Creating the Connected Utility: The Wireless Backbone

Background

The challenges associated with extending mobility in the industrial environment of a utility are very different from any other environment. Achieving success and cost-efficiency in delivering the Connected Utility requires an understanding of the unique challenges and how those challenges translate into specifications for the smart grid backbone — the wireless infrastructure. The coverage area for a utility can extend for many miles and needs to reach headquarters, generation, distribution, substation facilities, and all the way to customer homes. The physical area is vast, and consists of varying physical environments where reliable wireless connectivity must be established in spite of elements that might include environmental factors – such as extreme temperatures or wind as well as obstacles like buildings or large equipment.

In addition, protocols that were designed specifically for Local Area Networks (LANs) rather than for Internet usage can cause performance degradation when used in a wireless system. The reason behind these performance limitations can be traced directly to the protocol. While some of these protocols work very well over provisioned high-speed wired networks, they do not translate well into the wireless arena. This is due, in large measure, to the limited bandwidth available in wireless as well as the large number of small packets the protocol requires for transmission over the network. These protocols are extremely inefficient for use in wireless networks.

In addition to differences in the physical environment, there are many application differences as well. Many enterprises simply require the ability to connect mobile computers wirelessly on an ad hoc basis. While utilities have similar requirements, they in fact need much more. They are looking to create a safe and reliable smart grid that closes the loop between supply and demand. In addition, they are looking to connect sensor networks that can provide real-time system or equipment information that is crucial to the general health of the business by revealing a pending machinery issue that can be resolved — before it impacts customers, profitability, or employee safety. Achieving success in the challenging utility environment is dependent upon understanding the unique requirements, and how those requirements translate into criteria for the selection of the most crucial aspect of any mobility solution — the wireless backhaul. The selection of the right infrastructure will:

• Ensure the performance and functionality needed today
• Ensure that the system selected can grow as the business needs change and grow
• Reduce risk
• Enable maximum success — and return on investment

Reliability

For the Connected Utility, maximum uptime is crucial. A wireless system that offers maximum Mean Time Between Failure (MTBF) specifications and multiple levels of redundancy is crucial to ensuring the uninterrupted network availability required to protect productivity and profitability. Performance-enhancing features that contribute to reliability provide granular control over the availability and quality of the wireless connection. Equipment that can automatically change to a different channel if there is too much noise ensures that users maintain a robust connection in spite of challenging environmental conditions. Traffic control features provide granular control over types of traffic — for example, the ability to segment voice and data traffic helps ensure the quality of voice calls.

Security

Security plays a big part in ensuring reliability. The network must be protected from unauthorized users who could initiate attacks that can lead to downtime, the introduction of erroneous information or the theft of company or customer data. To achieve a level of security on the wireless system to meet your system requirements, the wireless system should offer a comprehensive portfolio of security features that can be layered as needed to achieve the right level of security for different applications. In addition to controlling who accesses the wireless system, data should be protected as it travels over the wireless infrastructure. And the ability to monitor the wireless system in real time is critical to enabling the swift action required to minimize the effects of any security breach. Key features should include:

ITY

• Integrated firewall
• Access control
• Data protection
• Monitoring
• Intrusion Protection

Bandwidth vs. Throughput

Bandwidth is a measure of the capacity of the link. Throughput is the rate at which usable data can be sent over the channel. Throughput in terms of usable data may vary depending on:

• Types of Packets
• Packets per Second (Multipoint Downlink ~ 3,000 packets per second/Multipoint Uplink ~ 1,500 packets per second)
• Operating System of the Sending and Receiving Machines
• Performance of Networking Equipment between the Two Endpoints or the Network Interface of the Sending and Receiving Machines
• Performance of the Application Software

The types of packets sent over the multipoint system will have an impact on the throughput of the link based on the size of the packet being passed. This is a function of the application.

First, the increase in the number of acknowledgements that now must be sent back over the link decreases efficiency; smaller packets translate to a higher number of acknowledgments (ACK). Second, smaller packets don’t always align well to the 64 byte data slots. To illustrate, think about the Ethernet as a freight train where each train car is capable of carrying 64-bytes of information. If a packet contains 80-bytes of information, it will be broken down into two train cars. The first car will carry 64-bytes while the second car carries 16-bytes. As you will note, the second car is only partially full and has 48 bytes of unused space.

As with any wireless system, the method of packet transmission (how the wireless system transmits the information) as well as the size of Ethernet packets must be considered. Some programs transmit large numbers of very small packets containing keyboard, mouse and screen information. These small packets can seriously degrade the performance of most wireless systems; therefore, understanding a wireless system’s capabilities with respect to packet rates is important in designing an efficient network.

Interference – Licensed and Unlicensed

While operating in a licensed band adds an initial cost to the bottom line, the license itself means that no one else can operate in that frequency. Relative to interference, the network design must only account for self-induced interference. When deploying a wireless network in the license-exempt bands, interference from your own network is only one issue to be considered – interference from other networks must also be taken into account. These interfering sources may be present at the time of initial network deployment, or they may be deployed a year or more down the road.

In order to ensure that a wireless system will last for a significant period of time providing an adequate return on investment, operations in these bands must take into account all forms of interference. Equally important, customers must have confidence at a high level that the technology driving the network which is delivering business-critical broadband connections is reliable and stable.

When setting up a Point-to-Point (PTP) network in license-exempt bands, interference is still an issue. These problems are not as significant as those encountered in Point-to-Multipoint (PMP) networks. However, interruption to these links can often have an even greater impact, as they typically carry traffic for many sources at a time.

The ability of a network deployed in license-exempt bands to tolerate interference – both self-induced and from outside sources – is largely a function of the equipment being used. It is important that the core product itself be designed from the ground up with stability and RF robustness as a key design goal.

Management

A key IT concern is the overall manageability of wireless solutions. Wireless infrastructure in a utility environment can span very large areas. Management of wireless solutions often ripple into ongoing operational costs that may be even more costly than the capital required to purchase and deploy the system itself — and can actually erode the benefits of the mobility solution. To address this issue, your need comprehensive management solutions that provide central and remote management of many aspects of your wireless network.

With centralized visibility and control, personnel will no longer need to physically check network equipment, traveling to the various areas where infrastructure is installed, and downtime can be significantly reduced. The resulting savings in time and cost yields a better return on investment — and lower total cost of ownership. For maximum benefits, look for management solutions that provide complete control over all the aspects of your mobility solution, reaching beyond the wireless infrastructure to encompass other RF networks as well as the mobile devices on the network — and the applications, operating system and firmware installed on those devices.

Summary

Enabling the Connected Utility requires a true wireless network ecosystem — comprised of multiple wireless infrastructure components needed to provide the most cost-effective and reliable network, including:

• Mesh capabilities enable the extension of wireless connectivity into outdoor areas and hard to wire areas indoors, as well as the connection of two wired networks — all without the expense of installing additional cable or fiber.
• Point-to-point solutions provide low-cost networking between facilities.
• Point-to-multipoint private wide area networks enable the extension of the network anywhere, ensuring coverage wherever it is needed and the network is always available when needed, while reducing the use and cost associated with public wireless WAN use.

Integrating various types of wireless networks to obtain coverage where it is needed is the key. And the selection of an end-to-end solution offering a wide range of wireless options designed to be layered can ensure ease of deployment, integration, and management of a wireless ecosystem.