Connectivity Anytime, Anywhere

Everyone wants to be a part of a connected world. The LTE wireless technology provides the means to be connected anywhere, and to continuously improvise on it. Apart from meeting the high data rate/low latency demands, LTE works on many public safety aspects to be chosen as the standard to be used in many applications, which helps in ensuring the safety of mankind.

LTE comes with an additional advantage (in terms of architecture) compared to previous technology such as 2G or 3G. Its Flat architecture and overall IP communication between different network elements makes it simple and easy to maintain. This is advancement in technology converging to 5G standard with various features getting introduced in LTE-Advanced, such as Carrier Aggregation, Machine Type Communications, enhanced CoMP, Multi-cast services, Energy saving features (GO Green initiative), Interference mitigations, Device-to-Device (D2D) Communication, and so on.

The Problem:

Natural disasters tend to cause damage to infrastructure which leads to slow recovery during the situation. Better communication services in times of crises, help in quicker recovery and relief to man. A mechanism to communicate in the absence of network infrastructure is essential. This will not only provide aid during natural disaster, but in other ways also, that have been discussed below.

Being in a connected wireless world, everyone expects to be connected anywhere, and in any situation whether it is a natural disaster that causes the existing network to go defunct due to damage, or in remote places where networks are not prevalent. 3GPP is introducing a new concept to help in the above situation, by introducing UE to UE communication without the Access or core network involvement. The potential of this new feature, also known as D2D, getting introduced by 3GPP standard in Release 12 specifications is a matter of interest. This uses proximity services to enable UE to UE communication.

The Solution:

Device-to-Device, that is, D2D is a new communication type which refers to LTE radio technology being used by devices to communicate with each other instead of using whole network components. When the devices are in close proximity, they can directly communicate instead of via network resources. This will be mainly used for public safety applications (when natural disasters cause damage to network infrastructure, D2D can continue to communicate, also in remote areas which lack network). The other main usage of this communication is during social events, advertisements, sports events, vehicle communications, home device co-ordinations / communications etc.

The main advantage of using the D2D type communication is that user can be connected in any situation even without network infrastructure. The other advantage of using the D2D type communication is faster communication, peak data rate without using network resources, and less interference as devices are communicating directly, and saving power as network resources are better utilized.

The devices communicating with each other may not be required to be in the coverage of any network, that is, UEs which are not in coverage can communicate. The following communications are possible:

  • Out-of-coverage UE1 to out-of-coverage UE2
  • Out-of-coverage UE1 to in-coverage UE2
  • In-coverage UE1 to out-of-coverage UE2
  • In-coverage UE1 to in-coverage UE2


There are a few challenges also, namely security (authorization/authentication), billing, different operator devices, device discovery (what means and devices to be used) and their associations.

The major design challenges include:

  • Usage of FDMA technique for devices as the data sent by one device in DL is UL for other device, so whether to use SC-FDMA or some other means.
  •  Dynamic Resource Allocation by devices instead of the network taking the decision
  • Synchronization between devices
  • Different algorithm run by the network needs to be considered, for example, power control, and adaptation of link
  • Coordination between different features

Two main components of D2D communication:

  • D2D Discovery enables a device to use the LTE radio technology to discover the presence of other D2D-capable devices in its nearby locations and if permitted, to get information about them and their services.
  • D2D Communication is the facility for D2D devices to use the LTE radio technology to communicate directly with each other, without routing the traffic through LTE network components. The network enables the service by controlling the radio resource allocation and security of the connections initially, as well as modifications or mobility aspects.

Devices will discover the services (via other devices) which are in proximity with minimal assistance from the network. For example, if you are in a mall and looking for specific items, which can be searched via devices, acquaintances in the vicinity, or advertisements, other devices can help provide you with information on great deals and offers.

This proves extremely helpful in ensuring public safety. In fact some countries have already started working in this direction to upgrade their safety systems such as Police, Fire, Medical emergency services to upgrade to new technology for faster and reliable communication. D2D can help here as these public safety measures should work even if there is minimal support available from the network infrastructure as in case of natural disasters. A special ProSe (Proximity service) carrier dedicated for this service will be used for communication.

There will be many challenges in implementing this complex feature to satisfy the need of the end-user, but as this will be part of the 3GPP standard and will be a successful in the near future to meet the demand of multiple organizations whether it is social networking, public safety, marketing or advertisement.

Though the basic part of D2D is added in 3GPP in Release 12, it will be addressed fully with different aspects in future releases.

The conclusion is that this feature is going to be very useful mainly in the public safety domain where a user can be connected anywhere, in any situation. The other advantage mainly includes the better utilization of the network infrastructure by using it for industries such as advertising and marketing.

The Aricent LTE solution is being used by many customers across the globe. The Aricent LTE stack (eNB or CN) is a well-known and proven base platform to develop these new features as an add-on to existing stack elements and thereby reduce time-to-market in the final solution.

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