Spread Spectrum Transmission Comparison
Introduction to Spread Spectrum Transmission
Guidelines
• What is it? Spread spectrum is a form of wireless communications in which the frequency of the transmitted signal is deliberately varied.
• Why is it important? Spread-spectrum transmission is more resistant to outside interference.
• What issues are addressed? Spread-spectrum transmission can send more bits at one time than a similar narrowband transmission.
• How does it work? RF signals that are transmitted on more than one frequency are important in order to communicate and keep things going without being limited to one station or frequency.

Frequency Hopping Spread Spectrum (FHSS)
Guidelines
• What is it? It is one of two basic modulation techniques used in spread spectrum signal transmission.
• How does it work? It works by using a short burst is transmitted at one frequency, followed by a short burst transmitted at another frequency, and so on, until the entire transmission is completed.
• What issues are addressed? If interference detected on any one frequency it can skip that signal and move on to another completing the transmission.
• Why is it important? It maintains a better signal.

Direct Sequence Spread Spectrum (DSSS)
Guidelines
• What is it? It is a wireless modulation technique that uses an expanded redundant code to transmit each data bit.
• How does it work? It uses an expanded redundant code to transmit each data bit where each bit is converted to a series of bits before being transmitted.
• What issues are addressed? Interference and error correction are addressed along with shared frequency bandwidth and Security.
• Why is it important? A different sequence of bits is inserted. This is known as the chipping code.

Comparison between FHSS and DSSS
Technique Advantages Disadvantages
FHSS less prone to interference; have the potential for a higher number of colocation units; transmits a short burst on one frequency that is typically only 1 MHz Works better in large areas of coverage multiple collocated cells, noises & interference, multipath, and Bluetooth
DSSS Error correction; Less interference on other systems; Shared frequency bandwidth and Security System collocation, Multipath effects, and Bluetooth