two-way systems are push, pull and poll capable.

There are also three types of communication modes commonly associated with AMR: mobile wireless, fixed wireless and fixed wired. Two-way fixed systems show the most capability in terms of supporting extended functionality such as outage management restoration and customer disconnect/reconnect capabilities. When choosing a communication type, it is essential that utilities consider the future intended functionality of their AMR systems. In an effort to save costs, some utilities choose too simplified a system and trade off this additional functionality.

Mobile wireless AMR communication systems have become popular because of their lower cost and the fact that they require less overall backhaul infrastructure. These systems read meters using walk-by and drive-by techniques via ERT radio read. Because these systems are not truly fixed, their functionality beyond meter reading is somewhat limited. However, in terms of overall system cost, mobile communication systems can be very competitive.

Fixed wired AMR communication system options include narrowband power line carrier (PLC), telephone and Internet protocol. PLC systems have become quite popular in recent years. The advantage of PLC systems is that the wires are utility-owned, have long range capability and are virtually independent of geographical terrain. However, PLC systems are inexorably linked to the power distribution system and are directly affected by any modifications made to it by the utility. When considering PLC, the distribution system must be thoroughly analyzed from its metering endpoints to the chosen concentration points (usually at substations) to ensure that it is a communication medium capable of passing the AMR data signals. In these systems, additional system costs can also be incurred in the form of line traps,

coupling devices or power distribution apparatus that is PLC communications signal compliant.

One advantage of using Internet IP as a communication system is that the infrastructure already exists, and it provides very high data transmission rates. However, to ensure that such a system works universally, utilities would have to work with multiple Internet service providers to develop a system that has full compatibility with various hardware and software platforms utilized by their customers.

Fixed wireless AMR communication system options consist of public radio systems, (paging, GPRS), private radio systems, (licensed and unlicensed), and satellite systems.

When choosing a wireless AMR system, a utility should consider several factors. The target area’s population density dictates endpoint-to-con-centrator ratios. Some wireless systems are more suited to higher population densities while others are better suited to suburban and medium population densities. It is always worthwhile to remember that for a given amount of radiated RF power the greater the frequency the shorter the transmission distance. The majority of wireless AMR offerings utilize unlicensed frequencies in the UHF (300MHz – 3GHz) radio frequency band.

Another issue utilities face when choosing wireless AMR systems is the placement and siting of data concen-

trators. Some mesh systems utilize concentrators as metering endpoints. Other systems ensure adequate coverage and mitigate propagation issues by installing collector concentrators at higher elevations, usually on local streetlights. If the utility does not own these structures they would need to negotiate joint use agreements with local entities.

Satellite AMR systems are not as popular; however, the basic idea appears to be well-suited for remote, isolated areas.

In fixed wireless AMR systems, network topology is another parameter where there are numerous options. Older systems tend to use hierarchical, star and point-to-point communication techniques. In recent years mesh and hybrid mesh networks have become more popular and have proved to be very reliable in densely populated areas. In a mesh

 

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