D2D-U: DEVICE-TO-DEVICE COMMUNICATIONS INUNLICENSED BANDS FOR 5G SYSTEM
ABSTRACT
Device-to-Device (D2D) communication, which enablesdirect communication between nearby mobile devices, isan attractive add-on component to improve spectrum efficiencyand user experience by reusing licensed cellular spectrum in 5Gsystem. In this paper, we propose to enable D2D communicationin unlicensed spectrum (D2D-U) as an underlay of the uplink LTEnetwork for further booming the network capacity. A sensingbasedprotocol is designed to support the unlicensed channelaccess for both LTE and D2D users. We further investigate thesubchannel allocation problem to maximize the sum rate of LTEand D2D users while taking into account their interference to theexisting Wi-Fi systems. Specifically, we formulate the subchannelallocation as a many-to-many matching problem with externalities,and develop an iterative user-subchannel swap algorithm.Analytical and simulation results show that the proposed D2D-Uscheme can significantly improve the system sum-rate.
EXISTING SYSTEM:
As LTE-U technology shows satisfying performance, D2Dcommunications underlaying LTE networks in the unlicensedspectrum becomes a natural solution to further improve systemthroughput, in particular hotspot areas with large number ofD2D links. However, due to the mutual interference aLTE-U network, D2D users, and the opportunistic feature ofunlicensed channel access in existing Wi-Fi systems, D2DUnlicensed(D2D-U) communication turns out to be muchcomplicated. In this paper, we investigate the underlaid D2Dcommunications in the unlicensed spectrum. Note that differentfrom most previous peer-to-peer communication technologiesin the unlicensed spectrum such as Wi-Fi Direct, which builds the network upon the IEEE 802.11 infrastructuremode and allows users to negotiate with each other inan AP-like method, D2D-U requires assist and control from thecentral BS. With the involvement of BS, D2D users can workas an underlay of LTE system in both licensed and unlicensedspectra.As aforementioned, the major challenges of implementingD2D-U are (1) the opportunistic feature of unlicensed channelaccess due to current 802.11 mechanism adopted by Wi-Fisystems; and (2) the interference management issue athe three types of systems, i.e., the access and transmissionof D2D-U users do not cause significant interference to theexisting Wi-Fi system as well as the LTE-U system. Tocope with the first challenge and be compatible with currentLTE standards1, we design a duty cycle based protocol, in which the BS schedules transmissions according tothe data demand. To tackle the second challenge, unlike thework in which only maximizes the total sum-rate, weinvestigate the subchannel allocation problem to leverage themaximization of the sum-rate of LTE-U and D2D-U usersand the protection of Wi-Fi performance. This subchannelallocation problem is originally a mixed-integer non-linearprogramming (MINLP) problem, which is generally NP-hard.
PROPOSED SYSTEM:
In this paper, we investigate the underlaid D2Dcommunications in the unlicensed spectrum. Note that differentfrom most previous peer-to-peer communication technologiesin the unlicensed spectrum such as Wi-Fi Direct, which builds the network upon the IEEE 802.11 infrastructuremode and allows users to negotiate with each other inan AP-like method, D2D-U requires assist and control from thecentral BS. With the involvement of BS, D2D users can workas an underlay of LTE system in both licensed and unlicensedspectra.The major contributions of this paper are summarized asfollows.• We propose a feasible duty cycle based protocol forthe LTE-U and D2D-U users to utilize the unlicensedspectrum.• An approximated model is elaborated to evaluate theinterference to Wi-Fi networks introduced by LTE-U andD2D-U users.• We investigate the subchannel allocation problem by amany-to-many matching game with externality, and analyzeits stability, convergence, complexity, and optimality.
CONCLUSIONS
In this paper, we investigate the D2D-U technology, inwhich the D2D users operate as an underlay to the LTEsystem in both licensed and unlicensed spectra. A duty cyclebased protocol is designed for LTE-U and D2D-U userswhile protecting the existing Wi-Fi systems. Considering the maxcomplicated mutual interference between LTE, D2D, and WiFisystems, we study the subchannel allocation problem forD2D and LTE users sharing both licensed and unlicensedsubchannels to leverage the performance degradation in Wi-Fisystems and the maximization of the sum-rate in LTE/D2Dnetworks. Specifically, we formulate the allocation problemas a many-to-many matching game with externalities, anddevelop a low-complexity user-subchannel swap matchingalgorithm. In addition, power control can be done in parallelwith subchannel assignment. Analytical and simulation resultsshow that enabling D2D-U communications can significantlyimprove the system sum-rate. Besides, the subchannel allocationstrategy for LTE-U and D2D users is closely related tohow the BS adjusts the interference to Wi-Fi systems. In anaggressive strategy where the Wi-Fi performance degradationis not considered seriously, the BS allows more D2D and LTEusers to transmit on the unlicensed spectrum. On contrary, ina Wi-Fi friendly strategy, the BS tends to permit only a smallfraction of D2D users to transmit on the unlicensed spectrum.
REFERENCES
[1] H. Zhang, Y. Liao, and L. Song, “Device-to-Device CommunicationsUnderlaying Cellular Networks in Unlicensed Bands”, in Proc. IEEEICC, Paris, France, May 2017.
[2] K. Doppler, M. Rinne, C. Wijting, C. B. Ribeiro, and K. Hugl, “Deviceto-DeviceCommunication as an Underlay to LTE-advanced Networks”,IEEE Commun. Mag., vol. 47, no. 12, pp. 42-49, Dec. 2009.
[3] L. Lei, Z. Zhong, C. Lin, and X. Shen, “Operator Controlled Deviceto-DeviceCommunications in LTE-advanced Networks”, IEEE WirelessCommun., vol. 19, no. 3, pp. 96-104, Jun. 2012.
[4] G. Fodor, E. Dahlman, G. Mildh, S. Parkvall, N. Reider, G. Mikl_os,and Z. Tur_anyi, “Design Aspects of Network Assisted Device-to-DeviceCommunications”, IEEE Commun. Mag., vol. 50, no. 3, pp. 170-177,Mar. 2012.
[5] H. Zhang, L. Song, and Z. Han, “Radio Resource Allocation for Deviceto-DeviceUnderlay Communication Using Hypergraph Theory”, IEEETrans. Wireless Commun., vol. 15, no. 7, pp. 4852-4861, Jul. 2016.
[6] L. Song, D. Niyato, Z. Han, and E. Hossain, Wireless Device-to-DeviceCommunications and Networks, Cambridge University Press, UK, 2015.
[7] C. H. Yu, K. Doppler, C. B. Ribeiro, and O. Tirkkonen, “ResourceSharing Optimization for Device-to-Device Communication UnderlayingCellular Networks”, IEEE Trans. on Wireless Commun., vol. 10, no. 8,pp. 2752-2763, Aug. 2011.
[8] H. Min, J. Lee, S. Park, and D. Hong, “Capacity Enhancement Usingan Interference Limited Area for Device-to-Device Uplink UnderlayingCellular Networks”, IEEE Trans. Wireless Commun., vol. 10, no. 12,pp. 3995-4000, Dec. 2011.
[9] A. Aijaz, H. Aghvami, and M. Amani, “A Survey on Mobile DataOffloading: Technical and Business Perspectives”, IEEE Wireless Commun.,vol. 20, no. 2, pp. 104-112, Apr. 2013.
[10] K. Lee, J. Lee, Y. Yi, I. Rhee, and S. Chong, “Mobile Data Offloading:How Much Can WiFi Deliver?”, IEEE/ACM Trans. Networking, vol. 21,no. 2, pp. 536-550, Apr. 2013.
[11] M. Bennis, M. Simsek, A. Czylwik, W. Saad, S. Valentin, and M. Debbah,“When Cellular Meets WiFi in Wireless Small Cell Networks?”,IEEE Commun. Mag., vol. 51, no. 6, pp. 44-50, Jun. 2013.
[12] H. , P. Wang, and D. Niyato, “A Dynamic Offloading Algorithmfor Mobile Computing”, IEEE Trans. Wireless Commun., vol. 11, no. 6,pp. 1991-1995, Jun. 2012.
[13] Y. Gu, Y. Zhang, L. X. Cai, M. Pan, L. Song, and Z. Han, “ExploitingStudent-Project Allocation Matching for Spectrum Sharing in LTEUnlicensed”,in Proc. IEEE GLOBECOM, San Diego, CA, Dec. 2015.
[14] 3GPP TR 36.808, “Evolved Universal Terrestrial Radio Access (EUTRA);Carrier Aggregation; Base Station (BS) radio transmission andreception”, Release 10, Jul. 2013.
[15] A. Al-Dulaimi, S. Al-Rubaye, Q. Ni, and E. Sousa, “5G CommunicationsRace: Pursuit of More Capacity Triggers LTE in Unlicensed Band”,IEEE Veh. Technol. Mag., vol. 10, no. 1, pp. 43-51, Mar. 2015.