Weight Training For Antenna Array Beam Patterns in FDD/TDMA Terminals

Abstract

A method for weight training for beamforming in handset terminals deployed in a system employing Frequency Division Duplexing and Time-Division Multiple Access (FDD/TDMA). Generally there is signal in time slots that are not destined for a certain terminal. During this time the receiver scans a beam around the terminal and measures received signal strength, determining the best beam angle and storing corresponding weights for transmission.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a transceiver.

FIG. 2 is a schematic diagram of a frame structure for GSM.

FIG. 3 is a schematic diagram of antenna beam patterns corresponding to the stored antenna weights.

FIG. 4 is a schematic diagram of a method to generate the directional antenna patterns.

FIG. 5 is a flowchart of the scanning process.

Claims

1. A method for weight training reception and transmission beam forms in a frequency division duplex/time division multiple access handset terminal, the method comprising the steps of transmitting through a plurality of antennae adapted to a beam pattern with highest average received power and determining the beam pattern with highest average received power, wherein determining the beam pattern with highest average received power comprises the steps of selecting a terminal, measuring the received signal power during a time slot destined for a user other than the terminal, and averaging the received signal power with the average received power for the receive beam pattern, and comparing the average received power of each time slot, wherein measuring the received signal power comprises generating a receive beam pattern during an occupied time slot and measuring the signal power received during the time slot, wherein generating a receive beam pattern during an occupied time slot comprises the method of measuring received signal power in time slots not assigned to the terminal to determine which time slots are occupied.

2. The method of claim 1 further comprising the steps of sweeping through all the antenna weights stored for a certain antenna array and measuring the average received power for each antenna pattern wherein an antenna pattern corresponds to a plurality of weights, each associated with one element of an antenna array.

3. The method of claim 1 further comprising a method of fine-adjustment comprising adjusting a transmit antenna pattern to alternate between a left adjacent antenna pattern and a right adjacent antenna patterns wherein the method comprises one of causing a change of a transmit antenna pattern to the left adjacent antenna pattern if the received power corresponding to the left adjacent antenna pattern is higher than the received power corresponding to the right adjacent antenna pattern by a certain amount, causing a change of a transmit antenna pattern to the right adjacent antenna pattern if the received power corresponding to the right adjacent antenna pattern is higher than the received power corresponding to the left adjacent antenna pattern by a certain amount, and causing no change of a transmit antenna pattern if the difference between the received power corresponding to the right adjacent antenna pattern and the received power corresponding to the left adjacent antenna pattern is less than a certain amount.

4. The method of claim 1 further comprising the method of averaging the received signal power over several frames to compensate for fading effects before determining the beam pattern with highest average received power.

5. The method of claim 1 further comprising computing a transmit weight for each element of an antenna array wherein computing a transmit weight comprises the method of adding a phase shift to the receive weight wherein the phase shift is computed by multiplying a frequency of operation by a time delay.

6. The method of claim 1 further comprising the maximal ratio combining of received signals from each element of an antenna array.

7. The method of claim 1 further comprising the step of scaling back the transmit power by the array gain, whereby battery life is extended.

8. A method for achieving maximal ratio combining comprising the steps of setting all but one of the antenna weights to zero, measuring the signal power for each antenna, scaling the magnitude of the antenna weights proportional to the square root of the received power, and adjusting the phase of each antenna element during the time slots destined for other terminals and alternating between a left adjacent antenna beam pattern and a right adjacent antenna beam pattern during the time slot of the destined terminal.