Journal Papers

1. Juping Zhang, Minglei You, Gan Zheng, Ioannis Krikidis, and Liqiang Zhao, Model-driven Learning for Generic MIMO Downlink Beamforming with Uplink Channel Information, IEEE Transactions on Wireless Communications, vol. 21, iss. 4, pp. 2368-2382, April 2022.
2. Liqiang Zhao, Guorong Zhou, Gan Zheng, Chih-Lin I, Xiao-Hu You, and Lajos Hanzo, Open-Source Multi-Access Edge Computing for 6G: Opportunities and Challenges, IEEE Access, vol. 9, pp. 158426-158439, 2021.
3. Haiyan Tu, Liqiang Zhao, Chen Feng, and Cheng Guo, NOMA-enabled Cellular Radio Access Networks Relying on Control- and User-Plane Separation, IEEE Transactions on Vehicular Technology, vol. 70, iss. 10, pp. 11116-11120, October 2021.
4. Yaoyuan Zhang, Liqiang Zhao, Gan Zheng, Xiaoli Chu, Zhiguo Ding, and Kwang-Cheng Chen, Resource Allocation for Open-Loop Ultra-Reliable and Low-Latency Uplink Communications in Vehicular Networks, IEEE Transactions on Vehicular Technology, vol. 70, iss. 3, pp. 2590-2604, March 2021.
5. Guorong Zhou, Liqiang Zhao, Yunfeng Wang, Gan Zheng, and Lajos Hanzo, Energy Efficiency and Delay Optimization for Edge Caching Aided Video Streaming, IEEE Transactions on Vehicular Technology, vol. 69, iss. 11, pp. 14116-14121, November 2020.
6. Pengfeng Hou, Andrew W. Eckford, and Liqiang Zhao, Analysis and Design of Two-Hop Diffusion-based Molecular Communication with Ligand Receptors, IEEE Access, vol. 8, pp. 189458-189470, 2020.
7. Cheng Guo, Liqiang Zhao, Chen Feng, Zhiguo Ding, and Huiming Wang, Secrecy Performance of NOMA Systems with Energy Harvesting and Full-duplex Relaying, IEEE Transactions on Vehicular Technology, vol. 69, iss. 10, pp. 12301-12305, October 2020.
8. Guorong Zhou, Liqiang Zhao, Gan Zheng, and Lajos Hanzo, Utility Analysis of Radio Access Network Slicing, IEEE Transactions on Vehicle Technology, vol. 69, iss. 1, pp. 1163-1167, January 2020.
9. Xiaohuan Rao, Liqiang Zhao, Kai Liang, and Kezhi Wang, Edge Caching and Computation Offloading in Fog-enabled Radio Access Network, Wireless Personal Communications, vol. 109, pp. 297–313, November 2019.
10. Kai Liang, Gexian Liu, Liqiang Zhao, Xiaoli Chu, Shuai Wang, and Lajos Hanzo, Performance Analysis of Software-defined Radio Access Networks Relying on Control- and User-Plane Separation, IEEE Transactions on Vehicle Technology, July 2019, vol. 68, iss. 7, pp. 7241-7245.
11. Cheng Guo, Liqiang Zhao, Chen Feng, Zhiguo Ding, and Hsiao-Hwa Chen, Energy Harvesting Enabled NOMA Systems with Full-duplex Relaying, IEEE Transactions on Vehicle Technology, July 2019, vol. 68, iss. 7, pp. 7179-7183.
12. Cheng Guo, Jie Xin, Liqiang Zhao, and Xiaoli Chu, Performance Analysis of Cooperative NOMA and OMA with Energy Harvesting in Multi-Cell Networks, China Communications, 2019, 16 (11): 120-130.
13. Guogang Zhao, Sheng Chen, Lin Qi, Liqiang Zhao, and Lajos Hanzo, Mobile-Traffic-Aware Offloading for Energy- and Spectral-Efficient Large-Scale D2D-Enabled Cellular Networks, IEEE Transactions on Wireless Communications, June 2019, Vol. 18, No. 6, pp. 3251-3264.
14. Xiaohuan Rao, Liqiang Zhao, Xiaoli Chu, and Kwang-Cheng Chen, Energy Efficiency of Stratosphere Heterogeneous Wireless Networks, Physical Communication, June 2019, Vol. 34, No. 6, pp. 19-26.
15. Kai Liang, Liqiang Zhao, Gan Zheng, and Hsiao-Hwa Chen, Non-uniform Deployment of Power Beacons for Wireless Powered Communication Networks, IEEE Transactions on Wireless Communications, March 2019, Vol. 18, No. 3, pp. 1887-1899.
16. Jianbo Du, Liqiang Zhao, Jie Feng, Xiaoli Chu, and Chih-Lin I, Enabling Low-Latency Applications in LTE-A based Mixed Cloud/Fog-Radio Access Networks, IEEE Transactions on Vehicle Technology, February 2019, Vol. 68, No. 2, pp. 1757-1771.
17. Liqin Shi, Liqiang Zhao, Gan Zheng, Incentive Design for Cache-Enabled D2D Underlaid Cellular Networks Using Stackelberg Game, IEEE Transactions on Vehicle Technology, January 2019, Vol. 68, No. 1, pp. 765-779.
18. Cheng Guo, Abdelmalik N. Aljalaiy, Chen Feng, Liqiang Zhao, Victor C. M. Leungy, and Rabab K. Ward, Compute-and-Forward for Uplink Non-Orthogonal Multiple Access, IEEE Wireless Communication Letters, December 2018, Vol. 7, No. 6, pp. 986-989.
19. Guogang Zhao, Sheng Chen, Shaoshi Yang, Liqiang Zhao, and Lajos Hanzo, Energy-Spectral-Efficiency Analysis and Optimization of Heterogeneous Cellular Networks: A Large-Scale User-Behavior Perspective, IEEE Transactions on Vehicle Technology, May 2018, Vol. 67, No. 5, pp. 4098-4112.
20. Jianbo Du, Liqiang Zhao, Jie Feng, and Xiaoli Chu, Computation Offloading and Resource Allocation in Mixed Fog/Cloud Computing Systems with Min-Max Fairness Guarantee, IEEE Transactions on Communications, April 2018, Vol. 66, no. 4, pp. 1594-1608.
21. Bodong Shang, Liqiang Zhao, and Kwang-Cheng Chen, and Xiaoli Chu, An Economic Aspect of Device-to-Device Assisted Offloading in Cellular Networks, IEEE Transactions on Wireless Communications, April 2018, vol. 17, no. 4, pp. 2289-2304.
22. Liqin Shi, Liqiang Zhao, Kai Liang, and Hsiao-Hwa Chen, Wireless Energy Transfer Enabled D2D in Underlaying Cellular Networks, IEEE Transactions on Vehicle Technology, February 2018, vol. 67, no. 2, pp. 1845-1849.
23. Shuai Wang, Liqiang Zhao, Kai Liang, Xiaoli Chu, and Bingli Jiao, Fair Power Allocation for Full-Duplex Wireless-Powered Communication Networks, Physical Communication, February 2018, vol. 26, no. 2, pp. 134-140.
24. Qiong Shi, Liqiang Zhao, Yaoyuan Zhang, Gan Zheng, F. Richard Yu, and Hsiao-Hwa Chen, Energy-efficiency versus Delay Tradeoff in Wireless Networks Virtualization, IEEE Transactions on Vehicular Technology, January 2018, vol. 67, no. 1, pp. 837-841.
25. Zhao Hui, Zhao Liqiang, Liang Kai, and Pan Chengkang, Radio Access Network Slicing based on C/U Plane Separation, China Communications, 2017 , 14 (12) :134-141.
26. Kai Liang, Liqiang Zhao, Kun Yang, and Xiaoli Chu, Online Power and Time Allocation in MIMO Uplink Transmissions Powered by Wireless Energy Transfer, IEEE Trans. on Vehicular Technology, August 2017, Vol. 66, No. 8, pp. 6819-6830.
27. Guogang Zhao, Sheng Chen, Liqiang Zhao, and Lajos Hanzo, Joint Energy-Spectral-Efficiency Optimization of CoMP and BS Deployment in Dense Large-Scale Cellular Networks, IEEE Transactions on Wireless Communications, July 2017, Vol. 16, No. 7, pp. 4832-4847.
28. Bodong Shang, Liqiang Zhao, Kwang-Cheng Chen, Operator’s Economy of Device-to-Device Offloading in Underlaying Cellular Networks, IEEE Communications Letters, April 2017, Vol. 21, No. 4, pp. 865-868.
29. Liqin Shi, Liqiang Zhao, Kai Liang, Power Allocation for Wireless Powered MIMO Transmission with Non-linear RF Energy Conversion Models, China Communications, 2017, 14 (2): 57 – 64.
30. Kai Liang, Liqiang Zhao, Xiaoli Chu, and Hsiao-Hwa Chen, An Integrated Architecture for Software Defined and Virtualized Radio Access Networks with Fog Computing, IEEE Network Magazine, January/February 2017, Vol. 31, No. 1, pp. 80-87.
31. Kai Liang, Liqiang Zhao, Xiaohui Zhao, Yong Wang, and Shumao Ou, Joint Resource Allocation and Coordinated Computation Offloading for Cloud and Fog Radio Access Networks, China Communications, 2016, 13(2z), pp. 131-139.
32. Kai Liang, Liqiang Zhao, Zhiguo Ding, and Hsiao-Hwa Chen, Double Side Signal Splitting SWIPT for Downlink CoMP Transmissions with Limited Capacity Backhaul, IEEE Communications Letters, December 2016, Vol. 20, No. 12, pp. 2438-2442. 
33. Jianbo Du, Liqiang Zhao, Jie Feng, Jie Xin, and Yong Wang, Enhanced PSO based Energy-Efficient Resource Allocation and CQI based MCS selection in LTE-A Heterogeneous System, China Communications, November 2016, 13(11), pp. 197-204. 
34. Yaoyuan Zhang, Liqiang Zhao, Nan Li, Guopeng Zhang, and Hsiao-Hwa Chen, A Virtualized Resource Management Scheme for Heterogeneous Cellular Networks, Wireless Communications and Mobile Computing, October 2016, Vol. 16, No. 17, pp. 3163-3174. 
35. Xiaoxiao Zhang, Liqiang Zhao, and Kai Liang, Heterogeneous Control and Data Sub-network for Millimeter-wave Communications, China Communications, 2015, 12 (1), pp. 58-66.
36. Kai Liang, Liqiang Zhao, Kun Yang, Zheng Gan, and Wei Ding, A Fair Power Splitting Algorithm for Simultaneous Wireless Information and Energy Transfer in CoMP Downlink Transmission, Wireless Personal Communications, July 2015, Vol. 85, No. 4, pp. 2687-2710. 
37. Liqiang Zhao, Yuanyuan Wang, Kun Yang, Jiangtao Yi, and Hailin Zhang, Nash Bargaining Solution Based Joint Time-Frequency-Code-Power Resource Management Algorithm for TD-LTE Systems, International Journal of Communication Systems, October 2014, vol. 27, no. 10, pp. 1752-1765. 
38. Kai Liang, Liqiang Zhao, Yalina Liu, Qingxue Liu, Kun Yang, and Zhili Sun, Enhanced IEEE 802.11 MAC Protocol for Precision Formation Flyging-based Distributed Spacecraft, Wireless Personal Communications, June 2014, vol. 79, no. 1, pp. 375-388. 
39. Liqiang Zhao, Kai Liang, David Loperz-Perez, An Enhanced Signal-Timing-Offset Compensation Algorithm for Coordinated Multipoint-to-Multiuser Systems, IEEE Communications Letter, June 2014, Vol. 18, No. 6, pp. 983-986. 
40. Liqiang Zhao, Li Cong, Wei Ding, Xinheng Wang, and Hailin Zhang, Incomplete Cooperation-based Services Differentiation in WLANs, Wiley Journal of Wireless Communications and Mobile Computing, April 2012, vol. 12, no. 6, pp. 481-491. 
41. Liqiang Zhao, Li Cong, Feixia Liu, Kun Yang, and Hailin Zhang, Joint time-frequency-power resource allocation for low-medium-altitude platforms-based WiMAX Networks, IET Communications, 4 May 2011, Vol. 5, No. 7, pp. 967-974. 
42. Li Cong, Liqiang Zhao, Hailin Zhang, Kun Yang, Guopeng Zhang, and Wenkai Zhu, Pricing-Based Game for Spectrum Allocation in Multi-Relay Cooperative Transmission Networks, IET Communications, February 2011, Vol. 5, No. 4, pp. 563-573.
43. Li Cong, Liqiang Zhao, Kun Yang, Guopeng Zhang, and Hailin Zhang, A Stackelberg Game for Resource Allocation in Multiuser Cooperative Transmission Network, Wiley Journal of Wireless Communications and Mobile Computing, January 2011, Vol.11, No. 1, pp.129-141. 
44. Liqiang Zhao, Jie Zhang, and Hailin Zhang, Hub-Polling-based IEEE 802.11 PCF with Integrated QoS Differentiation, Wiley Journal of Wireless Communications and Mobile Computing, September 2009, Vol. 9, No. 9, pp. 1220-1230. 
45. Liqiang Zhao, Le Guo, Jie Zhang, and Hailin Zhang, Game-theoretic Medium Access Control Protocol for Wireless SensorNetworks, IET Communications, August 2009, vol. 3, no. 8, pp. 1274-1283.
46. Yumin Wu, Kun Yang, Liqiang Zhao, and X. Cheng, Congestion-aware Proactive Vertical Handoff Algorithm in Heterogeneous Wireless Networks, IET Communications, July 2009, vol.3, no. 7, pp. 1103-1114. 
47. Guopeng Zhang, Hailin Zhang, Liqiang Zhao, Wei Wang, and Li Cong, Fair Resource Sharing for Cooperative Relay Networks Using Nash Bargaining Solutions, IEEE Communications Letters, June 2009, vol.13, no.6, pp. 381-383. 
48. Guopeng Zhang, Li Cong, Liqiang Zhao, Kun Yang, and Hailin Zhang, Competitive Resource Sharing Based on Game Theory in Cooperative Relay Networks, ETRI Journal, Feb. 2009, vol.31, no.1, pp. 89-91. 
49. Liqiang Zhao, Huawei Zhang, Jie Zhang, and Hailin Zhang, Selfish Traffic with Rational Nodes in WLANs, IEEE Communications Letters, September 2008, Vol. 12, No. 9, pp. 645-647. 
50. Liqiang Zhao, Joyce Y. Wu, Hailin Zhang, and Jie Zhang, Integrated QoS Differentiation over IEEE 802.11 WLANs, IET Communications, February 2008, Vol. 2, No. 2, pp. 329-335. 
51. Liqiang Zhao, Jie Zhang, and Hailin Zhang, Using Incompletely Cooperative Game Theory in Wireless Mesh Networks, IEEE Network, January/February 2008, Vol. 22, No. 1, pp. 39-44. 
52. Liqiang Zhao, Jie Zhang, and Hailin Zhang, Directional DCF - a MAC Protocol to Simultaneously Support Both Omni-directional and Smart Antennas in a Same WLAN Cell, IET Communications, August 2007, Vol. 1, No. 4, pp. 765-771. 
53. Liqiang Zhao, Jie Zhang, and Hailin Zhang, GDCF: Game-theoretic Distributed Co-ordination Function in WLANs, Electronics Letters, 26 April 2007, Vol. 43, No. 9, pp. 510-511. 
54. Liqiang Zhao, Changxin Fan, Enhancement of QoS Differentiation over IEEE 802.11 WLAN, IEEE Communications Letters, August 2004, Vol. 8, No. 8, pp. 494-496. 
55. Liqiang Zhao, Changxin Fan, M-PCF: modified IEEE 802.11 PCF protocol implementing QoS, Electronics Letters, 21 November 2002, Vol. 38, No. 24, pp. 1611-1613.

Conference Papers

1. Muhammad Muhammad Bala, Liqiang Zhao, Zhen Gao, Leveraging Blockchain for Isolation Enhancement of Network Slices, IEEE Global Communications Conference (Globecom), Rio de Janeiro, Brazil, 4 - 8 December 2022.
2. Manhua Zhu, Haiyan Tu, Yunfeng Wang, Guorong Zhou, Liqiang Zhao, Microservice-based Management and Orchestration of 5G Core Network, IEEE 33rd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 12 - 15 September 2022, Virtual Conference.
3. Yuyang Wang, Liqiang Zhao, Haiyan Tu, Guorong Zhou, Qingyu Yin, Design and Implementation of Endogenous Intelligence-based Multi-Access Edge Computing, IEEE 33rd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 12 - 15 September 2022, Virtual Conference.
4. Yinxin Li, Haiyan Tu, Guorong Zhou, Ting Li, Yunfeng Wang, and Liqiang Zhao, Design and Implementation of Adaptive-Bitrate-Streaming-based Edge Caching, IEEE 95th Vehicular Technology Conference (VTC 2022-Spring), Helsinki, Finland, 19-22 June 2022.
5. Huixian Gu, Weiwen Cai, Liqiang Zhao, Weimin Luo, Guorong Zhou, Qiming Chen, Haiyan Tu, Zhigang Wang, Shuchun Li, Dynamic Game-based Caching Replacement in Edge Networks, IEEE 95th Vehicular Technology Conference (VTC 2022-Spring), Helsinki, Finland, 19-22 June 2022.
6. Shuai Wang, Liqiang Zhao, Kai Liang, Gan Zheng, Secrecy Profits Analysis of Wireless-Powered Networks with Randomly Distributed Eavesdroppers, IEEE International Conference on Communications (ICC), 20-24 May 2019, Shanghai, China.
7. Yanjun Guo, Liqiang Zhao, Xiaodi Lu, Jian Yang, Yong Wang, Qi Liu, Jiahui Qiu, Fog-enabled WLAN for Indoor Positioning, IEEE Vehicular Technology Conference (VTC), 28 April - 1 May 2019, Kuala Lumpur, Malaysia.
8. Guorong Zhou, Liqiang Zhao, Qiong Shi, Gan Zheng, and Kwang-Cheng Chen, Rate-Delay Performance of Radio Access Network Slicing, IEEE Global Communications Conference (Globecom), 9-13 December 2018, Abu Dhabi, UAE.
9. Pengfeng Hou, Andrew W. Eckford, and Liqiang Zhao, Improving Receiver Performance of Diffusion-Based Molecular MIMO Communication, IEEE International Conference on Nanotechnology, 23-26 July 2018, Ireland.
10. Pengfeng Hou, Andrew W. Eckford, and Liqiang Zhao, Signal Transduction for Two-Hop Molecular Communication Networks, IEEE International Symposium on Information Theory, June 17-22, 2018, USA.
11. Xiaohuan Rao, Liqiang Zhao, Bodong Shang, and Kwang-Cheng Chen, Performance Analysis of Wireless Powered Cellular Network: Radom Deployment of Power Beacons, IEEE International Conference on Communications (ICC), 20-24 May 2018, USA.
12. Gexian Liu, Liqiang Zhao, Bodong Shang, Xiaoli Chu, and Kwang-Cheng Chen, Optimal Pricing Strategy of Telecom Operator in Cellular Networks with Random Topologies, IEEE International Conference on Communications (ICC), 20-24 May 2018, USA.
13. Jie Feng, Liqiang Zhao, Jianbo Du, Xiaoli Chu, and F. Richard Yu, Computation Offloading and Resource Allocation in D2D Network with Fog Computing, IEEE International Conference on Communications (ICC), 20-24 May 2018, USA.
14. Jie Feng, Liqiang Zhao, Jianbo Du, Xiaoli Chu, and F. Richard Yu, Energy-efficient Resource Allocation in Fog Computing Supported IoT with Min-max Fairness Guarantees, IEEE International Conference on Communications (ICC), 20-24 May 2018, USA.
15. Jianbo Du, Liqiang Zhao, Jie Feng, Xiaoli Chu, and F. Richard Yu, Economical Revenue Maximization in Cache Enhanced Mobile Edge Computing, IEEE International Conference on Communications (ICC), 20-24 May 2018, USA.
16. Bodong Shang, Liqiang Zhao, Kwang-Cheng Chen, and Xiaoli Chu, Energy Efficient D2D-Assisted Offloading with Wireless Power Transfer, IEEE Global Communications Conference (Globecom), 4-8 December 2017, Singapore.
17. Liqin Shi, Liqiang Zhao, Kai Liang, Xiaoli Chu, Gang Wu, and Hsiao-Hwa Chen, Profit Maximization in Wireless Powered Communications with Non-linear Energy Conversion and Storage Efficiencies, IEEE International Conference on Communications (ICC), 21-25 May 2017, Paris, France.
18. Bodong Shang, Liqiang Zhao, and Kwang-Cheng Chen, Enabling Device-to-Device Communications in LTE-Unlicensed Spectrum, IEEE International Conference on Communications (ICC), 21-25 May 2017, Paris, France.
19. Yaoyuan Zhang, Liqiang Zhao, David Lopez-Perez and Kwang-Cheng Chen, Energy-Efficient Virtual Resource Allocation in OFDMA Systems, IEEE Global Communications Conference (Globecom), 4-8 December 2016, Washington, DC USA. 
20. Liqin Shi, Liqiang Zhao, and Kai Liang, Battery State Based Power and Time Allocation in Wireless Powered MIMO Uplink Transmission, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), September 4-7, 2016, Valencia, Spain. 
21. Bodong Shang, Liqiang Zhao, Kwang-Cheng Chen, and Guogang Zhao, Energy-efficient Device-to-Device Communication in Cellular Networks, IEEE Vehicular Technology Conference (VTC), 15-18 May 2016, Nanjing, China. 
22. Jie Feng, Liqiang Zhao, Chen Chen, Zhiyuan Ren, User-oriented Load Balance in Software-Defined Campus WLANs, IEEE Vehicular Technology Conference (VTC), 15-18 May 2016, Nanjing, China.
23. Cheng Guo, Liqiang Zhao, Guowei Fan, Kai Liang, and Fumiyuki Adachi, Capacity-and-Energy Efficient Resource Allocation for Emergency Communications, IEEE Vehicular Technology Conference (VTC), 11-14 May 2015, Glasgow, Scotland. 
24. Liqiang Zhao, Guogang Zhao and Tim O'Farrell, Efficiency Metrics for Wireless Communications, the 24^th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 8-11 September 2013, London, UK. 
25. Liqiang Zhao, Baoliang Li, and Kaikai Meng, Bing Gong, and Yuan Zhou, A Novel  User Scheduling for Multiuser MIMO Systems with Block Diagonalization, the 24th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 8-11 September 2013, London, UK. 
26. Liqiang Zhao, Chi Zhang, Lajos Hanzo, and Hailin Zhang, Power-Efficient Radio Resource Allocation for Low-Medium-Altitude Aerial Platform Based TD-LTE Networks, IEEE Vehicular Technology Conference (VTC), 3-6 September 2012, Québec City, Canada. 
27. Liqiang Zhao, Jiangtao Yi, Fumiyuki Adachi, Chi Zhang, and Hailin Zhang, Radio Resource Allocation for Low-Medium-Altitude Aerial Platform Based TD-LTE Networks against Disaster, IEEE Vehicular Technology Conference (VTC), 6-9 May 2012, Yokohama, Japan.
28. Liqiang Zhao, Jian Cai, and Hailin Zhang, Radio-Efficient Adaptive Modulation and Coding: Green Communication Perspective, IEEE Vehicular Technology Conference (VTC), 5-18 May 2011, Budapest, Hungary. 
29. Liqiang Zhao, Li Cong, Wei Ding, Hailin Zhang, and Jie Zhang, Game-theoretic EDCA in IEEE 802.11e WLANs, IEEE Vehicular Technology Conference (VTC), 21-24 September 2008, Calgary, Canada.
30. Liqiang Zhao, Wei Ding, Hailin Zhang, and Jie Zhang, Game-theoretic Particle Swarm Optimization for WMNs, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 15-18 September 2008, Glamorous Cannes, France. 
31. Liqiang Zhao, Jie Zhang, and Hailin Zhang, Using Incompletely Cooperative Game Theory in Wireless Sensor Networks, IEEE Wireless Communications and Networking Conference (WCNC), 31 March - 3 April 2008, Las Vegas, USA. 
32. Liqiang Zhao, Jie Zhang, Kun Yang, and Hailin Zhang, Using Incompletely Cooperative Game Theory in Mobile Ad Hoc Networks, IEEE International Conference on Communications (ICC), Glasgow, UK, 24-27 June 2007.