Difference Between FHSS and DSSS (With Table)

Technology and inventions are some of the core components that have made the world easier and, overall, faster year by year. In today’s world, people often come in confusion in the selection of connection. Spread Spectrum technology is one of the best communication methods.

FHSS and DSSS are types of technologies, types of spectrums really that make the connection between people and maintain it. The reason was why one would get confused between the two types of connection because their concept is the same, but their use of bringing that concept into practical ways is different.

FHSS vs DSSS

The difference between FHSS and DSSS is their different ways of transmitting the information into a wider bandwidth. Both the spread spectrums use different processes/technologies. FHSS uses the process of “hopping” while DSSS connects the signals through pseudo-noise.

FHSS is one of the two-spread spectrum technology, which is a form of radio transmission. It bounces or rather hops from frequency to frequency. That is the reason for its full name being Frequency Hopping Spread Spectrum. It is used in any Wireless Local Area Network, also known as LAWN.

DSSS is also a spread spectrum technology which uses the technique of “pseud noise” to send data signal from a place to another. It sends the signal into a wide bandwidth. In order to fulfill this, it breaks down the data, and afterward, a “chipping code” is generated. The chipping code should be longer to avoid any errors while transferring the data.

Comparison Table Between FHSS and DSSS

Parameters of ComparisonFHSSDSSS
AbbreviationFrequency-hopping spread spectrumDirect-sequence spread spectrum
Delivery capability the connection 3 Mbps 11 Mbps
Rate of Signal to Noise Ratio18 dB 12 dB
Advantages The bandwidth of this system is large. The system can be programmed to avoid parts of the spectrum, etc.It is simpler to hide the signal. It is less expensive than FHSS, etc.
Disadvantages Errors in the connection, Not much useful for great range, etc.A Wide-band channel is required, Needs a longer acquisition time period, etc.
Examples Bluetooth, Military use, etc.Wi-Fi, CDMA, etc.

What is FHSS?

FHSS is a type of spread spectrum, which is cleared by its full name Frequency-hopping spread spectrum. It has taken some time and various inventors to finally have the technology we use nowadays. It was called Secret Communication System earlier. It is very much based on a process called “Hopping,” where the connection “hops” from frequency to frequency.

There are two types of FHSS: Fast hopped FHSS and Slow hopped FHSS.

  1. Fast Hopped FHSS: The process of hopping gets concluded faster in comparison with the information bit rate.
  2. Slow Hopped DSSS: Hopping is done slower than the information bit rate.

The hopping may be random while catching the signal, but it is predictable. It is done to fulfill two aims, that are: Avoid interception and Reduce the interference between the signal. Mostly, it is seen that the rate of hopping from one channel to another is twice or more than twice in a second. If the transmission is in synchronization, the possibility of a stable channel is maintained.

What is DSSS?

DSSS is a popular telecommunication process. The full meaning of DSSS is Direct-sequence speed spectrum and is one of the most used technologies of the speed spectrum. Unlike like in FHSS technology, DSSS encodes the data into chips and not from hopping signal to signal. To be particular, it uses an 11-chip sequence.

PN sequence, which translates into Pseudorandom noise, is a big part of this process. It is also known as Pseudo-Random Binary Sequence (PRBS). They are the main source of spreading the information or the data from the sending end to the receiving end.

It can also be used in those areas where the frequency of radio signal is found low, but the downfall can be that it would be costly. Aside from this advantage, DSSS provides higher throughput in the bandwidth and greater length of range than FHSS.

Main Differences Between FHSS and DSSS

  1. The process of decoding is easier in FHSS in comparison with DSSS. A particular algorithm is needed in DSSS to establish the connection between the sender and the receiver.
  2. Though there are errors in both of the technologies, It is seen that the rate of errors is more in FHSS than in the DSSS system. The bandwidth of the FHSS system drops every time any device gets close to a blocked frequency while hopping from channel to channel.
  3. DSSS is comparatively more reliable than the system of FHSS. The rate of reliability in applications is lower in FHSS. But for especially for mobile use and applications, FHSS is more power-efficient.
  4. The acquisition time, that is, the time it takes to change an analog signal into a digital one, is more in DSSS systems than in FHSS systems.
  5. DSSS is rather more expensive than FHSS. At a lower Mbps, like 2 Mbps, FHSS would be less costly, but generally, radio signals are used at higher Mbps, DSSS would be less expensive than FHSS.

Conclusion 

Today, communication is done pretty much via electronic devices. It is as important as traditional communicating of one-to-one. FHSS and DSSS are both spread spectrum technology. They have come a long way from being used in military service to now, being wireless and used by general civilians.

But with these newer versions and inventions, the chance of getting the information hacked by people or disturbing or destroying the signals by viruses increases as well. Now, The more secure the connection, the more chance of people using that particular connection. People should know the information, the advantages, and disadvantages while choosing which system is needed for them which would provide them with the best results.

References

  1. https://ieeexplore.ieee.org/abstract/document/504932
  2. https://www.sciencedirect.com/science/article/abs/pii/S1874490717300447
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