5G Mobile Networks: Requirements, Enabling Technologies, and Research Activities 41
one of the key components of the 5G system [22]. In general, the operation of D2D
communication can be in‐band D2D on licensed cellular spectrum (e.g. LTE) and
out‐of‐band D2D on unlicensed spectrum (e.g. WiFi). There are a number of use
cases and application scenarios for D2D, such as proximity‐based services,
Figure 2.6 (a) M2M communications and use case examples; and (b) D2D communications and use
case examples.
M2M Servers
Mobile Core Network
Client
Applications
Monitoring and Metering
Home and Industry Automation
Health Care
Automotive
M2M Gateway
M2M Gateway
M2M
Gateway
(a)
Content distribution
Gaming
Offloading
Relaying
D2D link
Cellular link
Base Station
Device
(b)