Spectral efficiency of random CDMA with constant envelope modulation

Müller, Ralf R.; Lampe, A.

doi:10.1016/j.aeue.2011.01.009

Cited by 7 publications

(6 citation statements)

References 19 publications

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“…Even though this signal format is phase-continuous and despreading and dada detection are separable, the data signal is limited in a minimumshift keying (MSK) format and the scheme is a compromise between performance and complexity. There are also some other researches that concentrate on spreading sequences design to eliminate the multiaccess interference (MAI) and achieve multiuser communication [9][10][11][12][13]. However, all of these studies did not consider RAKE receiver for DSSS-CPM system.…”

Section: Introductionmentioning

confidence: 99%

Coherent RAKE Receiver for CPM-Based Direct Sequence Spread Spectrum

Zhou¹,

Wang

Er-yang

2016

Mathematical Problems in Engineering

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Direct sequence spread spectrum (DSSS) using continuous phase modulation (CPM) inherits the techniques' benefits, constant envelope, anti-interference, and spectral efficiency. To get diversity gains over a Rayleigh-fading multipath channel as in conventional direct sequence spread-spectrum binary phase shift keying (DSSS-BPSK) system, a new class of coherent RAKE receivers is proposed in this work. By introducing chip branch metric to the receiver scheme, despreading and data detection can be done meanwhile based on Maximum Likelihood Sequence Detection (MLSD). Compared to the conventional RAKE receiver which sums decision metrics symbol-by-symbol, the proposed DSSS-CPM RAKE receiver accumulates symbol branch metric increments over every phase state of multiple paths after chip phase synchronization. Numerical results show that DSSS-CPM using the synchronous despreading and demodulation algorithm has no performance loss compared to CPM system that employs MLSD algorithm under the same test conditions. Moreover, the proposed RAKE receiver outperforms conventional RAKE receiver and achieves a remarkable diversity gain of bit error rate (BER) under the Rayleigh-fading multipath channel.

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Section: Introductionmentioning

confidence: 99%

Coherent RAKE Receiver for CPM-Based Direct Sequence Spread Spectrum

Zhou¹,

Wang

Er-yang

2016

Mathematical Problems in Engineering

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“…4 This last result is the reason why in the following we will discard higher order modulations and focus only on binary modulations. Therefore, a comparison among the SS-FH-CPM system and other binary systems, namely those proposed in [4], [8], and [9], named in the following GiLuRe, MuLa, and Mu, respectively, is needed. We fix the total bandwidth BT ≃ 38 for all the four systems and chose the spreading factors of GiLuRe, MuLa, and Mu systems, and the value of h max for the proposed system accordingly.…”

Section: B Overall Spectral Efficiencymentioning

confidence: 99%

“…The SIC MUD is then formed by U enhanced SISO SUDs, each of which computes the mean vector µ (ℓ) n and the covariance matrix Φ (ℓ) n for every symbol interval through (8) and (10), inverts Φ (ℓ) n and then computes the branch metric in (11). Finally, it computes the a posteriori probabilities…”

Section: ) Hic-based Receivermentioning

confidence: 99%

“…For the GiLuRe system we have chosen the 2-RC format (for a fair comparison with the proposed SS-FH-CPM system) and random chips as described in [4]. For the MuLa system we have chosen a roll-off factor α = 0 since it is the value providing the best spectral efficiency [8]. Finally, for the Mu system we used the same parameters used in [9], i.e., p = 1/3, 10 4 primary iterations, 10 3 secondary iterations and random initial binary chips.…”

Section: B Overall Spectral Efficiencymentioning

confidence: 99%

“…The receiver, as in the linearly-modulated DS-SS systems, is composed by an analog (and therefore expensive) despreader and a detector. Müller and Lampe proposed in [8] a DS-SS system using linear modulations with constant envelope and continuous phase. To avoid phase jumps to occur at every symbol change, they pose few constraints on the information symbol alphabet, the spreading factor, and the symbol waveform.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

CPM-based spread spectrum systems for multi-user communications

Mazzali

Colavolpe

Buzzi

2012

2012 IEEE International Conference on Communications (ICC)

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Abstract-We propose a new spread spectrum (SS) system based on continuous-phase modulations (CPMs). The main idea is to exploit the sequence of modulation indices of a multi-h CPM as a frequency-hopping (FH) sequence. Spectral spreading, flatness and smoothness can be easily achieved by an appropriate choice of the maximum value of the modulation index and of the length of the index sequence. We will show that the proposed CPM-based spread spectrum system achieves an overall spectral efficiency larger than that of a single-user single-h CPM transmission even when a single-user detector is employed at the receiver. It also outperforms other solutions in the literature. In addition, we will also derive some suboptimal multi-user detectors.

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A method using optimized combinations based on energy spectrum extension factor to reduce MAI in asynchronous DS-CDMA systems

Guo

2017

AEU - International Journal of Electronics and Communications

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Spectral efficiency of random CDMA with constant envelope modulation

Cited by 7 publications

References 19 publications

Coherent RAKE Receiver for CPM-Based Direct Sequence Spread Spectrum

Coherent RAKE Receiver for CPM-Based Direct Sequence Spread Spectrum

CPM-based spread spectrum systems for multi-user communications

A method using optimized combinations based on energy spectrum extension factor to reduce MAI in asynchronous DS-CDMA systems

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