DIRECTION DETERMINATION IN CELLULAR MOBILE COMMUNICATIONS NETWORK

摘要

In order to improve carrier to interferenceratios on the down link in mobile communications networks,it is proposed to transmit on the down link in a beamsteered at the base station towards the mobile terminal.In order to do that it is necessary to know in whichdirection the mobile terminal is located. There isdisclosed a method of ascribing a direction to the locationof a mobile terminal from an antenna array. A sequence ofsymbols from each antenna in the array, is stored. Thesequence contains a known training sequence. The sequenceis space processed iteratively so as to produce the effectof the array having a major lobe in its polar diagram at aplurality of different successive directions. A set ofcross correlations metrics is derived by calculating across correlation metric for each direction between thecombined signals and the known training sequence. Theratio is calculated of the cross correlation metric foreach direction to the power of the combined signals forthat direction to produce a set of direction metrics. Adirection is ascribed to the mobile terminal using thedirection metrics to determine which direction is mostlikely.