Optimal time-hopping codes for multi-user interference mitigation in ultra-wide bandwidth impulse radio

Martret, Christophe J. Le; Deleuze, A.-L.; Ciblat, Philippe

doi:10.1109/twc.2006.1638672

Cited by 21 publications

(45 citation statements)

References 13 publications

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“…is the u−th developed time hopping code (DTHC) as defined in [5]. The UWB signal is sent through a multipath channel with N p paths and processed at the BS by a rake receiver containing L r fingers.…”

Section: System Modelmentioning

confidence: 99%

“…The UWB signal is sent through a multipath channel with N p paths and processed at the BS by a rake receiver containing L r fingers. The intersymbol interference (ISI) can be neglected by inserting a guard time at the end of each frame [3], [5], [12]. If the user u is assumed to be of interest, its received signal at the BS can be decomposed as [5]:…”

Section: System Modelmentioning

confidence: 99%

“…TH-UWB is a code division multiple access (CDMA) technology; multiple users can access to the channel at the same time by assigning a time-hopping code (THC) to each user. In [5], the authors showed that an optimal THC design rule can be derived by minimizing the variance of the multiple access interference (MAI), but without considering the general multirate case.…”

Section: Introductionmentioning

confidence: 99%

“…An accurate MAI model based on [5] is derived for multi-rate TH-UWB communication systems and the proofs of theorems given in [1] are provided. These proofs significantly enhance our previous paper since the intercode correlation in the general multi-rate context was unknown and far from trivial.…”

Section: Introductionmentioning

confidence: 99%

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Multi-Rate Resource Allocations for TH-UWB Wireless Communications

Mary

Fijalkow

Poulliat³

2012

IEEE Trans. Wireless Commun.

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Abstract-In this paper, we are interested in resource allocation strategies for wireless time-hopping ultra-wide band (TH-UWB) communications with multiple rate capabilities between users. Multiple rates are achieved by assigning different processing gains, i.e. N f , to users. For this purpose, the multiple-access interference (MAI) variance accounting for multi-rate is needed. It is a challenging task due to the lack of a suitable closedform expression for the MAI variance in a multi-rate context. We further study the multi-rate resource allocation problem in uplink TH-UWB systems for which an optimal search cannot be envisaged due to the exponential complexity induced. Our contribution lies in three-fold: i) A new intercode correlation expression accounting for multi-rate communications is derived, and the variance of the MAI averaging over the codes is obtained.ii) The multi-rate resource allocation problem is tackled by relaxing the integer constraint on the processing gains and modeled via a signomial programming problem. iii) Based on this, a branch and bound (BB) algorithm is derived for the allocation of the processing gains in TH-UWB systems. We also propose a really simple heuristic with linear complexity for the N f allocation. We show that the algorithm proposed outperforms the BB algorithm in average throughput and average starvation rate 1 .

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Section: System Modelmentioning

confidence: 99%

Section: System Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-Rate Resource Allocations for TH-UWB Wireless Communications

Mary

Fijalkow

Poulliat³

2012

IEEE Trans. Wireless Commun.

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“…is defined as follows: c n (j) is non-null if and only if the j th chip associated with the n th way of communication is occupied by a pulse [3].…”

Section: System Modelmentioning

confidence: 99%

Multicode based communications in Impulse Radio UWB systems

Bouton

Ciblat

Martret³

2009

2009 IEEE International Conference on Ultra-Wideband

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Abstract-In order to boost the data-rate in Impulse Radio UWB systems (which is necessary in some applications such as video stream), we propose to allocate more than one time-hopping code to the same user. In the case of a rake receiver, a new kind of interference associated with extra codes allocated to the user of interest is induced. Consequently the impact of these extra codes on the data rate is not straightforward. In order to evaluate the benefit of our proposition, we derive a closed-form for the multicode interference variance in the context of a time-hopping ultra wideband impulse radio based system. This enables us to theoretically analyze the influence of the number of additional codes on the real achievable data rate. As a low-complexity and low-cost terminal is recommended, it is common to consider a rake receiver structure. Consequently, the performance is quite poor and the data rate is thus limited. One way to increase the data rate is to provide several channels of communication to the same user. Therefore we propose to allocate several time-hopping codes to the user who requires high data rate. If rake reception is carried out, these additional codes will unfortunately generate interference disturbing the data detection of the user of interest. Therefore, the data rate will not increase linearly with the number of allocated codes. In order to analyze the influence of the number of additional codes on the data rate, we first suggest to derive the variance of the multicode interference in a closed-form expression. Thanks to the analytical evaluation of the variance, we secondly provide a data rate approximation with respect to the number of additional time-hopping codes. Moreover, the provided closed-form expression of the variance of the multicode interference can then be studied with respect to either the number of pulses per symbol, or the statistical parameters of the propagation channel. I. INTRODUCTION

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Performance Characterization of UWB SSMA Using Orthogonal PPM-TH in Dense Multipath

Ramirez-Mireles

2006

Personal Wireless Communications

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In this work we study ultra wideband (UWB) communications over dense multipath channels using orthogonal pulse position modulation (PPM) for data modulation and time-hopping (TH) for code modulation. We consider the effects of the multiple access interference (MUI) in asynchronous spread spectrum multiple access (SSMA) based on random TH codes. We consider a realistic multipath channel to analyze the effects of the transmission rate in the number of users for different bit error rate (BER) values.

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Optimal time-hopping codes for multi-user interference mitigation in ultra-wide bandwidth impulse radio

Cited by 21 publications

References 13 publications

Multi-Rate Resource Allocations for TH-UWB Wireless Communications

Multi-Rate Resource Allocations for TH-UWB Wireless Communications

Multicode based communications in Impulse Radio UWB systems

Performance Characterization of UWB SSMA Using Orthogonal PPM-TH in Dense Multipath

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