Base station hand-off mechanism for cellular communication system

• US 6,708,032 B2
• Filed: 05/24/2001
• Issued: 03/16/2004
• Est. Priority Date: 03/04/1999
• Status: Expired due to Term

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Brasic, Joseph A., Willingham, Julian Bartow, Martin, Gayle Patrick, Fortier, Gates H.
• Primary Examiner(s): Trinh, Sonny
• Application Number:
  US09/866,343
• Publication Number:
  US 20010027103A1
• Time in Patent Office: 1,027 Days
• Field of Search: 455/436, 455/437, 455/438, 455/439, 455/440, 455/441, 455/562.1, 455/25, 455/450, 455/524, 455/456.1, 455/443, 455/444, 455/442, 342/368, 342/371, 342/372, 342/432
• US Class Current: 455/436
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 36/326 by proximity to another entity

Abstract

A channel hand-off control mechanism for a cellular communication network uses the same channels employed for communications between base stations of adjacent cells and a mobile transceiver, as the mobile transceiver moves between those cells, in order to locate the mobile transceiver relative to the base stations, so that the acquiring base station may readily place a narrowbeam channel on the mobile transceiver at hand-off. Each base station employs a phased array antenna, which allows the base station to controllably define its antenna coverage pattern with respect to any mobile transceiver, so as to minimize interference from one or more other transceivers, reducing frequency reuse distance.

Claims

1. For use with a cellular wireless communication system having a plurality of geographically distributed cells containing respective base stations with which one or more mobile transceivers communicate over assigned communication channels, a communication infrastructure for controlling the transfer of a mobile transceiver, communicating over a first communication channel with a first base station of a first cell, to a second communication channel through which said mobile transceiver communicates with a second base station of a second cell, in the course of said mobile transceiver moving from said first cell to said second cell, comprising:

a first communication subsystem installed at said first base station, and being operative to determine the direction of said mobile transceiver relative to said first base station, and to convey to said second base station first steering vector information representative of the direction of said mobile transceiver relative to said first base station; and

a second communication subsystem installed at said second base station, and being operative to generate a second steering vector, representative of the direction of said mobile transceiver relative to said second base station, in accordance with said first steering vector information conveyed thereto from said first base station, and to transmitting energy on said second communication channel at a confined beam width in said direction of said mobile transceiver relative to said second base station, and wherein

said second base station contains a phased array antenna, by way of which communication with said mobile transceiver is conducted, and wherein said second communication subsystem is operative to transmit energy on said second communication channel at a confined beam width obtained by said phased array antenna, in said direction of said mobile transceiver relative to said second base station, and wherein

said second communication subsystem is operative to transmit an omnidirectional energy burst from a single antenna element of a phased array antenna at a transmission power level of NP, where N is ratio of the average gain of said phased array antenna to the gain of one antenna element of said phased array antenna, and P is the power required for said omnidirectional energy burst to establish a communication link with said mobile transceiver at a boundary of said second cell at the full gain of said phased array antenna.

2. For use with a cellular wireless communication system having a plurality of geographically distributed cells containing respective base stations with which one or more mobile transceivers communicate over assigned communication channels, a communication infrastructure for controlling the transfer of a mobile transceiver, communicating over a first communication channel with a first base station of a first cell, to a second communication channel through which said mobile transceiver communicates with a second base station of a second cell, in the course of said mobile transceiver moving from said first cell to said second cell, comprising:

a first communication subsystem installed at said first base station, and being operative to determine the direction of said mobile transceiver relative to said first base station, and to convey to said second base station first steering vector information representative of the direction of said mobile transceiver relative to said first base station; and

a second communication subsystem installed at said second base station, and being operative to generate a second steering vector, representative of the direction of said mobile transceiver relative to said second base station, in accordance with said first steering vector information conveyed thereto from said first base station, and to transmitting energy on said second communication channel at a confined beam width in said direction of said mobile transceiver relative to said second base station, and wherein

said second base station contains a phased array antenna, by way of which communication with said mobile transceiver is conducted, and wherein said second communication subsystem is operative to transmit energy on said second communication channel at a confined beam width obtained by said phased array antenna, in said direction of said mobile transceiver relative to said second base station, and wherein

said second communication subsystem is operative to transmit over said second communication channel to said mobile transceiver using a reduced beam width directivity pattern produced by said phased array antenna, in which the average power allocated to each element of said phased array antenna is the power required to establish a communication link with said mobile transceiver at a boundary of said second cell at the full gain of said phased array antenna.

3. For use with a cellular wireless communication system having a plurality of geographically distributed cells containing respective base stations with which one or more mobile transceivers communicate over assigned communication channels, a communication infrastructure for controlling the transfer of a mobile transceiver, communicating over a first communication channel with a first base station of a first cell, to a second communication channel through which said mobile transceiver communicates with a second base station of a second cell, in the course of said mobile transceiver moving from said first cell to said second cell, said communication infrastructure comprising:

a second base station communication subsystem that is operative, while said mobile transceiver is located in said first cell and is transmitting on said first communication channel, to

monitor transmissions from said mobile transceiver and derive an antenna steering vector representative of the direction of said mobile transceiver relative to said second base station,

tune a transceiver for conducting communications with said mobile transceiver on said second communication channel, and adjust antenna parameters to form a confined width beam for said second communication channel in said direction of said mobile transceiver relative to said second base station, and transmit energy on said second communication channel at said confined width beam in said direction of said mobile transceiver relative to said second base station, so as to stimulate said mobile transceiver to transmit on said second communication channel; and

a mobile transceiver subsystem that is operative, in response to receipt of energy transmitted thereto on said second communication channel from said second base station, to conduct communications with said second base station on said second communication channel.

4. The communication infrastructure according to claim 3, wherein said second base station communication infrastructure is operative to refine said steering vector, as necessary, while said mobile transceiver is located in said second cell, to maintain communication over said second communication channel between said second base station and said mobile transceiver, at a reduced width beam in the direction of said mobile transceiver relative to said second base station.

5. A method of controlling the transfer of a mobile wireless transceiver, communicating over a first communication channel with a first base station of a first cell, to a second communication channel through which said mobile transceiver communicates with a second base station of a second cell, in the course of said mobile transceiver moving from said first cell to said second cell, said method comprising the steps of:

(a) generating narrowbeam communication directivity patterns at said first and second base stations through which said first and second communication channels may be directed toward said mobile transceiver;

(b) performing a steering vector measurement upon one of said first and second communication channels; and

(c) directing the narrowbeam directivity pattern for said second communication channel from said second base station toward said mobile subscriber in accordance with said steering vector measurement performed in step (b), and wherein

step (b) comprises stimulating said mobile transceiver to transmit on said second communication channel and, in response to a transmission from said mobile transceiver on said second communication channel, determining the direction of said mobile transceiver relative to said second base station, and adjusting the transmission of energy on said second communication channel from said second base station to said mobile transceiver, and wherein

step (b) comprises stimulating said mobile transceiver by transmitting a less than omnidirectional energy burst from said second base station.

6. A method of controlling the transfer of a mobile wireless transceiver, communicating over a first communication channel with a first base station of a first cell, to a second communication channel through which said mobile transceiver communicates with a second base station of a second cell, in the course of said mobile transceiver moving from said first cell to said second cell, said method comprising the steps of:

(a) generating narrowbeam communication directivity patterns at said first and second base stations through which said first and second communication channels may be directed toward said mobile transceiver;

(b) performing a steering vector measurement upon one of said first and second communication channels; and

(c) directing the narrowbeam directivity pattern for said second communication channel from said second base station toward said mobile subscriber in accordance with said steering vector measurement performed in step (b), and wherein

step (b) comprises stimulating said mobile transceiver to transmit on said second communication channel and, in response to a transmission from said mobile transceiver on said second communication channel, determining the direction of said mobile transceiver relative to said second base station, and adjusting the transmission of energy on said second communication channel from said second base station to said mobile transceiver, and wherein

step (b) comprises stimulating said mobile transceiver by transmitting an omnidirectional energy burst from said second base station.

7. The method according to claim 6, wherein said second base station contains a phased array antenna and wherein step (b) comprises transmitting said omnidirectional energy burst from a single antenna element of said phased array antenna.

8. The method according to claim 7, wherein step (b) comprises transmitting said omnidirectional energy burst from said single antenna element at a transmission power level of NP, where N is ratio of the average gain of said phased array antenna to the gain of one antenna element of said phased array antenna, and P is the power required for said energy burst to establish a communication link with said mobile transceiver at a boundary of said second cell at the full gain of said phased array antenna.

9. The method according to claim 7, wherein step (c) comprises transmitting over said second communication channel to said mobile transceiver using a reduced beam width directivity pattern produced by said phased array antenna, in which the average power allocated to each element of said phased array antenna is the power required to establish a communication link with said mobile transceiver at a boundary of said second cell at the full gain of said phased array antenna.

10. A method of controlling the transfer of a mobile wireless transceiver, communicating over a first communication channel with a first base station of a first cell, to a second communication channel through which said mobile transceiver communicates with a second base station of a second cell, in the course of said mobile transceiver moving from said first cell to said second cell, said method comprising the steps of:

(a) generating narrowbeam communication directivity patterns at said first and second base stations through which said first and second communication channels may be directed toward said mobile transceiver;

(b) performing a steering vector measurement upon one of said first and second communication channels; and

(c) directing the narrowbeam directivity pattern for said second communication channel from said second base station toward said mobile subscriber in accordance with said steering vector measurement performed in step (b), and wherein

step (b) comprises stimulating said mobile transceiver to transmit on said second communication channel and, in response to a transmission from said mobile transceiver on said second communication channel, determining the direction of said mobile transceiver relative to said second base station, and adjusting the transmission of energy on said second communication channel from said second base station to said mobile transceiver, and wherein

step (b) comprises determining the direction of said mobile transceiver relative to said first base station, and supplying said second base station with first steering vector information representative of the direction of said mobile transceiver relative to said first base station, and generating a second steering vector representative of the direction of said mobile transceiver relative to said second base station, in accordance with said first steering vector information.

11. The method according to claim 10, wherein step (b) further includes refining said second steering vector, as necessary, while said mobile transceiver is located in said second cell, to maintain communication over said second communication channel between said second base station and said mobile transceiver, at a reduced beam width in the direction of said mobile transceiver relative to said second base station.