The latest PLC standards are PRIME; a multicarrier-based ... 14Mbit/s. LTE: an emerging technology option ... meter wireless communications market in Europe.
TELITFuture market
M2M Communications Technology Trends
www.ctvr.ie
Keith Nolan, CTVR / The Telecommunications Research Centre, Trinity College Dublin
>> In Europe, the dominant technologies used for
smart metering are power line carrier (PLC) and general packet radio service (GPRS). In the US RF mesh solutions are used in almost 90% of smart metering deployments with GPRS and PLC accounting for the majority of the remaining share. PLC using the older X10, CEBus, and LonWorks protocols are among the lowest cost solution options for smart grid deployments, however scalability is severely hampered by the need for frequent aggregation points, hostile power line RF environment, the need to own the grid infrastructure, and applicability for one m2m market sector only. The latest PLC standards are PRIME; a multicarrier-based PLC standard that offers increased robustness and data rates for smart meter deployments and G3-PLC™; also a multicarrier-based PLC technology that was developed by Maxim to meet the requirements of Electricité Réseau Distribution France (ERDF). G3-PLC has now gained worldwide interest and is under consideration by the ITU, IEEE, IEC and ISO standards committees. PRIME is also only suitable for mainly smart meter deployments. GPRS is a second generation (2G/2.5G) cellular network technology that was introduced in 2000 as part of 3G upgrade plan for GSM. GPRS uses the spare timeslots in unused time division multiple access (TDMA) GSM channels. EDGE is a data system built on GSM networks and
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is referred to as a 2.5G cellular network technology or ‘pre-3G’. EDGE offers up to four times greater data rate than GPRS. 3G arrived with the introduction of high speed packet access (HSPA) which can support downlink speeds of between 1.8 to 14Mbit/s. LTE: an emerging technology option LTE is the latest in the commercially deployable cellular network technologies and the standard provides for peak downlink rates of 300Mbit/s and peak uplink rates of 75Mbit/s. LTE is referred to as 4G and it is emerging as a communications technology option for smart metering. LTE is seen as the natural upgrade path for carriers with GSM/UMTS networks and deployments are currently underway worldwide. The key features of LTE also include low-latency operation (in the order of milliseconds in ideal environments) and an all-IP network. The data capacity and low-latency features of LTE are essentially an overkill for the actual data requirements of m2m applications. The power demands associated with LTE
in particular are expected to prove challenging for a large scale m2m deployment in a power constrained environment. However, it is likely that LTE will win out as the technology of choice quite simply because it is being adopted by most operators worldwide as their preferred technology for the next 20-30 years, it's an all-IP technology, and they can upgrade their existing infrastructure to support LTE rather than start from scratch. In the U.S., where RF mesh solutions are more predominant, solutions include IEEE 802.15.4 ZigBee and proprietary standards namely, Z-Wave and FlexNet. Scalability is restricted due to the need for specific frequency bands in the case of Z-Wave and FlexNet. The short distances (up to 10 meters) involved in a ZigBee mesh solution and the need for frequent backhaul limits the scalability of this option. In-building solutions also include WirelessHART, a wireless sensor networking protocol, and ISA-100, an international standard for wireless systems for industrial automation. The main reason why RF mesh technologies are more widely used in the
U.S. is due to a more favorable spectrum regulatory environment that allows devices to use license-exempt spectrum in the 902-928MHz range with a 1W maximum transmitted power capability for systems employing at least 50 channels. This is unique to ITU Region 2 (Americas, Greenland, some eastern Pacific islands). In contrast, RF mesh devices in Europe are currently limited to the use of a single channel in 868MHz with a 25mW power limitation for short range devices. This severe power restriction significantly restricts the communications range of the devices to in-room/in-home operation. WiFi and WiMAX The typical WiFi communications range extends to approximately tens of meters indoors for 2.4GHz and it can be less for 5GHz. Building penetration abilities
are severely hampered by the frequency range characteristics, operation is limited to line of sight, and the ISM frequency bands can feature multiple other services and interference sources that can adversely affect the performance of WiFi. The IEEE 802.16 family of worldwide interoperability for microwave access (WiMAX) is designed for wireless connectivity across larger geographical areas than is possible with WiFi. The advent of LTE has reduced the worldwide interest in WiMAX however. Weightless is an emerging proto-standard for m2m that takes advantage of unused frequency spectrum in the UHF band referred to as TV whitespaces. Weightless is being developed primarily by UK-based company Neul through the Cambridge Wireless Standards Special Interest Group
Established Cost
LTE
Emerging
HSPDA WiMAX EDGE
GPRS
WiFi
IEEE 802.15 Weightless
X10, CEBus, LonWorks
Scalability
(SIG). It is specifically designed for scalable wireless m2m applications where the chip cost for high volume deployments is less than US$1. In the figure below, the range of technology choices considered for m2m are mapped in terms of cost and ability to scale for high volume m2m deployments. In this figure, the evolution of cellular technologies from 2G e.g. GSM/ GPRS/EDGE, 3G e.g. HSPA, and on to 4G e.g. LTE, allows for an increase in the number of devices to be supported. But there is the significant drawback of increased chipset prices and operator-related costs. PLC, GPRS, and LTE are not sufficient for power-constrained and high-volume, low-cost applications in market sectors beyond the smart grid. However, in the case of PLC and cellular standards (predominately GPRS), these technologies are currently accounting for almost all early deployments of smart meter wireless communications market in Europe. No single solution There is no single solution that will suit all m2m requirements, on-the-ground business environments, existing operators, and spectrum regulatory policies. The future trend is likely to be the continuance of PLC and RF mesh for smart meter/smart grid applications and the increasing dominance of LTE as older technologies like GSM/ GPRS are phased out over the coming years.
