{HEAD ~ The reference signals} are used to determine {TAIL ~ propagation characteristics} of communication channels between the base and mobile stations and optimize, in real time, parameters of receivers of the mobile stations for processing the following data signals 
are used to determine
{ HEAD ~ The reference signals } are used to determine { TAIL ~ propagation characteristics } of communication channels between the base and mobile stations and optimize , in real time , parameters of receivers of the mobile stations for processing the following data signals
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