Channel estimating apparatus, channel estimating method, base station, and communication system

Abstract

A channel estimating apparatus includes a receiver that receives reference signal groups that are respectively transmitted from wireless communications units and that each include a reference signal that is allocated a common channel resource allocated to a reference signal in another reference signal group; a first estimating unit that based on a reference signal that is in a first reference signal group among the received reference signal groups and that is allocated a unique channel resource not allocated to a reference signal in another reference signal group, estimates a reference signal that is in the first reference signal group and allocated the common channel resource; and a second estimating unit that based on the reference signal estimated by the first estimating unit, estimates a reference signal that is in a second reference signal group among the received reference signal groups and that is allocated the common channel resource.

1 . A channel estimating apparatus comprising:
 a wireless communication interface; and   a processor configured for
 controlling the wireless communication interface to receive reference signal groups that are respectively transmitted from wireless communications units and that each include a reference signal that is allocated a common channel resource allocated to a reference signal in another reference signal group among the reference signal groups; 
 in accordance with a reference signal that is in a first reference signal group among the reference signal groups received by the wireless communication interface and that is allocated a unique channel resource not allocated to a reference signal in another reference signal group, first estimating a reference signal that is in the first reference signal group and allocated the common channel resource; and 
 in accordance with the reference signal estimated by the first estimating, second estimating a reference signal that is in a second reference signal group among the received reference signal groups and that is allocated the common channel resource. 
   
     
     
         2 . The channel estimating apparatus according to  claim 1 , wherein
 the first estimating by the processor includes estimating a reference signal in the first reference signal group and allocated the common channel resource, the first reference signal group having a relatively high strength among the received reference signal groups, and   the second estimating by the processor includes estimating a reference signal in the second reference signal group and allocated the common channel resource, the second reference signal group having a relatively low strength among the received reference signal groups.   
     
     
         3 . The channel estimating apparatus according to  claim 1 , wherein
 the second estimating by the processor further includes estimating in accordance with a reference signal that is in the second reference signal group and allocated a unique channel resource, the reference signal that was estimated in accordance with the reference signal estimated by the first estimating.   
     
     
         4 . The channel estimating apparatus according to  claim 1 , wherein
 the first estimating by the processor further includes estimating in accordance with the reference signal estimated by the second estimating, the reference signal that is in the first reference signal group and allocated the common channel resource.   
     
     
         5 . A base station comprising:
 a wireless communication interface; and   a processor configured for
 controlling the wireless communication interface to transmit to a terminal apparatus, a first reference signal group that includes a reference signal that is allocated a common channel resource allocated to a reference signal in a second reference signal group transmitted to the terminal apparatus from another base station. 
   
     
     
         6 . The base station according to  claim 5 , wherein
 processor controls the wireless communication interface to allocate to a reference signal in the first reference signal group, a unique channel resource that is not allocated to a reference signal in the second signal group, where the allocated unique channel source is orthogonal to the channel resource of a reference signal that is in the first reference signal group and allocated a unique channel resource.   
     
     
         7 . The base station according to  claim 6 , wherein
 the processor controls the wireless communication interface to alternately allocate a subcarrier to each reference signal that is allocated a unique channel resource, the allocated subcarriers being orthogonal to one another.   
     
     
         8 . The base station according to  claim 6 , wherein
 the processor controls the wireless communications interface to allocate a sub-frame head slot to each reference signal that is allocated a unique channel resource that is not allocated to a reference signal in the second signal group.   
     
     
         9 . A base station comprising:
 a first wireless communication interface;   a second wireless communication interface; and   a processor configured for
 controlling the first wireless communication interface to transmit a first reference signal group to a terminal apparatus, and 
 controlling the second wireless communication interface to transmit to the terminal apparatus, a second reference signal group that includes a reference signal that is allocated a common channel resource allocated to a reference signal in the first reference signal group.