Single-carrier FDMA: a new user-centric approach

What is the state-of-the-art of Ad Hoc Networks? A picture of it has been showed through the researches submitted to the last edition of AdHocNets Conference, held last September in Italy.

The Best Paper awarded at the conference has been presented by a team coming from the School of Electrical & Computer Engineering of the National Technical University of Athens. Eirini Eleni Tsiropoulou, Ioannis Ziras and Symeon Papavassiliou exposed their study titled ‘Service Differentiation and Resource Allocation in SCFDMA Wireless Networks through User-Centric Distributed Non-Cooperative Multilateral Bargaining’.

Single carrier frequency division multiple access (SC-FDMA) The SC-FDMA, which utilizes single carrier modulation and frequency domain equalization, is the primary multiple access scheme for the uplink of the 4G wireless communication systems. In the SC-FDMA the total bandwidth is divided into orthogonal subcarriers in order to be allocated to multiple users. Many studies have been devoted to the resource allocation problem in the uplink of SC-FDMA wireless networks, especially about issues related to users’ occupied subcarriers and their corresponding uplink transmission power. Considering the inherent difficulty to jointly allocate a continuous resource, various heuristic subcarrier allocation methods have been proposed, while equal-bit-equal-power (EBEP) allocation or the water-filling method have been primarily adopted to allocate users’ uplink transmission power.

What is new in AdHocNets 2015 Best Paper? The main novelty of the proposed framework is that the mobile users are able to select different discount factors to enter the multilateral bargaining process. This procedure allows a better representation of users’ needs in occupying system resources.

How it works Each user adopts a general and realistic utility function, which represents user’s service QoS-aware performance efficiency as a tradeoff between the number of user’s reliably transmitted bits and the corresponding consumed power. The joint subcarriers and user’s uplink transmission power allocation problem is formulated as a user-centric distributed non-cooperative optimization problem. Given the subcarriers allocation, a power control optimization problem is formulated and solved. In this manner, user’s optimal uplink transmission power per each occupied subcarrier is determined. Then, an iterative, distributed and low-complexity algorithm is proposed to converge to a stable subcarriers and uplink transmission power allocation.

Future perspectives Considering the promising results of the approach, future works will focus on extending and applying the proposed framework in multi-service and multitier wireless networks, such as two-tier femtocell networks. Furthermore, the model could be also applied to the 5G networks, especially to M2M and D2D communication networks.

If you are interested in reading the full paper, it is available on the European Union Digital Library (EUDL)