Transceiver for a base station with smart antenna and a switched beamforming method in downlink

• US 20050136980A1
• Filed: 10/29/2004
• Published: 06/23/2005
• Est. Priority Date: 12/19/2003
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Bang, Seung-Chan, Kim, Il-Gyu, Jwa, Hye-Kyung
• Granted Patent: US 7,313,417 B2
• Time in Patent Office: Days
• US Class Current: 455/562.100
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming

Abstract

Disclosed is a transceiver for a base station with a smart antenna having a plurality of antennas. The transceiver comprises: a multipath searching unit for searching multipath delay information for each demodulation channel; a demodulating unit for forming an adaptive beam for each demodulation channel by using the multipath delay information for each demodulation channel for receiving signals and performing demodulation to the received signals and outputting at least one adaptive beam weight vector; a controlling unit for selecting at least one downlink beam index for each channel; and a modulating unit for selecting the downlink switched beams and forming switching beam for modulating signals of each channel and outputting the modulated signals in downlink.

Claims

1. A transceiver for a base station with a smart antenna having a plurality of antennas, comprising:

a multipath searching unit for searching multipath delay information for each demodulation channel for signals received through the antennas;

a demodulating unit for forming an adaptive beam for each demodulation channel by using the multipath delay information for each demodulation channel for receiving signals, performing demodulation to the received signals, and outputting at least one adaptive beam weight vector for each demodulation channel, the adaptive beam weight vector being occurred during demodulation;

a controlling unit for selecting at least one downlink beam index for each channel by using correlation of the adaptive beam weight vector and the pre-established plurality of switched beam weight vectors; and

a modulating unit for selecting the downlink switched beams corresponding to at least one downlink beam index respectively, forming switching beams for modulating signals of each channel, and outputting the modulated signals in downlink.

2. The transceiver of claim 1, wherein the demodulating unit comprises a plurality of demodulators, and each demodulator comprises:

a plurality of adaptive beamforming finger blocks; and

a combiner for combining the outputs from the plurality of adaptive beamforming finger blocks and outputting the combined outputs to a channel decoder.

3. The transceiver claim 2, wherein the plurality of adaptive beamforming finger blocks comprises:

an adaptive beam weight vector operator for real-time extracting the adaptive beam weight vector from the received signals by using the multipath delay information;

a multiplier for real-time multiplying the received signals by the outputs from the adaptive beam weight vector operator; and

a finger for receiving the output from the multiplier, performing dispreading of the DS-CDMA signals by using the multipath delay information, performing time-tracking, channel estimating, and coherent demodulation, transferring the demodulated symbol to the combiner, and continuously outputting a time averaged energy of the demodulated symbol, and

the adaptive beam finger block real-time provides the adaptive beam weight vector outputted from the adaptive weight vector operator and the symbol energy from the finger to the controlling unit.

4. The transceiver of claim 1, wherein the controlling unit comprises:

a weight vector table, in which switched beam weight vectors are pre-established in accordance with an uplink frequency;

a per-channel adaptive beam weight vector selector for selecting at least one adaptive weight vector from the plurality of the adaptive beam weight vectors outputted from the demodulating unit, the selection beginning from the vector with greatest finger energy;

a per-channel vector inner product and square device for finding the inner product of the selected adaptive beam weight vector and the switched beam vector of the weight vector table and outputting its squared inner product; and

a per-channel beam index selector for selecting a beam index from outputs of the vector inner product and square device and outputting a downlink beam index.

5. The transceiver of claim 4, wherein the beam index selector calculates squared inner products vectors such as equation W_t,k=∥

R_i^HA_k∥

² (here, the H is an hermitian operator) from at least one adaptive beamforming weight vector A_k(k=0,1, . . . ,K) selected from the per-channel adaptive beam weight vector selector; and

the switched beamforming weight vectors R_j(j=0,1, . . . ,L) which number is same with the number of pre-stored switched beams in downlink; and

selects the downlink beam index by using the squared inner products vectors.

6. The transceiver of claim 4, wherein an uplink switched beam weight vector producing the same pattern with the downlink switched beam pattern, is used, of which frequency is set in uplink, when a FDD (frequency division duplex) method having different frequencies between the downlink and the uplink is used.

7. The transceiver of claim 4, wherein the per-channel adaptive beam weight vector selector selects at least one beam index and uses the beam index as a downlink switched beam index from squared inner product of the downlink switched beam, the selection beginning from the greatest squared inner product, when the number of the adaptive beam weight vector selected from the per-channel adaptive beam weight vector selector is 1.

8. The transceiver of claim 4, wherein the switched beam weight vector table is commonly used for the channels in which the downlink switched beam is formed.

9. The transceiver of claim 4, wherein the downlink beam index to any channel is selected based on total receiving energy for each switched beam for the channel.

10. The transceiver of claim 1, wherein the modulating unit comprises:

a plurality of modulators for modulating the encoded data for each channel at the base station for downlink transmission according to the W-CDMA reference and dispersing the modulated data;

a plurality of per-channel downlink beam selectors for selecting at least one downlink switched beam by using at least one downlink index for each channel, and outputting the signals outputted from the modulators as the selected downlink switched beam;

a plurality of per-beam adders for adding each output from the plurality of the downlink beam selectors for each beam;

a plurality of downlink switched beam formers for forming each switched beam by using the downlink switched beam weight vector pre-established at each beam; and

a plurality of per-antenna adders for adding each output from the plurality of downlink switched beam formers at each antenna and outputting the added output.

11. The transceiver of claim 10, wherein each downlink beam selector outputs at least one switched beam and does not output other beams which are not selected.

12. The transceiver for a base station for forming downlink switched beam in a wireless communication system comprising:

a plurality of array antennas for providing a beam pattern to a terminal user in downlink or uplink;

an RF/IF converter for converting signals transmitting or receiving through the array antennas from a radio frequency band to an immediate frequency band;

a multipath searcher for searching a multipath delay information for signals received from each channel through the array antenna;

an adaptive beamforming demodulator for forming an adaptive beam for each demodulation channel for receiving signals by using the multipath delay information for each demodulation channel and performing demodulation to the received signals, and outputting the adaptive beam weight vector for each channel, the adaptive beam weight vector being occurred during demodulation;

a downlink beam controller for selecting at least one downlink beam index for each channel by using correlation of the adaptive beam weight vector and the established plurality of switched beam weight vectors; and

a switching beamforming modulator for selecting at least one downlink switched beam corresponding to at least downlink beam index respectively, forming switching beams to the modulating signals for each channel, and outputting the modulated signals switching beams in downlink.

13. A downlink switched beamforming method at a base station with a plurality of antennas comprising:

a) searching multipath delay information on signals received through the antennas for each demodulation channel;

b) forming an adaptive beam for receiving signals for each demodulation channel by using the multipath delay information, and performing demodulation to the received signals;

c) outputting an adaptive beam weight vector for each channel, occurred during demodulation;

d) selecting at least one downlink beam index for each channel by using correlation of the adaptive beam weight vector and the established plurality of switched beam weight vectors; and

e) selecting downlink switched beams corresponding to at least one downlink beam index respectively, forming switching beams for modulating signals of each channel, and outputting the modulated signals in downlink.

14. The downlink switched beamforming method of claim 13, wherein in the stage d), squared inner products vectors such as equation W_t,k=∥

R_i^HA_k∥

² (here, the H is an hermitian operator) is calculated from at least one adaptive beamforming weight vector A_k(k=0,1, . . . ,K) selected from the per-channel adaptive beam weight vector selector; and

the switched beamforming weight vectors R_j(j=0,1, . . . ,L) of which number is same with the number of pre-stored switched beams in downlink; and

the downlink beam index is selected by using the squared inner products vectors.

15. The downlink switched beamforming method of claim 13, wherein in the stage d), the uplink switched beam weight vector is used, the uplink switched beam weight vector forming the same pattern with the downlink beam pattern, of which frequency in uplink is set with the switched beamforming weight vector, when frequency in downlink is different from the frequency in uplink.

16. The downlink switched beamforming method of claim 13, wherein in the stage d), at least one beam index is selected from the squared inner product of the downlink switched beam and used as a downlink beam index, the selection being made the greatest squared inner product as reference when the number of the adaptive beam weight vector is 1.

17. The downlink switched beamforming method of claim 13, wherein in the stage d), the downlink beam index is selected based on total receiving energy for each switched beam.