A centralized feedback control model for resource management in wireless networks

In a wireless environment, guaranteeing QoS is challenging because applications at multiple devices share the same limited radio bandwidth. In this paper we introduce and study a resource management model for centralized wireless networks, using feedback control theory. Before applying in practice, the proposed model is evaluated using the well-known 20-sim dynamic system simulator. The experimental results show that flexible and efficient resource allocation can be achieved for a variety of system parameters and WLAN scenarios; however, care should be taken in setting the control parameters and coefficients

Low-cost QoS-enabled Wireless Network with Interworked WLAN and WiMAX

The WLAN and WiMAX standards are candidate solutions for a low-cost broadband wireless network. Interworking the two networks, using the network-layer QoS mechanisms of the Next Generation Network, will allow them to complement each other. This paper proposes integrating the WLAN and WiMAX link-layer QoS mechanisms of the NGN to ensure that QoS is maintained over the wireless link. The wireless QoS mechanism in WLAN and WiMAX are analyzed and an integration framework is propose

Feedback Based Bandwidth Allocation with Call Admission Control for Providing Delay Guarantees in IEEE 802.11e Networks

The 802.11e working group has recently proposed innovative functionalities in order to support delay-sensitive multimedia applications, such as real-time voice and video, in Wireless Local Area Networks (WLANs). In particular, the 802.11e proposal introduces: (1) the Hybrid Coordination Function (HCF), which is an improved channel access method aimed at allocating the first-hop WLAN bandwidth to delay-insensitive and delay-sensitive flows; (2) a Call Admission Control (CAC) algorithm for preventing network overloads, which would drastically degrade the service o#ered by the network; (3) and a Signalling scheme for service request and QoS service level negotiation

Control-theoretic approaches for efficient transmission on IEEE 802.11e wireless networks

With the increasing use of multimedia applications on the wireless network, the functionalities of the IEEE 802.11 WLAN was extended to allow traffic differentiation so that priority traffic gets quicker service time depending on their Quality of Service (QoS) requirements. The extended functionalities contained in the IEEE Medium Access Control (MAC) and Physical Layer (PHY) Specifications, i.e. the IEEE 802.11e specifications, are recommended values for channel access parameters along traffic lines and the channel access parameters are: the Minimum Contention Window CWmin, Maximum Contention Window CWmax, Arbitration inter-frame space number, (AIFSN) and the Transmission Opportunity (TXOP). These default Enhanced Distributed Channel Access (EDCA) contention values used by each traffic type in accessing the wireless medium are only recommended values which could be adjusted or changed based on the condition of number of associated nodes on the network. In particular, we focus on the Contention Window (CW) parameter and it has been shown that when the number of nodes on the network is small, a smaller value of CWmin should be used for channel access in order to avoid underutilization of channel time and when the number of associated nodes is large, a larger value of CWmin should be used in order to avoid large collisions and retransmissions on the network. Fortunately, allowance was made for these default values to be adjusted or changed but the challenge has been in designing an algorithm that constantly and automatically tunes the CWmin value so that the Access Point (AP) gives out the right CWmin value to be used on the WLAN and this value should be derived based on the level of activity experienced on the network or predefined QoS constraints while considering the dynamic nature of the WLAN. In this thesis, we propose the use of feedback based control and we design a controller for wireless medium access. The controller will give an output which will be the EDCA CWmin value to be used by contending stations/nodes in accessing the medium and this value will be based on current WLAN conditions. We propose the use of feedback control due to its established mathematical concepts particularly for single-input-single-output systems and multi-variable systems which are scenarios that apply to the WLAN