Mobile battery discharge minimization in indoor wireless networks by antenna switching

• US 6,594,475 B1
• Filed: 09/09/1999
• Issued: 07/15/2003
• Est. Priority Date: 09/09/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Prakash, Amol, Dang, Manpreet Singh, Anvekar, Dinesh Kashinath
• Primary Examiner(s): NGUYEN, DUC M
• Application Number:
  US09/392,426
• Time in Patent Office: 1,405 Days
• Field of Search: 455/522, 455/69, 455/38.3, 455/562, 455/574, 455/133-135, 455/277.1, 455/277.2, 455/101, 455/561, 340/7.32, 340/7.33, 340/7.36
• US Class Current: 455/277.1
• CPC Class Codes: H04B 7/0808 comparing all antennas before reception
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 84/10 Small scale networks; Flat hierarchical networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus minimize battery discharge of mobile communication devices in short range wireless radio communication networks by switching receiving antennas to minimize transmitted power for a mobile communication device. Multiple receiving antennas and at least one transmitting antenna are used. The receiving antennas are switched for each mobile communication device to minimize transmitted power required by a mobile communication device. Switching between receiving antennas is accomplished by measuring power of a signal received from a mobile communication device at each receiving antenna, and selecting a receiving antenna based on the measured power. A database of switchings is maintained for the mobile communication devices, and an initial selection of a receiving antenna is based on the last switching or a trend indicated by most recent switchings. Alternatively, the initial switching is to a centrally located receiving antenna.

Claims

1. A method of minimizing battery discharge of mobile communications devices in short range wireless radio communication networks comprising the steps of:

providing multiple receiving antennas and a single separate transmitting antenna,

measuring power of a signal received from a mobile communication device at each receiving antenna,

switching receiving antennas for each mobile communication device to minimize transmitted power required by a mobile communication device by selecting only a single receiving antenna based on prior recent uplink power measurements, and

instructing a mobile communication device by a base station as to a power level to use for the next uplink transmission.

2. The method recited in claim 1, wherein the step of antenna switching comprises the steps of

maintaining a database of switchings for mobile communication devices, and

selecting only a single receiving antenna based on most recent switching.

3. A method of minimizing battery discharge of mobile communication devices in short range wireless radio communication networks comprising the steps of:

transmitting from a base station to a mobile communication device a data packet on a downlink through a single transmitting antenna,

determining at the mobile communication device a transmission power level to be used based on information from a received data packet to the base station,

transmitting by the mobile communication device a data packet to the base station on an uplink,

measuring at the base station power levels of a data packet received from the mobile communication device on a plurality of receiving antennas separate from the transmitting antenna,

determining from said measured power levels a next receiving antenna from the plurality of receiving antennas to be switched for receiving signals from the mobile communication device, and

switching receiving antennas to minimize transmitted power required by the mobile communication device by selecting only a single receiving antenna.

4. The method recited in claim 3, further comprising the steps of:

initially determining by the base unit a receiving antenna to be switched for receiving signals from the mobile communication device before the step of transmitting, and

switching to the initially determined receiving antenna.

5. The method recited in claim 4, wherein the step of initially determining a receiving antenna comprises the steps of:

maintaining a database of switchings for mobile communication devices, and

selecting a receiving antenna based on most recent switchings.

6. The method recited in claim 4, wherein the step of initially determining a receiving antenna comprises the steps of:

storing an indication of a last used receiving antenna of the mobile communication device, and

selecting a receiving antenna based on the last used receiving antenna.

7. The method recited in claim 4, wherein the step of initially determining a receiving antenna comprises the step of selecting a centrally located receiving antenna.

8. An apparatus for minimizing battery discharge of mobile communication devices in short range wireless radio communication networks comprising:

a single transmitting antenna connected to a base station for communicating with one or more mobile communication devices,

a plurality of receiving antennas separate from the transmitting antenna for receiving signals from a mobile communication device, and

means for switching receiving antennas for the mobile communication devices to minimize transmitted power required by a mobile communication device by selecting only a single receiving antenna based on prior recent uplink power measurements, said means comprising

a power measurement unit for each of the plurality of receiving antennas, and

an antenna switch controlled by measured power of a received signal from a device.

9. The apparatus recited in claim 8, said means for switching receiving antennas further comprising:

a signal splitter for each of the plurality of receiving antennas, each said splitter providing an output to a corresponding power measurement unit and an output to the antenna switch, and

an antenna switching controller receiving outputs from the power measuring units and controlling the antenna switch.

10. The apparatus recited in claim 9, wherein a first and weaker signal part from a signal splitter is connected to a corresponding power measuring unit, and a second and stronger signal part from the signal splitter is connected to an input of the antenna switch.

11. The apparatus recited in claim 10, wherein the power measuring units can tune to transmissions from a mobile communication device and determine relative strength of the received signal excluding interfering signals, if any.

12. The apparatus recited in claim 9, wherein the antenna switching controller determines a receiving antenna which receives the maximum signal power during a current measurement interval, as a next receiving antenna to be switched.

13. The apparatus recited in claim 9, wherein the antenna switching controller determines a next antenna to be switched based on stored past values of signal power levels received from a mobile communication device through the plurality of receiving antennas.

14. The apparatus recited in claim 8, wherein the transmitting antenna is located such that a given geographical space is covered by its transmissions and sufficiently high power levels are received by mobile communication devices at all points within the space.

15. The apparatus recited in claim 14, wherein the plurality of receiving antennas are uniformly distributed within the coverage space to ensure that optimum transmitted signal power level is required by a mobile unit.

16. The apparatus recited in claim 15, wherein a receiving antenna is located at the same location as the transmitting antenna.

17. The apparatus as recited in claim 8, wherein the receiving antenna switched for a mobile communication device during a first packet reception is a receiving antenna which is closest to a center of an area covered by the transmitting antenna.