Patent ID: 7386306

Claim:
A communications system, comprising: a plurality of multi-sector cells, including a first multi-sector cell and a second multi-sector cell, each multi-sector cell including a plurality of sectors and a sector transmitter for each sector of the multi-sector cell, said first and second multi-sector cells being physically adjacent cells; wherein said first multi-sector cell includes a base station that uses a single carrier frequency in each of a plurality of different sectors of said first cell, a first carrier frequency being used in a first sector of said first cell and a second carrier frequency being used in a second sector of said first multi-sector cell, the first and second carrier frequencies being different; and wherein said second multi-sector cell includes a second base station that uses said first and second carrier frequencies in a first sector of said second multi-sector cell; and wherein said plurality of multi-sector cells further includes: a third multi-sector cell, said third multi-sector cell including a base station which uses at least said first and second carrier frequencies in each of the sectors of said third cell, wherein the base station of said third multi-sector cell further uses a third carrier frequency in each of said sectors of said third multi-sector cell; and wherein a first frequency band is associated with and includes said first carrier frequency, a second frequency band is associated with and includes said second carrier frequency, and a third frequency band is associated with and includes the third carrier frequency, the first, second and third frequency bands being non-overlapping frequency bands of the same size and including a plurality of uniformly spaced tones used to transmit symbols; wherein each of said first, second, and third frequency bands have a bandwidth which is 2 MHz or less and wherein the total bandwidth occupied by said 3 bands is at most 6 MHz; and wherein each base station includes means for controlling each sector transmitter to periodically transmit a narrowband signal at a high power level on each carrier used for downlink signals in the sector into which the sector transmitter transmits, said narrowband signal including a signal transmitted over a tone with tone power being at least 20 times the average per tone transmission power in each carrier.