Spread spectrum rake receiver

Abstract

Even when the number of paths is increased, interfering noises can be effectively reduced by a rake receiver for use in a spread spectrum communication system. The rake receiver includes a timing detecting unit detecting a reception timing t i (i=1 to N) of each of N paths when direct spread spectrum signals of the N paths are received; an inverse spreading timing setting unit setting, as a timing for inverse spreading, a timing t i,j,k (k=1 to N, k≠j) at which an inverse spread value is obtained that has interference and correlation from the jth (j=1 to N, j≠i) path included in the inverse spread value of the ith path counted from the reception timing t i (i=1 to N) detected by the timing detecting unit; a plurality of correlators each obtaining an inverse spread signal of the received signal corresponding to each timing set by the inverse spreading timing setting unit; and a signal composing unit composing outputs of the plurality of correlators.

1 - 11 . (canceled) 
   
   
       12 . A receiver which receives signals through multi-paths, comprising:
 a multi-path interference reducing unit to reduce an interference from another path to an inverse spreading result, at a receiving timing for a corresponding path;   a rake synthesizing unit to synthesize inverse spreading results at receiving timings for respective paths among the multi-paths; and   a selector to select a path for which the interference is reduced by the multi-path interference reducing unit, based on a channel estimated value for the path, wherein   an inverse spreading result at a receiving timing corresponding to the path selected by the selector is applied to synthesizing unit after the interference is reduced by the multi-path interference reducing unit.   
   
   
       13 . A receiver which receives signals through multi-paths, comprising:
 an inverse spreading unit to obtain a first inverse spreading result at a first receiving timing for a first path among multi-paths; and   a multi-path interference reducing unit to synthesize the first inverse spreading result with a second inverse spreading result, which is obtained at a second receiving timing preceded by a difference between receiving timings for the first path and a second path which is later than the first path, from a receiving timing for any path among the multi-paths except the second path, wherein   the second inverse spreading result synthesized with the first inverse spreading result is limited to an inverse spreading result obtained at a timing different from receiving timings for any paths among the multi-paths.   
   
   
       14 . A receiver which receives signals through multi-paths, comprising:
 a first multi-path interference reducing unit to perform multi-path reducing process for an inverse spreading result obtained by inverse spreading at a timing for a first path among the multi-paths;   a second multi-path interference reducing unit to perform multi-path reducing process for an inverse spreading result obtained by inverse spreading at a timing for a second path among the multi-paths;   a level adjusting unit to adjust levels of output signals from the first multi-path interference reducing unit and the second multi-path interference reducing unit, respectively; and   a rake synthesizing unit to synthesize the level adjusted output signals from the first multi-path interference reducing unit and the second multi-path interference reducing unit.   
   
   
       15 . A method for use in a receiver which receives signals through multi-paths, comprising:
 reducing an interference from another path to an inverse spreading result, at a receiving timing for a corresponding path;   synthesizing inverse spreading results at receiving timings for respective paths among the multi-paths; and   selecting a path for which the interference is reduced, based on a channel estimated value for the path, wherein   an inverse spreading result at a receiving timing corresponding to the selected path is applied to the synthesizing after the interference is reduced.   
   
   
       16 . A method for use in a receiver which receives signals through multi-paths, comprising:
 obtaining a first inverse spreading result at a first receiving timing for a first path among multi-paths; and   synthesizing the first inverse spreading result with a second inverse spreading result, which is obtained at a second receiving timing preceded by a difference between receiving timings for the first path and a second path which is later than the first path, from a receiving timing for any path among the multi-paths except the second path, wherein   the second inverse spreading result synthesized with the first inverse spreading result is limited to an inverse spreading result obtained at a timing different from receiving timings for any paths among the multi-paths.   
   
   
       17 . A method for use in a receiver which receives signals through multi-paths, comprising:
 performing a first multi-path interference reducing process for an inverse spreading result obtained by inverse spreading at a timing for a first path among the multi-paths;   performing a second multi-path interference reducing process for an inverse spreading result obtained by inverse spreading at a timing for a second path among the multi-paths;   adjusting levels of output signals from the first multi-path interference reducing proces and the second multi-path interference reducing process, respectively; and   synthesizing the level adjusted output signals from the first multi-path interference reducing process and the second multi-path interference reducing process.