Downlink Radio Resource Allocation Strategies in LTE Networks

LTE system presents a very challenging multiuser communication problem: Many User Equipments (UEs) in the same geographic area requiring high on-demand data rates in a finite bandwidth with low latency. Multiple access techniques allow UEs to share the available bandwidth by allotting each UE some fraction of the total system resources [1]. One of these multiple access techniques is Orthogonal Frequency Division Multiple Access (OFDMA) which is adopted by 3GPP release 8 due to its flexibility for accommodating many UEs with widely varying applications, data rates, and QoS requirements. Consequently, this would reveal the need for schemes of scheduling and resource allocation in LTE Networks.

Generally, there is a strong motivation beyond the scheduling and resource allocation to improve system performance by increasing the spectral efficiency of the wireless interface, and hence improve the system capacity. However, random fluctuations in the wireless channel preclude the continuous use of highly bandwidth efficient modulation, hence utilizing the Adaptive Modulation and Coding (AMC) technique [2]. Besides, the strategy used to allocate resources in the downlink direction has further impacts on spectral efficiency improvement. Given that the resources in LTE-based OFDMA are represented by

slots

Slot

– the basic unit of resource allocation in time and frequency domain. Thus, in this chapter we are interested on strategies of slot allocation in the downlink LTE networks which are combined with AMC and multiuser diversity techniques.