Contributions to Analysis and Mitigation of Cochannel Interference in Cellular Wireless Networks

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2016-08-19
Degree programme
110 + app. 64
Aalto University publication series DOCTORAL DISSERTATIONS, 142/2016
Cellular wireless networks have become a commodity. We use our cellular devices every day to connect to others, to conduct business, for entertainment. Strong demand for wireless access has made corresponding parts of radio spectrum very valuable. Consequently, network operators and their suppliers are constantly being pressured for its efficient use. Unlike the first and second generation cellular networks, current generations do not therefore separate geographical sites in frequency. This universal frequency reuse, combined with continuously increasing spatial density of the transmitters, leads to challenging interference levels in the network. This dissertation collects several contributions to analysis and mitigation of interference in cellular wireless networks. The contributions are categorized and set in the context of prior art based on key characteristics, then they are treated one by one. The first contribution encompasses dynamic signaling that measures instantaneous interference situations and allows only for such transmissions that do not harm each other excessively. A novel forward signaling approach is introduced as an alternative to traditional reverse signaling. Forward signaling allows the interference management decisions to be done at the receiver, where there is more relevant information available. The second contribution analyzes cross-link interference in heterogeneous networks. Cross-link interference is interference between downlink and uplink transmissions that can appear in time-division duplex (TDD) networks. It is shown that uplink reception of small cells can be disturbed considerably by macrocell downlink transmissions. We proposes an intuitive solution to the problem based on power control. Users in small cells have generally enough power headroom as the distance to the small base station is often short. The third contribution provides an extensive analysis of a specific interference managment method that the Long-Term Evolution (LTE) applies in cochannel heterogeneous deployments. We analyze this so-called time muting using a modern stochastic geometry approach and show that performance of the method strongly depends on residual interference in the muted sections of time. The fourth and last contribution analyzes the impact of interference rank, i.e., number of spatial streams at the interferer, on a beamformed or spatially block coded transmission. It is shown that when the interferer chooses to transmit multiple spatial streams, spreading the power in spatial domain has potential to decrease probability of outage at neighbor receiver, especially if the neighbor transmission uses beamforming.
Supervising professor
Wichman, Risto, Prof., Aalto University, Department of Signal Processing and Acoustics, Finland
interference management, cellular, wireless
Other note
  • [Publication 1]: M. Čierny, P. Janis, R. Wichman, C. Ribeiro. Exclusion Regions via Handshaking Protocol for Inter-Cell Interference Management. In 45th Annual Conference on Information Sciences and Systems, CISS 2011, Baltimore, MD, March 2011.
    DOI: 10.1109/CISS.2011.5766135 View at publisher
  • [Publication 2]: M. Čierny, C. Ribeiro, R. Wichman, O. Tirkkonen. SINR Prediction Versus Reverse Reporting for Soft Reuse and Interference Management. In 11th European Wireless Conference, EW 2011, Vienna, Austria, April 2011.
  • [Publication 3]: M. Čierny, C. Ribeiro, R. Wichman, O. Tirkkonen. Inter-Cell Interference Management in OFDMA TDD Downlink Using Sounding/Silencing Protocol. In IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2011, Toronto, ON, pp. 839-843, September 2011.
    DOI: 10.1109/PIMRC.2011.6140085 View at publisher
  • [Publication 4]: M. Čierny, R.Wichman, J. Hamalainen, C. Ribeiro, Z. Ding, X. Liu. On TDD Cross-Tier In-Band Interference Mitigation: A Practical Example. In 7th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2012, Stockholm, Sweden, June 2012.
    DOI: 10.4108/icst.crowncom.2012.248599 View at publisher
  • [Publication 5]: M. Čierny, H. Wang, R. Wichman, Z. Ding, C. Wijting. On Number of Almost Blank Subframes in Heterogeneous Cellular Networks. IEEE Transactions on Wireless Communications, vol. 12, no. 10, pp. 5061-5073, September 2013.
    DOI: 10.1109/TWC.2013.090513.121756 View at publisher
  • [Publication 6]: M. Čierny, R. Wichman, Z. Ding. Impact of Base Station Time Synchronization Mismatch on Almost Blank Subframes. IEEE Communications Letters, vol. 17, no. 11, pp. 2092-2095, October 2013.
    DOI: 10.1109/LCOMM.2013.101413.131652 View at publisher
  • [Publication 7]: M. Čierny, Z. Ding, R. Wichman. Higher Rank Interference Effect on Weak Beamforming or OSTBC Terminals. IEEE Transactions on Wireless Communications, vol. 14, no. 9, pp. 4948-4957, May 2015.
    DOI: 10.1109/TWC.2015.2429648 View at publisher