Repeating station, a communication apparatus, and a directivity control method

• US 7,606,531 B2
• Filed: 07/05/2005
• Issued: 10/20/2009
• Est. Priority Date: 07/05/2004
• Status: Expired due to Fees

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Furuno, Tatsuo, Asai, Takahiro, Suda, Hirohito, Tanaka, Tetsu
• Primary Examiner(s): Nguyen; Duc
• Assistant Examiner(s): Nguyen; Hai V
• Application Number:
  US11/172,951
• Publication Number:
  US 20060003697A1
• Time in Patent Office: 1,568 Days
• Field of Search: 455/11.1
• US Class Current: 455/11.1
• CPC Class Codes: H04B 7/1555 Selecting relay station antenna mode, e.g. selecting omnidirectional -, directional beams, selecting polarizations
• CPC Class Codes: H04B 7/15571 by signal isolation, e.g. isolation by frequency or by antenna pattern, or by polarization
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels

Abstract

A repeating station, a communication apparatus, and an antenna directivity control method are disclosed. The repeating station includes

• • a first antenna group including at least one antenna element,
  • a second antenna group that is different from the first antenna group, the second antenna group including two or more antenna elements adjusted so that radiation in the direction of the first antenna group is reduced, wherein the second antenna group is adjusted such that radiated power in the direction of the first antenna group is reduced.

Claims

1. A repeating station comprising:

a first antenna group including at least one antenna element;

a second antenna group that is different from the first antenna group, the second antenna group including a plurality of antenna elements;

a plurality of signal generating units, each corresponding to one of said antenna elements of the second antenna group, configured to generate a directivity adjustment signal to be transmitted from each of the antenna elements of the second antenna group,

a received power measuring unit configured to measure the radiated power of signals transmitted by the second antenna group and received by the first antenna group; and

a weight calculating unit configured to calculate transmission weights to be multiplied by corresponding signals to be transmitted from the antenna elements of the second antenna group such that the radiated power is reduced in a direction that causes a feedback to the first antenna group, and such that the radiated power is made uniform in other directions,

wherein the adjustment is performed by the weights, wherein the weight calculating unit calculates the transmission weights based on at least one of

making a sum of squares of all transmission weights a fixed value,

making one certain transmission weight a fixed value, and

making a transmission weight of one antenna element of each of a plurality of adaptive array antennas included in the second antenna group a fixed value, and each of said plurality of antenna elements of the second antenna group is adjusted so that radiated power in the direction of the first antenna group is reduced.

2. The repeating station as claimed in claim 1, wherein the antenna elements that constitute the second antenna group are arranged so that an antenna pattern that is synthetically formed by the antenna elements becomes omni-directional.

3. The repeating station as claimed in claim 1, further comprising:

a received power measuring unit configured to measure received power of the directivity adjustment signal received at the first antenna group; and

a directivity control unit configured to control the directivity of each of the plurality of antenna elements of the second antenna group based on the received power.

4. The repeating station as claimed in claim 1, further comprising:

a transmitting antenna quantity change signal receiving unit configured to receive a notice signal of a transmitting antenna, said signal used to determine whether the number of antenna elements to be used by the repeating station is to be changed based on communication quality.

5. The repeating station as claimed in claim 1, further comprising:

a signal generating unit configured to generate a directivity adjustment signal to be transmitted from each of the antenna elements of the second antenna group.

6. The repeating station as claimed in claim 1, wherein the first antenna group includes a plurality of adaptive array antennas, each of which adaptive array antennas includes a plurality of antenna elements;

and

the weight calculating unit calculates receiving weights that are multiplied by corresponding received signals so that gain in an arrival direction of a loop interference from the second antenna group is reduced, and the gain in other directions is made uniform based on the received power.

7. The repeating station as claimed in claim 6, wherein the weight calculating unit calculates the receiving weights based on at least one of making a sum of squares of all receiving weights a fixed value, making one certain receiving weight a fixed value, and making a receiving weight of one antenna element of each of the adaptive array antennas a fixed value.

8. The repeating station as claimed in claim 1, further comprising:

a loop interference canceling unit configured to cancel a signal fed back to the first antenna group from the second antenna group.

9. The repeating station as claimed in claim 1, further comprising:

a transmitting start/halt control unit configured to control a transmitting start and a transmitting halt based on a signal that indicates a transmitting start and transmitting halt of a transmitting signal.

10. A communication apparatus comprising:

a received signal property calculating unit configured to calculate a property of a received signal;

a determining unit configured to determine whether to start or stop transmission of a transmission signal from a repeating station based on the property of the received signal; and

a transmission guard interval length control unit configured to control the guard interval length for transmission data based on a processing delay at the repeating station and a signal that indicates whether to start or stop transmission of a transmission signal from another communication apparatus and transmitted from the repeating station.

11. The communication apparatus as claimed in claim 10, wherein the received signal property calculating unit is further configured to calculate at least one of received power and antenna correlation as the property of the received signal using the signal received by a receiving antenna.

12. The communication apparatus as claimed in claim 10, further comprising:

a guard interval length control unit configured to control a guard interval length based on a result of the determining unit.

13. The communication apparatus as claimed in claim 10, further comprising:

a transmitting antenna quantity change signal receiving unit configured to receive a notice signal of a transmitting antenna, said signal used to determine whether the quantity of the antenna elements to be used by the repeating station is to be changed based on communication quality.

14. A directivity control method for a repeating station, comprising:

transmitting a directivity adjustment signal from each of a plurality of antenna elements of a second antenna group, said directivity adjustment signal being generated at a plurality of signal generating units, each corresponding to one of said plurality of antenna elements;

measuring received power of the directivity adjustment signal received by a first antenna group including at least one antenna element;

adjusting the directivity of each of the plurality of antenna elements of the second antenna group based on the received power;

measuring the radiated power of signals transmitted by the second antenna group and received by the first antenna group; and

calculating transmission weights to be multiplied by corresponding signals to be transmitted from the antenna elements of the second antenna group such that the radiated power is reduced in a direction that causes a feedback to the first antenna group, and such that the radiated power is made uniform in other directions, wherein the adjusting step is performed by the weights, and the calculating step calculates the transmission weights based on at least one of

making a sum of squares of all transmission weights a fixed value,

making one certain transmission weight a fixed value, and

making a transmission weight of one antenna element of each of a plurality of daptive array antennas included in the second antenna group a fixed value.