Resource reservation is one of the effective solutions in guaranteeing the quality-of-service (QoS) in communication networks. In this paper, we propose a novel resource reservation scheme for dynamically managing the bandwidth resources in IEEE 802.11e-based wireless local area networks (WLANs). The proposed solution consists of two components namely (i) dynamic medium access control (MAC) scheduler and (ii) adaptive admission control algorithm. Once resources occupied by certain stations become idle due to the end of QoS data session, the proposed MAC scheduler will either release the resources to the non-real-time traffic flows (NRTTFs) or re-allocate them to other real-time traffic flows (RTTFs) which require dedicated resources. The re-allocating process is implemented with the support of the novel adaptive admission control algorithm (AACA) that decides which RTTF can gain access to the available resources in a distributed manner. Evaluation of our proposed scheme is conducted in several scenarios through extensive ns2 simulation. The simulation results indicate that the proposed distributed resource reservation scheme significantly improves the efficiency of resource distribution with real-time and non-real time traffic flows in WLANs, while guaranteeing the QoS for the admitted RTTFs.

Abstract-Guaranteeing quality of service is one of the most critical challenges in IEEE 802.11-based wireless networks. This paper proposes an analytical framework to evaluate hybrid MAC scheduling mechanisms with distributed resource reservation, that was proposed for the IEEE 802.11e enhanced distributed channel access protocol for guaranteeing quality of service. The hybrid MAC scheduling mechanisms split the airtime into service intervals with contention-free period for quality of service guaranteed real-time sessions, and contention access period for other traffic sessions. The distributed resource reservation ensures that the resources are allocated to real-time sessions without the support of a centralised controller -this makes it suitable for ad-hoc networking applications. The proposed analytical framework models the quality of service (i.e. delay and throughput) performance of real-time sessions with dedicated resources in a distributed environment, and also estimates the overall capacity of the network. Moreover, the derived models can be used to investigate the impact of changes to individual system parameters, such as service interval or size of transmission opportunity. The simulation results show that the proposed analytical framework precisely models the quality of service performance of real-time sessions and predicts the optimum resource allocation for improved network capacity.

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Providing guaranteed quality of service for multimedia applications is a challenging topic in wireless mesh networks. This paper proposes a distributed resource reservation mechanism with novel admission control in order to guarantee quality of service performance of real-time sessions while improving bandwidth utilization in wireless mesh networks. The proposed resource reservation mechanism establishes logical clusters for identifying interference relationships between nodes and avoids simultaneous transmissions from interfering nodes. Following the established logical clusters, a cooperative contention and collision free channel access is achieved in hybrid medium access control for multi-hop data forwarding in wireless mesh networks. In order to efficiently utilize the scarce resources in contention-free period, soft and hard resources are reserved for real-time sessions according to their quality of service demands. This is achieved by a novel admission control algorithm. Further, an analytical model is derived for investigating the resource reservation parameters of the proposed mechanism. Simulation results show that the proposed mechanism guarantees the QoS for real-time sessions while improving the bandwidth utilization.

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