Communication terminal apparatus, base station apparatus, and radio communication method

• US 20040203829A1
• Filed: 12/18/2002
• Published: 10/14/2004
• Est. Priority Date: 08/02/2000
• Status: Active Grant

• Current Assignee: INVT SPE LLC (SoftBank Group Corp.)
• Original Assignee: Junichi Aizawa, Kenichi Miyoshi, Osamu Kato
• Inventors: Aizawa, Junichi, Miyoshi, Kenichi, Kato, Osamu
• Granted Patent: US 7,206,587 B2
• Time in Patent Office: Days
• US Class Current: 455/452.1
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/247 where the output power of a terminal is based on a path parameter sent by another terminal
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/54 based on quality criteria
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A communication mode determination section 201 determines the communication mode based on the CIR measured by a CIR measurement section 219; a DRC signal creation section 202 creates a DRC signal with a number corresponding to the communication mode; and a DRC power controller 205 refers to a transmission power table 206 showing the correspondence between DRC numbers and transmission power, and, based on the transmission power of the pilot signal output from a pilot power controller 209, increases transmission power in proportion as the DRC signal indicates that downlink channel quality is good.

Claims

1. A communication terminal apparatus used in a communication system in which communication resources are allocated to each communication terminal apparatus based on downlink channel quality, said communication terminal apparatus comprising:

a measurer that measures downlink channel quality and

a transmitter that transmits a notification signal to notify a base station apparatus of information that indicates said downlink channel quality;

wherein said notification signal includes information made less susceptible to errors in a propagation path, the information, among information indicative of channel quality, having a possibility of decreasing the downlink throughput when the information is received erroneously in said base station apparatus.

2. The communication terminal apparatus according to claim 1, wherein said transmitter transmits with less susceptibility to errors in a propagation path in proportion to a notification signal that indicates that said downlink channel quality is good.

3. The communication terminal apparatus according to claim 2, wherein said transmitter transmits with transmission power increased in proportion to a notification signal that indicates that said downlink channel quality is good.

4. The communication terminal apparatus according to claim 3, further comprising a controller that controls transmission power of a pilot signal,

wherein said transmitter transmits with a notification signal that indicates said downlink channel quality better than a predetermined channel quality set to higher transmission power than pilot signal transmission power, and a notification signal that indicates said downlink channel quality poorer than a predetermined channel quality set to lower transmission power than pilot signal transmission power.

5. The communication terminal apparatus according to claim 3, further comprising:

a table that indicates a correspondence between a notification signal and transmission power; and

a rewriter that rewrites contents of said table in accordance with a control signal from a base station apparatus,

wherein said transmitter adjusts a notification signal to predetermined transmission power based on said table.

6. The communication terminal apparatus according to claim 2, wherein said transmitter transmits after performing conversion to a code word with a size of a code word minimum distance proportional to a notification signal that indicates that said downlink channel quality is good.

7. The communication terminal apparatus according to claim 6, further comprising:

a table that indicates a correspondence between a notification signal and a code word; and

a rewriter that rewrites contents of said table in accordance with a control signal from a base station apparatus,

wherein said transmitter converts a notification signal to a predetermined code word based on said table.

8. The communication terminal apparatus according to claim 2, further comprising a determiner that determines a communication mode indicated by a combination of modulation method and coding method based on channel quality,

wherein said transmitter makes a notification signal a signal that indicates a communication mode.

9. The communication terminal apparatus according to claim 2, wherein:

said measurer measures pilot signal reception quality; and

said transmitter makes a notification signal a signal that indicates a pilot signal reception quality value.

10. The communication terminal apparatus according to claim 1, wherein:

said measurer measures pilot signal reception quality; and

said transmitter transmits a notification signal made less susceptible to errors in a propagation path in proportion to information for which an amount of change is large within information used to indicate a pilot signal reception quality value.

11. The communication terminal apparatus according to claim 10, wherein said transmitter transmits a notification signal converted to a code word whose code length is proportional to a value of an upper digit.

12. The communication terminal apparatus according to claim 10, wherein said transmitter transmits a notification signal with transmission power increased in proportion to a value of an upper digit.

13. The communication terminal apparatus according to claim 10, wherein said transmitter transmits a notification signal spread with a spreading code whose spreading factor is higher in proportion to a value of an upper digit.

14. A base station apparatus comprising:

a receiver that receives a notification signal transmitted from the communication terminal apparatus according to claim 1;

a measurer that measures reception power of a notification signal;

a detector that detects a notification signal whose reception power is less than a predetermined threshold value; and

a determiner that determines downlink communication resource allocation using a notification signal excluding a detected notification signal from a received plurality of notification signals.

15. The base station apparatus according to claim 14, further comprising:

a calculator that calculates a rate of detection by said detector; and

a transmitter that transmits a control signal instructing a communication terminal apparatus to rewrite said table based on a result of comparison of a rate of detection and a predetermined threshold value.

16. A base station apparatus comprising:

a receiver that receives a notification signal transmitted from the communication terminal apparatus according to claim 1;

a measurer that measures likelihood of a notification signal;

a detector that detects a notification signal whose likelihood is less than a predetermined threshold value; and

a determiner that determines downlink communication resource allocation using a notification signal excluding a detected notification signal from a received plurality of notification signals.

17. The base station apparatus according to claim 16, further comprising:

a calculator that calculates a rate of detection by said detector; and

a transmitter that transmits a control signal instructing a communication terminal apparatus to rewrite said table based on a result of comparison of a rate of detection and a predetermined threshold value.

18. A radio communication method, wherein:

a communication terminal apparatus, when transmitting a notification signal to notify a base station apparatus of information that indicates downlink channel quality, transmits a notification signal having information made less susceptible to errors in a propagation path, the information, among information indicative of said downlink channel quality, having a possibility of decreasing the downlink throughput when the information is received erroneously in said base station apparatus; and

said base station determines downlink communication resource allocation in accordance with a notification signal.

19. The radio communication method according to claim 18, wherein said communication terminal apparatus transmits with less susceptibility to errors in a propagation path in proportion to a notification signal that indicates that said downlink channel quality is good.

20. The radio communication method according to claim 18, wherein said communication terminal apparatus measures pilot signal reception quality, and transmits a notification signal made less susceptible to errors in a propagation path in proportion to information for which an amount of change is large within information used to indicate a reception quality value.