| As the 8PSK modulation is introduced into the EDGE system, it becomes infeasible to impletment the MLSE algorithm in the EDGE re ceiver. So, reduced states sequence estimation algorithm comes into bei ng. This paper is just the research of the reduced states sequence esti mation algorithm.After a breif introduction on the channel propagation environment and the mix-modualtion procession of GMSK and 8PSK symbols, This paper mainly introduces four parts:The firt part is the principle and implemention of the reduced stat es equalization algorithm. It mainly introduces the two realization way of the reduced states equalization algorithm:DDFSE and RSSE, to dec rease the states number, the former way only deducts the channel taps number which are used to form the state machine, while the later one using a symbol subset partioning to get a further states reduction.The second part is the soft information calculation method. This p art mainly introduces the VALPP algorithm of the traditional GMSK bi nary modulation, and the 8PSK-VALPP algorithm which is used to gen erating the bit-level soft information of 8-ary based on the binary VAL PP algorithm.The third part introduced the prefilter. No matter DDFSE and RSS E, they all calls for a all-pass filter before the equalizaiotn module, wh ich will changes the mix-phase channel into its minimum-phase equival ent. This all-pass filter is jus the prefilter, it only changes the input si gnal's phase. The fourth part this paper provides a well detaild simulation verifi cation. The simulation result shows that, the RSSE soft output sequenc e estimation method with a prefilter, plays an quite important role in i mproving the performance of EDGE receiver. |
