9 octobre 2019

Catégorie : Stagiaire

**Internship M2:** Error probability bounds in two-way communication channel.

**Where:** Institute of Electronics and Telecommunication of Rennes (IETR)

**When and duration:** February, 6 months.

**Contact:** Dr. Philippe Mary, philippe.mary@insa-rennes.fr

*Laboratory*:**IETR: Institut d’Electronique et de Télécommunications de Rennes**

** Start date : **February

Ultra-reliable low-latency communication (URLLC) is one of the main awaited use-case of the fifth generation of wireless systems. This use-case category should be able to provide services for latency sensitive applications like factory automation, autonomous driving or remote surgery. These applications require about 1 ms latency (at most) and a packet error rate of 10^{-5 }[1]. For this internship, we are considering the scenario where a two-way communication occurs between two nodes A and B. We may also refer to this scenario as the *transaction channel*. The low latency constraint requires to work with a finite number of channel uses (c.u.) n, i.e. packet length, hence the asymptotic framework of the Shannon’s theory (infinite n and vanishing error probability) cannot capture the tradeoff between latency and reliability. One has to resort with finite block length information theory which dealt with fundamental performance of communications when the number of c.u. remains bounded [2]. When it comes to finite block length regime, the number of c.u. used for channel estimation in block fading channel is very important because of the tradeoff between the accuracy on the channel state information (CSI) estimation and the data rate of useful data [3,4]. In the particular case of the transaction channel, the communication B to A occurs if and only if A to B succeeded. The error probability of the transaction depends on the error done in the links A to B and B to A. The error probability E1, i.e. on A to B, depends on the strategy employed, i.e. pilot assisted or non-coherent transmission. However, B to A may benefit from the CSI estimated at B. Moreover, if B to A occurs, then A to B succeeded and the entire packet from A to B can be used as a pilot to refine the CSI estimation.

**This internship aims at evaluating the performance of the transaction communication when CSI has been estimated on the entire length of the packet from A to B****. The sensibility of the error probability to the CSI estimation will be characterized according to the number of c.u. used for channel estimation in each communication link.**

A tentative schedule for the internship would be:

1)State of the art on short packet communications

2)Implementation of known bounds on the error probability and rate when considering full or partial CSI

3)Evaluation of the error probability in the transaction channel according to the accuracy on CSI.

*References*

[1] “Minimum requirements related to technical performance for IMT-2020 radio interface(s)”,*Report ITU-R M.2410-0*, Nov. 2017.

[2] Y. Polyanskiy, H. V. Poor and S. Verdu, “Channel coding rate in the finite blocklength regime”, *IEEE Transactions on Information Theory*, vol. 56, no. 5, pp. 2307-2359, May 2010.

[3] J. Östman, R. Devassy, G. C. Ferrante and G. Durisi, "Low-Latency Short-Packet Transmissions: Fixed Length or HARQ?" *2018 IEEE Globecom Workshops (GC Wkshps)*, Abu Dhabi, United Arab Emirates, 2018, pp. 1-6.

[4] J. Östman, G. Durisi, E. G. Ström, M. C. Coşkun and G. Liva, "Short Packets Over Block-Memoryless Fading Channels: Pilot-Assisted or Noncoherent Transmission?"*IEEE Transactions on Communications*, vol. 67, no. 2, pp. 1521-1536, Feb. 2019.

*Key skills *

The candidate should apply for an MSc degree, or equivalent, in one of the following field: information theory, signal processing, electrical engineering, applied mathematics. He should have a strong background in probabilities and information theory. The candidate should be familiar with Matlab and C/C++ languages or Python.

*Key words: *

Information theory, short packet communications, block fading channels, pilot-assisted, non coherent transmission.

*How to apply:*

- Email a motivation letter

- Full CV with project and courses that could be related to the subject

- Complete academic records (from Bachelor to first year of MSc)

- **Applications will be reviewed when they arrive until one candidate is selected**

(c) GdR 720 ISIS - CNRS - 2011-2019.