Implementation of multi carrier-code division multiple access-frequency division multiple access with beyond 4G specifications

Hybrid code division multiple access techniques present the open door for the future of code division multiple access and wireless communications. Multicarrier CDMA is the most popular type of hybrid CDMA because of its robustness against multipath fading channels and flexible multiple access capability. MC-CDMA is a predictable technique for future high data rate wireless communication systems according to these appealed properties. The main drawback of MC-CDMA is the power level in uplink, i.e. the ratio of peak power to the average power is high and leads to high instantaneous power which is required in transmission of mobile station. However, there are many researchers working towards reducing the level of the transmitted power. This research presents new method of peak to average power ratio (PAPR) reduction. The proposed method is making use of the characteristics of uplink for current 4th Generation (single carrier frequency division multiple access) which has low PAPR into current MC-CDMA system to reproduce a new MC-CDMA system (MC-CDMA-FDMA) with low PAPR and keep all the characteristics of the basic MC-CDMA system. MC-CDMA-FDMA reduced the level of power from 10 dB to 2 dB in case of 64 FFT size and Walsh Hadamard code is used in spreading block. In addition bit error rate has been reduced from 96x10-5 bps to 82x10-5 bps comparing to SC-FDMA bit error rate. The proposed system also has high flexibility to deal with modern communication systems with minimum required hardware at the base station through optimization of FFT size. The simulation results show that MC-CDMA-FDMA system will be a good candidate for beyond 4th Generation for mobile communication

Spectral efficiency improvement of low peak-to-average power ratio complete complementary code division multiple access systems

An investigation into the peak-to-average power ratio (PAPR) performance of cyclic rotation complete complementary code division multiple access (CR-CC-CDMA) has been conducted. Additionally, a novel orthogonal signalling technique, referred to as complementary rotation keying (CRK), has been developed for improving the spectral efficiency (SE) of CC-CDMA whilst maintaining a low PAPR. The CRK system is based on the concept of CR of CC codes in order to allow interoperability with CR-CC-CDMA systems. To this end, both systems employ a similar transmitter and receiver structure. The CR-CC-CDMA technique suffers from increased PAPR as SE per user is increased. The CRK system offers an improvement in SE, while maintaining the PAPR of a CC-CDMA system. The bit error rates of both systems were unaffected in a joint system, indicating complete interoperability. This allows dynamic adjustment of the PAPR and SE of any user in the system, with users being able to switch between both systems without causing multi user interference.Dissertation (MEng)--University of Pretoria, 2018.Electrical, Electronic and Computer EngineeringMEn

Etude et génération de formes d'ondes "ad hoc" pour les communications. (Une approche algébrique pour l'étude de l'efficacité spectrale et la réduction du PAPR dans les TDCS)

Avec le besoin croissant en bande-passante, les technologies dites de radio-cognitive sont de plus en plus étudiées par la communauté scientifique. L enjeu est d utiliser au mieux le spectre disponible. L'une de ces technologies, Transform Domain Communication System (TDCS), dont les performances en termes d efficacité énergétique et spectrale étaient jusqu'à présent méconnues, constitue le sujet d'étude de cette thèse. Après une présentation du contexte scientifique et industriel de la thèse, le système TDCS est introduit, ainsi que ses similarités et différences avec OFDM et MC-CDMA. Le système est ensuite décrit sous le formalisme algébrique des modulations linaires. Cela a permis d établir une expression de l efficacité spectrale du système. Plusieurs techniques sont alors proposées pour améliorer celle-ci tout en améliorant, dans certains cas, le taux d erreur binaire. Étant composé d un de plusieurs composantes sinusoïdales, le signal TDCS souffre d un fort Peak-to-Average Power Ratio (PAPR). La théorie ensembliste est alors présentée puis mise à profit en troisième partie de cette thèse pour proposer les algorithmes Douglas-Rachford et ROCS de réduction du PAPR des signaux TDCS. Ces algorithmes convergent plus rapidement et vers des valeurs plus basses que l algorithme POCS précédemment utilisé dans la littératureFor about ten years, spectrum scarcity and the growing need of bandwidth have pushed the studies on cognitive-radio technologies to counter this waste. Among them: the Transform Domain Communication System (TDCS), on which this thesis focuses. Until now, TDCS performance in terms of spectral and power efficiency was largely unknown. After introducing the thesis industrial and scientific context, the TDCS is introduced and compared with popular technologies such as OFDM and MC-CDMA. The system is then studied by means of the linear modulations algebraic framework. This has led to the TDCS spectral efficiency determination and to new design rules to jointly achieve a better spectral efficiency and a lower BER. Several methods are then proposed to further increase the spectral efficiency by means of a dense multidimensional modulation. Since a TDCS signal is made of several sines, it suffers from a strong Peak-to-Average Power Ratio (PAPR). Set theoretic estimation is then introduced in a third part and new PAPR-reduction algorithms such as Douglas-Rachford and Reflection Onto Convex Sets are brought to light and achieve better performance than the usual POCS algorithm regarding to the convergence rate, as well as the achieved PAPRTOULOUSE-INSA-Bib. electronique (315559905) / SudocSudocFranceF