M2M communication over cellular networks

How to deal with a thousand nodes: M2M communication over cellular networks

A. Maeder NEC Laboratories Europe [email protected]

Outline ▐ Introduction to M2M communications  The M2M use case landscape  Properties and requirements

▐ Challenges for mobile cellular networks  Architecture  Challenges on RAN and core network

▐ Current efforts in standardization  ETSI: end-to-end framework for M2M  3GPP: Keep the operators into the value chain  IEEE: Optimize the radio access

▐ Conclusion and outlook ITG Zukunft der Netze 2011

The M2M use case landscape

ITG Zukunft der Netze 2011

What is the issue? ▐ Cellular mobile networks are designed for human communication  Interactive communication between humans (voice, video)  Data communication involving humans (web browsing, file downloads, etc).  Communication is connection-centric

▐ Cellular mobile networks are optimized for traffic characteristics of human-based communication applications  Communication with a certain length (sessions) and data volume  Communication with a certain interaction frequency and patterns (talklisten, download-reading, etc.)

But: M2M communication is different


Example: Smart Grid/Smart Metering ▐ Control and reading of metering/infrastructure Wind Turbine

Home displays TV, Computer

Data Center

Solar Panel In-Home Energy Display

Wan Communication

Light

Meters Coms Appliances

Temperature

Breaker

Valves

Smart Water

Smart Gas Smart Elec.

Small message sizes Low to medium frequent communication Relaxed delay requirements High requirements on energy efficiency? Large number of devices “Alarm” scenarios ITG Zukunft der Netze 2011

Gateway

Image source: ETSI

Example scenario: smart meters per single cell

Estimation based on census data One smart meter assumed per household ITG Zukunft der Netze 2011

Example: Intelligent Transport Systems High speed mobility Very high mobility/latency requirements

Car-to-X: High mobility High speed Very low latency Security

Image source: ETSI ITG Zukunft der Netze 2011

Properties and requirements of M2M applications Smart meters

eHealth

ITS

Surveillance

Mobility

none

Pedestrian /vehicular

Vehicular

none

Message size

Small (few kB)

Medium?

Medium

large

Traffic pattern

Regular

Regular/irregular

Regular/irregular

Regular

Device density

Very high (up to ten thousands per cell)

Medium

High

low

Latency requirements

low (up to hours)

Medium (seconds)

Very high (few milliseconds)

Medium (< 200ms)

Power efficiency requirements

High (battery powered meters)

High (battery power devices)

Low

low

Reliability

High

High

High

medium

Security requirements

High

Very high

Very high

medium

Diverse and challenging requirements for today’s mobile networks Requirements and traffic patterns are not clear today! ITG Zukunft der Netze 2011

Cellular M2M architecture Mobile operator M2M operator domain domain HSS

M2M server applications M2M platform P-GW

MTC server abstraction layer

S-GW

MME Mobile operator core network

local

How to integrate? breakout

Radio Access Network (RAN)

management operation control

data transport addressing locating

MTC device

UE

small cell

eNB

MTC device

eNB femto/small cell UE

femto/small cell


eNB

MTC device

M2M device application

M2M device application

Challenges for radio access ▐ ▐ ▐ ▐ ▐ ▐

Many devices Long idle intervals Small message transmission Uplink is bottleneck Energy efficiency Human communication must not be affected! RACH Congestion

eNB


UE

1

eNB

Random Access Preamble

Random Access Response

3

2

Scheduled Transmission

Contention Resolution

4

Random access procedure in LTE for attachment, uplink bandwidth requests ▐ Proposed solutions: ▐ Dedicated RACH ▐ Time backoff classes ▐ Slotted access ▐ Group coordination ▐ Access barring ▐ Randomization

Challenges for non-access stratum Signaling congestion

HSS S6a

S11 MME

S/P-GW

S1-MME

▐ Each data transmission from idle mode requires a bearer setup  Complex procedure with several CN entities involved  Large overhead for small message sizes  May lead to signaling congestion and high computational load

S1-U

▐ Proposed solutions: eNB


 Signaling aggregation  Signaling rejection/differentiation  Signaling reduction for MTC device classes

Trade-off between control and scalability Security Charging QoS Management Monitoring Scheduled access

Control

Large device numbers Low latency Low power consumption Small burst transmission Low cost Low overhead

Scalability

Diverse and partially contradicting requirements Balancing mobile and M2M operator needs Is it sufficient to modify existing technologies?


Activities in standards: ETSI ▐ ETSI develops an end-to-end framework for M2M ▐ Architecture highlights  Generic service capabilities for M2M applications in M2M server, gateway and devices  M2M identification and addressing scheme Network Domain  Framework for security and service bootstrap  Resource management framework

▐ Independent of transport network Device and Gateway Domain ▐ Interaction with MNO core network functions (but not access) ITG Zukunft der Netze 2011

M2M Applications

M2M Service Capabilities

M2M Management Functions

Core Network (CN)

Network Management Functions Access Network

M2M Applications M2MService Capabilities M2M Gateway M2M M2MArea Area Network Network

M2M Device

M2M Applications M2M Service Capabilities M2M Device

Activities in standards: 3GPP ▐ Two work items: network improvements for MTC (NIMTC, Rel. 10) and system improvements for MTC (SIMTC, Rel. 11) MTC User ▐ Current focus on architecture (MTC server), Service Logic Components control plane, services, features: TR 23.888 MTC Server Generic Service Layer API ▐ Study on RAN improvements finished in Sept.  TR 37.868, section on RAN overload control  Extended Access Barring (EAB) selected as solution Focus on architecture/services /signaling

3GPP MTC Service Abstraction Layer MTCsms SMSC

MTCsms

MTC Device

MTCu

PDN

3GPP PLMN MTC Server IWK Function

3GPP bearer services / SMS / IMS

MTC Server

MTC Server

MTCsh

MTCi

PGW

...

HSS

3GPP HPLMN

3GPP VPLMN eNB, RNC or BSC

MTCi

3GPP MTC architecture ITG Zukunft der Netze 2011

MTCu MTC MTC MTC Device Device Device

3GPP MTC service abstraction

Activities in standards: IEEE 802.16p ▐ ▐ ▐ ▐

IEEE 802.16p: started in Sept. 2009 Extension of 802.16e (WiMAX) and 802.16m (WiMAX 2.0) MAC and minimal OFDMA PHY enhancements Current status: enhancements for network entry, group control, multicast, mobility, dedicated random access resources ▐ Letter ballot in Nov. 2011, publish 2012 MNO (Mobile Network Operator) Access Service Network

Focus on air interface/MAC

IEEE 802.16 Non M2M device

IEEE 802.16 M2M device

Non IEEE 802.16 M2M device

IEEE 802.16 M2M device

Connectivity Service Network

R1 M2M Server

R1

IEEE 802.16 BS

R1

802.16p M2M service reference system architecture ITG Zukunft der Netze 2011

M2M Subscriber

Conclusion and Outlook ▐ M2M is an enabler of the Internet of Things. ▐ M2M is challenging for today’s and future cellular networks:  Interworking between M2M operator and mobile operator.  Diverse traffic characteristics and requirements on QoS, energy efficiency, …

▐ Efforts in Standards: “Fix” existing systems by adding as much as necessary, as less as possible. ▐ Research needs to think beyond this approach  M2M applications imply novel network performance metrics  Flexible MAC, low-overhead protocols, virtualization, energy efficiency, hierarchical networks, …  First step: M2M traffic models for popular use cases (e.g. smart meters)!  Talk to industries and users of M2M communications.
