| A BER Performance of Analysis and Comparison for Ultra-Narrowband Digital Radio System |
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Young-Jun Chong1, Min-Soo Kang2, Sung-Jin You2, Dong-Min Lim3, Seung-Hyeub Oh4 |
1Radio Technology Group, ETRI
2Radio Technology Group, ETR
3Dept. of Electronic Engineering, Gyeongsang Universit
4Dept. of Electronics Engineering, Chungnam University |
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| Abstract |
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In this paper, we evaluate the performance of the digital modulation schemes described in the APCO Project 25 FDMA specifications which can be used for applying the ultra-narrowband technology to the current domestic simple two-way radio systems, and discuss difficulties in the DSP implementation of the systems. We analyze the effect on the systems' BER performance of receiver non-matched filter and frequency-offset between the transmitter and receiver oscillators. And we present a frequency offset compensation method for improving the system performance. The results of performance analysis showed that the CQPSK of APCO Project 25 using non-matched filter degraded the BER by 0.5～1.0 ㏈ comparing with PI/4 DQPSK using matched filter. In the event of 2 % frequency offset, about 1 ㏈ performance loss was produced at the BER of $$10^{-3}TEX>. With the frequency-offset compensation method implemented in the systems using phase recovery scheme of PSK synchronization detection, the performance degradation of about 1.0 ㏈ was occurred at the BER of $$10^{-3}TEX> for 10 % of frequency offset. The proposed method can be used for the improvement of system performance. |
| Key words:
Ultra-Narrowband Modulation, CQPSK, DQPSK, Frequency Offset Compensation |
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