Cross-layer Resource Allocation Algorithms With Guaranteed QoS In Wireless Communication Systems

Nowadays, with the rapid development of wireless communication, people have increasing demand on the rate and quality of communications. The Long Term Evolution(LTE) system support multimedia services of different quality of service(QoS) with all-IP compatible hierarchies in backbone core networks, such as voice, video, data and so on. In the all-IP scenario, making efficient use of the limited radio resources while satisfying QoS requirements of users have attracted much attention in the resource allocation over the 3G-LTE system.Wireless resources are mainly distributed in three layers of the communication protocols, namely Call Admission Control(CAC), Medium Access Control(MAC) and Physical layer(PHY). QoS guarantee mechanism is involved in all layers of the protocols, i.e. parameter setting in each layer of the protocols is related to the user’s QoS. In the existing protocols, the resource allocation algorithm results of the upper layer serve as inputs of the lower layer while the results of the lower layer are not fed back to the upper layer to form a closed-loop control system. This hierarchy is difficult to satisfy the QoS of users. Instead, using the resource allocation results of the lower layer protocols to revise the upper layer algorithms, i.e. cross-layer resource allocation, can solve this problem well.A Quality of Service(QoS) guaranteed cross-layer resource allocation algorithm with physical layer, MAC layer and Call Admission Control(CAC) considered simultaneously is proposed in this paper for the 3G-LTE full IP OFDMA and MIMO-OFDM communication system respectively, which can ensure the quality of multimedia services in full IP networks. The algorithm converts the physical resources such as sub-carriers, transmission power, and the QoS metrics into equivalent bandwidth which can be distributed by the base station in all three layers. In the proposed algorithm, the resource allocation results of the lower layer of the communication protocols can be quantitatively fed back to the upper layer algorithms to form a closed-loop control system. By this means, the QoS requirements in terms of bit error rate(BER), transmission delay and dropping probability can be guaranteed by the cross-layer optimal equivalent bandwidth allocation. The numerical results show that the proposed algorithm has higher spectrum efficiency compared to the existing systems.