to quantify the QoS levels of these networks. Extensive simulation studies are conducted to examine the effectiveness of this method. The results show that our...
To enhance the QoS performance in saturated multihop adhoc networks, it is essential to have cooperative algorithms for MAC layer contention resolution and TCP layer congestion control. This paper proposes a cross layer approach that modifies the back off mechanism and congestion control technique using Fibonacci sequence. Due to the golden section property of Fibonacci sequence, contention and congestion...
In IEEE 802.11 wireless networks, periodic channel scanning is an essential procedure to discover available access points (APs) in vicinity and to achieve fast handover. However, this procedure leads to unnecessary overhead in wireless networks and also interrupts ongoing communications of stations. In this paper, we propose a smart channel scanning scheme that minimizes the communication interruptions...
This paper first describes the architecture and the main services of the wireless network oriented ITS (Intelligent Transportation System). The services of CVIS (Cooperative Vehicle-Infrastructure System) and PTT (Push To Talk) voice are analyzed and modelled. Pointed scheduling schemes are proposed for different services according to their QoS requirements. For CVIS service, vehicle speed adapted...
There is an increasing trend of accessing multimedia and web services embedded with Presence service over the mobile, which have driven the telecom operators to look for the new and better ways to provide such services. Presence service puts a lot of load on the IMS network and it can contribute 50% or more to the total signaling load which can increase end-to-end delay. In this paper we have analyzed...
With the emergence of high bandwidth-delay product and heterogeneous wired / wireless networks, the standard TCP appears to be too conservative to offer reasonable performance. The use of parallel TCP connections has been suggested in such environments. We have demonstrated that, with the same level of aggressiveness, this approach can outperform the single-connection based approach. However, this...
Due to their dynamic topologies, providing quality of service (QoS) in wireless ad hoc networks introduces major new challenges to the research community. Now, the commercially available ad-hoc network products are those based on the IEEE802.11 Distributed Coordination Function (DCF). Cooperative communications fully leverages the broadcast nature of the wireless channel and spatial diversity, thereby...
With the emerging IEEE 802.11n standard, the WLAN is poised as a promising ubiquitous networking technology to support multimedia applications where providing QoS becomes imperative. However, the 802.11 WLAN is not designed to support delay sensitive traffic. This problem is magnified during a handover and typically results in excessive handover latency and packet loss. In addition, a 802.11 WLAN...
We present an "opportunistic" scheduling policy with the objective of improving delay performance for time-sensitive users in wireless networks. Since packet delay depends on both resource allocation and time-varying capacity of wireless channels, we introduce a search radius (SR) into the framework of packet fair queueing (PFQ) and employ maximum relative SNR (Max-rSNR) as scheduling rule...
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