A method of digital wireless transmission that allows a large number of users to share access to a single radio channel by assigning unique code sequences to each user.
A spread spectrum access technology that assigns a code to each multiple access stream of data bits, transmits the spread data streams, and then, at the receiver, despreads and reassembles the data streams to their original format.
CDMA separates communications by code. Voice is broken into digitised bits, and groups of bits are tagged with a code. Each code is associated with a single call in the network. Groups of bits from one call are randomly transmitted along with those of other calls. Then they are reassembled in the correct order to complete the conversation.
A method whereby many radios use the same frequency
In a CDMA system, each voice circuit is labeled with a unique code and transmitted on a single-channel simultaneously with many other coded voice circuits. This allows for greater bandwidth.
See CDMA (Code Division Multiple Access).
CDMA is a generic term that describes a wireless air interface based on code division multiple access technology. cdmaOne(tm) is a brand name, trademarked and reserved for the exclusive use of CDG member companies, that describes a complete wireless system that incorporates the interim standard (IS)–95 CDMA air interface, the American National Standards Institute (ANSI)–41 network standard for switch interconnection, and many other standards that make up a complete wireless system. CDMA2000 is a name identifying the 3G technology that is an evolutionary outgrowth of cdmaOne offering operators that have deployed a 2G cdmaOne system—a seamless migration path that economically supports an upgrade to 3G features and services within existing spectrum allocations for both cellular and personal communications system (PCS) operators. CDMA2000 supports the 2G network aspect of all existing operators regardless of technology (cdmaOne, IS–136 TDMA, or GSM). This standard is also known by its International Telecommunication Union (ITU) name International Mobile Telecommunications (IMT)–CDMA Multi-Carrier (1X/3X).
A digital wireless technology that uses a "spread spectrum" technique to scatter a radio signal across a wide range of frequencies. CDMA provides greater total capacity than other technologies, along with outstanding voice quality and fewer dropped calls. CDMA is the technology of choice for new third-generation systems.
CDMA is a coding scheme used as an access method that can enable carriers from different stations to use the same transmission equipment by employing a wider bandwidth than individual carriers.
A spread-spectrum digital cellular radio system in which different codes are used to distinguish sources.
2G and 2.5G- A digital cellular phone service that offers up to 20 times more call-handling capacity than conventional cellular systems by assigning a special electronic code to each signal, allowing more calls to occupy the same space and be spread over an entire frequency band. Developed by Qualcomm, Incl, which promotes CDMA as an alternative to Time Division Multiple Access technology.
A technique used to increase channel capacity which is associated with spread-spectrum systems. Typically each user is given a different pseudo-random spreading code. To communicate with a particular user, the sender must select the code assigned to that user. This technique can permit many users to operate simultaneously on the same frequency.
A spread spectrum technique to share bandwidth among a set of users.
Defines how a single channel can be allocated to support multiple users simultaneously so that all mobile users transmit on the same frequency with different pseudo-random signals. Originally developed to support voice. One of two digital cellular standards in the US.
CDMA technology exploits the orthogonality property of certain families of PN codes in order to increase channel capacity. Typically, each user is given a unique spreading code. To communicate with a particular user, the sender must use the same code assigned to that user. This technique permits many users to operate simultaneously over the same frequency band. Gold codes and Walsh codes are often used in CDMA systems.
A method for transmitting many simultaneous signals over a shared portion of the spectrum. GPS uses CDMA techniques with codes for their unique cross-correlation properties. The foremost application of CDMA is the digital cellular phone technology that operates in the 800MHz and 1.9GHz (PCS) bands. CDMA phones are noted for their excellent call quality and long battery life, and some phones can switch between both bands. CDMA is less costly to implement, requiring fewer cell sites than the GSM and TDMA digital cellphone systems and providing three to five times the calling capacity. It provides more than 10 times the capacity of the analog cellphone system (AMPS). CDMA has become widely used in North America and is also expected to become the third-generation (3G) technology used in the GSM system.
One method the digital technologies use for wireless phone service. CDMA encodes each call as a coded sequence across the entire frequency spectrum. Each conversation is modulated, in the digital domain, with a unique code that makes it distinguishable from the other calls in the frequency spectrum.
This technology converts analogue signals into digital which are then transmitted over a network. CDMA enables multiple phone calls to be carried on the same frequency by using a voice-coding system. For more information see How cell phones work – cellular access technologies (How Stuff Works, USA).
A multiple access scheme that uses Direct Sequence Spread Spectrum ( DSSS) code sequences as traffic channels in a common radio channel.
(CDMA) Method of combining multiple users on a given channel bandwidth using unique spreading codes, or hopping patterns to distinguish and given user.
A technique for spread-spectrum multiple access digital communication that creates channels through the use of noise-like carrier waves.
A spread-spectrum digital cellular radio system that used different codes to distinguish users.
CDMA A technology for digital transmission of radio signals between, for example, a mobile telephone and a radio base station, dividing a frequency into several codes.
A type of air interface which describes a technique of adding signal carrying capacity to a given bandwidth by allowing multiple signals to occupy the same frequency at the same time, and assigning each one the unique “ address” of the intended receiver. It is also used to describe a form of direct sequence spread spectrum.
An air interface technology that was developed by the U.S. military and commercialized by the U.S. company Qualcomm. CDMA assigns a code to all speech bits, sends a scrambled transmission of the encoded speech over the air and reassembles the speech to its original form at the other end. CDMA supports SMS with a message length of 120 characters. With CDMA, each conversation is digitized and then tagged with a code. The mobile phone receives a signal to locate that particular code and it then deciphers the conversation off the airwaves. It codes each conversation expanding it 128 times, making it easy to decipher at the receiving end.
A digital transmission technique in which a base station assigns a unique code to each mobile device to distinguish that particular device from all others on the air. The signals are encoded using the code that the receiver also knows and uses to decode the received signal. CDMA is one of several spread spectrum techniques.
Code division multiple access (CDMA) is a form of multiplexing (not a modulation scheme) and a method of multiple access that does not divide up the channel by time (as in time division multiple access), or frequency (as in frequency-division multiple access), but instead encodes data with a special code(PN sequences for reverse and Walsh codes for forward channnel) associated with each channel and uses the constructive interference properties of the special codes to perform the multiplexing. CDMA also refers to digital cellular telephony systems that make use of this multiple access scheme, such as those pioneered by Qualcomm, and W-CDMA by the International Telecommunication Union or ITU.