Book Chapters
1-M. Mohammadi, B. K. Chalise, H. A. Suraweera and Z. Ding, "Full-duplex non-orthognal multiple access systems," chapter in Full-Duplex Communications for Future Wireless Networks, (Eds. H. Alves, T. Riihonen and H. A. Suraweera), Springer, 2020.
2-M. Mohammadi, B. K. Chalise and H. A. Suraweera, "Full-duplex wireless-powered communications," invited chapter in Wireless Information and Power Transfer: A New Paradigm for Green Communications, (Eds. D. N. K. Jayakody, J. Thompson, S. Chatzinotas and S. Durrani), Springer, 2018.
Survey Papers
M. Mohammadi, Z. Mobini, D Gallappathtthige, and C. Tellambura, ``A Comprehensive survey on full-duplex communication: Current solutions, future trends, and open issues", IEEE Communications Survey & Tutorials, vol. 25, no. 4, pp. 2190--2244, Fourthquarter. 2023.
Journal Papers
X. Cao, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “RIS-Assisted XL-MIMO for Near-Field and Far-Field Communications", IEEE Transactions on Wireless Communications, Accepted, 2025.
D. -T. Hua, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Cell-free massive MIMO SWIPT with beyond diagonal reconfigurable intelligent surfaces", IEEE Transactions on
Communications, Accepted, 2025.
D. Galappaththige, M. Mohammadi, H. Q. Ngo, M. Matthaiou, and C. Tellambura, “Cell- Free Full-Duplex Communication – An Overview", IEEE Transactions on Communications, Accepted, 2025, Invited paper.
M. Z. Mumtaz, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Optimized energy harvesting in cell-free massive MIMO using Markov process evolution", IEEE Transactions on Green Communications and Networking, Accepted, 2025.
M. Mohammadi, L.-N. Tran, Z. Mobini, H. Q. Ngo, and M. Matthaiou, “Cell-free massive MIMO-assisted SWIPT for IoT networks,” IEEE Transactions on Wireless Communications, Accepted, 2025.
M. Z. Mumtaz, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Near-field energy harvesting using XL-MIMO over non-stationary channels", IEEE Wireless Communication Letters, vol. 14, no. 9, pp. 2922-2926, Sept. 2025.
M. Elfiatoure, M. Mohammadi, H. Q. Ngo, H. Shin, and M. Matthaiou, “Multiple-target detection in cell-free massive MIMO-assisted ISAC", IEEE Transactions on Wireless Communications, vol. 24, no. 5, pp. 4283-4298, May, 2025.
M. Mohammadi, Z. Mobini, H. Q. Ngo, and M. Matthaiou, “Ten years of research advances in full-duplex massive MIMO", IEEE Transactions on Communications, vol. 73, no. 3, pp. 1756-1786, Mar. 2025, Invited paper.
R. Chong, M. Mohammadi, H. Q. Ngo, S. L. Cotton, and M. Matthaiou, “Hybrid OTFS/OFDM Design in Massive MIMO”, IEEE Transactions on Communications, vol. 73, no. 3, pp. 1575-1590, Mar. 2025
M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Phase-shift and transmit power optimization for RIS-aided massive MIMO SWIPT IoT networks", IEEE Transactions on Communications, vol. 73, no. 1, pp. 631-647, Jan. 2025.
M. Mohammadi, Z. Mobini, H. Q. Ngo, and M. Matthaiou, “Next generation multiple access with cell-free massive MIMO", Proceedings of the IEEE, vol. 112, no. 9, pp. 1372-1420, Sept. 2024, Invited paper.
V. Ozduran, M. Mohammadi, N. Nomikos, I. S. Ansari, and P. Trakadas, “On the performance of uplink power-domain NOMA with imperfect CSI and SIC in 6G networks", Journal of Communications and Networks, vol. 26, no. 4, pp. 445-460, Aug. 2024.
M. Elfiatoure, M. Mohammadi, H. Q. Ngo, P. J. Smith, and M. Matthaiou, “Protecting massive MIMO-radar coexistence: Precoding design and power control,” IEEE Open Journal of the Communications Society, vol. 5, pp. 276-293, 2024.
M. Mohammadi, T. T. Vu, H. Q. Ngo, and M. Matthaiou, “Network-assisted full-duplex cell-free massive MIMO: Spectral and energy efficiencies,” IEEE Journal on Selected Areas in Communications, vol. 41, no. 9, pp. 2833-2851, Sept. 2023.
S. Haghguy, M. Mohammadi, Z. Mobini, and K-Kit Wong, “Decoupled UL/DL user association in wireless-powered HetNets with full-duplex small cells", IEEE Transactions on Vehicular Technology, vol. 72, no. 11, pp. 14341-14355, Nov. 2023.
V. Ozduran, M. Mohammadi, I. S. Ansari, and N. Nomikos, “Performance Analysis of Uplink Non-Orthogonal Multiple Access in the Presence of Co-Channel Interference", IEEE Transactions on Vehicular Technology, vol. 72, no. 9, pp. 11590-11602, Sept. 2023.
M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Cell-Free massive MIMO with OTFS modulation: Statistical CSI-based detection,” IEEE Wireless Communication Letters, vol. 12, no. 6, pp. 987-991, Jun. 2023.
M. Mohammadali, H. Q. Ngo, and M. Matthaiou, “Cell-free massive MIMO meets OTFS modulation,” IEEE Transactions on Communications, vol. 70, no. 11, pp. 7728–7747, Nov. 2022.
Z. Mobini, M. Mohammadi, T. A Tsiftsis, Z. Ding and C. Tellambura,"New Antenna Selection Schemes for Full-Duplex Cooperative MIMO-NOMA Systems," EEE Transactions on Communications, vol. 70, no. 7, pp. 4343-4358, July 2022.
M. Mohammadi, B. K. Chalise, H. A. Suraweera, H. Q. Ngo and Z. Ding, "Design and analysis of full-duplex massive antenna array systems based on wireless power transfer," IEEE Transactions on Communictions, vol. 69, pp. 1302-1316, Feb. 2021.
11. F. Feizi, M. Mohammadi, Z. Mobini, and C. Tellambura, “Proactive eavesdroppingvia jamming in full-duplex multi-antenna systems: Beamforming design and antenna selection", IEEE Transactions on Communications, vol.68, pp. 7563 - 7577, Dec. 2020.
A. Hakimi, M. Mohammadi, Z. Mobini, and Z. Ding, “Full-duplex non-orthogonal multiple access cooperative spectrum-sharing networks with non-linear energy harvesting", IEEE Transactions on Vehicular Technology, vol. 69, pp. 10925-10936, Oct. 2020.
A. Memarinejad, M. Mohammadi, M. Tavakoli, “Full-duplex NOMA cellular networks: Beamforming design and user scheduling", International Journal of Electronics and Communications, vol. 126, Nov. 2020, 153415.
Z. Mobini, M. Mohammadi and C. Tellambura, “Wireless-powered full-duplex relay and friendly jamming for secure cooperative communications", IEEE Transactions on Information Forensics & Security, vol. 14, pp. 621-634, Mar. 2019.
M. Mohammadi, X. Shi, B. K. Chalise, Z. Ding, H. A. Suraweera, C. Zhong and J. S. Thompson, "Full-duplex non-orthogonal multiple access for next generation wireless systems," IEEE Communications Magazine, vol. 57, pp. 110-116, May 2019.
Z. Mobini, M. Mohammadi, B. K. Chalise, H. A. Suraweera and Z. Ding, "Beamforming design and performance analysis of full-duplex cooperative NOMA systems," IEEE Transactions on Wireless Communications, vol. 18, pp. 3295-3311, June 2019.
S. Y. Derakhshandeh, Z. Mobini, M. Mohammadi, and M. Nokbakht, “UAV-assisted fault location in power Distribution systems: An optimization approach", IEEE Transactions on Smart Grid, vol. 10, pp. 4628-4636, July 2019.
A. Hakimi, M. Mohammadi, and Z. Mobini, “Throughput analysis of wireless-powered decode-and-forward relay systems with interference", Wireless Networks, vol. 25, pp. 2485-2495, Jul. 2019.
F. Jafarian, Z. Mobini and M. Mohammadi, “Secure cooperative network with multiantenna full-duplex receiver”, IEEE Systems Journal, vol. 13, pp. 2786-2794, Sept. 2019.
M. Mohammadi, B. K. Chalise, A. Hakimi, Z. Mobini, H. A. Suraweera and Z. Ding, "Beamforming design and power allocation for full-duplex non-orthogonal multiple access cognitive relaying," IEEE Transactions on Communications, vol. 66, pp. 5952-5965, Dec. 2018.
M. Mohammadi, H. A. Suraweera and C. Tellambura, "Uplink/downlink rate analysis and impact of power allocation for full-duplex cloud-RANs," IEEE Transactions on Wireless Communications, vol. 17, pp. 5774-5788, Sept. 2018.
A. Kuhestani, A. Mohammadi and M. Mohammadi, “Joint relay selection and power allocation in large-scale MIMO systems with untrusted relays and passive eavesdroppers", IEEE Transactions on Information Forensics & Security, vol. 13, pp. 341-355, Feb. 2018.
C. Psomas, M. Mohammadi, I. Krikidis and H. A. Suraweera, “Impact of directionality on interference mitigation in full-duplex cellular networks", IEEE Transactions on Wireless Communications, vol. 16, pp. 487-502, Jan. 2017.
M. Mohammadi, B. K. Chalise, H. A. Suraweera, C. Zhong, G. Zheng and I. Krikidis, "Throughput analysis and optimization of wireless-powered multiple antenna full-duplex relay systems," IEEE Transactions on Communications, vol. 64, pp. 1769-1785, Apr. 2016.
M. Mohammadi, “Analysis of low complexity uplink/downlink full-duplex wireless access with spatially random nodes", IET Communications, vol. 10, pp. 1777-1785, Sept. 2016.
Z. Mobini, S. Zokaei, M. Mohammadi, “ Joint power allocation and relay selection strategies for wireless multi-unicast network-coded systems”, Ad Hoc Networks, vol. 29, pp. 99-116, June 2015.
M. Mohammadi, H. A. Suraweera, Y. Cao, I. Krikidis and C. Tellambura, "Full-duplex radio for uplink/downlink wireless access with spatially random nodes," IEEE Transactions on Communications, vol. 63, pp. 5250-5266, Dec. 2015.
M. M. Razi, M. Mohammadi, M. Ardebilipour, M. Sebt, “Outage probability of opportunistic relaying in poisson wireless networks", Wireless Personal Communications, vol. 83, pp. 755-764, March 2015,
S. Hataminia, S. Vahidian, M. Mohammadi, M. Ahmadian-Attari, “Performance analysis of two-way decode-and-forward relaying in the presence of co-channel interferences", IET Communications, vol. 8, pp. 3349-3356, Dec. 2014.
M. Mohammadi, P. Sadeghi, T. A. Lamahewa, and M. Ardebilipour, “Impact of unknown time-varying fading on the information rates of amplify and forward cooperative systems", IEEE Transactions on Wireless Communications, vol. 12, pp. 146-157, Jan. 2013.
M. Mohammadi, P. Sadeghi, and M. Ardebilipour, “Node and symbol power allocation in time-varying amplify and forward dual-hop relay channels", IEEE Transactions on Vehicular Technology, vol. 62, pp. 432-439, Jan. 2013.
M. Mohammadi, Z. Mobini, B. Mahboobi, and M. Ardebilipour, “Performance analysis of generic amplify-and-forward cooperative networks over asymmetric fading channels", Wireless Personal Communications, vol. 72, pp. 49-70, Jan. 2013.
M. Mohammadi, M. Ardebilipour, Z. Mobini, R. Sadegh-Zadeh,“ Performance analysis and power allocation for multi-hop multi-branch amplify-and-forward cooperative networks over generalized fading channels", EURASIP Journal on Wireless Communications and Networking, pp. 1-13, Dec. 2013.
Conference Papers
Z. Mobini, M. Mohammadi, J. He, H. Q. Ngo, and M. Matthaiou, “Cell-free massive MIMO-assisted ISAC with beam scanning", in Proc. IEEE International Conference on Signal Processing Advances in Wireless Communications (SPAWC 2025), Special Session on Signal Processing for Cell-Free Massive MIMO Systems, Surrey, UK, July. 2025, pp. 1-5, (Invited paper).
H. Ni, M. Mohammadi, X. Mu, H. Q. Ngo, and M. Matthaiou, “Hybrid STAR-RIS: A unified approach to localization, communication, and power transfer", in Proc. IEEE International Conference on Signal Processing Advances in Wireless Communications (SPAWC 2025), Special Session on Smart Wireless Environment Enhanced Telecommunications, Surrey, UK, July. 2025, pp. 1-5, (Invited paper).
E. Campbell, M. Mohammadi, D. Mishra, and M. Matthaiou, “Beamforming and power allocation design for secure backscatter communication", in Proc. IEEE International Conference on Signal Processing Advances in Wireless Communications (SPAWC 2025), Special Session on Advanced Multiple Access Techniques for 6G, Surrey, UK, July. 2025, pp. 1-5, (Invited paper).
T. V. Chien, B. T. Duc, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Differential evolution for infeasible circumstances in network-assisted full-duplex cell-free massive MIMO",
in Proc. GECCO 2025, ACM , Malaga, Spain, July 2025.
M. Z. Mumtaz, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Near-field SWIPT using XL-MIMO: Power allocation and subarray activation", in Proc. IEEE International Conference on Communications (ICC 2025), Montreal, Canada, June 2025.
D. -T. Hua, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “SWIPT in cell-free Massive MIMO using stacked intelligent metasurfaces", in Proc. IEEE International Conference on Communications (ICC 2025), Montreal, Canada, June 2025.
R. Chong, M. Mohammadi, H. Q. Ngo, S. L. Cotton, and M. Matthaiou, “Multiple target detection in OTFS-ISAC", in Proc. IEEE International Conference on Communications (ICC 2025), Montreal, Canada, June 2025.
D. Galappaththige, M. Mohammadi, and C. Tellambura, “Concurrent, scheduled, or hybrid transmission protocol for ISAC", in Proc. IEEE International Conference on Communications (ICC 2025), Montreal, Canada, June 2025.
M. Z. Mumtaz, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Energy harvesting characterization in cell-Free massive MIMO using Markov chains", in Proc. IEEE Global Communications Conference (GLOBECOM 2024), December 2024.
I Kanbaz, M. Mohammadi, O. Yurduseven, and M. Matthaiou, “Beam-steering in super-directive antenna arrays using loaded parasitic elements", in Proc. 19th International Symposium on Wireless Communication Systems (ISWCS 2024), Rio de Janeiro, Brazil, July. 2024, (Invited paper).
D. -T. Hua, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Cell-free massive MIMO SWIPT with beyond diagonal reconfigurable intelligent surfaces," in Proc. IEEE Wireless Communications and Networking Conference (WCNC 2024), Dubai, United Arab Emirates, April 2024, pp. 1-6.
F. Jafarian, M. Ardebilipoor, M. Mohammadi, and M. Matthaiou, “Wireless information surveillance via STAR-RIS" in Proc. IEEE Wireless Communications and Networking Conference (WCNC 2024), , Dubai, United Arab Emirates, April 2024, pp. 1-6.
X. Cao, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “RIS-assisted XL-MIMO for coexistence of near-field and far-field communications," in Proc. IEEE Wireless Communications and Networking Conference (WCNC 2024), , Dubai, United Arab Emirates, April 2024, pp. 1-6.
M. Elfiatoure, M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Cell-Free massive MIMO for ISAC: Access point operation mode selection and power control," in Proc. IEEE Global Communications Conference (GLOBECOM 2023), December 2023.
M. Mohammadi, L.-N. Tran, Z. Mobini, H. Q. Ngo, and M. Matthaiou, “Cell-free massive MIMO and SWIPT: Access point operation mode selection and power control,” in Proc. IEEE Global Communications Conference (GLOBECOM 2023), December 2023.
R. Chong, M. Mohammadi, H. Q. Ngo, S. L. Cotton, and M. Matthaiou, “How to combine OTFS and OFDM modulations in massive MIMO?,” in Proc. IEEE Global Communications Conference (GLOBECOM 2023), December 2023.
M. Mohammadi, Z. Mobini, H. Q. Ngo, and M. Matthaiou, “Integration of massive MIMO and RIS to serve energy and information users,” in Proc. IEEE International Conference on Communications (ICC 2023), Rome, Italy, May 2023., pp. 895-900.
R. Chong, M. Mohammadi, H. Q. Ngo, S. L. Cotton, and M. Matthaiou, “On the achievable spectral efficiency of MMSE- based MIMO OTFS systems,” in Proc. IEEE International Symposium on Wireless Communications Systems (ISWCS 2022), October 2022, (Invited paper) .
M. Mohammadi, T. T. Vu, B. N. Beni, H. Q. Ngo, and M. Matthaiou, “Virtually full-duplex cell-free massive MIMO with access point mode assignment,” in Proc. IEEE International Conference on Signal Processing Advances in Wireless Communications (SPAWC 2022), July 2022, (Invited paper).
M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “Cell-free massive MIMO with OTFS modulation: Power control and resource allocation,” in Proc. IEEE International Conference on Communications (ICC 2022), May 2022.
M. Mohammadi, H. Q. Ngo, and M. Matthaiou, “When cell-free massive MIMO meets OTFS modulation: The downlink case,” in Proc. IEEE International Conference on Communications (ICC 2022), May 2022.
S. Asadollahi Dehkordi, M. Mohammadi, Z. Mobini, and S. Haghguy, “Coverage probability analysis of user association in NOMA-based full-duplex systems", in Proc. 30th Iranian Conference on Electrical Engineering (ICEE 2022), Tehran, Iran, May. 2022, pp. 1-6.
S. Haghguy, M. Mohammadi, and Z. Mobini, “Performance Analysis of Decoupled UL/DL User Association in Wireless-Powered Massive MIMO-Aided Heterogeneous Networks", in Proc. Fifth International Conference on Internet of Things and Applications (IoT 2021),Esfahan, Iran, May. 2021, pp. 1-6.
S. Sadeghi, M. Mohammadi, and Z. Mobini, “Outage Probability Analysis of Wirelesspowered Full-duplex Cognitive Non-Orthogonal Multiple Access Relaying Systems", in Proc. 28th Iranian Conference on Electrical Engineering (ICEE 2020), Tabriz, Iran, Aug. 2020, pp.1-6.
F. Feizi, M. Mohammadi, and Z. Mobini, “Proactive Eavesdropping via Jamming in Full-duplex Cellular Networks with Antenna Selection", in Proc. 9th International Symposium on Telecommunications (IST 2018), Tehran, Iran, Dec. 2018, pp. 641-646.
A. Hakimi, M. Mohammadi, and Z. Mobini, “Outage Probability of wireless-powered multi-antenna cooperative spectrum sharing networks with full-duplex and NOMA transmissions", in Proc. 9th International Symposium on Telecommunications (IST 2018), Tehran, Iran, Dec. 2018, pp. 127-132 (Best paper).
Z. Mobini, B. K. Chalise, M. Mohammadi, H. A. Suraweera and Z. Ding, "Proactive eavesdropping using UAV systems with full-duplex ground terminals," in Proc. 2018 IEEE International Conference on Communications Workshops (ICC Workshops), Kansas City, MO, May 2018, pp. 1-6.
M. Mohammadi, Z. Mobini, H. A. Suraweera and Z. Ding, "Antenna selection in full-duplex cooperative NOMA systems," in Proc. IEEE International Conference on Communications (ICC 2018), Kansas City, MO, May 2018, pp. 1-6.
Z. Mobini, M. Mohammadi, H. A. Suraweera and Z. Ding, "Full-duplex multi-antenna relay assisted cooperative non-orthogonal multiple access," in Proc. IEEE Global Communications Conference (GLOBECOM 2017), Singapore, Dec. 2017, pp. 1-7.
M. Mohammadi, B. K. Chalise, A. Hakimi, H. A. Suraweera and Z. Ding, "Joint beamforming design and power allocation for full-duplex NOMA cognitive relay systems," in Proc. IEEE Global Communications Conference (GLOBECOM 2017), Singapore, Dec. 2017, pp. 1-6.
M. Mohammadi, B. K. Chalise, H. A. Suraweera and Z. Ding, "Wireless information and power transfer in full-duplex systems with massive antenna arrays," in Proc. IEEE International Conference on Communications (ICC 2017), Paris, France, May 2017, pp. 6559-6564.
Z. Mobini, M. Mohammadi, and C. Tellambura, “Security enhancement of wireless networks with wireless-powered full-duplex relay and friendly jammer nodes,” in Proc. IEEE International Conference on Communications Workshops (ICC Workshops), Paris, France, May 2017, pp. 1329–1334.
M. Mohammadi, H. A. Suraweera and C. Tellambura, "Uplink and downlink rate analysis of a full-duplex C-RAN with remote radio head association," in Proc. European Signal Processing Conference (EUSIPCO 2016), special session on Recent Advances in Full-Duplex Radio: Advanced Signal Processing, Systems and Networks, Budapest, Hungary, Aug./Sept. 2016, pp. 778-782. (Invited paper)
M. Mohammadi, H. A. Suraweera and C. Tellambura, "Full-duplex cloud-RAN with uplink/downlink remote radio head association," in Proc. IEEE International Conference on Communications (ICC 2016), Kuala Lumpur, Malaysia, May 2016, pp. 1-6.
M. Mohammadi, H. A. Suraweera, G. Zheng, C. Zhong and I. Krikidis, "Full-duplex MIMO relaying powered by wireless energy transfer," in Proc. IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC 2015), special session on Recent Advances in Signal Processing for Inband Full-Duplex Radio, Stockholm, Sweden, June/July 2015, pp. 296-300, (Invited paper).
M. Mohammadi, H. A. Suraweera, I. Krikidis and C. Tellambura, "Full-duplex radio for uplink/downlink transmission with spatial randomness," in Proc. IEEE International Conference on Communications (ICC 2015), London, UK, June 2015, pp. 3511-3516.
M. Mohammadi, H. A. Suraweera and X. Zhou, “Outage probability of wireless ad hoc networks with cooperative relaying", in Proc. IEEE Global Communications Conference (GLOBECOM 2012), Anaheim, CA, Dec. 2012, pp. 4632-4638.
M. Mohammadi, P. Sadeghi, T. A Lamahewa, and M. Ardebilipour, “ The Impact of Unknown Correlated Rayleigh Fading on the information Rates of dual-hop Amplify and forward Relay channel”, In Proc. 5th International Conference on Signal Processing and Communication Systems (ICSPCS 2011), Honolulu, Hawaii, Dec. 2011, PP 1-6.
A. Kalantari, M. Mohammadi, and M. Ardebilipour, “ Performance analysis of Opportunistic Relaying over Imperfect Non-Identical Log-Normal Fading channel", in Proc. IEEE International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC2011), Toronto, Canada, Sept. 2011, pp. 1889-1893.
M. Mohammadi, B. Mahboobi, M. Ardebilipour, and Z. Mobini, “Power-Optimized Multi-Hop Multi-Branch Amplify-and-Forward Cooperative Systems", in Proc. 5th IEEE International Symposium on Wireless Pervasive Computing (ISWPC 2010), Modena, Italy, May 2010, pp. 534-539.
Z. Mobini, M. Mohammadi, and S. Zokaee, “ Reliable and distributed power optimized cooperative routing in wireless networks", in Proc. 6th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM2010), Chengdu, China, Sept. 2010, pp. 1-5.
M. Mohammadi, M. Ardebilipour, and Z. Mobini, “ Relay selection for multi-user MIMO amplify-and-forward relaying systems", in Proc. International Conference on Ultra Modern Telecommunications & Workshops (ICUMT 2009), St. Petersburg, Russia, Oct. 2009, pp. 1-6.