Interference reduction in shared-frequency wireless communication systems

• US 5,884,181 A
• Filed: 01/19/1996
• Issued: 03/16/1999
• Est. Priority Date: 01/19/1996
• Status: Expired due to Term

• Current Assignee: Nytell Software LLC (Intellectual Ventures LLC)
• Original Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Seidel, Scott Yates, Arnold, Hamilton W.
• Primary Examiner(s): LE, THANH C
• Application Number:
  US08/588,979
• Time in Patent Office: 1,152 Days
• Field of Search: 455/446, 455/447, 455/448, 455/449, 455/450, 455/452, 455/454, 455/455, 455/62, 455/63, 455/67.1, 455/12.1, 455/13.1, 455/427, 455/428
• US Class Current: 455/450
• CPC Class Codes: H04B 7/00 Radio transmission systems, i.e. using radiation field H04B10/00, H04B15/00 take precedence
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

An apparatus and method for reducing interference between an uplink transmitter of a space-based wireless communication system and an uplink or downlink receiver of a terrestrial wireless communication system are described. The space-based system may be a Fixed Satellite Service (FSS) system and the terrestrial system may be a Local Multipoint Distribution Service (LMDS) system. An ordered list of preferred uplink transmission frequencies is assigned to all FSS uplinks located in a particular cell of the LMDS system. Different ordered lists are used in different cells of the LMDS system, while uplinks located in the same cell can utilize the same ordered list. A given potentially-interfering uplink transmitter selects an uplink transmission frequency from the appropriate ordered list if the uplink is unable to operate outside the LMDS frequency band and there are no gaps in the LMDS spectrum which can accommodate the uplink transmission. The ordered list may be selected by the LMDS service provider such that the impact of interference from FSS uplinks can be readily predicted and minimized. The invention thus allows simultaneous access to a shared frequency band for both LMDS and FSS systems.

Claims

1. A method of reducing interference between an uplink transmitter of a first wireless communication system and a receiver of a second wireless communication system wherein the second communication system includes a plurality of cells, comprising the steps of:

assigning at least one preferred uplink transmission frequency to each of a plurality of uplink transmitters of the first communication system located in cells of the second communication system, such that at least one of the uplink transmitters located in one of the cells is assigned a different preferred frequency than another of the uplink tranmsitters located in another of the cells, said step of assigning including

determining the cell or cells of the second communication system in which each of the plurality of uplink transmitters is located,

assigning a common ordered frequency list to uplink transmitters located in the same cell, and

storing the common ordered list of preferred frequencies for the same cell in one or more memory locations accessible by up-link transmitters located in that cell; and

selecting uplink transmission frequencies in the first communication system in accordance with the assigned preferred frequencies.

2. A method of reducing interference between an uplink transmitter of a first wireless communication system and a receiver of a second wireless communication system, wherein the second communication system includes a plurality of cells, comprising the steps of:

assigning at least one preferred uplink transmission frequency to each of a plurality of uplink transmitters of the first communication system, located in cells of the second communication system, such that at least one of the uplink transmitters located in one of the cells is assigned a different preferred frequency than another of the up-link transmitters located in another of the cells; and

selecting uplink transmission frequencies in the first communication system in accordance with the assigned preferred frecuencies, wherein the step of selecting uplink transmission frequencies further includes the steps of;

determining if a given uplink transmitter will potentially interfere with the receiver of the second communication system; and

selecting an uplink transmission frequency inside a bandwidth of the receiver if the given uplink transmitter will not potentially interfere with the receiver.

3. A method of reducing interference between an uplink transmitter of a first wireless communication system and a receiver of a second wireless communication system, wherein the second communication system includes a plurality of cells, comprising the steps of:

assigning at least one preferred uplink transmission frequency to each of a plurality of uplink transmitters of the first communication system located in cells of the second communication system, such that at least one of the uplink transmitters located in one of the cells is assigned a different preferred frequency than another of the uplink transmitters located in another of the cells; and

selecting uplink transmission frequencies in the first communication system in accordance with the assigned preferred frequencies. said selecting step including

determining if a given uplink transmitter is able to operate outside a frequency band of the second communication system; and

selecting an uplink transmission frequency outside the frequency band of the second system if the given uplink transmitter is able to operate outside the frequency band.

4. A method of reducing interference between an uplink transmitter of a first wireless communication system and a receiver of a second wireless communication system, wherein the second communication system includes a plurality of cells. Comprising the steps of:

assigning at least one preferred uplink transmission frequency to each of a plurality of uplink transmitters of the first communication system located in cells of the second communication system, such that at least one of the uplink transmitters located in one of the cells is assigned a different preferred frequency than another of the uplink transmitters located in another of the cells, and

selecting uplink transmission frequencies in the first communication system in accordance with the assigned frequencies, the step of selecting uplink transmission frequencies further including the steps of;

retrieving channel plan information including an indication of any usable frequency gaps in the frequency band of the second system and an ordered frequency list, wherein the ordered frequency list includes the preferred frequency for a given uplink transmitter;

selecting an uplink transmission frequency in one of the frequency gaps of the frequency band of the second system if available; and

selecting an uplink transmission frequency from the ordered list if the frequency gaps are unavailable.

5. An apparatus for reducing interference between an uplink transmitter of a first wireless communication system and a receiver of a second wireless communication system, the second communication system including a plurality of cells, the apparatus comprising:

a processor coupled to the uplink transmitter in the first communication system and operative to select an uplink transmission frequency for the transmitter from at least a preferred transmission frequency assigned to that transmitter, wherein the preferred transmission frequency for the transmitter is assigned based on the cell of the second communication system in which the transmitter is located;

a memory coupled to the processor and operative to store the preferred uplink transmission frequency; and

wherein the processor is operative to retrieve channel plan information including an indication of frequency gaps in a frequency band of the second system and an ordered frequency list, the ordered frequency list including the preferred frequency for a given uplink transmitter.

6. The apparatus of claim 5 wherein the processor is operative to select an uplink transmission frequency for the given uplink transmitter in one of the frequency gaps of the second system if available.

7. The apparatus of claim 5 wherein the processor is operative to select an uplink transmission frequency for the given uplink transmitter from the ordered list if the frequency gaps are unavailable.