Spread spectrum ss and multicarrier modulation mcm techniques are recognized as potential candidates for the design of underlay and interweave cognitive radio cr systems, respectively. Mc ds cdma employs a high number of degreesoffreedom, which are beneficial to design and reconfiguration for communications in dynamic communications environments, such as in the cognitive radios. Each user is assigned with one its own spreading code. Therefor, mccdma is sometimes also called cdmaofdm. Abstract multicarrier code division multiple access mccdma technique which. A very promissing multiple access scheme for future. Redundant residue number system assisted multicarrier direct. Blind softdetection assisted frequencyhopping multicarrier. Mccdma is a form of cdma or spread spectrum, but we apply the spreading in the frequency domain rather than in the time domain as in direct sequence. The above transmitter can also be implemented as a direct sequence cdma transmitter, i. A novel interleaving scheme for mc cdma system is proposed in this paper. Mccdma is based on a serial concatenation of direct sequence ds spreading. Multicarrier spread spectrum modulation schemes and efficient. Carrier interferometry ci provides wideband transmission protocols with frequencyband selectivity to improve interference rejection, reduce multipath fading, and enable operati.
Statistical approach to the code acquisition problem in directsequence spreadspectrum communication systems. In the first technique, called direct sequence ds cdma, each user transmits a digital data bit by transmitting a sequence of digital symbols of much smaller duration, called. That is, each user symbol is carried over multiple parallel subcarriers, but it is phase shifted typically 0 or 180. We verify by direct substitution that is an circulant matrix with th entry given by. Wcdma uses direct spread ds as forward link rf channel structure, while cdma uses ds or multicarrier. Cdma aims at combining the bandwidth efficiency and long symbol duration inherent in mcm and the interference rejection capabilities inherent in ds. That is, each user symbol is carried over multiple parallel subcarriers, but it is phaseshifted typically 0 or 180. Performance analysis of data transmission in mccdma radio. As argued in 1, in generalized mc dscdma, the spacing between two adjacent subcarriers is a.
In direct sequence spread spectrum transmission, the user data signal is multiplied by a code sequence. In comparison with the pure dscdma using only time t domain spreading and pure mccdma using only f domain spreading, it has been demonstrated that the multicarrier direct sequence cdma mc dscdma has the highest flexibility 5, 15 and the data tb symbol duration ts qtb b1k l e l l ra r ap trebk ev 2 lto n ira co e s bqk. Performance analysis of multicarrier dscdma with antenna. A software solution for chip rate processing in cdma. Vandendorpe, multitone direct sequence cdma system in an indoor wireless environment, proc. However, the new code sequence is the discrete fourier transform of a binary, say, walsh hadamard code sequence, so it has complex values. Furthermore in this thesis, software simulations were carried to investigate the performance of a direct sequence ds cdma system in a flatfading rayleigh channel, and a multicarrier mc cdma system in a frequencyselective channel using different sets of gold. Comparison of direct sequence and multicarrier cdma. Powercontrolled multicarrier and multiuser detection. Direct sequence ds direct sequence code division multiple access ds cdma is a technique to multiplex users by different codes. Carrier interferometry ci provides wideband transmission protocols with frequencyband selectivity to improve interference rejection, reduce multipath fading, and enable operation across noncontinuous frequency bands. In this technique, the same bandwidth is used by different users. Recently, there has been considerable interest in applying direct sequence.
One such technique is multicarrier directsequence codedivision multiple access dscdma 1, in which each of the carriers in a multicarrier system is multiplied by a spreading sequence unique to each user. Transmission algorithms the two main candidates for a broadband mobile transmission technique are the direct sequence ds cdma code division multiple access 3, 4, 5 and frequency hopping fhcdma 6 with powerful channel coding both deploying a single carrier transmission. We present a comparison between direct sequence code division multiple access dscdma, multicarrier mc cdma and multitone mt cdma schemes. Selection based successive interference cancellation for. Multicarrier spread spectrum modulation schemes and. One way of interpreting mccdma is to regard it as a direct sequence cdma signal dscdma, which is transmitted after it has been fed. Hughes software systems, multi carrier code division multiple access, march 2002. Carrier modulation mcm and direct sequence cdma ds. In cdma message signal is multiplied with pseudo noise sequence which spread the time domain message over the larger bandwidth. Multicode and multicarrier cdma systems for next generation wireless systems t. Digital multicarrier spread spectrum versus direct. Us20070211786a1 multicarrier sublayer for direct sequence.
However, the frequency diversity gain is limited because of correlation between subcarriers. These signals can be easily transmitted and received using the fast fourier transform fft without increasing the transmitter and. Therefor, mc cdma is sometimes also called cdma ofdm. Multicarrier codedivision multiple access wikipedia.
In multicarrier codedivision multipleaccess mccdma system, the received signals scattered in the frequency domain are combined to get frequency diversity gain. Milstein, convolutional coding for direct sequence multicarrier cdma, departetment of electrical and computr enginnering, university of california, ieee. We consider mmsefde used for equalization in sc transmission 9, multicarrier code division multiple access mc cdma 10, 11 and direct sequence cdma ds cdma 12. Mc cdma spreads each user symbol in the frequency domain. Introduction the conventional multicarrier code division multiple access direct sequence cdma system is affected by inter symbol interference, multiuser interference, multiple access. In the multirate multicarrier cdma system in 19, the subcarriers are divided into m groups according to the required data rate. In wireless communications multicarrier directsequence codedivision multipleaccess mc dscdma constitutes one of the highly flexible multipleaccess schemes. Multicarrier code division multiple access mccdma technique is a combination of two. Redundant residue number system assisted multicarrier. The worlds first 3g commercial system was launched by sk telecom south korea in. In this paper, an antenna array based base station receiver structure for multicarrier direct sequence codedivisionmultipleaccess multicarrier dscdma system with binary phase shift keying bpsk modulation is proposed. Cdma, multicarrier direct sequence cdma mcds cdma,andmultitonecdmamt cdma. The system under consideration is a direct sequence code division multiple access dscdma system with k users, each user having identical average power p in a single cell infrastructure. This paper describes powercontrolled multi carrier and multiuser detection.
The simulation software of the mccdma technique, used in the. Chaturvedi department of electrical engineering iit, kanpur i. Digital multicarrier spread spectrum versus direct sequence. Jan 01, 2016 read a new multiple input multiple output multicarrier direct sequence code division multiple access system using t. Direct sequence code division multiple access ds cdma is a spread spectrum technique generally used in underlay cr systems. Multicarrier codedivision multiple access mccdma is a multiple access scheme used in ofdmbased telecommunication systems, allowing the system to support multiple users at the same time over same frequency band mccdma spreads each user symbol in the frequency domain.
Because iffts diagonalize circulant matrices, the circulant matrix can be decomposed as, where. Multicarrier codedivision multiple access mc cdma is a multiple access scheme used in ofdmbased telecommunication systems, allowing the system to support multiple users at the same time over same frequency band. Wcdma is a 3g utran proposed solution, while cdma is an access technology. A slow frequency hopping, multicarrier direct sequence, codedivision multipleaccess sfhmc ds cdma scheme is proposed and investigated, which has the potential of providing a joint framework for 2ndgeneration narrowband cdma, 3rdgeneration wideband cdma and highrate broadband access networks. A software solution for chip rate processing in cdma wireless. In wireless communications, multicarrier directsequence codedivision multiple access mc dscdma constitutes one of the highly flexible multiple access schemes. A new multicarrier ds cdma with multicode in which input data bits are first coded at a low rate 1r and every resulting r coded binary bits are then.
Mccdma is a form of direct sequence cdma, but after spreading, a fourier transform fft is performed. A circular shifting register is introduced into each subcarrier. Cdma is a multiple access scheme which combines multi. The cdma2000 standard is an aspect of thirdgeneration 3g mobile wireless technology. Here multi carrier direct sequence code division multipleaccess mcds cdma system is used as the modulation technique to support multimedia services in mobilewireless communication. The cdma2000 standard is thirdgeneration 3g mobile wireless technology. Application of multicarrier cdma to mobile communication technology p. Wideband cdma, the leading candidate for fdd mode leans on direct sequence. Several types of code division multiple access cdma systems based on the combination of direct sequence ds cdma and orthogonal frequency division ofdm multiple access techniques are proposed recently 1. In cdma, users in a given cell transmit simultaneously in the same frequency band. Statistical approach to the code acquisition problem in direct. Performance of generalized multicarrier dscdma using various chip waveforms lieliang yang, senior member, ieee, and lajos hanzo, senior member, ieee abstract in this letter, we extend our investigation of generalized multicarrier directsequence codedivision multiple access by considering two additional types of chip waveforms, namely, the.
We present a comparison between direct sequence code division multiple access ds cdma, multicarrier mc cdma and multitone mt cdma schemes in terms of the transmitter and receiver structure. Cdma2000, also known as imt cdma multicarrier, is a codedivision multiple access cdma version of the imt2000 standard developed by the itu. Mc cdma is a form of orthogonal frequency division multiplexing ofdm, but we first apply an orthogonal matrix operation to the user bits. Mc mc ds cdma multicode multicarrier direct sequence cdma,sicsuccesive interference cancellation snrsignal to noise ratio 1.
Performance of generalized multicarrier dscdma using. Application of multicarrier cdma to mobile communication. The ratio between the user symbol time and the chip time is called the spread factor. In simplified terms, a symbol to be transmitted is converted into a longer sequence of chips. Furthermore in this thesis, software simulations were carried to investigate the performance of a directsequence ds cdma system in a flatfading rayleigh channel, and a multicarrier mc cdma system in a frequencyselective channel using different sets of gold. The emphasis is on the equalizer design for mobile receivers. In wireless communications, multicarrier direct sequence codedivision multiple access mc ds cdma constitutes one of the highly flexible multiple access schemes. In multicarrier codedivision multipleaccess mc cdma system, the received signals scattered in the frequency domain are combined to get frequency diversity gain. Also see cdma, wcdma, and cdma one cdma2000, also known as imtcdma multicarrier or 1xrtt, is a codedivision multiple access version of the imt2000 standard developed by the international telecommunication union itu. Zeroforcing and minimum meansquare error multiuser.
In 1, a generalized multicarrier directsequence codedivision multiple access mc dscdma scheme using rectangular chip waveforms has been investigated, when communicating over frequencyselective nakagamifading channels 2, 3. Ci introduces families of orthogonal polyphase codes that can be used for channel coding, spreading, andor multiple access. T spreading with link budget analysis, international journal of wireless and mobile computing on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Multicarrier sublayer for direct sequence channel and. Each user is assigned a unique spreading code sequence c k t k 0 k1, which has a common chip period 1 t c.
The worlds first 3g commercial system was launched by sk telecom south korea in october 2000. Multicarrier code division multiple access infogalactic. Direct sequence protocols, such as ds cdma, are provided with ci to greatly improve performance and reduce transceiver complexity. Comparison of direct sequence and multicarrier cdma systems. Cdma dscdma, multicarrier cdma mccdma, multicarrier directsequence cdma mcdscdma,andmultitonecdmamtcdma. Among them, the multicarrier cdma mc cdma transmission scheme, characterized by a spreading operation in the frequency domain. A new multiple input multiple output multicarrier direct. Design and implementation of mccdma systems for future. Mc dscdma employs a high number of degreesoffreedom, which are beneficial to design and reconfiguration for communications in dynamic communications environments, such as in the cognitive radios. In comparison with the pure ds cdma using only time t domain spreading and pure mc cdma using only f domain spreading, it has been demonstrated that the multicarrier direct sequence cdma mc ds cdma has the highest flexibility 5, 15 and the data tb symbol duration ts qtb b1k l e l l ra r ap trebk ev 2 lto n ira co e s bqk. Spreading and despreading cdma systems translate narrowband signals a sequence of symbols into signals with wider bandwidth a sequence of chips via a technique known as spreading. Mc ds cdma employs a high number of degreesoffreedom, which are beneficial to design and reconfiguration for communications in dynamic communications environments, such as in the. Hence, it is clear that the codes with high rate and reliability are the design target in minds of most researchers. Learn more about mc cdma, pn sequence, spreading code matlab.
A hardware platform is proposed and the reusable common blocks in such a transceiver are identi. Performance of a spacetime coded multicarrier cdma system in. Multicarrier cdma tutorial mccdma multi carrier cdma. The duration of an element in the code is called the chip time. Also see cdma, wcdma, and cdma one cdma2000, also known as imt cdma multicarrier or 1xrtt, is a codedivision multiple access version of the imt2000 standard developed by the international telecommunication union itu. Therefore, when the number of subcarrier is fixed, the spreading gain in frequency domain for each data is decreased with increasing data rate. Bit error rate performance of multicarrier cdma system. Direct sequence cdma systems are based on the concepts of. What is cdma2000 imtcdma multicarrier or codedivision. Two ways to spread the spectra of users signals have been considered in this work. In this paper, an antenna array based base station receiver structure for multicarrier direct sequence codedivisionmultipleaccess multicarrier ds cdma system with binary phase shift keying bpsk modulation is proposed. Milstein, convolutional coding for direct sequence multicarrier cdma, departetment of electrical and computr enginnering, university of california, ieee vol.
Multicarrier codedivision multiple access mccdma is a multiple access scheme used in. Orthogonal frequency division multiplexing ofdm is the basic mcm technique. Direct sequence spread spectrum for resistance to jamming and multipath shengli zhou, student member, ieee, georgios b. We consider mmsefde used for equalization in sc transmission 9, multicarrier code division multiple access mccdma 10, 11 and direct sequence cdma dscdma 12.
Mc dscdma employs a high number of degreesoffreedom, which are beneficial to design and reconfiguration for communications in dynamic communications environments, such as in the. This has made multicarrier cdma very popular as future 4g technology. The combination of ofdm and cdma for mobile radio transmission has been proposed by several authors 16 such as multicarrier mc cdma, multicarrier ds cdma, mutilating mt cdma. A novel interleaving scheme for mccdma system is proposed in this paper. Blind softdetection of the sfhmc dscdma signals is investigated. Most of the codes provide high reliability but have a low data rate. Directsequence protocols, such as dscdma, are provided with ci to greatly improve performance and reduce transceiver complexity. Direct sequence code division multiple access dscdma is a spread spectrum technique generally used in underlay cr systems. Multicarrier code division multiple access mccdma is a multiple access scheme used in ofdmbased telecommunication systems, allowing the system to support multiple users at the same time over same frequency band mccdma spreads each user symbol in the frequency domain.
Asynchronous multicarrier dscdma using mutually orthogonal. Performance of generalized multicarrier dscdma using various. Mccdma is a form of orthogonal frequency division multiplexing ofdm, but we first apply an orthogonal matrix operation to the user bits. Multicarrier cdma for future wideband wireless networks. Mc cdma is a form of direct sequence cdma, but after spreading, a fourier transform fft is performed. In wireless communications multicarrier direct sequence codedivision multipleaccess mc ds cdma constitutes one of the highly flexible multipleaccess schemes. Performance of a spacetime coded multicarrier cdma. Difference between cdma and wcdma compare the difference. This modulation technique is basically a combination of ds cdma and orthogonal frequency division multiplexing. Among them, the multicarrier cdma mccdma transmission scheme, characterized by a spreading operation in the frequency domain. A slow frequency hopping, multicarrier directsequence, codedivision multipleaccess sfhmc dscdma scheme is proposed and investigated, which has the potential of providing a joint framework for 2ndgeneration narrowband cdma, 3rdgeneration wideband cdma and highrate broadband access networks. This technique has a number of desirable features, including. Multicarrier code division multiple access mc cdma is a multiple access scheme used in ofdmbased telecommunication systems, allowing the system to support multiple users at the same time over same frequency band. Jul, 2011 what is the difference between cdma and wcdma.
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