1. 频分多址(FDMA):
FDMA 是信道化协议,其中带宽被划分为各种频段。每个站都分配有频带来发送数据,该频带始终为特定站保留,如下所示:
不同站点的频段之间被一小段未使用频率的频带分隔开来,未使用的频带称为保护频带,以防止站点干扰。这就像数据链路层中的访问方法,其中每个站点的数据链路层告诉其物理层将传递给它的数据制成带通信号。信号是在分配的频带中创建的,物理层没有物理复用器。
2. 时分多址(TDMA):
TDMA 是信道化协议,其中信道带宽按时间划分到各个站点。每个站点都有一个时隙,站点只能在该时隙内传输数据,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。它是数据链路层中的一种访问方法。在每个站数据链路层告诉站使用分配的时隙。
FDMA和TDMA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. |