| Mobile communication displays the traits of broadband and high data rate, in response to this development trend,3GPP lunched LTE project. LTE use the new air interface technology, combine OFDM and MIMO technology. LTE can achieve100Mbit/s peak rate, but can’t reach the requirement of IMT-Advanced which was proposed by ITU-R. To meet the requirement,3GPP begun the standardization about LTE-A which is a further enhancement for LTE system. Carrier aggregation is one of the key technologies for LTE-A, it can aggregate multiple continuous or non-continuous component carriers to form a larger bandwidth which users can utilize the whole bandwidth to transmit data. The maximum bandwidth can be100MHz, while meeting the requirement of4G, it also ensure the backwards compatibility with LTE.In this paper, first combining with current specification, we briefly introduce the CA application scenarios, methods of spectrum aggregation, structure of CA protocol, types of carriers and carrier control. Based on the analysis of current CA specification, we researched on some hotspot in new carrier type standardization process. We introduce the standardization process and control channel design about synchronized NCT and non-synchronized NCT. In non-synchronized NCT, there is a new Cell-specific RS. And in order to improve spectrum efficiency, we need to provide a new solution to solve the DM-RS colliding with PSS/SSS. There is no synchronization signal in synchronized NCT so that resource can be reserved to transmit data. A solution about configuring synchronized NCT in LTE-A is designed in this paper.We built CRS link level simulation platform to evaluate dirrerent schemes of CRS bandwidth. According to the simulation parameters, we got the curve of RSRP accuracy and time/frequency tracking performance. From the perspective of RSRP measurement and time/frequency tracking, we analyzed the performance of different CRS bandwidth, and choosed the most suitable CRS bandwidth. |
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