A Code Division Multiple Access (CDMA) communication system which allocates different sets of frequencies to cells with different transmission power levels. Based upon the transmission power levels of a base station for each cell, each base station is assigned to one of at least two groups of base stations. Each group of base stations is assigned a set of frequencies for traffic communication. The set of frequencies assigned to one group of base stations does not overlap with the set of frequencies assigned to a different group of base stations.
In a communication system from a mobile station to a base station, a transmitter of the mobile station subjects a sequence of transmission signals to both of time division multiple access (TDMA) and code division multiple access (CDMA) to produce a radio output signal located in a time slot of a frame. The radio output signal obtained by the TDMA and CDMA is filtered or inversely spread to remove interference and noise from the radio output signal by the use of an adaptive filter which has taps controlled by an adaptive controller.
A direct sequence code-division multiple access (DS CDMA) communication system schedules conveyance of blocks (400) of information such that the blocks arrive at a base-site (130) just-in-time for transmission during a discrete frame (301-305) of an air-interface. The DS CDMA communication system implements both circuit switching and packet switching approaches to provide trunking efficiencies while balancing between system loading constraints and time delay of blocks (400) during conveyance.
A method of transmitting signals from a mobile unit to a base station in the reverse link direction using multi-tone techniques includes the step of dividing a frequency band into a plurality of generally even spaced tones. The tones are partitioned into a predetermined number of tone sets which each contain a predetermined number of tones. Each unit within a given sector is assigned a tone set for transmitting information signals. The tones within each tone set are selected so that the modulated signals transmitted by each unit are orthogonal with respect to all other tone sets assigned to units in that sector. Adjacent cells have no more than one tone in common.
In channel allocation, the objective is to allocate channels to desired connections using the available frequency spectrum as effectively as possible so that the connections will not cause excessive interference to each other. This invention presents a method based on time blocking of transmission in connections using different transmission powers, in order further to improve the allocation of channels.
A cellular-telephone base station (12) services a cell (14) that encompasses cells (16 and 18) serviced by other base stations (20 and 22). The base station (12) associated with the overlaid cell (14) communicates with mobile stations within its cell (14) by way of code-division multiple-access (CDMA) channels in a first frequency band. The CDMA channels by which the other base stations (20 and 22) communicate with mobile stations in their respective cells (16 and 18) occupy a second frequency band. Although the two smaller-cell base stations (20 and 22) employ the same frequency band, they are not contiguous, and they are separated enough so that they interfere only negligibly. Consequently, their channel capacities exceed those of conventionally configured CDMA cells of the same bandwidth.
