FDMA，TDMA和CDMA之间的区别

1.频分多址(FDMA)：
FDMA是一种信道化协议。在此带宽被划分为各个频带。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，具体如下：

图– FDMA

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。在分配的频带中创建信号，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，信道的带宽在时间的基础上被划分为多个站。每个站都有一个时隙，该站只能在该时隙内发送数据，如下所示：

图– TDMA

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。

3.码分多址(CDMA)：
在CDMA中，所有站都可以同时发送数据。它允许每个站点始终在整个频率上传输数据。多个同时传输被唯一的代码序列分隔。每个用户都分配有唯一的代码序列。

图– TDMA

在上图中，有4个标记为1、2、3和4的站。分配给各个站的数据分别为d ₁ ，d ₂ ，d ₃和d ₄ ，分配给各个站的代码为c ₁ ，c ₂ ， c ₃和c ₄ 。

FDMA，CDMA和TDMA之间的区别：

FDMA	TDMA	CDMA
FDMA stands for Frequency Division Multiple Access.	TDMA stands for Time Division Multiple Access.	CDMA stands for Code Division Multiple Access.
In this, sharing of bandwidth among different stations takes place.	In this, only the sharing of time of satellite transponder takes place.	In this, there is sharing of both i.e. bandwidth and time among different stations takes place.
There is no need of any codeword.	There is no need of any codeword.	Codeword is necessary.
In this, there is only need of guard bands between the adjacent channels are necessary.	In this, guard time of the adjacent slots are necessary.	In this, both guard bands and guard time are necessary.
Synchronization is not required.	Synchronization is required.	Synchronization is not required.
The rate of data is low.	The rate of data is medium.	The rate of data is high.
Mode of data transfer is continuous signal.	Mode of data transfer is signal in burts.	Mode of data transfer is digital signal.
It is little flexible.	It is moderate flexible.	It is highly flexible.