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IKTPLUSS-IKT og digital innovasjon

SEquences and Their Applications

Alternative title: SEquences and Their Applications

Awarded: NOK 8.7 mill.

In the realm of wireless communications, two predominant forms of interference present significant challenges. Multiple access interference (MAI) occurs when signals from multiple users overlap, leading to confusion and loss of clarity in signal reception. Multipath interference (MPI) arises when a signal takes various paths to reach the receiver, resulting in signal distortion due to the different arrival times. One strategy for combating these interferences is to carefully design sequences and/or waveforms with desirable properties at the transmitters. The varying demands of diverse communication environments necessitate a range of criteria for sequence design. In this context, complementary sequences and their generalized variants, e.g., complete complementary codes, are highly demanded. Complementary sequences with zero autocorrealtion sum are designed to cancel out interference when combined, significantly reducing the impact of multipath interference. Complete complementary codes (CCCs) with both zero auto- and cross-correaltion sum take this concept further, addressing both multiple access and multipath interferences effectively. They are structured in such a way that when used across multiple users, the interference from one user's signal on another's is minimized, enhancing signal clarity and reliability. Some generalizations of CCCs in the field were proposed to improve one aspect of the design with a loosened restriction on another aspect as a compensation, such as quasi complementary sequence sets and zero-complementary codes. One primary objects of the SETA project is to fundamentally investigate the optimality of sequence sets, which can be generally interpreted as the theoretic BESTNESS that sequence sets can achieve, and to provide explicit constructions of those optimal sequence sets. Another primary object is to explore their potentials in the emergying communication technologies. Since the project's kick-off, the consortium of the SETA project made significant progress on the proposed work packages. Currently, we have proposed tighter bounds on parameters of QCCSs with different approaches, which provide a better understanding of the topic; moreover, we have proposed a systematic framework of explicitly constructing CCSs flexible with parameters that are not possible to achive with existing constructions in the literature.

Sequences have applications in a variety of areas, ranging from the Venus Radar Project, the Mars Mariner in 1960/70s to the DNA sequence assembly, global positioning system, mobile, and wireless communications in the 21st century. Sequences are of particular importance in the CDMA systems. In recent evolution from the 4G to 5G mobile networks, one critical problem is to design multiple access schemes that can meet 5G's heterogeneous demands on high data rate, high reliability, high throughput, low latency, massive connectivity, etc. New non-orthogonal multiple access (NOMA) schemes have been proposed, resulting in new research problems and directions for the sequence design. The SETA project will study sequences from both theoretical and applied perspectives: 1) we propose to derive new theoretical bounds on parameters of sequences and to design new (families of) sequences with optimal parameters; 2) we propose to study the emerging NOMA schemes, explore the applications of sequences in enhancing performance and security of NOMA, and design new sequence-based NOMA schemes for uplink transmissions. The SETA project will be carried out at the Selmer Center in Secure Communications, Univ. of Bergen, which is an internationally renowned research group in sequence design, cryptography and coding theory. The project participants include both top experts and promising young researchers in the field: Guang Gong (Univ. of Waterloo, Canada), Pingzhi Fan and Yang Yang (Southwest Jiaotong Univ., China), Zilong Liu (Univ. of Essex, UK), Constanza Riera (Høyskole på Vestland, Norway) and a local partner Tor Helleseth. The project applies for funding for one 3-year postdoc, one 3-year Ph.D. and other associated expenses during 2020.07-2024.06. The project participants will collaboratively work on the research problems, make academic visits, and disseminate the research results (approx. 30 papers) at top/leading journals, conferences, industry summits, and other public media.

Funding scheme:

IKTPLUSS-IKT og digital innovasjon