D2D - Device to Device Communication

D2DDevice to Device Communication

Aluno: Francisco Bento da Silva NetoMO611 - Teleprocessamento e RedesProfessor: Nelson Fonseca, Ph.D

Instituto de Computação

Agenda● Background ● D2D vs Ad-hoc● D2D overview● D2D discovery

o Priorio Posteriori

● D2D communicationo Inbando Outband

● D2D security● D2D use cases● Conclusion

Background● Challenges for future wireless communication:

o Massive growth in the number of connected devices. (50 billion)o Massive growth in traffic volume (1000x in 10 years) due to new

users / communicating machineso Increasingly wide range of applications with varying requirements and

characteristics: Multi-Gbps in specific scenarios, Tens of MBps almost everywhere, communicating machines

Background● Needed enhancements to support future wireless communication:

o General enhancements applicable to a wide range of scenarios and use caseso Enhancements specifically targeting small-cell/local-area deployments.o Enhancements specifically targeting new use cases, such as machine-type

communication (MTC) and national security and public safety services (NSPS).

● LTE evolution: LTE Release 12 and beyond (LTE-B)

o Proximity Services (ProSe): D2D discovery D2D communication

Background● D2D in one image:





● Securityo The security features of WiFi and Bluetooth are much less robust than

those used in public cellular systems. They would not be adequate for major public services and they would be unsuitable for public safety applications.

● Independence from cellular networks

o WiFi and Bluetooth operate independently from cellular radio technology such as LTE. Any form of device-to-device discovery based on them would have to run in parallel with cellular radio operation, which would be inefficient and would become a significant drain on device batteries.

D2D vs Ad-hoc

● Unlicensed spectrum

o WiFi and Bluetooth operate in unlicensed spectrum, without any centralised control of usage or interference. This is not generally a problem when usage densities are low, but it would become a major limitation as proximity-based services proliferate. Throughput, range and reliability would all suffer.

● Manual pairing

o WiFi and Bluetooth rely on manual pairing of devices to enable communication between them, which would be a serious stumbling block for autonomous, dynamic proximity-based services.

● Transmission distance and data transfer rate (see next slide)

D2D vs Ad-hoc

Wireless technologies comparison





D2D Overview● Devices communicates with each other without intermediate nodes

(Offloads traffic from the core network)

● Uses cellular spectrum (licensed band)

● Proximity of equipments provides:o High bit rates / low delayso Low energy consumption

● Radio resources may be simultaneously used by cellular and D2D links so that the same spectral resource can be used more than once within the same cell (reuse gain)

● Uses the same pre-existing cellular infrastructure: supports more services and improves current services and applications





D2D Discovery● Devices can discover the presence of other devices in their vicinity

● Proximity discovery is a natural trigger for direct communication

● Proximity discovery can be used as a standalone service and not trigger communication (social networking)

● General requirements:

o Fast discovery

o Low energy consumption

o Minimize additional interference to the WAN and resource degradation

D2D Discovery: Methods● D2D provides 2 methods of discovery:

● Network discovery (Radio)

o A device is able to discover and be discovered by other devices in radio proximity

● User assisted discovery (Application Layer)

o A user of a service or social networking application is able to discover and be discovered by other users of the same service or social networking application

D2D Discovery: Node/Peer discovery● Before two devices can directly communicate with one another, they must

first discover that they are near each other

● Two peer devices need to meet in space, time and frequency

● No coordinated discovery: Peer discovery is a randomized procedure, in which a device sends signals without any knowledge about the location of the intended peer (energy consuming)

● Coordinated discovery: The network uses its knowledge of approximate device locations to recognize devices which could benefit from D2D communications. When a D2D pair has been found, the network coordinates the time and frequency allocation for sending/scanning for beacons

D2D Discovery: Beacon

Sadly not this:

● Beacon: A known synchronization or reference signal sequence ○ Similar to secondary synchronization sequence in LTE or frequency

hopping sequence (FHS) in bluetooth





D2D Discovery: Priori discovery● Network (and/or devices themselves) detects D2D candidates before the start of

the communication session between the devices

● Extreme approach:

o Network assigns beacon resources to the devices

o Beacon are broadcast in the coverage area of the cell, so D2D devices can readily find one another

● Alternative approach:o Device willing to engage in D2D communication sends a request to the network to

indicate its interest

o Device can provide information about the specific service it is interested in. Network will initiate the discovery process when a pair of devices are likely to benefit from D2D communication (passive)

D2D Discovery: Priori discovery





D2D Discovery: Posteriori discovery● Use case: Network realizes that two D2D enabled devices with an ongoing

communication session (cellular mode) are in the proximity of each other

● Does not provide the same flexibility of supporting localized services as priori methods, but it is limited to offloading localized traffic

● Devices agree on a token that is unique to the already ongoing communication (similar to HTTP_SESSION mechanics)

● Once token is established devices register the token at the serving eNB (evolved Node B)

● Alternatively the eNB can analyze the source and destination IP addresses to detect D2D pairs communicating within the same cell (same subnet)

D2D Discovery: Posteriori discovery





● Licensed band:

o Better interference avoidance under a controlled environment

o Ex: Femtocells / picocells work under LTE-A licensed band

● Classified in:

o Inband D2D: Underlay Overlay

o Outband D2D Controlled Autonomous

D2D communication





● Communication occurs under licensed spectrum: Cellular spectrum is used for both cellular link and D2D

● High control over cellular (licensed) spectrum

● Underlay:

o Cellular and D2D communication share the same radio resources

● Overlay:

o Cellular and D2D are given dedicated cellular resources (a cellular resource is subtracted from cellular users)

● Underlay is more popular than overlay: probably due to its hight spectral efficiency

D2D communicationInband: Overview

● Pros:o Underlay D2D increase the spectral efficiency of cellular spectrum o Any cellular device is capable of using inband o QoS is easy because the cellular spectrum can be fully managed by the eNBo Transmission distance ~ 1km. o Data rate ~ 1Gbps

● Conso Cellular resources might be wasted in overlayo Interference mgmt among D2D and cellular transmission is very

challenging/complexo User cannot have simultaneous cellular and D2D transmission

D2D communicationInband: Pros and cons





● Communication occurs under unlicensed spectrum

● Aims to eliminate the interference issue between D2D and cellular links

● Requires an extra interface, usually Wi-Fi direct, ZigBee or Bluetooth

● Classified in:

o Controlled

The control of the second interface is under the cellular network● Similar to Android NFC / Android beam

o Autonomous

D2D controlled by the users: second interface is not under cellular control

● Transmission distance and data transfer rate is extremely lower than Inband

D2D communicationOutband: Overview

● Pros:

o No interference with cellular communication (unlicensed spectrum)

o Users can have simultaneous cellular and D2D transmission

● Cons

o Cellular devices requires two wireless interfaces (e.g. LTE and WiFi)

o Power consumption of the extra interface (WiFi)

o Lower transmission distance

o Lower transmission data rate

D2D communicationOutband: Pros and cons





D2D security1. Network access security:

o Security interactions between the user and access network, which provides protection against attacks on the radio access link;

2. Network domain security:

o it enables the secure data/control signal exchange among network elements, which provides protection against attacks on wire-line network;

3. User domain security (3):

o it secures the access to the mobile station;

D2D security4. Application domain security:

o it is an end-to-end security between the application on user equipment and on servers;

5. Visibility and configuration security:

o the set of features controls the availability and configuration of certain security service.

D2D security

[1] Network access security [2] Network domain security [3] User domain security [4] Application domain security [5] Visibility and configuration security





● Two categories:

o Simple D2D: sender and receiver exchange data with each other

o Relay: D2D user forward data from and to other users

● Use cases examples:

● Local Data Service

Information sharing (bittorrent)

Mobile multiplayer gaming

Mobile advertising (proximity services)

Streaming services (IPTV, google chromecast, apple airplay)

Social (Tinder, Waze, Facebook)

Community services

D2D use cases

● V2V - Vehicle to Vehicle communication:

o Collision avoidance system requires a very low latency for example to coordinate braking between vehicles

o V2V can provide not only information about the nearest car in front, but also from other cars within the communication range, including traffic (waze ?)

● Group handover of multiple users (for example in a Bus)

o By using D2D the devices in a group inform each other about the handover and its parameters with minimal signaling from the network

D2D use cases

● Multiuser cooperative communication (MUCC)

o Benefited user (BU) is in an area with poor cellular signal

o Another user is in an area with good cellular signal. This user may help BU to improve its signal and act as a supporting user (SU)

D2D use cases

● D2D communications with network coding

o Users requesting the same content can form cooperative clusters to achieve higher energy efficiency

o eNB transmits the content to the cluster heads

o Cluster heads multicasts the contents to the other devices within the cluster through D2D links

o Eg: world cup games

o IPTV:

o Multicast of linear channels, Pay-Per-View, Video Recording

D2D use cases

● Public safety (police, fire and ambulance services)

o Many of these organisations uses relatively old technology such as TETRA system developed in the 90’s with limited capability

o US government has expressed desire to move to LTE for public safety

o Crucial requirement for these users is the ability to communicate with each other outside of a mobile network (walkie talkie), which is not supported by LTE, but is one of LTE D2D objectives

D2D use cases

● Although basic requirements are set, details are being still studied/developed

● Big impact of the new technologies proposed:

o D2D discovery Good: Might be a key tool for social networking and other internet

apps Bad: Privacy concerns, device battery consumption

o D2D communication: Good: Offloading traffic, High data rate speeds Bad: Interference / deterioration of existing services

Conclusion

Questions ?

Thank you!Francisco Bento da Silva Neto, Jun 2014.

References:

●Shahid Mumtaz et al., "Odyssey of LTE-A D2D Communication:Tutorial Approach", IEEE Communications Surveys and Tutorials, Dec. 2013

●Gábor et. al. “Design Aspects of Network Assisted Device to Device Communication”, IEEE communication Magazine March 2012

●K. Doppler, M. P. Rinne, P. Janis, C. Ribeiro, and K.Hugl, “Device-to-Device Communications; Functional Prospects for LTE-Advanced Networks”. IEEE International Conference on Communications Workshops, 2009, Jun. 2009, pp.1– 6

●M. Hajiaghayi, C. Wijting, C. Ribeiro, M. T. Hajiaghayi, "Efficient and practical resource block allocation for LTE-based D2D network via graph coloring", Springer Science+Business Media, New York, 2013

●Alastair Brydon, "Opportunities and threats from LTE Device-to-Device (D2D) communication", Unwired insight - The wireless blog, Feb. 2014

Engineering

D2D - Device to Device Communication