CDMA is a digital cellular phone technology that uses spread-spectrum wireless networking technologies. Code Division Multiple Access CDMA can be used to refer both to a type of digital cellular phone system and to the specific media access method used by this kind of cellular system.
CDMA uses the spread spectrum wireless networking technology—first developed for military communication systems in the s because it spreads its transmission over a large bandwidth, making it difficult to jam. The spread spectrum approach assigns a special digital code sequence to each user, and all users share the same broad portion of the radio frequency spectrum.
The capacity of a microcell is 1. The combined microcell and macrocell have a capacity of 2. The RF dependability, soft hand-off factors, interference, and power levels of cells are also examined. The RF dependability of macrocells will deteriorate faster than that of microcells.
Microcell engineering guidelines are also offered for a commercial CDMA system. Findings suggest that integrating the microcell in an existing CDMA network might be an effective method to boost hot-spot and dead-spot coverage. Satellites transmit at two frequencies at the same time, however owing to PRN code modulation, their signals do not conflict appreciably.
The satellite signals may be isolated and identified using the CDMA approach since each satellite is issued a unique PRN code and all PRN code sequences are substantially uncorrelated with one another. A GPS receiver must repeat the PRN sequence for the chosen satellite together with the replica carrier signal to monitor one satellite in common view with multiple other satellites using the CDMA method. Because the ionospheric delay is connected by a scale factor to the difference in signal time of arrival TOA for the low carrier frequencies, two carrier frequencies are given to allow the two frequency users to monitor it.
Users of a single frequency L1 must estimate the ionospheric delay using modeling parameters sent to them in a navigation message. Each piconet has its unique pattern of spreading. To allow many users to be multiplexed over the same physical channel, CDMA uses spread-spectrum technology and a specific coding system where each transmitter is allocated a code.
Data and speech packets are segregated using codes and then sent across a wide frequency range with CDMA technology. Spread-spectrum wireless networking is used by CDMA. It can refer to a specific media access technique utilized by this sort of cellular system as well as a form of the digital cellular phone system.
CDMA combines voice and data into a single digital transmission at 9. With the revolution in cellular telecommunications that occurred in the s a then little know company named Qualcomm working on DSSS transmissions started to look at this as the basis for a cellular telecommunications multiple access scheme - CDMA - code division multiple access. As a result this it was possible to start writing a specification for CDMA in This was only one cellular telecommunications system, although it was the first.
Its development lead on to the CDMA series of standards. CDMA is a form of spread spectrum transmission technology based around a scheme called direct sequence spread spectrum. Direct sequence spread spectrum, DSSS is a form of radio transmission used in a variety of radio transmissions.
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