Workshop on Massive Uncoordinated Access Protocols

Friday, 12 June 2015 • 09:00 – 18:00

WS-07: Massive Uncoordinated Access Protocols (MASSAP)

Organizer: Enrico Paolini (University of Bologna, Italy)

Uncoordinated multiple access protocols, such as random access ones, represent a key element of communications systems where a very large population of users, each with sporadic and unpredictable activity, need to transmit over a shared medium. Their role is relevant in delay-critical applications, such as interactive satellite communications, real-time machine-type communication, etc. While traditional uncoordinated access protocols treat collisions as a waste and are designed to avoid them, several innovative developments were recently proposed, such as physical layer network coding and various techniques based on successive interference cancellation, where interference is embraced and creatively utilized. A completely new perspective was thus opened for uncoordinated protocols, paving the way to dramatic performance improvements, and rendering the throughput of random access channels competitive with that of coordinated protocols. These new approaches also created a new conceptual relationship with error correcting codes, thereby opening fundamentally new problems for two rather separated research communities.

Welcome Session

Keynote-1: Wireless Lowband Communications: Massive and Ultra-Reliable Access

The upcoming 5G wireless communication systems will not only be "4G, but faster". Instead, they will feature two new wireless modes: massive and ultra-reliable access, respectively. These modes require rather low data rates and we put them under the term lowband communication; they will support new applications, such as massive sensing, ultra-reliable vehicular links or low-latency remote control. Although the scenarios and the performance objectives of massive access are not identical with those for ultra-reliable access, there are at least two key enablers that are common for both of them: (1) efficient communication with short packets and (2) non-orthogonal protocols for uncoordinated access. This talk will first treat the problem of communication with short packets, where the data size is comparable to the size of the metadata, i.e. control information, which is not the case in broadband communication. Communication of short packets that come from a massive number of devices and/or need to meet a latency constraint requires fundamental rethinking of the packet structure and the associated communication protocols. In the second part, the talk will discuss the role of the paradigm of coded access and Successive Interference Cancellation (SIC) in lowband communications. Coded access protocols will be discussed in the context of classical random access setting with a single receiver, but also in the context of new types of multiple access problems that arise in relation to direct device-to-device (D2D) communications.

Performance of Uncoordinated Medium Access Schemes - I

All-to-all Broadcast for Vehicular Networks Based on Coded Slotted ALOHA
Mikhail Ivanov, Fredrik Brännström and Alexandre Graell i Amat (Chalmers University of Technology, Sweden); Petar Popovski (Aalborg University, Denmark)
pp. 10102-10106

Performance of Uncoordinated Medium Access Schemes - II

On the capacity of a random access channel with successive interference cancellation
Gino T. Peeters and Benny Van Houdt (University of Antwerp, Belgium)
pp. 10107-10112
Uncoordinated Rate Selection: Approaching the Capacity of Gaussian MAC without Coordination
Sriharsha Madala and Krishna Narayanan (Texas A&M University, USA)
pp. 10113-10118
SINR Profile for Spectral Efficiency Optimization of SIC Receivers in the Many-User Regime
Josep Sala (Universitat Politècnica de Catalunya, Spain); Javier Villares and Francesc Rey (Technical University of Catalonia, Spain)
pp. 10119-10124
Intra-Slot Interference Cancellation for Collision Resolution in Irregular Repetition Slotted ALOHA
Giovanni Interdonato (University Mediterranea of Reggio Calabria, Italy); Stephan F. Pfletschinger and Francisco Vázquez-Gallego (Centre Tecnològic de Telecomunicacions de Catalunya (CTTC), Spain); Jesus Alonso-Zarate (Centre Tecnologic de Telecomunicacions de Catalunya - CTTC, Spain); Giuseppe Araniti (University Mediterranea of Reggio Calabria, Italy)
pp. 10125-10130
On Interference Cancellation and Error Control in Massive Uncoordinated Peer-to-Peer Networks
Fulvio Babich and Massimiliano Comisso (University of Trieste, Italy)
pp. 10131-10135
Distributed Estimation of Sparse User Activity for Multi-base Station On-Off Random Access
Dusan Jakovetic and Dragana Bajovic (BioSense Center, University of Novi Sad, Serbia); Dejan Vukobratović (University of Novi Sad, Serbia)
pp. 10136-10141

Keynote-2: Scalable Random Access using Compressed Sensing for Massive MTC

In this talk we will illuminate some aspects and challenges of 5G random access particularly in the context of "one shot" transmission and "scalability" of massive MTC traffic. It is argued that such traffic shall not be forced into the 4G bulky access procedures and that its special characteristics will make it amenable for advanced solutions. In the first part we will derive some of the main properties to be exploited further on such as limited asynchronous access, user activity, small message size, increased pilot overhead etc. We will show how these properties can be captured using the notion of "sparsity" and introduce the relevant compressed sensing (CS) theory. In the second part we will discuss some of the recent coding approaches such as ALOHA OFDM(A), Coded ALOHA etc. and related fundamental limits in this regard. We will discuss pro and cons for each of each of the schemes. Moreover we will discuss in detail how CS based signal processing can be beneficial for such solutions. In the final part we will discuss some further upcoming challenges such as low latency and "fast" security for massive MTC access.

Recent Advances in Uncoordinated Access Techniques - I

Joint channel estimation and activity detection for multiuser communication systems
Gabor Hannak, Martin Mayer, Alexander Jung, Gerald Matz and Norbert Goertz (Vienna University of Technology, Austria)
pp. 10142-10147

Recent Advances in Uncoordinated Access Techniques - II

A Pseudo-Bayesian Approach to Sign-Compute-Resolve Slotted ALOHA
Jasper Goseling (University of Twente, The Netherlands); Čedomir Stefanović (Aalborg University & University of Novi Sad, Denmark); Petar Popovski (Aalborg University, Denmark)
pp. 10148-10152
Noise-Loop Multiple Access for Wireless Communications
Lorenzo Mucchi (University of Florence, Italy); Luca Simone Ronga (CNIT, Italy); Giovanni Chisci (University of Ferrara, Italy); Enrico Del Re (University of Florence & CNIT, Italy)
pp. 10153-10157
Enhanced Spatial Group Based Random Access for Cellular M2M Communications
Han Seung Jang (Korea Advanced Institute of Science and Technology, Korea); Su Min Kim (Korea Polytechnic University, Korea); Hong-Shik Park (Korea Advanced Institute of Science and Technology (KAIST), Korea); Dan Keun Sung (Korea Advanced Institute of Science and Technology, Korea)
pp. 10158-10163
Multi-Receiver Aloha Systems - a Survey and New Results
Andrea Munari (RWTH Aachen University, Germany); Federico Clazzer (German Aerospace Center (DLR), Germany); Gianluigi Liva (DLR - German Aerospace Center, Germany)
pp. 10164-10170
Finite Length Analysis of Irregular Repetition Slotted ALOHA (IRSA) Access Protocols
Enrico Paolini (University of Bologna, Italy)
pp. 10171-10176