LTE Transmition Techniques

After development of more than 20 years, mobile communication acquired huge success mainly through traditional voice service. But along with the development of the data service, this kind of condition will change gradually. Anticipate till 2012, the data service will exceed voice service. Customers can use some new applications and services, including IP phone, multi-media news, on-line game, music download, and mobile TV, etc...This still is a beginning only, being customer to understand the ability of the 3 G system gradually, they will expect more and more abundant data service. These new service may be provided by current or advanced technique and the network. At the same time, the 3 G technique must deal with the competition fom other techniques such as WiMAXs.The 3GPP LTE (Long Term Evolution) emphasize the aspect of the consideration mainly including lower latency, higher data rate, enlarger system capacity, etc..For satisfying these requests, the system structure needs to be redesigned.The research will focus on some aspects as follows: Air interface of the physical layer, interfaces of L2 and L3, the adjustment of the UTRAN structure and radio frequency related problem etc..Spreading-Interleaved Frequency Division Multiple Access (IFDMA) providing code domain multiplexing for one IFDMA channel shows improved spectrum efficiency and good back compatibility with CDMA systems while maintaining advantages of IFDMA systems. A generalized Rake receiver for Spreading-IFDMA is proposed in this paper, which combines jointly de-repetition, equalization, and de-spreading processing. Similar to the conventional CDMA systems, the guard interval in Spreading-IFDMA symbols is not necessary, which means that spectrum efficiency can be further improved over IFDMA systems. With digital simulations and performance analysis, the proposed generalized Rake receiver demonstrates better BER performance, robustness, and lower computational complexity. Generalized Rake receiver by using multipath components information combines jointly de-repetition, equalization, and de-spreading processing for Spreading-IFDMA systems. Similar to the CDMA systems, guard interval in transmitted symbols of Spreading-IFDMA with the proposed receiver is not necessary and hence the frequency spectrum efficiency can further be improved. By using Rake combination methods for multiple fingers, the proposed generalized Rake receiver demonstrates better BER performance, robustness, and lower computational complexity.