Efficient implementation and optimization of adVanced messAge paSsing-based receIvers fOr future wireless Networks – EVASION

Recently, the academic and even the industrial community has showed a renewed interest in approximate Bayesian inference and derivative message passing techniques, thanks to new interference cancellation receivers based on expectation propagation (EP). These emerging solutions have shown near optimal performance with attractive complexity-performance trade-offs with respect to conventional approaches based, for instance, on belief propagation (BP). These new algorithms are also able to produce useful signal estimates uncorrelated with the observations, a property which considerably reduces error propagation in the interference cancellation process inherent to these iterative receivers. This fact makes them very promising candidates in all situations in which interference cancellation is used and/or necessary.
EVASION aims to extend EP-based message passing algorithms to a broad range of use cases for 4G/5G wireless cellular networks, mobile ad hoc networks and also high frequency (HF) communication systems. These use cases include for instance equalization for orthogonal frequency division multiplexing (OFDM) or single carrier (SC) systems and multi-dimensional constellation detection used in multi-user or single-user multiple input multiple output (MIMO) communications, or in non-orthogonal multiple access (NOMA) both for OFDM and SC, the latter being less investigated in the open literature. Comparisons with other related approximate message passing algorithms will be performed. Moreover, in certain NOMA schemes, multi-dimensional constellations can be indeed decoded using the message passing approach in a non-binary framework. In this context, we will also investigate the design of efficient channel coding schemes, reaching best achievable information rates when considering joint detection and decoding, and compare it with EP-based receiver with serial interference cancellation which has already shown interesting potential.
The project will improve EP-based message passing algorithm technological maturity in the previously quoted applications by investigating: (a) the role of imperfect/quantized channel state information, (b) the impact of variables’ quantization and dynamics restrictions, and (c) the interactions with channel coding. The consortium will select and publish part of the investigated receiver algorithms in AFF3CT, an open-source software toolbox.
We believe that such message passing algorithms have a common structure which allows finding generic implementation architectures, which can be adapted with limited changes to the variety of previously quoted applications. EVASION will study two types of architecture: (i) the classical iterative detection architecture based on a loopy factor graph, and (ii) the deep unfolded/unrolled architecture which is by essence a pipelined architecture. We recall that deep unfolding is an emerging paradigm in deep learning, which will be used to optimize both algorithm performance and its implementation.
Finally, the consortium will provide an FPGA implementation of selected message passing algorithms, under implementation constraints provided by the industrial partner. The concept of “hardware in the loop” that associates software simulations and hardware prototyping will be applied during the implementation of algorithms selected in the early phase of the project. This methodology enables to accelerate the validation of the architecture and, at the same time, to evaluate the architecture design impact on the transmission system performance.
EVASION is expected to produce significant innovation in the area of advanced receivers with EP and in particular of simplifications and optimizations for their practical implementation. Besides traditional scientific dissemination activities, the consortium will establish at the beginning of the project an agreed and common strategy for open source software production and intellectual property protection.