MMFSK-EOD System Using Binary Hopping Patterns

摘要

In power-line communications reduction of the radiation power is becoming one of the most important problems. In our previous paper, advantage of the spread spectrum system over OFDM system in the radiation power was shown. In this paper, to reduce the radiation power further, improving methods of error performances of the MMFSK-EOD system (MMFSK system using even odd discrimination method) have been studied. In our old MMFSK-EOD system we specify even- odd patterns (EO patterns) only for Group A hopping patterns. However, when we use a hopping pattern in which even numbers and odd numbers are chosen freely, errors arisen in the first demodulation stage, which select the transmitted A hopping pattern out of group A hopping patterns, influence the second demodulation stage operation and deteriorate the error probability characteristics of the system considerably. To improve the error performance of the system, in this paper use of a new category hopping patterns named binary hopping patterns is proposed. Binary hopping patterns are defined as a hopping pattern group in which E and O represent one of specified neighboring level values. In the second demodulation stage, majority decision logic is used to determine the transmitted hopping pattern B{sub}j and the level L{sub}h. When binary hopping patterns are used, errors arisen from the first demodulation stage can be removed through the majority decision logic, as a result, the error probability characteristics of the system can be considerably improved. In this paper, principle of the improving effect of the binary hopping pattern system is presented, and, to verify the effectiveness the system a result of computer simulation is shown. Some other additional results of studies to improve the error performance of the MMFSK-EOD systems are shown also.