SDR cognitive networks – The future of massive IoT

Christophe Fourtet (SigFox)

Abstract:
After eight decades of radiocommunications dominated by governmental, navigation and military usages, wide commercial applications have exploded since the early 80’s, following the expansion of wired communications. A tendency to “consume megahertz” has appeared in consumer’s habits, and this appetite doesn’t seem to be stoppable. However, radiocommunications are like energy, food, dependent on a limited resource to be shared : Spectrum. On top of this, the IoT revolution is bringing new paradigms: Ultra-low energy consumptions, tiny amount of data from an extraordinary large variety of sources, random access to the resource, etc… All this leads to a necessity for new approaches like Software Defined Radio & Networks, and even more, “cognitive” radio & networks. It is fundamental to somehow distribute signal and data processing everywhere in the chain, from antennas to data API’s, in order to drastically increase the ability of our radio systems to cope with random access, high spectrum sharing rates, and to get rid of inevitable interferences.

Yes, A.I. is arriving in radiocommunications as well !

https://iot2017.mit.edu/508-2/

Coding Schemes for the Uncoordinated Unsourced Multiple Access Gaussian Channel

Krishna Narayanan (Texas A&M)

Abstract:
In the uncoordinated unsourced multiple access channel model introduced by Polyanksiy, a set of nodes each wish to communicate a short packet to a central receiver. In a twist from the standard multiple access channel, the receiver seeks to learn the set of transmitted messages without regard to which transmitter is associated with which message. Polyanksiy provided an achievability result for this communication problem and Ordentlich and Polyanksiy devised the first practical coding scheme. In this talk, we propose a new coding scheme for this problem that substantially improves the state of the art. Our proposed paradigm is composed of four main ingredients: (i) the transmission period is partitioned into sub-blocks, thereby instituting a slotted framework; (ii) The message (data) is split into two parts and one part chooses an interleaver for a low density parity check (LDPC) type code. This part of the message is encoded using spreading sequences or codewords that are designed to be decoded by a compressed sensing type decoder; (iii) The other part of the message is encoded using a low density parity check (LDPC) type code and decoded using a joint message passing decoding algorithm designed for the $T$-user binary input real adder channel; (iv) users repeat their codeword in multiple sub-blocks, with the transmission pattern being a deterministic function of message content and independent of the identity of the user. When decoded using a successive interference canceller type decoder, this coding scheme provides excellent performance. We will also point out connections between the unsourced multiple access channel problem and unsolved problems in compressed sensing and lattice coding.

https://iot2017.mit.edu/narayanan/

Wireless node identification: Fundamental limits and practical design

Dongning Guo (Northwestern)

Abstract:

A critical task in massive-access wireless networks is to quickly and reliably identify all transmitting nodes in a neighborhood. This is also known as neighbor discovery. We show that identification through a multi-access channel is in fact a compressed sensing problem by nature. We study the fundamental limits of node identification in the many-user information theory setting. We also describe practical designs for fast node identification with and without perfect synchronization.

https://iot2017.mit.edu/guo/

Revising the Problem of Access Protocols in Ultra-Reliable Wireless Communications

Petar Popovski (Aalborg University)

Abstract:

Ultra-reliable low latency communication (URLLC) is an important new feature brought by 5G, with a potential to support a vast set of applications that rely on mission-critical links. Establishing and transmitting a short data packet is associated with multiple steps of the access protocols that involve auxiliary procedures (e.g. channel estimation) and exchange of metadata. The requirement for very high reliability is propagated and further augmented to each of those steps. This talk elaborates on the models used for access protocols and, specifically, provides a critical look on the assumptions used in random access protocols. The talk presents models for grant-free access and contrasts them to the traditional resource reservation procedures used in cellular systems. Specifically, the talk highlights the design alternatives for the authentication procedures, usually treated as an “afterthought” in the theoretical treatment of access protocols. Finally, a discussion is provided on techniques based on coded random access and successive interference cancellation with latency/reliability constraints.

https://iot2017.mit.edu/iot-reliable-communications-i-talk/