1. By Bekir Kendirci Supervised By Dr. H. Zhu
Device-to-Device(D2D) Communications in Cellular Networks
2. CONTENT OVERVIEW OF DEVICE-TO-DEVICE A.INTRODUCTION
B.ADVANTAGES C.CHALLENGES OBJECTIVES OF PROJECT TECHNICAL ISSUES
SCENARIO SIMULATION and RESULTS FURTHER WORKS
3. OVERVIEW OF DEVICE-TO-DEVICE A.INTRODUCTION Device to device
(D2D) communications are when two user equipments are close enough
to each other, the devices may communicate directly or via base
station assistance. D2D technology enables a direct link (uplink or
downlink resources) between user equipments (UEs) without help of
base station.
4. B.ADVANTAGES Efficient and improved performance for UEs such
as battery life, energy consumption. Lower latency can be achieved.
Higher data rates can be achieved. D2D communication provides
offloading in cellular networks so workload of the base stations
are reduced thus network can be used more effectively. D2D can
increase resource utilization and also extend coverage of cellular
network.
5. C.CHALLENGES Interference management for communication
network. Radio resource allocation and resource management. Mode of
D2D ; licensed or unlicensed and network assisted or unassisted
Distance between UEs, distance between base station and D2D pairs.
Choosing frequency resource for direct link of D2D pair (uplink or
downlink).
6. OBJECTIVES OF PROJECT Measuring efficiency of D2D
performance. D2D performance without and with interferences from
each other and base station. Radio resource management: comparison
of dowlink and uplink resources for D2D direct link. Frequency
reuse for D2D pairs in the cell by diving cell into sectors.
7. TECHNICAL ISSUES Orthoganal Freqeuncy Division Muliplex
(OFDM) with 256-fft is used . Quadrature Amplitude Modulation(QAM)
with 4,16 and 64 modulation orders. Fading Rayleigh is used as
channel One cell scenario with D2D pairs, base station and cellular
user. Interference from D2D pairs, base station and cellular user.
Downlink and uplink frequency resources. Sample time is 5.21
us.
8. SCENARIO D2D pair 1 D2D pair 4 CEU1 CEU2 CEU3 Interference :
Signal : Interference from BS : Interference from CUE: D2D
communication scenario in a cell for downlik or uplink
resources.
9. SIMULATIONS AND RESULTS
10. TRANSMITTER OF D2D
11. RECEIVER OF D2D
12. CHANNEL Multipath Rayleigh Fading and Additive White
Gaussian Noise affect the system. Approximately no doppler shift
Channel effect is normalized by dividing it with complex gain
magnitude of Rayleigh channel.
13. RESULTS
14. FURTHER WORKS D2D communication can be examined by more
cell scenarios. D2D devices can be combined with difference
technologies such as MIMO. More realistic number of users and
scenarios can be built. Different enviroments can be examined
instead of using Rayleigh Channel, for example Nakagami Channel can
be used Adaptive modulation techniques can be added to model.