1.频分多址(FDMA):
FDMA是一种信道化协议,其中带宽被划分为各种频带。每个站点都分配有频段来发送数据,并且该频段一直为特定站点保留,如下所示:
不同站点的频带被未使用的频率的小频带分隔开,未使用的频带被称为防止站点干扰的保护频带。就像数据链路层中的访问方法一样,其中每个站的数据链路层告诉其物理层从传递给它的数据中获取带通信号。该信号在分配的频带中创建,并且在物理层没有物理多路复用器。
2.时分多址(TDMA):
TDMA是信道化协议,其中,信道的带宽在时间上被划分为多个站。每个站点都有一个时隙,站点只能在该时隙内发送数据,如下所示:
每个站必须知道其时隙的开始和时隙的位置。 TDMA需要不同站之间的同步。它是数据链路层中访问方法的类型。在每个站点,数据链路层告诉站点使用分配的时隙。
FDMA和TDMA之间的区别:
Sr. No. | FDMA | TDMA |
---|---|---|
1. | FDMA stands for Frequency Division Multiple Access. | TDMA stands for Time Division Multiple Access. |
2. | Overall bandwidth is shared among number of stations. | Time sharing of satellite transponder takes place. |
3. | Guard bands between adjacent channels is necessary. | Guard time between adjacent slots is necessary. |
4. | Synchronization is not required. | Synchronization is necessary. |
5. | Power efficiency is less. | Power efficiency is high. |
6. | It requires stability of high carrier efficiency. | It does not require stability of high carrier efficiency. |
7. | It is basically used in GSM and PDC. | It is basically used in advanced mobile phone systems. |