Sequans

About: Sequans is a company organization based out in Reading, United Kingdom. It is known for research contribution in the topics: Communication channel & MIMO. The organization has 73 authors who have published 126 publications receiving 1066 citations.

Multi-user MIMO and Carrier Aggregation in 4G systems: The SAMURAI approach

Abstract: The market success of broadband multimedia-enabled devices such as smart phones, tablets, and laptops is increasing the demand for wireless data capacity in mobile cellular systems. In order to meet such requirements, the introduction of advanced techniques for increasing the efficiency in spectrum usage was required. Multi User -Multiple Input Multiple Output (MU-MIMO) and Carrier Aggregation (CA) are two important techniques addressed by 3GPP for LTE and LTE-Advanced. The aim of the EU FP7 project on “Spectrum Aggregation and Multi-user-MIMO: real-World Impact” (SAMURAI) is to investigate innovative techniques in the area of MU-MIMO and CA with particular focus on the practical, real-life, implementation and system deployment aspects. In the present paper, we provided an overview of the up-to-date SAMURAI contributions together with a description of the SAMURAI demonstrators developed as core part of the project.

eMBMS over LAN

Abstract: There is provided an LTE device configured to connect to an LTE network, connect to or provide a LAN, and to provide eMBMS services over the LAN.

Method and device for timing synchronization and neighbor scanning for cellular OFDM Systems

Abstract: IN THE NAME OF SEQUANS COMMUNICATIONS A device for processing at least an incoming signal in a wireless communication system, said incoming signal being sent by a base station (BS) and comprising successive frames, each of which comprising at least a training symbol correlated to said base station (BS), and a data symbol carrying message data. The device comprises at least: - a first module (01) digitizing and sampling the incoming signal; - a second module (02) demodulating said digitized and sampled incoming signal, and generating a corresponding frequency domain symbol (R N ); - a timing synchronization and scanning module (10) suitable for detecting at least a time offset (τ) of said training symbol by using said corresponding frequency domain symbol (R N ); and - a timing post processing module (20) for processing said timing offset (τ) and for generating an improved timing offset (τ r ) used to start the sampling of following incoming signal.

Iterative compensated MMSE channel estimation in LTE systems

Abstract: In this paper, an iterative channel estimation algorithm is considered in LTE systems. In order to take advantage of “null” sub-carriers (guard band) in LTE systems and make the algorithm simpler, an iterative compensated MMSE (IC-MMSE) channel estimation algorithm is proposed in frequency domain. Together with a simple “linear interpolation” in time domain, channel estimates are obtained in an iterative way with lower complexity. Theoretical analysis shows that the compensation process does not affect the accuracy of iterative MMSE channel estimation. Simulation results confirm that the proposed channel estimation has very robust performance and approaches the best achievable performance.

Adaptive Multi-Channels Allocation in LoRa Networks

Abstract: In this paper, we consider an IoT dedicated network corresponding to a non licensed LoRa Low Power Wide Area Network. The LoRa network operates in the unlicensed 868 MHz band within a total bandwidth of 1 MHz divided into 8 orthogonal channels of 125 kHz each. Despite the high level of interference, this network offers long range communications in the order of 2 to 5 km in urban areas and 10 to 30 km in rural areas. To efficiently mitigate this high level of interference, LoRa network essentially relies on a Chirp Spread Spectrum (CSS) modulation and on repetition diversity mechanisms. The LoRa CSS modulation spreads the signal within a band of 125 kHz using 6 possible spreading factors (from 7 to 12) to target data rates (starting from 5 kbps for the closest node to 300 bps for the furthest ones). The repetition diversity mechanisms enable the data recovery when the transmission is subject to bad channel conditions or/and high interference levels. Although the CSS modulation protects edge-cell’s devices from the high level of interference induced by nodes in the proximity of the gateway, it fails to protect nodes at the edge of a given SF region and several trials are required to recover the packet. In this paper, we propose an adaptive multi-channels allocation policy that attributes multiple adjacent channels of 125 kHz for nodes situated at the edge of SF zones. We study the impact of this adaptive sub-band allocation on the gateways’ intensities, the rate distribution and the power consumption. Our results are based on a statistical characterization of the interference in the network as well as the outage probability in a typical cell.