Study on the Pattern of Slow Frequency Hopping Based on TDMA Time Slot
|School||Harbin Institute of Technology|
|Course||Information and Communication Engineering|
|Keywords||slow frequency hopping based on TDMA time slot sequence capacity trunking system TDMA|
Trunking system is developing rapidly in China recent years. iDEN system, TETRA system have been built in some cities, but high cost and low utilization ratio of frequency spectrum cause these system can only be used in few developed cities. In order to cover the extensive under developed area, it is necessary to design a trunking system which has the characteristic of lower cost and higher spectrum efficiency. According to the DMR standard we propose a new method to use slow frequency hopping channel based on TDMA time slot.Firstly, the article introduces the traditional design methods of frequency hopping sequences, and discusses the measurement and theoretical limits. According to the simulation of the m sequences and RS code sequences, it shows that the two sequences have excellent uniformity in frequency domain, greater frequency hopping gap and excellent performance of Hamming correlation.Secondly, it researches the design methods for counting type frequency hopping sequences. Prompted by the composition of the Bluetooth sequences generation, the idea of time counting method to build a new sequence as an innovation. The new sequences use ADD, XOR, and look-up table to facilitate hardware implementation. Simulation results based on these sequences shows that the new sequences has the satisfied uniformity in the frequency domain, large frequency hopping gap and good Hamming correlation characteristics, which all meet the design requirements.Finally, the article explores the subscriber capacity improvement by frequency hopping in trunking system. It discusses system capacity calculating method of slow frequency hopping based on TDMA time slot. It is believed that slow frequency hopping based on TDMA time slot has practical value in digital trunking system design, especially in capacity improvement and anti-interference.