A radio channel emulator for WCDMA, based on the hidden Markov model (HMM)

One of the main development and research subjects within the telecommunications area activity is the 3G mobile systems standardisation. The radio access is, of course, the main trouble in mobile systems, so it is important to investigate its implication. This paper describes a radio channel emulator for the UTRA-FDD made, based on the hidden Markov model (HMM). Since a statistical system behaviour is needed to train the HMM, off-line simulations have been made. The results between simulated and emulated statistics are presented. The use of emulation models implies a loss of accuracy with respect to simulation models, but is adequate to operate in real time. Certainly, the main advantage of using HMM in the emulator is the huge reduction in time, resources and effort with regard to a real simulation of the system. The emulator will allow in future works, for fast testing and comparison of several higher layer protocols and error control schemes.Peer ReviewedPostprint (published version

A generic radio channel emulator to evaluate higher layer protocols in a CDMA system

Currently, we are involved in the standardisation process to specify the next mobile system generation. A wideband code division multiple access (WCDMA) system is considered in most of the region versions. It would be very useful to count on a radio channel emulator which allows one to evaluate higher layers protocols within this context. This paper presents a radio channel emulator developed for a code division multiple access (CDMA) based system. Its versatility and low complexity have been exposed, and the validation process to check the model accuracy has also been shown for this system as an example.Peer ReviewedPostprint (published version

Performance of a linear interference canceller for a ds/cdma synchronous system based on the ekf delay estimator

Since the conventional detector often fails to produce reliable decisions for a CDMA channel, several new multiuser detectors have previously proposed. In the present paper, the authors propose both a simple linear scheme for interference cancellation, which exhibits good performance, and a synchronism scheme based on the extended Kalman filter (EKF) to achieve synchronization among the different users at the base station, for a direct-sequence code-division multiple-access (DS/CDMA) synchronous system. The influence of the synchronism scheme on the performance of the interference canceller is analyzed under Rayleigh multipath fading.Peer ReviewedPostprint (published version

On soft/hard handoff for packet data services in cellular CDMA mobiles systems

Benefits of macrodiversity operation for packet data services in third generation mobile systems are not obvious. Retransmission procedures to enhance link performance and higher downlink bandwidth requirements could question macrodiversity usage. This paper describes a simple methodology to compare soft and hard handoff performance in terms of transmission delay for packet data services. The handover procedures are based exclusively on power criteria and hysteresis margins.Peer ReviewedPostprint (published version

Multiple slot allocation for voice/data transmission over PRMA++ applied to FRAMES multiple access mode 1

This paper presents some simulation results of PRMA++ for voice and data transmission over a physical air interface platform defined in the ACTS European project FRAMES. Variations on the statistics of speech sources (activity factor, petition rate) are studied and conclusions are obtained for optimal frame dimensioning. For data transmission, a multiple slot allocation scheme is presented and results are shown for different source rates and packet lengths.Peer ReviewedPostprint (published version

Emulador de canales radio para sistemas de comunicaciones móviles

Peer ReviewedPostprint (published version

On the influence of the channel impulsional response estimation on the performance of a linear interference canceller for a DS/CDMA system

In a code division multiple access (CDMA) mobile radio communication system, interference from other users is one of the most critical drawbacks due to the lack of perfect orthogonality between user access codes. So far, practical systems have used power control to overcome fading and near/far effects. Another approach which also results in an important improvement of the capacity is the use of interference cancellers. A simple linear interference cancellation scheme for coherent BPSK modulation is proposed and analyzed under Rayleigh multipath fading, and in particular, the influence of the channel impulsive response estimation on the performance of the cancellation scheme has been assessed.Peer ReviewedPostprint (published version

The use of coding and diversity combining for mitigating fading effects in a DS/CDMA system

Spatial diversity is an attractive technology to cope with the fading channel encountered in mobile communications. This paper presents novel closed analytical expressions of the bit-error rate (BER) achievable in a coherent binary phase-shift-keying (CBPSK) direct-sequence code-division multiple-access (DS/CDMA) system for any power delay profile and for either postdetection selection or maximal ratio combining (MRC). In particular, expressions for the cutoff rate Ro and for its related parameter D are also formulated in order to assess the system performance under the consideration of some channel coding schemes. Finally, an exemplary study is carried out in order to illustrate the behavior of a realistic space-diversity code-division multiple-access (CDMA) system according to the analytical expressions that have been derivedPeer Reviewe

Capacidad de un sistema CDMA de comunicaciones moviles en presencia de canales dispersivos caracterizados con perfiles de retardo de potencia de tipo exponencial

CDMA is a digital multiple access technique in which each subscriber has his own identification code and all the transmitted signals share the same frequency band of the spectrum. This paper presents an approximative figure of the CDMA capacity and spectral efficiency in a cellular mobile environment with an exponential Power Delay Profile (PDP). Sorne error correction codes have been introduced in order to assess their performance in presence of ideal interleaving.Peer ReviewedPostprint (published version

Population-based multicase-control study in common tumors in Spain (MCC-Spain): rationale and study design

Introduction: We present the protocol of a large population-based case-control study of 5 common tumors in Spain (MCC-Spain) that evaluates environmental exposures and genetic factors. Methods: Between 2008-2013, 10,183 persons aged 20-85 years were enrolled in 23 hospitals and primary care centres in 12 Spanish provinces including 1,115 cases of a new diagnosis of prostate cancer, 1,750 of breast cancer, 2,171 of colorectal cancer, 492 of gastro-oesophageal cancer, 554 cases of chronic lymphocytic leukaemia (CLL) and 4,101 population-based controls matched by frequency to cases by age, sex and region of residence. Participation rates ranged from 57% (stomach cancer) to 87% (CLL cases) and from 30% to 77% in controls. Participants completed a face-to-face computerized interview on sociodemographic factors, environmental exposures, occupation, medication, lifestyle, and personal and family medical history. In addition, participants completed a self-administered food-frequency questionnaire and telephone interviews. Blood samples were collected from 76% of participants while saliva samples were collected in CLL cases and participants refusing blood extractions. Clinical information was recorded for cases and paraffin blocks and/or fresh tumor samples are available in most collaborating hospitals. Genotyping was done through an exome array enriched with genetic markers in specific pathways. Multiple analyses are planned to assess the association of environmental, personal and genetic risk factors for each tumor and to identify pleiotropic effects. Discussion: This study, conducted within the Spanish Consortium for Biomedical Research in Epidemiology & Public Health (CIBERESP), is a unique initiative to evaluate etiological factors for common cancers and will promote cancer research and prevention in Spain.The study was partially funded by the “Accion Transversal del Cancer”, approved on the Spanish Ministry Council on the 11th October 2007, by the Instituto de Salud Carlos III-FEDER (PI08/1770, PI08/0533, PI08/1359, PS09/00773, PS09/01286, PS09/01903, PS09/02078, PS09/01662, PI11/01403, PI11/01889, PI11/00226, PI11/01810, PI11/02213, PI12/00488, PI12/00265, PI12/01270, PI12/00715, PI12/00150), by the Fundación Marqués de Valdecilla (API 10/09), by the ICGC International Cancer Genome Consortium CLL, by the Junta de Castilla y León (LE22A10-2), by the Consejería de Salud of the Junta de Andalucía (PI-0571), by the Conselleria de Sanitat of the Generalitat Valenciana (AP 061/10), by the Recercaixa (2010ACUP 00310), by the Regional Government of the Basque Country by European Commission grants FOOD-CT- 2006-036224-HIWATE, by the Spanish Association Against Cancer (AECC) Scientific Foundation, by the The Catalan Government DURSI grant 2009SGR1489