LTE-Advanced for Device to Device and Machine-to-Machine Communication

Jangho Noh (A paper written under the guidance of Prof. Raj Jain) DownloadPDF


Machine-to-Machine (M2M) communication is widely deployed and offers various applications such as e-Health, smart city, and public safety. Also, due to its accessibility, LTE-A will play an important role in deploying M2M communication. M2M networks will be used with Device-to-Device (D2D) networks because D2D will reduce local end-to-end delay and decrease local M2M traffic. Further research needs to be done to meet the service requirements of the M2M and D2D networks.


LTE, LTE-Advanced, Architecture, D2D Communication, M2M Communication, Data flow, Service Requirements

Table of Contents

1 Introduction
2 Architectures 3 Data Flow and Service Requirements 4 Summary
List of Acronyms

1 Introduction

M2M communications is a technology which allows obtaining and delivering needed information easily and based on it, having access to various services. M2M devices are expected to rapidly increase in number: by 38% per annum from 0.6 million in 2015 to 3.1 billion in 2020. In addition, 34% of M2M 3.1 billion devices in 2020 are expected to be connected through LTE or LTE-A networks. They are expected to be used more extensively than Low-Power, and Wide-Area (LPWA) which have the second largest market share with 28% [cisco16] [cisco16a].

As M2M devices using LTE-A networks and the traffics these devices are rapidly increasing, network operators need to constantly increase their access and backhaul capacities, or introduce the technologies to reduce their network loads. D2D communications is the technology to reduce network loads. It allows data offloading by providing a direct communication.

The remainder of this paper is organized as follows. Section 2 examines 3GPP Architectures of LTE-A, M2M and D2D; and Section 3 looks at their data flow procedures and service requirements.

2. Architectures

This chapter examines LTE-A, D2D and M2M reference model defined in 3GPP and describes the essential entities that constitute the network and the function of each of the entities. LTE-A referred to 3GPP TS 23.401; D2D to 3GPP TR 23.703; and M2M to 3GPP TS 23.888 respectively. The overlapping functions in each of the models were dealt with only in the part of LTE-A architecture.

2.1 LTE-A Architecture

LTE-A is divided largely into two parts. The first part is related to the radio access network (E-UTRAN). The related entities are the User Equipment (UE) and the evolved Node B (eNB). The second part is the Evolved Packet Core (EPC) which constitutes the core network. Major EPC entities include MME, PGW, SGW, HSS, and PCRF. Figure 1 represents an LTE-A network reference model [3gpp401].

Figure 1: LTE-A Reference Model

Figure 1: LTE-A Reference Model

2.2 M2M Architecture

M2M Network is composed of Radio Access Network, EPC, Machine-Type Communications (MTC) device, MTC server and MTC user. The entities newly added to in the LTE-A Network are the MTC server and MTC-IWF.Figure 2 shows an M2M network reference model [3gpp888] [faye15].

M2M Reference Model

Figure 2: M2M Reference Model

There are three architectural models which differ depending on the ways that the MTC user is connected to the MTC device. The first model is a direct model which communicates with the LTE-A network without going through the MTC server. The second model is an indirect model which is connected to the LTE-A network through the MTC server. The last model is a hybrid model which uses both the direct and indirect model at the same time. In the hybrid model, the user plane is transmitted through the direct model and the control plane is processed by using the indirect model.

2.3 D2D Architecture

D2D communication allows a direct communication between devices without going through the core network, and thus improves the end-to-end latency as it decreases loads on the core network and reduces the number of the entities through which data should pass. The D2D reference model, which is work in progress, can be modified in the future. Figure 3 shows a D2D network reference model [3gpp703].

D2D Reference Model

Figure 3: D2D Reference Model

3 Data Flow and Service Requirements

This chapter briefly examines which traffic path the network use when data are sent from one UE to another UE. In addition, it describes necessary service requirements for proposed data flow when deploying M2M and D2D based on the LTE-A network.

3.1 LTE-A and M2M Data Flow and Service Requirements

As M2M assumes a connection through the interface of the existing LTE-A network, there is no difference in the data flow between the LTE-A and M2M network. Therefore, when a packet sent from one UE to another UE in the LTE-A and M2M network, it has to go through eNB, SGW, and PGW. Figure 4 shows this [3gpp401] [3gpp888].

LTE-A Network Traffic Flow

Figure 4: LTE-A Network Traffic Flow

  1. UE1 transmits the IP packet to eNB using the radio interface. Source IP address is the IP address of UE1 and destination IP address is that of UE2.
  2. After setting up the IP address of SGW as its destination address, and the IP address of eNB as its source address, eNB transmits the packet to SGW using the GPRS Tunneling Protocol (GTP) tunnel. When the packet is transmitted between eNB, SGW, PGW, the GTP tunnel is used; these entities have the function of mapping the GTP tunnel.
  3. SGW receives the IP packet and sets up the PGW IP address as its destination address and the IP address of SGW as its source address, and then transmits the packet to PGW using the GTP tunnel.
  4. PGW removes the GTP header and then forwards the packet to the router while the destination IP address sets up the IP address of UE2 and the source IP address sets up the IP address of UE1.
  5. PGW receives from the router the packet which has the IP address of UE2 as its destination address and that of UE1 as its source address.
  6. It sets up the IP address of SGW as its destination address and the IP address of PGW as its source address. After making the GTP header, it transmits the packet to SGW using the GTP tunnel.
  7. It sets up the IP address of eNB as its destination address while setting up the IP address of SGW as its source address and then transmits the packet, which includes the GTP header.
  8. Finally, eNB transmits the packet to UE2 using the data radio bearer.

However, M2M has several service requirements differentiated from the existing LTE-A network. Firstly, M2M requires different address system from the existing ones to accept a numerous number of devices. Secondly, it needs to control the overload arising when a countless number of devices are simultaneously connected to the network. Thirdly, the M2M applications cause mainly the uplink data traffic in comparison with the LTE applications which cause the downlink data traffic of video and others. Table 1 describes the characteristics of M2M network [3gpp368] [krjung10].

Characteristics Description
Low Mobility Do not move, move infrequently, Move within a certain region
Time Controlled Tolerate to send or receive data only during defined time interval
Time Tolerant Delay data transfer
Packet Switched (PS) Only Only require packet switched services
Small Data Transmissions Send or receive small amounts of data
Mobile Originated Only Only utilize mobile originated communications
MTC Monitoring Monitoring MTC device related events
Priority Alarm Message (PAM) Issue a priority alarm in the event of theft or other immediate attention
Secure Connection Require a secure connection between the MTC server and services
Location Specific Trigger Trigger MTC devices which are known by the MTC application in certain area
Network Provided Destination for Uplink Data All data from an MTC device to be directed to a network provided destination
Infrequent Transmission Send or receive data infrequently
Group Based MTC Features Group based collection of MTS features
Group Based Policing Group based management of MTS policies
Group Based Addressing Group based addressing of MTS identification

Table 1: the characteristics of M2M network (source ref: krjung10)

3.2 D2D Data Flow and Service Requirements

The data paths of D2D are classified into two: direct mode and locally-routed path. Direct path means a direct communication between UEs without using eNB while locally-routed data path represents communication between UEs using eNB. Both paths don't use EPC in the data plane but only in the control plane. Figure 5 shows this [3gpp703] [balji13].

D2D Data Flow

Figure 5: D2D Data Flow

UE discovers other UEs which are located around it. It measures the channel, shares the results with other UEs or the eNB through synchronizing with peer UEs, and generates the link with other UEs based on the results. eNB should control the D2D links to prevent D2D communication from interfering the link between eNB and other UEs. Table 2 describes the service requirements and proposed solutions [3gpp703].

Service Requirements Proposed Solutions
Discovery - Direct discovery
- EPC-level ProSe discovery
- Targeted discovery
- IMS based discovery
- Network based discovery
Communication - Group Owner mode
- Ad-Hoc mode
- Hybrid mode for one-to-many communication
- Network independent LTE direct communication (one-to-one)
- Network-authorized LTE direct communication (one-to-one)
- LTE direct communication (one-to-many)
WLAN Direct communications - EPC support for WLAN Direct communication
- ProSe assisted WLAN Direct communication
- Network-assisted WLAN Direct communication
Relay - UE-to-UE Relay using IP Routing and Forwarding
- UE-to-UE Relay operating at the application layer
- UE-to-Network Relay using Layer 3 Routing based on EPS Bearer
- Relay as v4/v6 IP router with application level gateway functions
Management - Identity
- Authorization
- Charging
- Capability Handling
- Service Continuity

Table 2: D2D Required Functions and Proposed Solutions

4 Summary

We have examined the reference models and data flow of LTE-A network-based M2M and D2D network so far. The use of the M2M network is rapidly spreading as it can be used for wide range of applications such as e-Health, smart city, and public safety. The LTE-A, already extensively used, is playing an important role in deploying the M2M network. The advantageous points provided by the data offloading are also definite. M2M is expected to be used along with the D2D network as D2D network will reduce local end-to-end delay and decrease the local M2M traffic.


  1. [cisco16] Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2015-2020 White Paper, Cisco, Feb 01, 2016
  2. [cisco16a] VNI Mobile Forecast Highlights 2015-2020, Cisco, 2015
  3. [3gppue] LTE ue-Category, 3GPP, July 10, 2014
  4. [3gpp401] 3GPP, TS 23.401, "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access", V13.5.0 December 2015
  5. [3gpp368] 3GPP, TS 22.368, "Service requirements for Machine-Type Communications (MTC); Stage 1 (Release 13)", V13.1.0 December 2014
  6. [3gpp703] 3GPP TR 23.703, "Study on architecture enhancements to support Proximity-based Services (ProSe)", V12.0.0 Feb 2014
  7. [3gpp888] 3GPP, "TS 23.888: System improvements for Machine-Type Communications", September 2012
  8. [balji13] B. Raghothaman et al., "Architecture and protocols for LTE-based device to device communication," in Proc. ICNC, 2013, pp. 895-899.
  9. [faye15] Fayezeh Ghavimi, Hsiao-Hwa Chen, "M2M Communications in 3GPP LTE/LTE-A Networks: Architectures, Service Requirements, Challenges, and Applications", IEEE Communications Surveys and Tutorials 17(2), 2015, pp. 525-549.
  10. [krjung10] K.-R. Jung, A. Park, and S. Lee, “Machine-Type-Communication (MTC) device grouping algorithm for congestion avoidance of MTC oriented LTE network,” Communications in Computer and Information Science, vol. 78, 2010, pp. 167 - 178.

List of Acronyms

3GPP 3rd Generation Partnership Project
DPF Direct Provisioning Function
eNB Evolved Node B
EPC Evolved Packet Core
EPS Evolved Packet System
E-UTRAN Evolved Universal Terrestrial Radio Access Network
GTP GPRS Tunneling Protocol
HSS Home Subscriber Server
IMS IP Multimedia Subsystem
IWF Interworking Function
LPWA Low-Power, Wide-Area
MME Mobility Management Entity
MTC Machine-Type Communications
MTC-IWF Machine-Type Communication-InterWorking Function
PCRF Policy and Charging Rules Function
PDN Public Data Network
PGW PDN Gateway
ProSe Proximity-based Services
PSAP Public-safety answering point
SGSN Serving GPRS Support Node
SGW Serving Gateway
UE User Equipment

Last Modified: April 17, 2016
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