| 摘要 |
A base station within a cell of an orthogonal frequency division multiplexing (OFDM) based spread spectrum multiple access system employs sectorization as a way to reduce the intercell interference. The cell is sectorized from a transmission point of view by the directionality of the downlink antenna, and the OFDM tone set employed in each cell is correspondingly sectorized, i.e., each sector in the cell is allocated a set of tones within a sub-band of the available frequency bandwidth for use when transmitting into that sector. The sub-bands assigned to each sector are periodically changed, or "hopped", among the available sub-bands within the totally available bandwidth. Such subband hopping is a so-called "slow" hopping, in that it is not performed on a symbolby-symbol basis but instead occurs only after more than one symbol has been transmitted in a sector on tones within the sub-band. Each sector employs its own pilot signal, which is assigned one or more tones within the sub-band currently employed by that sector. Similarly, for the uplink, the base station may employ a directional receiver antenna. Preferably, the mobile terminal only transmits on a tone that is within a sub-band that is allocated to the sector in which the mobile terminal is located. This, sub-band, however, need not correspond to the same location within the bandwidth as the sub-band used by the downlink to communicate with the mobile terminal.
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