Space Division Multiple Access Frequency Hopping Communication System

Since 90's in the 20th century, array signal processing has been introduced to mobile communications, which brought SDMA(Space Division Multiple Access) technique. With the SDMA technique, the capacity of present communication system can be greatly improved, and the anti-interference capability of present communication system can be also improved since SDMA makes it possible to antagonize spacial interference. The SDMA technique has great potential to be applied in the future civilian or military mobile communication system.Frequency-hopping communication is a kind of spectrum spread communication. In frequency-hopping, a Pseudo Noise (PN) code is used to control frequency synthesizer, which makes the carrier frequency of transmitted signal hop in certain way and spreads the spectrum of transmitted signal in order to improve the anti-interference capability. Frequency-hopping communication has been widely used in tactical wireless communications.This paper researches SDMA application in frequency-hopping communication system.It needs beam-forming which is supported by array signal processing to realize SDMA. In point of data dependency, beam-forming can be classified to data independent beam-forming, optimal beam-forming and adaptive beam-forming. For frequency-hopping communication system, beam-forming can be performed after the dehopping. In order to adopt digital signal processing, base-band signal is first picked up from the dehopped signal with intermediate frequency, then used to beam-forming which is implemented in base-band.For frequency-hopping communication system with SDMA beam-forming, frequency-hopping will affect beam-forming. To decrease the effect on SDMA beam-forming by frequency-hopping, phase pre-complementation can be employed for data independent beam-forming, and memories can be added to save or restore adaptive beam-forming weights respectively on each hopped frequency for adaptive beam-forming.A simulation platform for SDMA technique application in frequency-hopping communication system is proposed in this paper, and some related simulations have been carried out in the platform. Simulation results indicate that the capability of anti-interference of system can be improved more efficiently when SDMA technique is applied in frequency-hopping communication system.