Owing to the addition of various security overheads at different layers, the cumulative encapsulation causes more access delay in the uplink data transmission in WiMax resulting in low throughput. The upstream channel is a stream of minislots with a dynamic mix of contention and reservation based opportunities affording privacy between transmitter and receiver. The contention resolution algorit...

The 802.11 families are considered as the most applicable standards for Wireless Local Area Networks (WLANs) where nodes make access to the wireless media using random access techniques. In such networks, each node adjusts its contention window to the minimum size irrespective to the number of competing nodes. So in the case of large number of nodes, the network performance is reduced because o...

In this paper, the performance of the carrier sense multiple access with collision avoidance (CSMA/CA) protocol at MAC layer with sensing errors at physical layer is investigated. Here the sensing errors are captured by modifying the Markov chain model widely used for the CSMA/CA analysis called Bianchi’s model. We investigate the throughput as a function of carrier sensing error probabilities:...

In current WLAN system that is designed for best-effort communications, there is not any quality of service (QoS) differentiation support. In this paper, we propose a fully distributed medium access control (MAC) adaptation method for service differentiation. It is implemented by dynamically updating the MAC layer parameters (such as contention window) to adapt to the network conditions in a cl...

The medium access control (MAC) protocol is the main element which determines the system performance in wireless local area networks. The MAC technique of the IEEE 802.11 protocol is called Distributed Coordination Function (DCF). In IEEE 802.11 Wireless Local Area Networks (WLANs), network nodes experiencing collisions on the shared channel need to backoff for a random period of time, which is...

In this paper, we develop an analytical model to discuss the unfairness problem related with dualradio/singleradiovehicle that exists in IEEE 802.11p-based vehicular networks. According to IEEE 1609.4 standard, dual-radiovehicle accesses continuously channel through control channel interval(CCHI) and service channel interval (SCHI),but single-radio vehicle only simultaneously accesses channel i...

Binary Exponential Backoff (BEB) is the De-facto mechanism for contention control in IEEE 802.11 Wireless LAN. The exponential growth of Contention Window (CW) in all BackOff (BO) stages and randomness in BO selection causes unnecessary waiting time, high collision rate and unfairness in accessing the channel among the nodes. To overcome these anomalies, this paper proposes Hashing Based Distri...

The IEEE 802.11e draft supplement standard provides Quality of Service (QoS) support for real-time applications. This paper focuses on performance evaluation of the 802.11e contention based access mechanism called Enhanced Distributed Channel Access (EDCA). It presents a comparative study of the different EDCA parameters selection and their impact on network utilisation and performance. The use...

IEEE 802.16 PMP mode recommends using truncated Binary Exponential Backoff (BEB) algorithm to resolve the contention when multiple Subscriber Stations (SSs) compete for the connection and resource allocation from the Base Station (BS). The BEB approach may not be effective and transmission opportunities (TOs) may be wasted due to independent contention and backoff of each SS. This paper propose...