Short Packets over Block-Memoryless Fading Channels: Pilot-Assisted or Noncoherent Transmission?
Journal article, 2019

We present nonasymptotic upper and lower bounds on the maximum coding rate achievable when transmitting short
packets over a Rician memoryless block-fading channel for a given requirement on the packet error probability.We focus on the practically relevant scenario in which there is no a priori channel state information available at the transmitter and at the receiver. An upper bound built upon the min-max converse is compared to two lower bounds: the first one relies on a noncoherent transmission strategy in which the fading channel is not estimated explicitly at the receiver; the second one employs pilot-assisted transmission (PAT) followed by maximum-likelihood channel estimation and scaled mismatched nearest-neighbor decoding at the receiver. Our bounds are tight enough to unveil the optimum number of
diversity branches that a packet should span so that the energy per bit required to achieve a target packet error probability is minimized, for a given constraint on the code rate and the packet size. Furthermore, the bounds reveal that noncoherent transmission is more energy efficient than PAT, even when the number of pilot symbols and their power is optimized. For example, in Rayleigh fading, for the case when a coded packet of 168 symbols is transmitted using a channel code of rate 0.48 bits/channel use, over a block-fading channel with block size equal to 8 symbols, PAT requires an additional 1.2 dB of energy per information bit to achieve a packet error probability of 10􀀀3 compared to a suitably designed noncoherent transmission scheme. Finally, we devise a PAT scheme based on punctured tail-biting quasi-cyclic codes and ordered statistics decoding, whose performance is close (1 dB gap at 10^-3 packet error probability) to the ones predicted by our PAT lower bound. This shows that the PAT lower bound provides useful guidelines on the design of actual PAT schemes.

Finite blocklength

Short-packet channel-codes

Short packets

wireless channel


Rician fading


Johan Östman

Chalmers, Electrical Engineering, Communication, Antennas and Optical Networks

Giuseppe Durisi

Chalmers, Electrical Engineering, Communication, Antennas and Optical Networks

Erik Ström

Chalmers, Electrical Engineering, Communication, Antennas and Optical Networks

Mustafa Cemil Coskun

German Aerospace Center (DLR)

Gianluigi Liva

German Aerospace Center (DLR)

IEEE Transactions on Communications

00906778 (ISSN)

Vol. 67 2 1521-1536 8486997

SWIFT : short-packet wireless information theory

Swedish Research Council (VR) (2016-03293), 2017-01-01 -- 2020-12-31.

Theory and practice for optimum spectral efficiency for ad-hoc wireless networks with strict requirements on latency and reliability

Swedish Research Council (VR) (2014-6066), 2015-01-01 -- 2018-12-31.

Areas of Advance

Information and Communication Technology

Subject Categories


Communication Systems

Signal Processing



More information

Latest update

3/5/2020 1