Device to Device Communications will enable on cellular 4G/5G networks soon, There are many research aspects in D2D Communications, Mode Selection Network Coding MIMO Multi-Hop the most complicated Interference scenarios are coming

1. Enable Device-to-Device Communications
Underlaying Networks: Challenges and
Research Aspects
Electrical Engineering and Computer Science Dept. of
Shahid Beheshti University
Course name: Mobile Communications
Advisor: Dr. Ghorashi
Lecturer: M. Naslcheraghi
Feb, 2015

2. Outline
• Introduction
• Challenges and Standard Summary
• Research Aspects
– Interference Management in D2D Communications
– Power Control
– D2D Communications with Multi-Antenna Transmission Techniques
– Multi-Hop D2D Communications with network coding
– D2D Communications in Heterogeneous Networks
– Performance Evaluation
• Conclusion
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3. Introduction
• D2D is a new communication scenario, it brings
communication between two and/or more devices in a
large scale network.
• Resources will be used: (uplink or downlink)
• Fast access on radio spectrum
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4. Challenges and Standard summary
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• Challenges
– Power Consumption
– Interference Management
– Appropriate Radio Link
– Cluster Level V.S Global Scale synchronization
– D2D devices ID
– Visibility
– Security features
– Clusters from D2D pairs
– Cooperative networks to improve public safety
– Multi-Hop D2D in HetNets
– D2D service zone in a large scale networks
– Density of users
– Mode selection

5. – Mode selection
» Silent Mode: The network cannot accommodate the D2D communication
request due to lack of resources or too strong interference to the nearby
CUE(s)
» Non-Ortoghonal Sharing Mode: This is also called reuse mode, in which the
D2D communication will share the same resources with existing CUE(s).
» Orthogonal Sharing Mode: This is called also dedicated mode. In this mode,
the cellular network has abundant channel resources to orthogonal CUE(s).
Apparently there is no interference between DUE(s) and CUE(s).
» Cellular Mode: The two UE(s) will communicates as traditional CUEs, that is,
communicate with each other through eNB.
Challenges and Standard summary
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6. Challenges and Standard summary
• Standardization
– Air interface
– Discovering D2D pairs
– Communication protocols
– Application services
– Security
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7. Research Aspects
• Interference Management
• D2D pairs ( DUE(s) ) activated on the cellular network and uses the
same resources that traditional UE(s) are using.
• If resources are same, so interference is inevitable in cellular network.
» Leads to different interference problems in both Downlink and Uplink
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8. • Interference Management
– Downlink
Research Aspects
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9. • Interference Management
– Uplink
Research Aspects
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10. Research Aspects
• Power Control
– Priority of CUE(s) in resource allocation strategies in cellular
networks is higher that DUE(s), so power control algorithms
should focus on DUE(s) to prevent high power usage in D2D
pairs. Because high power usage leads to generate high power
Interference.
– This can be investigated in perspective of: Mode Selection and
Resource Allocation
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11. Research Aspects
• D2D Communications with Multi-Antenna Transmission
Techniques
– Using multiple antennas could prevent interference in front of
CUE(s), so we can investigate on antenna designs for D2D
Devices.
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12. Research Aspects
• Multi-Hop D2D Communications with Network Coding
– D2D pairs can communicate in broadband mode and help other
UE(s) to connect to eNB(s) easier and faster. This is Multi-Hop
D2D scenario.
– It can be used when multiple Nodes are requesting same resources in a cluster.
– Network coding can be investigated in such a cooperative
networks
– Two-way relay channel (TWRC)
– Multiple-access relay channel (MARC)
So this aspect of research can be investigated in both “D2D” and “Networking
Coding” perspective.
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13. Research Aspects
• D2D Communications in Heterogeneous Networks
– Despite of homogeneous networks, HetNets have multiple
types of eNB(s), traditional macro eNB(s), Picos, Femtos, etc.
– Mode selection in these networks is more complicated:
– Silent Mode
– Non-orthogonal sharing with eNB mode (D2D pair communication shares the
same channel resources from eNB(s))
– Non-orthogonal sharing with relay mode (D2D pair communication shares the
same channel resources with a relay)
– Orthogonal sharing mode
– Cellular mode (UEs communicate with each other through eNB)
– Relay mode (UEs communicate with each other through a relay)
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14. Research Aspects
• Performance Evaluation
– A simulation on performance of D2D enabled cellular network
performed:
– Mode selection: Non-orthogonal sharing
– Network type: Homogeneous
– Number of active D2D pairs: N=5
– One CUE
– Channel modeling: Point-to-Point with Rayleigh fading
– Exponential pass loss: alpha=4
– Noise type: Additive Gaussian
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15. • Uplink
– A distance
controlling
mechanism
performed
(Rgu=0.2)
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Analysis on D2D enabled
Cellular network

16. Analysis on D2D enabled
Cellular network
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• Downlink
– A distance
controlling
mechanism
performed (Rgd
=0.5*R)

17. • Consider that distance between DUE(s) and eNB is
same in both Downlink and Uplink.
Analysis on D2D enabled
Cellular network
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18. Conclusion
• When D2D enabled on cellular networks, it can improve
throughput of network if appropriate radio resource
sharing, Interference management and power control
launched. After then, More research aspects will be
prompted:
» Interference Management
» Multi-Hop D2D communications with network coding
» D2D communications with Multi-Antenna transmission techniques
» D2D communication in HetNets
» Mechanisms such as mode selection
» Resource allocation
» Power control
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19. • Reference
– Enable Device-to-Device Communications Underlaying Cellular Networks: Challenges and
Research Aspects, IEEE Communications Magazine June 2014 , Lili Wei, Rose Qingyang Hu, Yi
Qian, and Greg Wu.
– Feedback & Download:
• Email:
– M.naslcheraghi@sbu.ac.ir
– M.naslcheraghi@Teleinfra.net
• Direct Link Access: www.Teleinfra.Net/download/D2D.pdf