OFDM vs Frequency Hoping spread spectrum

In summary, OFDM (Orthogonal Frequency Division Multiplexing) and frequency hopping spread spectrum are two techniques used for encoding digital data. OFDM offers higher data rates, better spectral efficiency, and more robustness against interference compared to frequency hopping spread spectrum. However, frequency hopping spread spectrum is often used in applications where security and resistance to jamming are critical. It is possible to combine both techniques for even better performance, but there may be limitations such as synchronization errors for OFDM and vulnerability to interception for frequency hopping spread spectrum.
  • #1
dervast
133
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Hi i am not surew i have well understand some issues about modulation schemes. I have read that the 802.16 use ofdm modulation and FHSS technique. Can someone explain what's the difference between OFDM and FHSS and how these two things cooperate?
 
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  • #2
ODFM is how data is encoded on the carrier.
FHSS is a chanel switching algorithim.
 
  • #3


OFDM (Orthogonal Frequency Division Multiplexing) and FHSS (Frequency Hopping Spread Spectrum) are two different modulation schemes used in wireless communication systems. While both are used in the IEEE 802.16 standard, they serve different purposes and have distinct characteristics.

OFDM is a multi-carrier modulation technique that divides the available bandwidth into multiple subcarriers, each carrying a small portion of the total data. These subcarriers are orthogonal to each other, meaning they do not interfere with each other. This allows for efficient use of the available bandwidth and improves the overall system capacity. OFDM is used in Wi-Fi, 4G LTE, and other high-speed wireless communication systems.

On the other hand, FHSS is a spread spectrum technique that spreads the signal over a wide frequency band by rapidly hopping between different frequencies. This makes the signal more resistant to interference and jamming. FHSS is commonly used in military and government communication systems, as well as in Bluetooth and some wireless LANs.

In the IEEE 802.16 standard, OFDM is used for the physical layer (PHY) and FHSS is used for the medium access control (MAC) layer. This means that OFDM is responsible for transmitting the data, while FHSS is responsible for managing access to the shared communication medium.

In summary, the main difference between OFDM and FHSS is that OFDM is a modulation technique that divides the available bandwidth into multiple subcarriers, while FHSS is a spread spectrum technique that spreads the signal over a wide frequency band. In the 802.16 standard, OFDM and FHSS work together to provide efficient data transmission and ensure secure and reliable communication.
 

What is OFDM and frequency hopping spread spectrum?

OFDM (Orthogonal Frequency Division Multiplexing) is a method of encoding digital data on multiple carrier frequencies to increase bandwidth efficiency. Frequency hopping spread spectrum (FHSS) is a technique where the carrier frequency is rapidly changed according to a pseudo-random sequence.

What are the advantages of OFDM over frequency hopping spread spectrum?

OFDM offers higher data rates, better spectral efficiency, and more robustness against interference compared to frequency hopping spread spectrum. It also allows for easier implementation and lower complexity in hardware.

When would you recommend using frequency hopping spread spectrum over OFDM?

Frequency hopping spread spectrum is typically used in applications where security and resistance to jamming are critical, such as military communication systems. It is also suitable for applications with low data rates and the need for longer transmission range.

Can OFDM and frequency hopping spread spectrum be used together?

Yes, it is possible to combine OFDM and frequency hopping spread spectrum in a hybrid approach. This can provide the benefits of both techniques, such as high data rates and robustness against interference and jamming.

Are there any potential drawbacks or limitations of OFDM and frequency hopping spread spectrum?

One limitation of OFDM is its sensitivity to synchronization errors, which can lead to performance degradation. Frequency hopping spread spectrum may also be vulnerable to interception and decoding by advanced signal processing techniques.

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