Time spread modulation system for digital land mobile radio communication

✍ Scribed by Hideichi Sasaoka; Eiji Kato

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 943 KB
• Volume: 76
• Category: Article
• ISSN: 8756-6621
• DOI: 10.1002/ecja.4410760506

✦ Synopsis

This paper proposes an improvement of the timespread modulationldemodulation system in land mobile radio communications. The following elaborations are employed in the proposed system. The quadrature modulation with fading compensation is employed to improve the spectral efficiency. The interleaving is employed toenhance the time-spreading effect. The maximumlikelihood estimation is employed to improve the error rate.

To demonstrate the usefulness of the proposed method, the bit-error rate is examined by computer simulation. It is seen as a result for the four-symbol time-spread that Eb/No is approximately 12 dB and 18 dB for the bit-error rate (BER) of lo-* and lo-', respectively. The foregoing performance is better compared to the theoretical performance for the absolute phase coherent detection QSK, with Eb/No being better by 2.5 dB for BER = lo-'. It is Seen also that the performance is improved by increasing the number of timespread symbols to 6 and 8. The proposed system also is compared to the case of the Reed-Solomon code applied to the multivalued QAM modulation system. The difference of performances is discussed from the theoretical viewpoint.