A study on the optimal degree-of-freedoms of cellular networks: Opportunistic interference mitigation

• Published in: 2010 Conference Record of the Forty Fourth Asilomar Conference on Signals, Systems and Computers pp. 2067 - 2071
• Main Authors: Bang Chul Jung, Dohyung Park, Won-Yong Shin
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.11.2010
• Subjects: Interference; Land mobile radio cellular systems; Measurement; MIMO; Protocols; Signal to noise ratio; Upper bound
• ISBN: 1424497221; 9781424497225
• ISSN: 1058-6393; 2576-2303
• DOI: 10.1109/ACSSC.2010.5757912

We introduce an opportunistic interference mitigation (OIM) protocol for cellular networks, where a user scheduling strategy is utilized in uplink K-cell environments with time-invariant channel coefficients and base stations (BSs) having M receive antennas. In the OIM scheme, each BS opportunistically selects a set of users who generate the minimum interference to the other BSs. We consider two OIM protocols according to the number S of simultaneously transmitting users per cell. Then, their performance is analyzed in terms of degrees-of-freedom (DoFs). As our main result, it is shown that KS DoFs are achievable if and only if the total number N of users in a cell scales at least as SNR (K-1)S . These results indicate that there exists a trade-off between the achievable number of DoFs and the scaling parameter N by tuning the number S of selected users. By showing an upper bound on the DoFs, it is also shown that the OIM scheme with M selected users is DoF-optimal. Finally, numerical evaluation is performed.