LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Scheduling in WiMAX

Packet scheduling is the process of resolving contention for shared resources in a network. The process involves allocating resources among the users and determining their transmission order. Scheduling algorithms for a particular network need to be selected based on the type of users in the network and their QoS requirements. For real-time applications such as video conferencing, voice chat, and audio/video streaming, delay and delay jitter are the most important QoS requirements. Delay jitter is the inter-packet arrival time at the receiver and is required to be reasonably stable by real-time applications. On the other hand, for non-real time application such as FTP, throughput is the most important QoS requirement. Some applications, such as web-browsing and email do not have any QoS requirements. In a network, different types of applications with diverse QoS requirements can co-exist. The task of a scheduling algorithm in such a network is to categorize the users into one of the pre-defined classes. Each user is assigned a priority, taking into account his QoS requirements. Subsequently, resources are allocated according to the priority of the users while fairness is observed.

Besides having a very close coupling with the QoS requirements of the users, the design of a scheduling algorithm also depends on the type of the network it is intended for. A wireless network can be categorized into a single-hop or a multi-hop network. A single-hop network contains ...