WeC2- Coding Techniques

Wednesday, 19 June 2019, 14:00-15:30, Room 2

 

Session Chair: Claudio Paoloni (Lancaster University, United Kingdom (Great Britain))

 
Optimal Sequence and SINR for Desired User in Asynchronous CDMA System

Hirofumi Tsuda (Kyoto University & Graduate School of Informatics, Japan)
We consider asynchronous CDMA systems in no-fading environments and focus on a certain user. This certain user is called a desired user in this paper. In such a situation, an optimal sequence, maximum Signal-to-Interference plus Noise Ratio (SINR) and the maximum capacity for a desired user are derived with other spreading sequences being given and fixed. In addition, the optimal sequence and SINR for a desired user are written in terms of the minimum eigenvalue and the corresponding eigenvector of a matrix, respectively. Since it is not straightforward to obtain an explicit form of the maximum SINR, we evaluate SINR and obtain the lower and upper bounds of the maximum SINR. From these bounds, the maximum SINR may get larger as the quantities written in terms of quadratic forms of other spreading sequences decreases.

 

An Unnoticed Property in QC-LDPC Codes to Find the Message from the Codeword in Non-systematic Codes

Alireza Hasani (Brandenburg University of Technology Cottbus-Senftenberg & IHP GmbH – Innovations for High Performance Microelectronics, Germany); Lukasz Lopacinski (IHP, Germany); Steffen Büchner (Brandenburgische Technische Universität Cottbus-Senftenberg, Germany); Jörg Nolte (BTU Cottbus, Germany); Rolf Kraemer (IHP Microelectronics, Frankfurt/Oder & BTU-Cottbus, Germany)
The generator matrix of quasi-cyclic low-density parity-check (QC-LDPC) codes is not, in general, in systematic form. Therefore, finding the message corresponding to a detected codeword at the receiver is not as straightforward as it is in the case of systematic codes. In this paper, we propose two methods for finding the message from the codeword in a QC-LDPC code. The first method is a general scheme which views the problem as a set of linear equations. This method is hardly realizable in hardware due to complexity. The second method is an alternative scheme which makes use of the particular structure in generator matrices of QC-LDPC codes in order to find the message from a non-systematic codeword. We examine a large class of non-systematic Latin-square QC-LDPC codes and one of the IEEE 802.16e standard QC-LDPC codes, and show that they have the required structure to be usable by the algorithm. The latter method is realizable in hardware and can be implemented with a digital circuit consisting of XOR gates.

 

Packet Recovery Latency of a Rate-less Polar Code in Low Power Wide Area Networks

Yi Yu (ISEP, France); Lina Mroueh (Institut Supérieur d’Electronique de Paris, France); Guillaume Vivier (Sequans, France); Michel Terré (CNAM, France)
In this paper, we consider a Low Power Wide Area Networks (LPWAN) operating either in a licensed-exempt band. In order to enhance the receiver sensitivity, low complexity repetition schemes that benefit from the time-varying channel condition are widely used. In this case, successful data recovery requires a significant channel variation from a bad to a good state depending on the data rate. This induces a relatively high decoding latency especially for slow time-varying channel. The main objective of this paper is to reduce the packet recovery latency by exploiting multiple channel states defined with respect to various transmission data rates, that are enabled by a rate-less polar code. We characterize the good channel sequence state of this code, and evaluate its latency performance in a slow and fast-time varying context.

 

5G New Radio over Satellite Links: Synchronization Block Processing

Harri Saarnisaari (University of Oulu, Finland); Jean-Michel Houssin and Thibault Deleu (Thales Alenia Space, France)
Harmonization of terrestrial standards such that they would support satellite elements would offer several benefits. Such work has started at 3GPP relating to 5G new radio (NR). Downlink initial access is one of the topics that has to be evaluated in this respect among many others. This paper studies detection of the synchronization signals included in the synchronization (SS) block of the 5G NR signal in satellite channels that have large, up to 720 kHz, Doppler frequency shift at 30 GHz carrier frequency. Furthermore, the reception of system information data in the SS block is considered. It is shown that using dedicated large frequency shift aware detectors it is possible to meet the 5G NR requirements in the detection part. However, the data part cannot be reliably received using one-shot reception at low signal-to-noise values. Some alternative solutions are considered and evaluated though some of them require changes to the standard in order to be efficient.

 

Integrating Sparse Code Multiple Access with Circularly Pulse-Shaped OFDM Waveform for 5G and the Factories of the Future

Yenming Huang (National Taiwan University & Graduate Institute of Communication Engineering, Taiwan); Rueibin Yang and Borching Su (National Taiwan University, Taiwan)
Circularly pulse-shaped orthogonal frequency division multiplexing (CPS-OFDM) waveform integrated with sparse code multiple access (SCMA) is proposed for 5G and the Factories of the Future (FoF). The physical-layer properties of low out-of-subband emission (OSBE) and low peak-to-average power ratio (PAPR) claimed by CPS-OFDM can be well preserved with the top-down codebook used in SCMA. Simulation results also reveal that the proposed transmission method possesses higher detection reliability and spectral efficiency than those of other existing SCMA-OFDM-based schemes in practical FoF environment.