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Compare SDMA, TDMA, FDMA, CDMA techniques.

written 4.5 years ago by teamques10 ★ 70k

modified 4.0 years ago by binitamayekar ★ 6.7k

mobile communication wireless networks

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written 4.5 years ago by teamques10 ★ 70k

Approach	SDMA	TDMA	FDMA	CDMA
Idea	Space is segmented into  cells or sectors.	Sending time is segmented into time slots either demand fdriven or fixed patterns.	Frequency band is segmented into subbands.	Spectrum is spread by orthogonal codes.
Terminals	Only one terminal can be active in one cell or one sector.	All terminals are active for a small period of time on same frequency.	Every terminal has its own frequency uninterrupted.	All terminals can be active at the same place and same time uninterrupted.
Signal Separation	Cell structure, directed antennas	Synchronization in the time domain	Fitering in the frequency domain	Code plus special recievers
Transmission Scheme	Continuous	Discontinuous	Continuous	Continuous
Cell capacity	Depends on cell area	Limited	Limited	Interference limited system
Advantages	simple, increases capacity	flexible, fully digital	simple, robust	flexible, soft handover
Disadvantages	inflexible, antennas are fixed	Guard sppace needed, syynchronization is difficult	inflexible	complex recievers
Comment	Used only with TDMA, CDMA and FDMA	used with SDMA and FDMA	used with TDMA and SDMA	used with TDMA and FDMA

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