Search results
Results From The WOW.Com Content Network
CDMA is a spread-spectrum multiple-access technique. A spread-spectrum technique spreads the bandwidth of the data uniformly for the same transmitted power. A spreading code is a pseudo-random code in the time domain that has a narrow ambiguity function in the frequency domain, unlike other narrow pulse codes. In CDMA a locally generated code ...
In telecommunications, especially radio communication, spread spectrum are techniques by which a signal (e.g., an electrical, electromagnetic, or acoustic) generated with a particular bandwidth is deliberately spread in the frequency domain over a wider frequency band. Spread-spectrum techniques are used for the establishment of secure ...
Chip (CDMA) In digital communications, a chip is a pulse of a direct-sequence spread spectrum (DSSS) code, such as a pseudo-random noise (PN) code sequence used in direct-sequence code-division multiple access (CDMA) channel access techniques. In a binary direct-sequence system, each chip is typically a rectangular pulse of +1 or −1 amplitude ...
e. Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many frequencies occupying a large spectral band. The changes are controlled by a code known to both transmitter and receiver. FHSS is used to avoid interference, to prevent eavesdropping, and to enable code ...
In telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. After the despreading or removal of the direct-sequence modulation in the ...
Multi-carrier code-division multiple access (MC-CDMA) is a multiple access scheme used in OFDM -based telecommunication systems, allowing the system to support multiple users at the same time over same frequency band. MC-CDMA spreads each user symbol in the frequency domain. That is, each user symbol is carried over multiple parallel ...
Code-division multiplexing (CDM), code-division multiple access (CDMA) or spread spectrum is a class of techniques where several channels simultaneously share the same frequency spectrum, and this spectral bandwidth is much higher than the bit rate or symbol rate. One form is frequency hopping, another is direct sequence spread spectrum.
CDMA spectral efficiency refers to the system spectral efficiency in bit/s/Hz/site or Erlang /MHz/site that can be achieved in a certain CDMA based wireless communication system. CDMA techniques (also known as spread spectrum) are characterized by a very low link spectral efficiency in (bit/s)/Hz as compared to non-spread spectrum systems, but ...