Provisioning of multimedia services in 802.11-based networks: facts and challenges

QoS provisioning in IEEE 802.11 networks is a nontrivial task due to a certain degree of randomness in the contention-based medium access control protocol. The problem often resides in the fact that flows belonging to the same service class use the same MAC parameters regardless of their respective bit rates. Assigning static MAC parameters confines WLAN deployment possibilities, and often leads to throughput fairness rather than perceived QoS fairness. This creates situations where network resources as well as their potential profitability are underex-ploited. Restricting the volume of traffic load carried by the network is a primordial task in order to preserve QoS performances of active multimedia services. In this article we review existing approaches to deliver QoS to real-time services in order to gain thorough insight into inhibiting factors inherent to contention-based 802.11 networks. The emphasis is put on studying the possible means to sustain QoS guarantees, which is of utmost importance for network operators willing to commit theirs underlying resources through service level agreements.