Scheme for realizing path selection using optimum path selection threshold in radio communication

• US 7,151,948 B2
• Filed: 06/20/2003
• Issued: 12/19/2006
• Est. Priority Date: 06/20/2002
• 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: Ishiguro, Takayuki, Moon, Sung Uk, Yamada, Mayu, Ishii, Hiroyuki
• Primary Examiner(s): Andereson, Matthew
• Assistant Examiner(s): DAO, MINH D
• Application Number:
  US10/465,612
• Publication Number:
  US 20030236074A1
• Time in Patent Office: 1,278 Days
• Field of Search: 455/522, 455/415, 455/418, 455/567, 375/148, 375/150, 375/227
• US Class Current: 455/522
• CPC Class Codes: H04B 1/70755 Setting of lock conditions, e.g. threshold
• CPC Class Codes: H04B 1/7113 Determination of path profile
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
• CPC Class Codes: H04L 25/0218 with detection of nulls

Abstract

A receiver of a mobile station or a base station in radio communications is formed by a correlation unit for generating a delay profile for specifying paths by taking correlations by using replica signals for a received pilot signal, and a path selection unit for comparing a power level of each path in the delay profile with a threshold determined according to an index value regarding a communication state, selecting paths for which a comparison result satisfies a prescribed condition as valid paths, and outputting a selected delay profile formed by the valid paths as a channel estimation value.

Claims

1. A communication control system for controlling radio communications between a transmitter and a receiver, comprising:

a correlation unit configured to receive a pilot signal which is a sequence known at the receiver and transmitted by the transmitter, and generate a delay profile for specifying paths by taking correlations by using replica signals for a received pilot signal;

a threshold determination unit configured to determine a threshold according to an index value regarding a communication state; and

a path selection unit configured to compare a power level of each path in the delay profile with the threshold, select paths for which a comparison result satisfies a prescribed condition as valid paths, and output a selected delay profile formed by the valid paths as a channel estimation value;

wherein the index value indicates one of a number of users communicating simultaneously, a number of traffics, a MCS (Modulation and Coding Scheme) level, a modulation scheme by which communications are currently carried out, and a fading frequency, the threshold being determined according to said one of the number of users communicating simultaneously, the number of traffics, the MCS level, the modulation scheme by which communications are currently carried out, and the fading frequency.

2. A communication control method for controlling radio communications between a transmitter and a receiver, comprising:

transmitting a pilot signal which is a sequence known at the receiver, from the transmitter;

receiving the pilot signal at the receiver, and generating a delay profile for specifying paths by taking correlations by using replica signals for a received pilot signal;

determining a threshold according to an index value regarding a communication state; and

comparing a power level of each path in the delay profile with the threshold, selecting paths for which a comparison result satisfies a prescribed condition as valid paths, and outputting a selected delay profile formed by the valid paths as a channel estimation value;

wherein the index value indicates one of a number of users communicating simultaneously, a number of traffics, a MCS (Modulation and Coding Scheme) level, a modulation scheme by which communications are currently carried out, and a fading frequency, the threshold being determined according to said one of the number of users communicating simultaneously, the number of traffics, the MCS level, the modulation scheme by which communications are currently carried out, and the fading frequency.

3. A mobile station device for carrying out radio communications with a base station, comprising:

a correlation unit configured to receive a pilot signal which is a sequence known at the mobile station device and transmitted by the base station, and generate a delay profile for specifying paths by taking correlations by using replica signals for a received pilot signal; and

a path selection unit configured to compare a power level of each path in the delay profile with a threshold determined according to an index value regarding a communication state, select paths for which a comparison result satisfies a prescribed condition as valid paths, and output a selected delay profile formed by the valid paths as a channel estimation value;

wherein the index value indicates one of a number of users communicating simultaneously, a number of traffics, a MCS (Modulation and Coding Scheme) level, a modulation scheme by which communications are currently carried out, and a fading frequency, the threshold being determined according to said one of the number of users communicating simultaneously, the number of traffics, the MCS level, the modulation scheme by which communications are currently carried out, and the fading frequency.

4. The mobile station device of claim 3, further comprising:

a threshold determination unit configured to acquire the index value, and determine the threshold according to an acquired index value.

5. The module station device of claim 3, wherein the path selection unit has a function for acquiring the threshold determined at the base station according to the index value.

6. A base station device for carrying out radio communications with a mobile station, comprising:

a correlation unit configured to receive a pilot signal which is a sequence known at the base station device and transmitted by the mobile station, and generate a delay profile for specifying paths by taking correlations by using replica signals for a received pilot signal; and

a path selection unit configured to compare a power level of each path in the delay profile with a threshold determined according to an index value regarding a communication state, select paths for which a comparison result satisfies a prescribed condition as valid paths, and output a selected delay profile formed by the valid paths as a channel estimation value;

wherein the index value indicates one of a number of users communicating simultaneously, a number of traffics, a MCS (Modulation and Coding Scheme) level, a modulation scheme by which communications are currently carried out, and a fading frequency, the threshold being determined according to said one of the number of users communicating simultaneously, the number of traffics, the MCS level, the modulation scheme by which communications are currently carried out, and the fading frequency.

7. The base station device of claim 6, further comprising:

a threshold determination unit configured to acquire the index value, and determine the threshold according to an acquired index value.

8. The mobile station device of claim 6, wherein the path selection unit has a function for acquiring the threshold determined at the mobile station according to the index value.

9. A base station device for carrying out radio communications with a mobile station, comprising:

a transmission unit configured to transmit a pilot signal which is a sequence known at the mobile station, to the mobile station, such that the mobile station generates a delay profile for specifying paths by taking correlations by using replica signals for the pilot signal received from the base station device, which is to be used in a path selection by the mobile station to select paths which satisfy a prescribed condition as valid paths;

a threshold determination unit configured to acquire an index value regarding a communication state, and determine a threshold to be compared with a power level of each path in the delay profile by the path selection at the mobile station, according to an acquired index value; and

a threshold notification unit configured to notify the threshold determined by the threshold determination unit to the mobile station;

where in the index value indicates one of a number of users communicating simultaneously, a number of traffics, a MCS (Modulation and Coding Scheme) level, a modulation scheme by which communications are currently carried out, and a fading frequency, the threshold being determined according to said one of the number of users communicating simultaneously, the number of traffics, the MCS level, the modulation scheme by which communications are currently carried out, and the fading frequency.

10. A base station device for carrying out radio communications with a mobile station, comprising:

a transmission unit configured to transmit a pilot signal which is a sequence known at the mobile station, to the mobile station, such that the mobile station generates a delay profile for specifying paths by taking correlations by using replica signals for the pilot signal received from the base station device, which is to be used in a path selection by the mobile station to select paths which satisfy a prescribed condition as valid paths; and

an index value notification unit configured to acquire an index value regarding a communication state, which is to be used in determining a threshold to be compared with a power level of each path in the delay profile by the path selection at the mobile station, and notify an acquired index value to the mobile station;

wherein the index value indicates one of a number of users communicating simultaneously, a number of traffics, a MCS (Modulation and Coding Scheme) level, a modulation scheme by which communications are currently carried out, and a fading frequency, the threshold being determined according to said one of the number of users communicating simultaneously, the number of traffics, the MCS level, the modulation scheme by which communications are currently carried out, and the fading frequency.