频分复用 (FDM)：
它是用于模拟系统的多路复用技术。在 FDM 中，需要 Guard band，FDM 的频谱效率低。在 FDM 中，带宽 (B) 用于不同的源。
正交频分复用 (OFDM)：
它也是模拟系统中使用的复用技术。在OFDM中，不需要保护频带，并且OFDM的频谱效率高，这与FDM相反。在 OFDM 中，单个数据源连接所有子信道。
让我们看看 FDM 和 OFDM 之间的区别：
| S.NO | FDM | OFDM |
|---|---|---|
| 1. | FDM stands for Frequency Division Multiplexing. | OFDM stands for Orthogonal Frequency Division Multiplexing. |
| 2. | In FDM, Guard band is required. | While in OFDM, Guard band is not compulsory. |
| 3. | The spectral efficiency of FDM is low. | While the spectral efficiency of OFDM is high. |
| 4. | The effect of interference in FDM is face down. | The effect of interference in OFDM is trivial. |
| 5. | There is no relationship exist between the carriers in FDM. | There is exist the relationship between the carriers in OFDM. |
| 6. | In FDM, Bandwidth(B) is committed to the different sources. | In OFDM, Single data source attaches all the sub-channels. |
| 7. | FDM supports low data rate. | While OFDM gives higher data rate. |
| 8. | Carriers in FDM are loosely arranged and much aside from each other | Carriers in OFDM are densely arranged and close to each other. |
| 9. | Applications of FDM are in radio and satellite communication. | Applications of OFDM are in LTE technologies and broadband internet. |