844 B
844 B
Channel access method for shared mediums
Time Division (TDMA)
assigns time-slots to each transmitter in which they are allowed to send. Dynamic slots can be used to adjust for variable bit-rate streams.
Frequency Division (FDMA)
assigns parts of the total bandwidth into multiple channels.
Code Division (CDMA)
Uses orthogonal codes assigned to transmitters, allowing them to send on the same time and frequency.
Both TDMA and FDMA need guard intervals that remain relatively fixed with rising numbers of participants. CDMA in comparison is directly limited by the Shannon-Hartley channel capacity, meaning that an increased noise floor introduced by an increasing number of transmitters results in temporarily decreased call quality, whereas other channel division methods would usually result in permanently decreased quality.