Final Report Summary - ENIGMA (Engineering Network and Interference Geometry for the Analysis and Design of Next Generation Wireless Networks)
Our society, industry and service sectors are poised to become increasingly more dependent on next generation wireless telecommunication technologies. The signs are already here and clearly visible. For example, 4G (Fourth Generation) wireless networks have transformed mobile handsets into intelligent terminals for providing easy anytime-anywhere access to all sorts of information and services in our daily lives, including location tracking, high definition video streaming, and portfolio monitoring and management. 5G femtocells overlaying on the existing wireless cellular architecture are envisioned to turn our homes and offices into miniature cellular networks for improved wireless coverage [Bleicher, 2013].
Cognitive radio networks are expected to solve the radio spectrum scarcity problem and to unlock the potential of industry and service sectors for product innovation and useful intellectual property generation [Goldsmith et al., 2009]. Information and communication technologies empowered with next generation wireless telecommunication protocols for machine-to-machine communication is expected to decrease total greenhouse gas emissions from all industry sectors by 15%, which can be translated into €600 billion savings per year by 2020 [The Climate Group 2008]. The use of wireless mobile technologies for all kinds of medical and public health practices such as patient monitoring and mobile telemedicine is starting to unlock the innovative capacity of European health related industries [World Health Organization, 2011].
Such a wide range of application areas brings together new interoperability challenges for heterogenous network architectures and requires innovative approaches for interference mitigation to support data rates as high as 1 Gbits/sec in low mobility and 100 Mbits/sec in high mobility environments. Primary objective of this project is to engineer network and interference geometry to derive fundamental performance bounds and metrics, and to propose novel optimal or near-optimal control algorithms to mitigate interference for the 5G or beyond 5G heterogeneous wireless and complex networks. This project aims to build a stochastic geometry based foundation for wireless networks by synthesizing more realistic network and wireless PHY models with geometric network analysis in a principled manner to determine collective network behavior and to calculate important performance bounds and metrics including, but not limited to, successive interference cancellation probability, outage probability, area spectral efficiency and transport capacity of wireless networks.
Management and allocation of scarce radio resources dynamically appear to be much more important than ever before for next generation wireless telecommunication systems. Otherwise, data rates to be delivered to end-users would stay much below the target rates due to interference. This project also aims to derive techniques, algorithms and protocols that will combat devastating effects of interference and that will maximize bit rates subject to various constraints such as peak power, fairness and feedback constraints.
This EU FP7 People Career Integration Grant, called in short ENIGmA, is executed between 01/04/2012 and 31/03/2016. During its execution, a multitude of important contributions in parallel to the project's goals and vision set forth in the project proposal have been made for revealing hidden underlying dynamics and operating principles for next generation wireless heterogenous and complex networks. These contributions can be categorized along three main dimensions:
(i) Geometric Design and Analysis of Next Generation Wireless Heterogenous Networks [Inaltekin, 2012a; 2012b], [Samarasinghe, Inaltekin and Evans, 2013a; 2013b; 2013c; 2014a; 2014b; 2014c; 2016], [Ak, Inaltekin and Poor, 2016a; 2016b].
(ii) Protocol and Algorithm Design for Next Generation Wireless Heterogenous Networks [Inaltekin and Hanly, 2012], [Samarasinghe, Inaltekin and Evans, 2013d; 2013e], [Yuksekkaya, Inaltekin and Toker, 2013; 2015], [Yuksekkaya, Inaltekin, Toker and Yanikomeroglu, 2015], [Nekouei, Inaltekin and Dey, 2013; 2014a; 2014b; 2016], [Demir, Inaltekin and Toker, 2014; 2015], [Sezer, Gezici and Inaltekin, 2014; 2015], [Sarikaya, Inaltekin, Alpcan and Evans, 2016].
(iii) Analysis of Distributed Processes Running on Complex Networks [Inaltekin, Chiang and Poor, 2014].
During the whole life-cycle of the project over 01/04/2012-31/03/2016, the total number of scholarly publications adds up to 26 (11 journal + 14 conference + 1 book chapter) plus 3 journal papers in review and/or under preparation. These contributions certainly improve our understanding of wireless networking, and improved wireless networking is of particular importance to our society, industry and service sectors that are increasingly looking to wireless mobile technologies for energy efficiency, environment protection and health monitoring. They also benefit European Union's excellence and competitiveness in ICT by developing a new principled and theoretical foundation for the analysis and design of next generation wireless heterogenous and complex communication networks.
REFERENCES
[Ak, Inaltekin and Poor, 2016a] S. Ak, H. Inaltekin and H. V. Poor, “Gaussian approximation for the downlink interference in heterogenous cellular networks," in Proc. 2016 IEEE International Symposium on Information Theory, Barcelona, Spain, Jul 2016.
[Ak, Inaltekin and Poor, 2016b] S. Ak, H. Inaltekin and H. V. Poor, “Downlink outage performance of heterogenous cellular networks,” in Proc. 2016 IEEE International Symposium on Information Theory, Barcelona, Spain, Jul 2016.
[Bleicher, 2013] A. Bleicher, "A surge in small cells," IEEE Spectrum, vol. 50, pp. 38–39, Jan. 2013.
[Demir, Inaltekin and Toker, 2014] U. Demir, H. Inaltekin and C. Toker, “Optimal power control in two-tier networks with DC programming,“ in Proc. 2014 IEEE 23th Signal Processing and Communications Applications Conference (SIU), Trabzon, Turkey, Apr 2014.
[Demir, Inaltekin and Toker, 2015] U. Demir, H. Inaltekin and C. Toker, “Optimal power control in two-tier networks at low SNR regime,“ in Proc. 2015 IEEE 23th Signal Processing and Communications Applications Conference (SIU), Malatya, May 2015.
[Inaltekin, 2012a] H. Inaltekin, "Gaussian approximation for the wireless multi-access interference distribution," IEEE Trans. Signal Process., vol. 60, no. 11, Nov 2012.
[Inaltekin, 2012b] H. Inaltekin, "Gaussian approximation for the wireless multi-access interference distribution and its applications," Technical Report, available online: http://arxiv.org/abs/1204.3812 April 2012.
[Inaltekin and Hanly, 2012] H. Inaltekin and S. V. Hanly, "Optimality of binary power control for the single cell uplink," IEEE Trans. Inf. Theory, vol. 58, no. 10, Oct 2012.
[Inaltekin, Chiang and Poor, 2014] H. Inaltekin, M. Chiang and H. V. Poor, "Delay of social search on small-world random geometric graphs," Journal of Mathematical Sociology, vol. 38, no. 1, pp. 1-46, 2014.
[Nekouei, Inaltekin and Dey, 2013] E. Nekouei, H. Inaltekin and S. Dey, "Distributed cognitive multiple access networks: Power control, scheduling and multiuser diversity," in Proc. 2013 IEEE International Symposium on Information Theory, Istanbul, Turkey, July 2013.
[Nekouei, Inaltekin and Dey, 2014a] E. Nekouei, H. Inaltekin and S. Dey, "Fundamental capacity limits of multiple access cognitive radio networks," Chapter 10 in "Mechanisms and Games for Dynamic Spectrum Allocation," Edited by T. Alpcan, H. Boche, M. Honig and H. V. Poor, Cambridge University Press, 2014.
[Nekouei, Inaltekin and Dey, 2014b] E. Nekouei, H. Inaltekin and S. Dey, "Power control and asymptotic throughput analysis for the distributed cognitive uplink," IEEE Trans. Commun., vol. 62, no. 1, pp. 41-58, Jan 2014.
[Nekouei, Inaltekin and Dey, 2016] E. Nekouei, H. Inaltekin and S. Dey “Throughput Analysis for the Cognitive Uplink Under Limited Primary Cooperation,” IEEE Trans. Commun., to appear.
[Ozfatura, Ercetin and Inaltekin, 2014] M. E. Ozfatura, O. Ercetin and H. Inaltekin, “Optimizing playback delay for multiuser video streaming,” in Proc. IEEE 25th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Washington, DC, Sep 2014
[Ozfatura, Ercetin and Inaltekin, 2016] M. E. Ozfatura, O. Ercetin and H. Inaltekin, “Optimal network-assisted multi-user DASH video streaming,” IEEE Trans. Mobile Compute., under review.
[Samarasinghe, Inaltekin and Evans, 2013a] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal SNR-based coverage in Poisson cellular networks with power density constraints," in Proc. 2013 IEEE Australian Communications Theory Workshop, Adelaide, Australia, Jan-Feb 2013.
[Samarasinghe, Inaltekin and Evans, 2013b] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal SINR-based coverage in Poisson cellular networks with power density constraints," in Proc. 2013 IEEE 78th Vehicular Technology Conference - Fall Meeting, Las Vegas, Sept 2013.
[Samarasinghe, Inaltekin and Evans, 2013c] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Outage capacity of opportunistic beamforming with random user locations," in Proc. 2013 IEEE Global Communications Conference, Atlanta, Dec 2013.
[Samarasinghe, Inaltekin and Evans, 2013d] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal selective feedback policies for opportunistic beamforming," IEEE Trans. Inf. Theory, vol. 59, no. 5, pp. 2897-2913, May 2013.
[Samarasinghe, Inaltekin and Evans, 2013e] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal user selection and the feedback-capacity tradeoff for opportunistic beamforming," ELSEVIER Performance Evaluation, vol. 70, no. 7-8, pp. 472-492, July 2013.
[Samarasinghe, Inaltekin and Evans, 2014a] T. Samarasinghe, H. Inaltekin and J. S. Evans, "On the outage capacity of opportunistic beamforming with random user locations," IEEE Trans. Commun., vol. 62, no. 8, Aug 2014.
[Samarasinghe, Inaltekin and Evans, 2014b] T. Samarasinghe, H. Inaltekin and J. S. Evans, "On optimal downlink coverage in Poisson cellular networks with power density constraints," IEEE Trans. Commun., vol. 62, no. 4, Mar 2014.
[Samarasinghe, Inaltekin and Evans, 2014c] T. Samarasinghe, H. Inaltekin and J. S. Evans, ``Maximizing the coverage-intensity product in random cellular networks," in Proc. 2014 IEEE Australian Communications Theory Workshop, Sydney, Australia, Feb 2014.
[Samarasinghe, Inaltekin and Evans, 2016] T. Samarasinghe, H. Inaltekin and J. S. Evans, “Modeling and analysis of opportunistic beamforming for Poisson wireless networks,” IEEE Trans. Wireless Commun., vol. 15, no. 5, May 2016.
[Sarikaya, Inaltekin, Alpcan and Evans, 2016] Y. Sarikaya, H. Inaltekin, T. Alpcan and J. Evans, “Dynamic control of interference limited underlay D2D networks,” IEEE Trans. Mobile Compute., under review.
[Sezer, Gezici and Inaltekin, 2014] A. D. Sezer, S. Gezici and H. Inaltekin, “Optimal channel switching strategy for average capacity maximization,” in Proc. 39th International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Florence, Italy, May 2014.
[Sezer, Gezici and Inaltekin, 2015] A. D. Sezer, S. Gezici and H. Inaltekin, “Optimal channel switching for average capacity maximization,” IEEE Trans. Commun., vol. 63, no. 6, Jun 2015.
[The Climate Group 2008] The Climate Group, “SMART 2020: Enabling the low carbon economy in the information age,” Technical Report 2008.
[World Health Organization, 2011] World Health Organization, "mHealth: New horizons for health through mobile technologies," Global Observatory for
eHealth Series, vol. 3, 2011.
[Yuksekkaya, Inaltekin and Toker, 2013] B. Yuksekkaya, H. Inaltekin and C. Toker, "Optimum uplink power control under power and interference constraints," in Proc. 2013 IEEE 78th Vehicular Technology Conference - Fall Meeting, Las Vegas, Sept 2013.
[Yuksekkaya, Inaltekin, Toker and Yanikomeroglu, 2015] B. Yuksekkaya, H. Inaltekin, C. Toker and H. Yanikomeroglu, “Power control for two-tier SIMO-MIMO uplink under interference constraints,” in Proc. 2015 IEEE 23th Signal Processing and Communications Applications Conference (SIU), Malatya, Turkey, May 2015.
[Yuksekkaya, Inaltekin and Toker, 2015] B. Yuksekkaya, H. Inaltekin and C. Toker, “Near-optimum power control for two-tier SIMO uplink under power and interference constraints,” in Proc. 2015 IEEE 16th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Stockholm, Sweden, Jun-Jul 2015.
Cognitive radio networks are expected to solve the radio spectrum scarcity problem and to unlock the potential of industry and service sectors for product innovation and useful intellectual property generation [Goldsmith et al., 2009]. Information and communication technologies empowered with next generation wireless telecommunication protocols for machine-to-machine communication is expected to decrease total greenhouse gas emissions from all industry sectors by 15%, which can be translated into €600 billion savings per year by 2020 [The Climate Group 2008]. The use of wireless mobile technologies for all kinds of medical and public health practices such as patient monitoring and mobile telemedicine is starting to unlock the innovative capacity of European health related industries [World Health Organization, 2011].
Such a wide range of application areas brings together new interoperability challenges for heterogenous network architectures and requires innovative approaches for interference mitigation to support data rates as high as 1 Gbits/sec in low mobility and 100 Mbits/sec in high mobility environments. Primary objective of this project is to engineer network and interference geometry to derive fundamental performance bounds and metrics, and to propose novel optimal or near-optimal control algorithms to mitigate interference for the 5G or beyond 5G heterogeneous wireless and complex networks. This project aims to build a stochastic geometry based foundation for wireless networks by synthesizing more realistic network and wireless PHY models with geometric network analysis in a principled manner to determine collective network behavior and to calculate important performance bounds and metrics including, but not limited to, successive interference cancellation probability, outage probability, area spectral efficiency and transport capacity of wireless networks.
Management and allocation of scarce radio resources dynamically appear to be much more important than ever before for next generation wireless telecommunication systems. Otherwise, data rates to be delivered to end-users would stay much below the target rates due to interference. This project also aims to derive techniques, algorithms and protocols that will combat devastating effects of interference and that will maximize bit rates subject to various constraints such as peak power, fairness and feedback constraints.
This EU FP7 People Career Integration Grant, called in short ENIGmA, is executed between 01/04/2012 and 31/03/2016. During its execution, a multitude of important contributions in parallel to the project's goals and vision set forth in the project proposal have been made for revealing hidden underlying dynamics and operating principles for next generation wireless heterogenous and complex networks. These contributions can be categorized along three main dimensions:
(i) Geometric Design and Analysis of Next Generation Wireless Heterogenous Networks [Inaltekin, 2012a; 2012b], [Samarasinghe, Inaltekin and Evans, 2013a; 2013b; 2013c; 2014a; 2014b; 2014c; 2016], [Ak, Inaltekin and Poor, 2016a; 2016b].
(ii) Protocol and Algorithm Design for Next Generation Wireless Heterogenous Networks [Inaltekin and Hanly, 2012], [Samarasinghe, Inaltekin and Evans, 2013d; 2013e], [Yuksekkaya, Inaltekin and Toker, 2013; 2015], [Yuksekkaya, Inaltekin, Toker and Yanikomeroglu, 2015], [Nekouei, Inaltekin and Dey, 2013; 2014a; 2014b; 2016], [Demir, Inaltekin and Toker, 2014; 2015], [Sezer, Gezici and Inaltekin, 2014; 2015], [Sarikaya, Inaltekin, Alpcan and Evans, 2016].
(iii) Analysis of Distributed Processes Running on Complex Networks [Inaltekin, Chiang and Poor, 2014].
During the whole life-cycle of the project over 01/04/2012-31/03/2016, the total number of scholarly publications adds up to 26 (11 journal + 14 conference + 1 book chapter) plus 3 journal papers in review and/or under preparation. These contributions certainly improve our understanding of wireless networking, and improved wireless networking is of particular importance to our society, industry and service sectors that are increasingly looking to wireless mobile technologies for energy efficiency, environment protection and health monitoring. They also benefit European Union's excellence and competitiveness in ICT by developing a new principled and theoretical foundation for the analysis and design of next generation wireless heterogenous and complex communication networks.
REFERENCES
[Ak, Inaltekin and Poor, 2016a] S. Ak, H. Inaltekin and H. V. Poor, “Gaussian approximation for the downlink interference in heterogenous cellular networks," in Proc. 2016 IEEE International Symposium on Information Theory, Barcelona, Spain, Jul 2016.
[Ak, Inaltekin and Poor, 2016b] S. Ak, H. Inaltekin and H. V. Poor, “Downlink outage performance of heterogenous cellular networks,” in Proc. 2016 IEEE International Symposium on Information Theory, Barcelona, Spain, Jul 2016.
[Bleicher, 2013] A. Bleicher, "A surge in small cells," IEEE Spectrum, vol. 50, pp. 38–39, Jan. 2013.
[Demir, Inaltekin and Toker, 2014] U. Demir, H. Inaltekin and C. Toker, “Optimal power control in two-tier networks with DC programming,“ in Proc. 2014 IEEE 23th Signal Processing and Communications Applications Conference (SIU), Trabzon, Turkey, Apr 2014.
[Demir, Inaltekin and Toker, 2015] U. Demir, H. Inaltekin and C. Toker, “Optimal power control in two-tier networks at low SNR regime,“ in Proc. 2015 IEEE 23th Signal Processing and Communications Applications Conference (SIU), Malatya, May 2015.
[Inaltekin, 2012a] H. Inaltekin, "Gaussian approximation for the wireless multi-access interference distribution," IEEE Trans. Signal Process., vol. 60, no. 11, Nov 2012.
[Inaltekin, 2012b] H. Inaltekin, "Gaussian approximation for the wireless multi-access interference distribution and its applications," Technical Report, available online: http://arxiv.org/abs/1204.3812 April 2012.
[Inaltekin and Hanly, 2012] H. Inaltekin and S. V. Hanly, "Optimality of binary power control for the single cell uplink," IEEE Trans. Inf. Theory, vol. 58, no. 10, Oct 2012.
[Inaltekin, Chiang and Poor, 2014] H. Inaltekin, M. Chiang and H. V. Poor, "Delay of social search on small-world random geometric graphs," Journal of Mathematical Sociology, vol. 38, no. 1, pp. 1-46, 2014.
[Nekouei, Inaltekin and Dey, 2013] E. Nekouei, H. Inaltekin and S. Dey, "Distributed cognitive multiple access networks: Power control, scheduling and multiuser diversity," in Proc. 2013 IEEE International Symposium on Information Theory, Istanbul, Turkey, July 2013.
[Nekouei, Inaltekin and Dey, 2014a] E. Nekouei, H. Inaltekin and S. Dey, "Fundamental capacity limits of multiple access cognitive radio networks," Chapter 10 in "Mechanisms and Games for Dynamic Spectrum Allocation," Edited by T. Alpcan, H. Boche, M. Honig and H. V. Poor, Cambridge University Press, 2014.
[Nekouei, Inaltekin and Dey, 2014b] E. Nekouei, H. Inaltekin and S. Dey, "Power control and asymptotic throughput analysis for the distributed cognitive uplink," IEEE Trans. Commun., vol. 62, no. 1, pp. 41-58, Jan 2014.
[Nekouei, Inaltekin and Dey, 2016] E. Nekouei, H. Inaltekin and S. Dey “Throughput Analysis for the Cognitive Uplink Under Limited Primary Cooperation,” IEEE Trans. Commun., to appear.
[Ozfatura, Ercetin and Inaltekin, 2014] M. E. Ozfatura, O. Ercetin and H. Inaltekin, “Optimizing playback delay for multiuser video streaming,” in Proc. IEEE 25th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Washington, DC, Sep 2014
[Ozfatura, Ercetin and Inaltekin, 2016] M. E. Ozfatura, O. Ercetin and H. Inaltekin, “Optimal network-assisted multi-user DASH video streaming,” IEEE Trans. Mobile Compute., under review.
[Samarasinghe, Inaltekin and Evans, 2013a] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal SNR-based coverage in Poisson cellular networks with power density constraints," in Proc. 2013 IEEE Australian Communications Theory Workshop, Adelaide, Australia, Jan-Feb 2013.
[Samarasinghe, Inaltekin and Evans, 2013b] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal SINR-based coverage in Poisson cellular networks with power density constraints," in Proc. 2013 IEEE 78th Vehicular Technology Conference - Fall Meeting, Las Vegas, Sept 2013.
[Samarasinghe, Inaltekin and Evans, 2013c] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Outage capacity of opportunistic beamforming with random user locations," in Proc. 2013 IEEE Global Communications Conference, Atlanta, Dec 2013.
[Samarasinghe, Inaltekin and Evans, 2013d] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal selective feedback policies for opportunistic beamforming," IEEE Trans. Inf. Theory, vol. 59, no. 5, pp. 2897-2913, May 2013.
[Samarasinghe, Inaltekin and Evans, 2013e] T. Samarasinghe, H. Inaltekin and J. S. Evans, "Optimal user selection and the feedback-capacity tradeoff for opportunistic beamforming," ELSEVIER Performance Evaluation, vol. 70, no. 7-8, pp. 472-492, July 2013.
[Samarasinghe, Inaltekin and Evans, 2014a] T. Samarasinghe, H. Inaltekin and J. S. Evans, "On the outage capacity of opportunistic beamforming with random user locations," IEEE Trans. Commun., vol. 62, no. 8, Aug 2014.
[Samarasinghe, Inaltekin and Evans, 2014b] T. Samarasinghe, H. Inaltekin and J. S. Evans, "On optimal downlink coverage in Poisson cellular networks with power density constraints," IEEE Trans. Commun., vol. 62, no. 4, Mar 2014.
[Samarasinghe, Inaltekin and Evans, 2014c] T. Samarasinghe, H. Inaltekin and J. S. Evans, ``Maximizing the coverage-intensity product in random cellular networks," in Proc. 2014 IEEE Australian Communications Theory Workshop, Sydney, Australia, Feb 2014.
[Samarasinghe, Inaltekin and Evans, 2016] T. Samarasinghe, H. Inaltekin and J. S. Evans, “Modeling and analysis of opportunistic beamforming for Poisson wireless networks,” IEEE Trans. Wireless Commun., vol. 15, no. 5, May 2016.
[Sarikaya, Inaltekin, Alpcan and Evans, 2016] Y. Sarikaya, H. Inaltekin, T. Alpcan and J. Evans, “Dynamic control of interference limited underlay D2D networks,” IEEE Trans. Mobile Compute., under review.
[Sezer, Gezici and Inaltekin, 2014] A. D. Sezer, S. Gezici and H. Inaltekin, “Optimal channel switching strategy for average capacity maximization,” in Proc. 39th International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Florence, Italy, May 2014.
[Sezer, Gezici and Inaltekin, 2015] A. D. Sezer, S. Gezici and H. Inaltekin, “Optimal channel switching for average capacity maximization,” IEEE Trans. Commun., vol. 63, no. 6, Jun 2015.
[The Climate Group 2008] The Climate Group, “SMART 2020: Enabling the low carbon economy in the information age,” Technical Report 2008.
[World Health Organization, 2011] World Health Organization, "mHealth: New horizons for health through mobile technologies," Global Observatory for
eHealth Series, vol. 3, 2011.
[Yuksekkaya, Inaltekin and Toker, 2013] B. Yuksekkaya, H. Inaltekin and C. Toker, "Optimum uplink power control under power and interference constraints," in Proc. 2013 IEEE 78th Vehicular Technology Conference - Fall Meeting, Las Vegas, Sept 2013.
[Yuksekkaya, Inaltekin, Toker and Yanikomeroglu, 2015] B. Yuksekkaya, H. Inaltekin, C. Toker and H. Yanikomeroglu, “Power control for two-tier SIMO-MIMO uplink under interference constraints,” in Proc. 2015 IEEE 23th Signal Processing and Communications Applications Conference (SIU), Malatya, Turkey, May 2015.
[Yuksekkaya, Inaltekin and Toker, 2015] B. Yuksekkaya, H. Inaltekin and C. Toker, “Near-optimum power control for two-tier SIMO uplink under power and interference constraints,” in Proc. 2015 IEEE 16th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Stockholm, Sweden, Jun-Jul 2015.