Method and arrangement of increasing impairment co-variance matrix estimation accuracy

An arrangement of increasing impairment co-variance matrix Ru estimation accuracy in downlink in a user equipment in a communication network system comprising a plurality of communication network nodes communicating with one or more user equipments, where each network node is serving at least one cell in which one or more user equipments are located, the arrangement comprising:

• plural delay fingers configured to perform de-spread on high speed-downlink shared channel symbols to obtain de-spread symbols and a generator configured to form a matrix X of the obtained de-spread symbols;
• a processor for using the matrix X of de-spread symbols and channel estimates hc from common pilot channel and modulation scheme information to form a matrix S of recovered symbols in hard value;
• said processor further being arranged for using the matrix X of de-spread symbols and the channel estimates hc from common pilot channel, the modulation scheme information and the matrix S of recovered symbols in hard value to increase the estimation accuracy of the matrix S of recovered symbols in hard value;
• said processor further being arranged for repeating using the matrix X of de-spread symbols and the channel estimates hc from common pilot channel, the modulation scheme information and the matrix S of recovered symbols in hard value to increase the estimation accuracy of the matrix S of recovered symbols in hard value until the output symbols are the same as the input symbols or the number of iterations reaches a pre-defined maximum value;
• a generator configured to use the matrix X of de-spread symbols and the matrix S of recovered symbols in hard value with increased estimation accuracy to form an impairment co-variance matrix Ru estimate;
• and
• said processor further being arranged for using the impairment co-variance matrix Ru estimate and the channel estimates hc from common pilot channel to determine generalized RAKE combining weight w and to estimate common pilot channel signal to interference plus noise ratio.

A user equipment for increasing impairment co-variance matrix Ru estimation accuracy in downlink in a communication network system comprising communication network nodes each serving at least one cell in which the user equipment is located, the user equipment comprising:

• plural delay fingers configured to perform de-spread on high speed-downlink shared channel symbols to obtain de-spread symbols and a generator configured to form a matrix X of the obtained de-spread symbols;
• a processor for using the matrix X of de-spread symbols and channel estimates hc from common pilot channel and modulation scheme information to form a matrix S of recovered symbols in hard value;
• said processor further being arranged for using the matrix X of de-spread symbols and the channel estimates hc from common pilot channel, the modulation scheme information and the matrix S of recovered symbols in hard value to increase the estimation accuracy of the matrix S of recovered symbols in hard value;
• said processor further being arranged for repeating using the matrix X of de-spread symbols and the channel estimates hc from common pilot channel, the modulation scheme information and the matrix S of recovered symbols in hard value to increase the estimation accuracy of the matrix S of recovered symbols in hard value until the output symbols are the same as the input symbols or the number of iterations reaches a pre-defined maximum value;
• a generator configured to use the matrix X of de-spread symbols and the matrix S of recovered symbols in hard value with increased estimation accuracy to form an impairment co-variance matrix Ru estimate;
• and
• said processor further being arranged for using the impairment co-variance matrix Ru estimate and the channel estimates hc from common pilot channel to determine generalized RAKE combining weight w and to estimate common pilot channel signal to interference plus noise ratio.