Radio telephone system for minimizing co-channel interference utilizing geographic separation of signals and transmission power control
First Claim
1. A radio telephone system employing a central base station and a plurality of mobile receivers for operating in an area divided into a plurality of transmission sectors extending radially outward from said base station, said base station assigning a plurality of frequency hopping radio channels to each of said plurality of transmission sectors, said frequency hopping radio channels having at least first, second and third time division time slots, said system comprising:
- a first geographic zone located in the central portion of a first of said transmission sectors, said base station being capable of assigning a first of said time division time slots of each of said radio channels assigned to said first of said transmission sectors to a first set of users located in said first geographic zone;
a second geographic zone located in a fringe portion of said first of said transmission sectors, said base station being capable of assigning a second of said time division time slots of each of said radio channels assigned to said first of said transmission sectors to a second set of users located in said second geographic zone;
a third geographic zone located in a fringe portion of a second of said transmission sectors, said base station being capable of assigning said first of said time division time slots of each of said radio channels assigned to said second of said transmission sectors to a third set of users located in said third geographic zone;
a transmitter in said base station for generating transmissions from said base station in said first of said transmission sectors covering said first of said transmission sectors and overlapping into said third geographic zone of said second of said transmission sectors, said first sector transmissions from said base station in said first time division time slot having a first down-link transmission power;
a transmitter in said base station for generating transmissions from said base station in said second of said transmission sectors covering said second of said transmission sectors and overlapping into said second geographic zone of said first of said transmission sectors, said second sector transmissions from said base station in said first time division time slot having a second down-link transmission power, said first down-link transmission power being less than said second down-link transmission power.
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Accused Products
Abstract
A system for minimizing co-channel interference between transmission sectors at their common periphery. The system exploits the geographic separation of potentially interfering mobile transmitters and utilizes transmission power control. The system employs sectored antennas in a combined frequency hopping, TDMA system wherein each subscriber in a particular sector is assigned a time slot in the system based upon that subscriber'"'"'s geographic location within that sector. The transmission power in the sector is reduced during certain predetermined time slots and subscribers who are remote from the fringe of the sector are assigned to these power reduced time slots. During up-link the transmission power for subscribers located proximal to the fringe are reduced to cause less co-channel interference between their signals and the signals from other subscribers in different sectors having the same time slot.
45 Citations
8 Claims
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1. A radio telephone system employing a central base station and a plurality of mobile receivers for operating in an area divided into a plurality of transmission sectors extending radially outward from said base station, said base station assigning a plurality of frequency hopping radio channels to each of said plurality of transmission sectors, said frequency hopping radio channels having at least first, second and third time division time slots, said system comprising:
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a first geographic zone located in the central portion of a first of said transmission sectors, said base station being capable of assigning a first of said time division time slots of each of said radio channels assigned to said first of said transmission sectors to a first set of users located in said first geographic zone; a second geographic zone located in a fringe portion of said first of said transmission sectors, said base station being capable of assigning a second of said time division time slots of each of said radio channels assigned to said first of said transmission sectors to a second set of users located in said second geographic zone; a third geographic zone located in a fringe portion of a second of said transmission sectors, said base station being capable of assigning said first of said time division time slots of each of said radio channels assigned to said second of said transmission sectors to a third set of users located in said third geographic zone; a transmitter in said base station for generating transmissions from said base station in said first of said transmission sectors covering said first of said transmission sectors and overlapping into said third geographic zone of said second of said transmission sectors, said first sector transmissions from said base station in said first time division time slot having a first down-link transmission power; a transmitter in said base station for generating transmissions from said base station in said second of said transmission sectors covering said second of said transmission sectors and overlapping into said second geographic zone of said first of said transmission sectors, said second sector transmissions from said base station in said first time division time slot having a second down-link transmission power, said first down-link transmission power being less than said second down-link transmission power. - View Dependent Claims (2, 3, 4)
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5. A method of allocating radio channels in a radio telephone system employing a central base station and a plurality of mobile receivers for operating in an area divided into a plurality of transmission sectors extending radially outward from said base station, said base station assigning a plurality of frequency hopping radio channels to each of said plurality of transmission sectors, dividing said frequency hopping radio channels into at least first, second and third time division time slots, said system comprising:
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defining a first geographic zone located in the central portion of a first of said transmission sectors, assigning said first of said time division time slots of each of said radio channels to a first set of users located in said first geographic zone; defining a second geographic zone located in a fringe portion of said first of said transmission sectors, assigning a second of said time division time slots of each of said radio channels to a second set of users located in said second geographic zone; defining a third geographic zone located in a fringe portion of a second of said transmission sectors, assigning said first of said time division time slots of each of said radio channels to a third set of users located in said third geographic zone; transmitting a first sector signal from a transmitter in said base station to said first of said transmission sectors, said first sector signal covering said first of said transmission sectors and overlapping into said third geographic zone of said second of said transmission sectors; allocating a first down-link transmission power to said first sector signal in said first time division time slot; transmitting a second sector signal from a transmitter in said base station to said second of said transmission sectors, said second sector signal covering said second of said transmission sectors and overlapping into said second geographic zone of said first of said transmission sectors; allocating a second down-link transmission power to said second sector signal in said first time division time slot, said first down-link transmission power being less than said second down-link transmission power. - View Dependent Claims (6, 7, 8)
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Specification