The transforming telecommunication sector moves towards adopting the fifth generation (5G) of wireless networks in the near future featuring high data rates and low latency communication. However, in traditional cellular network, the cell-edge user experiences degraded quality of service compared to cell-center user due to the effect of the propagation environment on wireless transmission. In addition to that, the inter-cell interference from neighboring base stations further lowers the received signal power at the cell edge. This results in the variation of data rates among users at the cell edge and those near the cell center, which degrades the overall system performance. Cell-free is considered to be a beneficial technology as it allows each user to be jointly served by multiple base stations, therefore reducing the path loss effects and inter-cell interference for a user at a significant distance from any base station. Apart from poor performance at cell-edge, the network capacity in cellular network is often underutilized due to a static TDD configuration along with varying traffic demands in neighboring cells. Dynamic TDD is a promising technology to handle heterogeneous traffic demands, in which neighboring cells can schedule slots in the uplink/downlink directions depending on their local traffic demands, independent of each other. Nevertheless, a new challenge of cross-link interference between the base stations and user devices arises in dynamic TDD system which can be substantially mitigated on combining cell-free architecture with dynamic TDD because of the presence of in-built cooperation. The combined system offers several advantages such as providing uniform service in an area and improvement in spectral and energy efficiency. The system finds its application in advanced areas such as connected and autonomous vehicles, where the cell edge coverage is crucial in terms of reliability to ensure safety. Besides, the system can also be deployed to serve densely populated areas with varying UL/DL requirements, trains/metro stations, stadiums, concerts, shopping complexes, college campuses, etc. This project presents the hardware implementation of cell-free and dynamic TDD using the OpenAirInterface 5G new radio software stack, with the objective to experimentally understand the role of cell-free and dynamic TDD in providing better connectivity at the celledge and improving network throughput. It was a joint project with Himani Kamboj. My research area was to analyze the throughput, implement cell-free architecture with centralized processing and integrate cell-free and dynamic TDD system. The prototype of cell-free with dynamic TDD on 5G Testbed was successfully established and the measurements of individual setups for cell-free and dynamic TDD shows improvement over cellular network.
We have submitted the extended abstract at WSA 2021 conference. Title: Hardware Implementation and Evaluation of Cell-Free MIMO and Dynamic TDD using the OAI Codebase.
Himani Kamboj, Bhawesh Anand, Sanjhi Gupta, Ashish Meshram, Sudhakar Balijepalli, and Chandra R. Murthy
Our project has been shortlisted in the top 100 entries in DoT’s 5G Hackathon. We have submitted the final prototype and are waiting for the next phase result