Performance of STBC MC-CDMA systems over outdoor realistic MIMO channels

Portier, Fabrice; Baudars, J.-Y.; Hélard, Jean-François

doi:10.1109/vetecf.2004.1400485

Cited by 13 publications

(10 citation statements)

References 6 publications

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“…self interference plus noise) decreases per iteration due to the re-estimation of the channel. It has been evidenced that even a small number of iterations provides a significant improvement [28]. A satisfactory tradeoff between performance and complexity is achieved when the iterative process is terminated if either a max number of iterations j max = 8 or convergence for a small value of λ (e.g λ = 0.01) is reached [29].…”

Section: Simulation Parameters and Scenarios Definitionmentioning

confidence: 99%

An Enhanced Embedded-Pilot Channel Estimation Architecture for MIMO MC-CDMA Systems

Marousis

Skentos

Constantinou

2010

Wireless Pers Commun

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In this work an enhanced semi-blind channel estimator is presented for multicarrier CDMA systems with multiple transmit and receive antennas. The novel scheme is based on embedded pilots that are characterized as virtual users and their number is determined in a dynamic fashion according to the propagation channel conditions. The superimposed code-multiplexed pilots are used initially for channel estimation before the despreading operation, thus achieving per subcarrier estimation using the known unique multi-layer pattern of the virtual users. Afterwards, the estimation is enhanced by using the despread pilots. Furthermore, an iterative scheme is incorporated in channel estimation process minimizing the effect of multiuser interference and operates either in interference cancellation, or in virtual user mode. The proposed architecture is evaluated for spatial diversity systems (spacefrequency block coded) with two transmit and up to four receive antennas operating in realistic propagation channels for various modulation and coding schemes. The results demonstrate a significant performance improvement especially as the channel is dominated by its time variant characteristics. The dynamic assignment of spreading codes in the payload and the pilots offers to the system realistic flexibility and adaptivity in demanding channels achieving concurrently maximization of the real overall system throughput, while maintaining low overhead and complexity burden.

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Section: Simulation Parameters and Scenarios Definitionmentioning

confidence: 99%

An Enhanced Embedded-Pilot Channel Estimation Architecture for MIMO MC-CDMA Systems

Marousis

Skentos

Constantinou

2010

Wireless Pers Commun

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“…The velocity that is studied is 180 km/h, which relates to a maximum Doppler frequency f Dmax = 867 Hz. Note, the two antennas at the base station are spaced 10λ apart and the two antennas at the mobile terminal 0.5λ apart [12]. This model provides realistic PSDs and correlations in space-time-frequency based on the sum of rays approach.…”

Section: A Simulation Parametersmentioning

confidence: 99%

Iterative Channel Estimation for Orthogonal STBC MC-CDMA Systems over Realistic High-Mobility MIMO Channels

Portier

Sand

Hélard

2006

2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications

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Abstract-This paper investigates a downlink multiple-input multiple-output (MIMO) multi-carrier code division multiple access (MC-CDMA) system with pilot aided channel estimation (PACE) and iterative channel estimation (ICE) in the receiver. Due to the superposition of different users' spread data signals, zero-valued chips can occur after spreading, which can cause noise enhancement when using data estimates as reference signals in ICE. Hence, we propose a MIMO channel estimation method to overcome the above problem and avoid noise enhancement in ICE. Simulations results for PACE and ICE were computed for a realistic outdoor MIMO channel model. The results show that frame error rates of ICE are smaller than the ones of PACE.

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“…There are various channel estimation techniques available in literature to measure CSI at receiver [16] [17]. This paper has shown the results of QOSTBC and CR-QOSTBC schemes with Least Square (LS) channel estimation method.…”

Section: Introductionmentioning

confidence: 99%

Performance of CR-QOSTBC for Multiple Receive Antennas in MIMO Systems

Shah

Parmar

Kothari

et al. 2010

2010 International Conference on Computational Intelligence and Communication Networks

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Multipath fading is inherent in wireless communication systems. Diversity is the techniques which takes the advantage of multipath and mitigate the effect of fading and increase signal strength. Space Time Block codes (STBC) are used in MIMO systems to improve the performance by maximizing transmit and/or receive diversity. Among different schemes based on STBC, Quasi orthogonal space time block code (QOSTBC) is able to achieve full rate transmission for more than two transmit antennas. Constellation rotation quasi orthogonal space time block code (CR-QOSTBC), a modified QOSTBC improves performance further and gets full diversity along with full rate, to overcome the limitation of QOSTBC, which is unable to maintain orthogonality amongst the codes transmitted by different antennas. Objective of this paper is to observe improvement in BER with reference to number of receive antennas, as higher diversity can be achieved by increasing uncorrelated paths between transmitter and receivers using higher number of receive antennas. Simulations were carried out under ideal as well as realistic environment using least square technique with four antennas at transmitter side and variable receive antennas. Results of simulations presented in this paper indicate performance improvement of CR-QOSTBC over QOSTBC in flat fading channel environment. Simulation results also shows performance degradation in BER when channel is estimated at the receiver.

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Performance of STBC MC-CDMA systems over outdoor realistic MIMO channels

Cited by 13 publications

References 6 publications

An Enhanced Embedded-Pilot Channel Estimation Architecture for MIMO MC-CDMA Systems

An Enhanced Embedded-Pilot Channel Estimation Architecture for MIMO MC-CDMA Systems

Iterative Channel Estimation for Orthogonal STBC MC-CDMA Systems over Realistic High-Mobility MIMO Channels

Performance of CR-QOSTBC for Multiple Receive Antennas in MIMO Systems

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