.3 G Lte Downlink Adaptive Modulation And Coding Technology Research

Mobile communication has been one of the most potential hot spots in the field of nowadays telecommunication.People's daily lives have been changed a lot by the technologies developing through three generations.However,limitations of traditional 3G system have shown along with the rapidly growing applications on multi-media and high-speed data services.3GPP Long Term Evolution(LTE) is the largest research project on next generation techniques initiated by 3GPP.LTE techniques bases on OFDM/FDMA and it is a revolution in communication industry.In order to meeting the requirements of much higher spectrum efficiency and users' throughput,a lot of link adaptation techniques such as adaptive modulation and coding(AMC) and hybrid-ARQ(HARQ) are adopted in LTE.For better study on LTE key technologies,we built a physical layer simulation platform of LTE.The simulator mainly referred to the technical reports of 3GPP 25 series and 36 series.Meanwhile,the contributions to 3GPP conferences by a lot of main communication companies were also considered.By comparing our simulation results with the standard results contributed by many main communication companies, the Correctness of our platform can be validated.Base on the simulator,we analyzed the link level performances of AMC in LTE downlink under SIMO and MIMO conditions.In SIMO scenario,we offered an valid AMC scheme for downlink;while in MIMO scenario,we talked about the schemes for both single code word and double code word transmission.According to the link level simulation results,the AMC technique that is to keep the formats of transmission data always following the channel condition changes can provided obviously higher spectrum efficiency and more reliable transmission.And the combination of AMC and HARQ can be an effective way to gain a higher system performance.