Near-far problem on hybrid direct-sequence/slow-frequency-hopping spread-spectrum multiple-access

This paper investigates the bit error rate (BER) performance of hybrid direct-sequence/slow-frequency-hopping spread-spectrum multiple-access (DS/SFH-SSMA) operating in the environment with the near-far problem. Rate 1/2 convolutional code of constraint length 7 is applied with an appropriate interleaver to increase the diversity effect not only on time domain but also on frequency domain. As a result, we found that the BER performance of DS/SFH system was always satisfactory in the presence of near-far problem. On the other hand, poor BER performance of the direct-sequence system is found regardless of E_b /N₀ or number of users