WIRELESS COMMUNICATION METHOD, WIRELESS COMMUNICATION SYSTEM AND BASE STATION

• US 20110075749A1
• Filed: 01/27/2009
• Published: 03/31/2011
• Est. Priority Date: 01/28/2008
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Sahara, Toru, Murakami, Youhei
• Granted Patent: US 8,537,946 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2605 Symbol extensions, e.g. Zero Tail, Unique Word [UW]
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15
• CPC Class Codes: H04W 56/003 Arrangements to increase tolerance to errors in transmission or reception timing

Abstract

One of the objects of the present invention is to more completely avoid impossibility of access between a mobile station and a base station, in wireless communication using an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme. In one embodiment, a base station removes a guard interval from an OFDM symbol received from a PHS terminal through a timing correction channel at two different timings to obtain two effective symbols, calculates a timing correction amount by including one timing, at which an guard interval is removed for the effective symbol that has caused detection of one correlation peak within a predetermined timing detection range of two correlation peaks detected from the respective effective symbols, into a differential from reference timing of the base station at the time of detection of the one correlation peak, and transmits the timing correction amount to the PHS terminal by means of a timing correction burst.

Claims

1. A wireless communication method of conducting wireless communication between a mobile station and a base station by using an OFDM modulation scheme, the method comprising:

notifying a notification channel from the base station to the mobile station;

in the mobile station,

generating a channel to be frame synchronized with the notification channel and transmitting an OFDM symbol to the base station;

in the base station, as peak detection processes thereof,

removing a guard interval from the transmitted OFDM symbol at two different timings to obtain two effective symbols;

detecting two correlation peaks between the two respective effective symbols and a known symbol;

calculating a timing correction amount by including timing corresponding to a guard interval removed when generating the effective symbol that has exhibited a first correlation peak, which is detected within a predetermined timing detection range that is shorter an effective symbol length, of the two correlation peaks into a differential between the first correlation peak and reference timing of the base station;

transmitting the timing correction amount to the mobile station by means of a timing correction burst;

in the mobile station,

correcting transmission timing in accordance with the timing correction amount; and

transmitting a communication channel assignment request to the base station at the corrected transmission timing.

3. The wireless communication method claimed in claim 1,

wherein a differential of the two timings is shorter than the effective symbol length.

4. The wireless communication method claimed in claim 1,

wherein one of the two timings is reference timing of the base station.

5. The wireless communication method claimed in claim 1,

wherein if a communication channel is not assigned from the base station despite that the mobile station transmits a communication channel assignment request to the base station, the method regenerates a channel to be frame synchronized with the notification channel and transmits an OFDM symbol to the base station and implement the peak detection processes of the base station again.

2. A wireless communication method of conducting wireless communication between a mobile station and a base station by using an OFDM modulation scheme, the method comprising:

notifying a notification channel from the base station to the mobile station;

in the mobile station,

generating a channel to be frame synchronized with the notification channel and transmitting an OFDM symbol to the base station;

in the base station, with regard to peak detection processes thereof,

removing a guard interval from the transmitted OFDM symbol to obtain an effective symbol;

detecting two correlation peaks between the effective symbol and two known symbols having two different timings;

calculating a timing correction amount by including timing of the known symbol that has detected a first correlation peak, which is detected in a predetermined timing detection range that is shorter than an effective symbol length, of the two correlation peaks into a differential between the first correlation peak and reference timing of the base station;

transmitting the timing correction amount to the mobile station by means of a timing correction burst, and

in the mobile station,

correcting transmission timing in accordance with the timing correction amount; and

transmitting a communication channel assignment request to the base station at the corrected transmission timing.

10. The wireless communication method claimed in claim 2,

wherein a differential of the two timings is shorter than the effective symbol length.

11. The wireless communication method claimed in claim 2,

wherein one of the two timings is reference timing of the base station.

12. The wireless communication method claimed in claim 2,

wherein if a communication channel is not assigned from the base station despite that the mobile station transmits a communication channel assignment request to the base station, the method regenerates a channel to be frame synchronized with the notification channel and transmits an OFDM symbol to the base station and implement the peak detection processes of the base station again.

6. A wireless communication system comprising a mobile station and a base station, which conduct wireless communication by using an OFDM modulation scheme,

wherein the base station comprises:

a notification unit that notifies the mobile station of a notification channel;

a guard interval removing unit that removes a guard interval from an OFDM symbol transmitted from the mobile station through a channel generated by the personal channel at two different timings to obtain two effective symbols;

a timing detection unit that detects two correlation peaks between the two respective effective symbols and a known symbol; and

a correlation peak determination unit, which calculates a timing correction amount by including timing corresponding to a guard interval removed when generating the effective symbol that has exhibited a first correlation peak, which is detected within a predetermined timing detection range that is shorter than an effective symbol length, of the two correlation peaks into a difference between the first correlation peak and reference timing of the base station, and which transmits the timing correction amount to the mobile station by means of a timing correction burst, and

wherein the mobile station comprises;

a timing correction channel generation unit, which generates a channel to be frame synchronized with the notification channel, and which transmits a OFDM symbol to the base station;

a transmission timing correction unit that corrects transmission timing in accordance with the timing correction amount; and

a communication channel assignment request unit that transmits a communication channel assignment request to the base station at the corrected transmission timing.

7. A wireless communication system comprising a mobile station and a base station, which conduct wireless communication by using an OFDM modulation scheme,

wherein the base station comprises:

a notification unit that notifies the mobile station of a notification channel;

a guard interval removing unit that removes a guard interval from an OFDM symbol transmitted from the mobile station through a channel generated by the personal channel to obtain an effective symbol;

a timing detection unit that detects two correlation peaks between the effective symbol and two known symbols having two different timings; and

a correlation peak determination unit, which calculates a timing correction amount by including timing of the known symbol that has detected a first correlation peak, which is detected within a predetermined timing detection range that is shorter than an effective symbol length, of the two correlation peaks into a differential between the first correlation peak and reference timing of the base station, and which transmits the timing correction amount to the mobile station by means of a timing correction burst, and

wherein the mobile station comprises;

a timing correction channel generation unit, which generates a channel to be frame synchronized with the notification channel, and which transmits an OFDM symbol to the base station;

a transmission timing correction unit that corrects transmission timing in accordance with the timing correction amount; and

a communication channel assignment request unit that transmits a communication channel assignment request to the base station at the corrected transmission timing.

8. A base station that conducts wireless communication with a mobile station by using an OFDM modulation scheme, the base station comprising:

a notification unit that notifies the mobile station of a notification channel;

a guard interval removing unit that removes a guard interval from an OFDM symbol transmitted from the mobile station through a channel generated by the personal channel at two different timings to obtain two effective symbols;

a timing detection unit that detects two correlation peaks between the two respective effective symbols and a known symbol; and

a correlation peak determination unit, which calculates a timing correction amount by including timing corresponding to a guard interval removed when generating the effective symbol that has exhibited a first correlation peak, which is detected within a predetermined timing detection range that is shorter than an effective symbol length, of the two correlation peaks into a differential between the first correlation peak and reference timing of the base station, and which transmits the timing correction amount to the mobile station by means of a timing correction burst.

9. A base station that conducts wireless communication with a mobile station by using an OFDM modulation scheme, the base station comprising:

a notification unit that notifies the mobile station of a notification channel;

a guard interval removing unit that removes a guard interval from an OFDM symbol transmitted from the mobile station through a channel generated by the personal channel to obtain an effective symbol;

a timing detection unit that detects two correlation peaks between the effective symbol and two known symbols having two different timings; and

a correlation peak determination unit, which calculates a timing correction amount by including timing of the known symbol that has detected a first correlation peak, which is detected within a predetermined timing detection range that is shorter than an effective symbol length, of the two correlation peaks into a differential between the first correlation peak and reference timing of the base station, and which transmits the timing correction amount to the mobile station by means of a timing correction burst.