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Compare SDMA, TDMA, FDMA, CDMA techniques.
1 Answer
written 3.5 years ago by |
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 |