Showing papers by "Sequans published in 2020"

Advanced Dynamic Spectrum 5G Mobile Networks Employing Licensed Shared Access

Abstract: Spectrum sharing has been recognized as a key component for 5G and beyond wireless networks. Recent trials have revealed the business value of spectrum sharing via the licensed shared access model, wherein both the incumbent and the licensee operators are protected from harmful interference by sharing the available spectrum using long-term spectrum access agreements. Further increase in capacity gains can be achieved by exploiting dynamic spectrum access, where access is granted in shorter time intervals, and the Spectrum Access System, which is a more flexible version of traditional LSA. This article first hints at LSA-type spectrum sharing in regulatory and standards bodies, then proposes a few relevant scenarios that would take advantage of LSA, and finally presents an LSA system architecture and some enabling technologies for LSA/DSA/SAS. These include novel sensing, dynamic and radioaware resource allocation, and advanced cooperative communication techniques.

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.

A BER Analysis of NOMA on Rician Fading Channels

Abstract: Non-Orthogonal Multiple Access (NOMA) has been a hot research topic over the past years. The general trend in the NOMA literature is the so-called Power-Domain NOMA (PD-NOMA), which requires a strong power imbalance at the receiver between the superposed signals. Also, the focus in the literature has been on the derivation of information theoretic results, and practical bit error rate (BER) has not attracted much attention. In recent papers, some of the present authors revived an early NOMA concept, which we refer to as NOMA-2000. Performance of NOMA-2000 was investigated on AWGN channels and Rayleigh fading channels, and it was found that in most cases this technique significantly outperforms PD-NOMA. The purpose of this paper is to compare the BER performances of the two schemes on Rician fading channels, which provide a more accurate representation of the radio channel in dense urban environments. The results confirm that on Rician channels too PD-NOMA suffers a strong SNR degradation with static resource allocation and that NOMA-2000 provides substantially better performance. But with dynamic resource allocation and user pairing, both techniques achieve good performance as long as the channel overloading factor does not exceed some limit.

Radio Resource Dimensioning for Low Delay Access in Licensed OFDMA IoT Networks.

Abstract: In this paper, we focus on the radio resource planning in the uplink of licensed Orthogonal Frequency Division Multiple Access (OFDMA) based Internet of Things (IoT) networks. The average behavior of the network is considered by assuming that active sensors and collectors are distributed according to independent random Poisson Point Process (PPP) marked by channel randomness. Our objective is to statistically determine the optimal total number of Radio Resources (RRs) required for a typical cell. On one hand, the allocated bandwidth should be sufficiently large to support the traffic of the devices and to guarantee a low access delay. On the other hand, the over-dimensioning is costly from an operator point of view and induces spectrum wastage. For this sake, we propose statistical tools derived from stochastic geometry to evaluate, adjust and adapt the allocated bandwidth according to the network parameters, namely the required Quality of Service (QoS) in terms of rate and access delay, the density of the active sensors, the collector intensities, the antenna configurations and the transmission modes. The optimal total number of RRs required for a typical cell is then calculated by jointly considering the constraints of low access delay, limited power per RR, target data rate and network outage probability. Different types of networks are considered including Single Input Single Output (SISO) systems, Single Input Multiple Output (SIMO) systems using antenna selection or Maximum Ratio Combiner (MRC), and Multiuser Multiple Input Multiple Output (MU-MIMO) systems using Zero-Forcing decoder.

Enhanced NOMA scheme

Abstract: A method of transmission for increasing communication channel capacity comprising superposing a first signal on a second signal to form a combined signal, wherein allocation of users of the communication channel to the first and second signals is based dynamically on channel conditions.

HARQ feedback optimization techniques for improved reliability in Cellular Vehicle to Everything

Abstract: Vehicle to Everything (V2X) communication has been a topic of great interest for the past decade. Lately, a push from the automotive industry and regulators for inclusion of advanced use cases towards autonomous vehicles, has led to the search for improved solutions that can support the respective features. In this paper, Hybrid Automatic Repeat Request (HARQ) feedback solutions are explored in the context of group communications (groupcast) in cellular V2X. A solution is provided to combine reliability improvements while using the least possible amount of sidelink resources. Furthermore, for the case where members of the group are out of communication range of the transmitter, it is suggested to use the feedback response for selecting another member of the group to forward the message.

Driving circuit for single crystal RTC and RF clock

Abstract: A crystal driving circuit comprising a circuit input node and a circuit output node, a high power amplifier having a power consumption of more than 100 μW, a low power amplifier comprising a power consumption less than 10 μW, the circuit being arranged to selectively isolate the high power amplifier and associated load capacitance from the circuit input node and the circuit output node.

OFDM synchronization evaluation

Abstract: A method of evaluating OFDM synchronization between a transmitter and a receiver, the method carried out at the receiver and comprising, obtaining a non-coherent channel power estimate, obtaining a coherent channel power estimate, comparing the two estimates, and determining whether the receiver and the transmitter are synchronized based on the comparison.

Adaptive-SCL polar decoder

Abstract: A method of dynamically changing the list size of a successive cancellation list (SCL) decoder, the SCL decoder arranged to decode data received from a wireless communications system, the method comprising at each successive cancellation stage of the SCL decoder, determining a path metric of each path of the SCL decoder, selecting a differential path metric threshold, and dynamically changing the list size of the SCL decoder based on the differential path metric threshold and the path metric of each path of the cancellation stage, such that decoding sensitivity of the decoder is maintained and/or latency and error-correction performance of the decoder are balanced.

On-chip balun

Abstract: An on-chip balun comprising a primary side, a secondary side, and an integrated notch filter.