Apparatus and method for digital wireless communications

• US 6,748,023 B2
• Filed: 05/02/2003
• Issued: 06/08/2004
• Est. Priority Date: 01/19/1999
• Status: Expired due to Term

• Current Assignee: Sun Patent Trust
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Murakami, Yutaka, Takabayashi, Shinichiro, Orihashi, Masayuki, Matsuoka, Akihiko
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): WILLIAMS, LAWRENCE B
• Application Number:
  US10/427,992
• Publication Number:
  US 20030194020A1
• Time in Patent Office: 403 Days
• Field of Search: 375/130-150, 375/152, 375/261, 370/335, 370/342, 370/503, 455/522-574
• US Class Current: 375/298
• CPC Class Codes: H04L 2027/0024 at the receiver end
• CPC Class Codes: H04L 2027/0087 Out-of-band signals, (e.g. pilots)
• CPC Class Codes: H04L 2027/0093 Intermittant signals
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/206 using a pair of orthogonal carriers, e.g. quadrature carriers
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
• CPC Class Codes: H04L 27/3455 in order to facilitate carrier recovery at the receiver end, e.g. by transmitting a pilot or by using additional signal points to allow the detection of rotations
• CPC Class Codes: H04L 7/04 Speed or phase control by synchronisation signals H04L7/0075 takes precedence
• CPC Class Codes: H04L 7/06 the synchronisation signals differing from the information signals in amplitude, polarity or frequency or length

Abstract

In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Claims

1. A digital wireless communication apparatus comprising:

a first modulator that modulates a pilot symbol according to a first modulation scheme;

a second modulator that modulates specific symbols according to a second modulation scheme, which is different from said first modulation scheme;

a third modulator that modulates symbols other than said pilot symbol and said specific symbols according to a third modulation scheme, which is different from said first and second modulation schemes; and

a timing controller that controls the timing such that said specific symbols are inserted immediately before and after said pilot symbol.

2. The digital wireless communication apparatus according to claim 1, wherein said third modulation scheme is selected from a group of 64QAM modulation scheme, 16QAM modulation scheme, and QPSK modulation scheme.

3. The digital wireless communication apparatus according to claim 1, wherein said pilot symbol signal point has an amplitude greater than the maximum amplitude at signal points modulated according to the third modulation scheme in a signal space diagram.

4. A digital wireless communication method comprising:

the first modulating step of modulating a pilot symbol according to a first modulation scheme;

the second modulating step of modulating specific symbols according to a second modulation scheme, which is different from said first modulation scheme;

the third modulating step of modulating symbols other than said pilot symbol and said specific symbols according to a third modulation scheme, which is different from said first and second modulation schemes; and

the timing controlling step of controlling the timing such that said specific symbols are inserted immediately before and after said pilot symbol.

5. The digital wireless communication method according to claim 4, wherein said third modulation scheme is a modulation scheme selected from a group of 64QAM modulation scheme, 16QAM modulation scheme, and QPSK modulation scheme.

6. The digital wireless communication method according to claim 4, wherein said pilot symbol signal point has an amplitude greater than the maximum amplitude at signal points modulated according to the third modulation scheme in a signal space diagram.