Cross-Layer Design Using Adaptive Technique Over LTE

With the rapid development of wireless network technology, the quality of service(QoS) is becoming more strictly. The traditional networking architecture is designed withinlayers, and the disadvantages of the isolated approach are exposed in the next generation ofwireless communication. In order to use the limited wireless resources more flexibly andeffectively, and meet the QoS requirements of growing multimedia services, the cross-layerdesign is proposed. Cross-layer design breaks the traditional structure design. The keytechnologies used in each layer are studied, and the joint parameters are chose. Then, thejoint optimization is performed to maximize the overall system performance.LTE is the3G long-term evolution, and is being attracted more and more attentions. Itis a transition from3G to4G technology, which is named by3.9G. However, cross-layerdesign is still an open issue in the current LTE system,In this thesis, using the cross-layer design approach, the air interface stack is analyzed,and the link adaptive techniques are studied. Finally, the cross-layer design is proposed forUnacknowledged Mode (UM) and Acknowledged Mode (AM), respectively. In the UM,the hybrid automatic repeat request (HARQ) at the MAC layer and the AMC at thephysical layer are jointly combined to maximize the average spectral efficiency under theQoS constraints. The maximum number of HARQ retransmissions and the modulation andcoding scheme (MCS) are can be adjusted depending on the channel quality. In the AM,The lower three layers, physical layer, MAC layer and RLC layer, are jointly considered.The adaptive techniques in the three layers are studied, and the two-layer retransmissionmechanism and the AMC scheme are jointly analyzed to derive the closed-expressions ofthe system performance, such the average packet error rate, the average packet delay, andthe average spectral efficiency. Meanwhile, the segmentation, the parallel HARQ process,and the in-sequence delivery are analyzed. The results indicate that the proposedcross-layer design can further improve the spectral efficiency, compared to the current LTEsystem.