This paper describes what a municipal wireless network is, the basic wireless technology behind it, the types of applications municipalities can deploy over it, and critical success factors when choosing a solution vendor.
Summary
Municipal wireless networks based on wireless LAN technology have received much attention in the press lately. New products that are designed for the outdoors are allowing municipalities to use this cost-effective technology as an option when building outdoor wireless networks for private or public use. Understanding the technology basics as well as application possibilities for an outdoor municipal wireless LAN will help city and IT managers write more effective RFQs and make more informed vendor selections.
Challenge
Cities have long used outdoor wireless networks to more efficiently connect personnel whose primary jobs require them to be outside an office setting. Private radio access networks (RANs) and cellular wide-area networks (WANs) are commonly used by public safety personnel as well as city maintenance, building inspection, and transportation departments to send and receive information while out in the field. These networks work well for many applications, but may not provide ubiquitous coverage or sufficient bandwidth throughout the metropolitan area. The effectiveness of WANs depends upon the application and data needs. WAN download and upload speeds are typically much slower than wireless LAN speeds. For tasks that require large files, pictures, and video, using a WAN connection may be more frustrating than returning to an office. As for private radio networks, coverage and cost may be an issue. While the bandwidths may be much higher and security is tighter because the spectrum is licensed, these networks are built in much lower volumes than commercial networks and can be much more expensive.
Solution
Wireless LAN (WLAN) technology is well suited to address the issues of providing higher bandwidths at lower costs. When properly designed for outdoor deployment, WLANs can even be used to bridge the gap between RANs and WANs. For most cities, the right approach is to use a combination of all three outdoor wireless technologies. As an example, for suburban or rural cities, a high-bandwidth WLAN-based municipal network might be deployed within city limits; a private radio network might be used to connect city hall, fire and police facilities; and a wide-area cellular network might be relied on when city personnel travel outside of city limits.
Because using WLAN technology for municipal networks is a relatively new concept for many city managers and chief information officers, this paper will provide a basic understanding of wireless LAN terminology, municipal wireless network usage models and applications, and the important criteria to consider when you select a solution vendor.
Wireless LAN Technology Basics
Wireless LAN Standards, Speeds, and Range
WLANs are based on a set of industry standards developed by the IEEE. A wireless LAN is typically composed of wireless clients and infrastructure known as access points. Wireless clients are embedded inside mobile devices such as laptops, smart phones, or PDAs or can be standalone units such as a PC card, USB adapter, or customer premises equipment (CPE). The access point provides a bridge between the wireless and wired worlds, typically connecting into a standard Ethernet network. Any application that can run on an Ethernet network can also run over a WLAN network. The wireless LAN merely replaces the wired network.
The IEEE 802.11 standards body defines the communication protocol between the access point and client, and also provides standards for security, quality of service, and many other aspects of the network. Currently, there are three main standards: 802.11b, 802.11g, and 802.11a. The 802.11b and g standards operate in the 2.4-GHz spectrum, while the 802.11a standard operates in the 5.8-GHz spectrum. 802.11g provides 54 Mbps over-the-air data rates, and interoperates with 802.11b-based devices, which run at 11 Mbps. 802.11a also provides 54 Mbps over-the-air data rates. Actual effective bandwidths are less than this by approximately half because of the overhead of the communication protocol. In addition, as a wireless client moves away from an access point, the bandwidth is reduced because as the radio signal gets weaker it causes the client to transmit at lower speeds to ensure that the traffic is received.
802.11 devices typically have an unobstructed range of approximately 1000 feet outdoors. The actual range of the device depends on the specific buildings or foliage that may be present, the transmission power of the device and the receiver capabilities, and the spectrum it is operating in. Typically, the transmission encoding utilized by 802.11 in the 2.4-GHz band provides greater transmission range than in the 5-GHz band. Transmission range can often be increased by using an external antenna on the access point or client device or both. To create contiguous coverage, multiple access points are placed outdoors. Software can help automatically plan where the access points should be placed based on the bandwidth requirements of the users and applications. For higher overall speeds, access points can be grouped more closely together to ensure that clients operate at the higher speeds. As a client moves, it will roam from access point to access point. This roaming is imperceptible to users and is comparable to a cell phone handing off from cell tower to cell tower while a person is driving. Roaming is fast enough that it will not impact most applications.
Mesh Networking and Backhaul
Access points require a connection to the wide-area network or the private city network to enable wireless clients to access needed applications and data. Because access points must be mounted outdoors on utility poles or buildings, decreasing the number of backhaul connections is highly desirable. Backhaul connection options might include fiber, DSL, or wireless point-to-point bridges. In all cases, this connectivity, sometimes referred to as the metropolitan-area network (MAN), can be the most expensive portion of an outdoor municipal wireless network. To minimize this cost, access points intended for outdoor deployment employ wireless mesh networking technology. Mesh networking allows two access points to talk to each other directly over their wireless radios. As shown in Figure 1, a secondary access point, referred to plain mesh access point (MAP), does not require a direct connection to the MAN, but instead connects wirelessly to another access point, called the root access point (RAP), that does have a MAN connection.
Figure 1. Two-tier Mesh Architecture
Security
Outdoor wireless LANs should use the same security best practices as any enterprise wireless LAN network. IEEE 802.11i should be used for communications between the access point and client for private city network applications whenever possible. Mesh connections between access points are not covered by IEEE 802.11i; however, strong security is still required on these connections to ensure that eavesdropping does not occur. Many vendors use Advanced Encryption Standard (AES) encryption and strong mutual authentication methods between access points to secure this link.
Some municipalities will want to deploy the network for multiple uses. As an example, city personnel might use the network to access building inspection certificates while at the same time the public is allowed to use the network for general Internet access. In this case, the municipal wireless network must support multiple user types with differing security requirements. A capability called virtual LANs (VLANs) allows the same access point infrastructure to logically separate user traffic to ensure that city networks remain secure while public users have easy access to the Internet. In general, Cisco recommends using the principles of the self-defending network to secure any outdoor municipal wireless network. For more detailed information on securing an outdoor wireless network, see Best Practices for Outdoor Wireless Security.1
Outdoor Wireless Network Applications and User Types
Understanding the different users and the anticipated applications for a wireless network is an important first step in any decision about what wireless technology to use. Different types of users and applications necessitate different devices. This, in turn, will typically have an impact on the wireless network that is most appropriate. In general, there are three basic usage models for outdoor wireless networks:
• Municipality and city agency applications
• Public safety applications
• Public use applications, including use by residents, businesses, and tourists
Municipality and City Employee Applications
For many cities, streamlining workflow in the field represents an enormous potential reduction in the staff required to accomplish the city's work and an increase in productivity. A primary goal is enabling employees to remain in the field instead of having to return to a central office to receive the next assignment.. Using wirelessly enabled PDAs or laptops allows city personnel to receive job assignments, plans, or research material, or equipment databases while in the field. Bar code scanners can be used for asset or service tracking and can provide instant updates to other team members. With wireless mobility, city personnel can become more responsive to ad hoc assignment changes.
Another important application is automatic meter reading, which is currently a time-intensive task. A wireless network can aggregate data from automatic meter reading (AMR) solutions in areas of a city where a fiber network may not be available. This eliminates the need for manual reading, which is not only expensive, but may also be a safety risk for meter reading personnel. Even if meter reading is currently accomplished wirelessly by personnel in the field, you can save significant time and money by eliminating this step.
Another use of AMR is the real-time monitoring of water and electricity usage data, creating more visibility into consumption. With real-time monitoring, agencies can determine if a high usage of electricity or water at any given time could be a result of faults in the system, such as water leakage from broken pipes. A quick response can improve customer satisfaction with the agency performance in emergency situations.
Public Safety Applications
Public safety applications cover a broad spectrum of potential users: police, fire, emergency medical services, 911 centers, airports, and transit agencies. These users need levels of system coverage, capacity, security, and control that commercial carrier systems often cannot achieve. What's more, public safety agencies are often accustomed to deploying and managing their own private systems. Some examples of applications that improve the effectiveness of public safety agencies include the following:
• Mobile data access-Immediate, full-text access to DMV records, warrants, mug shots, criminal records, and Amber Alerts (high-priority bulletins about missing children) to speed decision making and increase safety
• Streaming video and digital images-Video surveillance from government buildings and businesses to gauge the nature of the response needed
• Building schematics and plans-Immediate access to schematics and plans as critical aid to fire safety personnel in search and rescue operations
• Ad hoc wireless networks-Critical for facilitating local communication among emergency responders
Mobile devices, such as laptops and PDAs, are most commonly used for these applications. The devices are generally used in response vehicles, or "ruggedized" for use outside the vehicle. Because of the highly sensitive nature of much of the information, security measures for these applications must be much more stringent than for municipal or public use applications.
Public Use Applications
Public use applications represent the most widely discussed area of outdoor wireless networks based on Wi-Fi. The permutations range from free, pervasive outdoor deployment in city centers for use by anyone, to daily fee-based systems and monthly subscriptions for businesses and residents in select areas. Applications using the network therefore will be broad, but in general, the primary goal is to provide a high-speed broadband connection, with the security of that connection left up to the user. While the laptop is currently the primary device for connecting to the network, a wide range of devices that are designed to connect to public Wi-Fi networks are becoming available. Examples include mobile data devices such as the RIM Blackberry, phones that operate as Wi-Fi devices, and even cameras that are enabled with embedded wireless LAN clients.
Benefits of a Municipal Wireless Network Based on Wireless LAN Technology
While not all applications are appropriate for a wireless LAN-based municipal network, the vast majority can be successfully deployed. There are several key characteristics of wireless LAN technology that make it attractive for broad outdoor deployment. They include:
• Low cost- Because of the high volume of WLAN devices used for enterprise and consumer applications, infrastructure costs are relatively low when compared to private radio networks.
• Client ubiquity-Wireless LAN clients are standard in almost all laptops, and increasingly in other devices such as smart phones and PDAs. This eliminates the need to purchase special client hardware or software for many field applications. Client ubiquity is also is a primary reason why municipal wireless networks can help cities increase digital inclusion or stimulate economic development-many citizens and visitors are likely to have a Wi-Fi client.
• Interoperability-Through the Wi-Fi Alliance, the vast majority of clients and infrastructure devices have been certified using well- defined interoperability testing, which ensures compatibility between a wide variety of different manufacturers products. In addition, Cisco Compatible Extensions, available on over 90 percent of shipping clients, ensures the widespread availability of client devices that are interoperable with a Cisco WLAN infrastructure and that take advantage of Cisco innovations for enhanced security, mobility, quality of service, and network management.
Selection Criteria when Choosing a Municipal Wireless Network Solution Vendor
It's important to carefully consider the choice to develop a municipal wireless network. IT leaders tasked with the challenge should employ a multistep process. This process includes:
• Surveying internal and external constituencies to develop a common vision for the network. Is the primary purpose of the network private city use, digital inclusion, or a multi-use?
• Conducting a gap analysis of any current outdoor wireless municipal networks already in the area in terms of coverage or application support.
• Analyzing internal resources available to support the network, including skilled personnel and funding sources.
• Soliciting proposals from multiple credible solution providers through a formal request for proposal process.
• Analyzing proposed networks and determining whether an existing service provider network will meet the city's needs or if a purpose-built network is required.
• Reaching out to the community and city departments continuously during the process to keep them informed.
• Providing education to the various users on an ongoing basis to ensure that the network capabilities and limitations are properly understood.
Once a needs evaluation is complete, city IT and other stakeholders can assess their options and optimize their requirements for their particular environment.
Centralized Configuration and Management
Outdoor wireless networks require centralized configuration and management. With the need to place outdoor access points high on utility poles and buildings, local access for reconfiguration is cost prohibitive and time consuming. Cisco's award winning Wireless Control System with its intuitive GUI provides centralized, simple methods for remote configuration and management of the outdoor wireless network. In addition, radio resource management (RRM) delivers automatic adjustments to the RF characteristics of the network. Interference or coverage holes that develop over time as a result of foliage growth or the deployment or other wireless networks are automatically identified and healed by the Cisco Unified Wireless Network.
Comprehensive Security Solution
Public safety and municipal applications conducted over an outdoor wireless network are really an extension of the city's internal network. As such, the same careful provisions used to protect the government network while allowing remote workers to connect at field offices, from home, or on the road should be employed for those personnel accessing the city's network via an outdoor wireless network. The Cisco approach to security is based on the Cisco Self-Defending Network and the SAFE Blueprint architecture from Cisco, which provide wired, wireless, data center, and Internet guest access that is integrated and secure. A security-aware infrastructure is one that will extend from the very core of the network to the end systems. Every device in the network-from mobile devices, to desktops, through the LAN, and across the WAN-plays a part in a globally distributed defense that secures the networked environment. Self-defending networks identify threats; react appropriately to the severity level; isolate infected servers, desktops, and mobile devices; and reconfigure network resources in response to an attack. Endpoint security applications include Cisco Network Admission Control (NAC), Cisco Security Agent, and Cisco Trust Agent. These technologies provide behavioral protection for PCs and servers to prevent damage from new, previously unknown attacks. They also provide posture information about the endpoint when host security policy requires validation prior to permitting network access.
Unification with Existing Indoor City Networks
For public safety or private municipal applications in smaller cities, it may make sense to consider the outdoor municipal wireless network to be an extension of the city's internal network. Cisco offers a comprehensive unified approach to the deployment and management of wired and wireless networks, whether internal or external to city buildings Cisco has integrated wireless LAN services with Layer 2 and 3 switching infrastructure. Pervasive wireless LAN deployment across entire enterprises and cities is motivating this evolution to integrate wireless-specific capabilities within the Layer 2 and 3 wired infrastructure. Integrating this functionality uses the bandwidth, security, redundancy, and management capabilities of the network and provides a strong platform for expansion. Cisco is the first to introduce this next-generation wireless LAN solution with the Cisco Catalyst® 6500 Wireless Services Module (WiSM) and the Cisco Catalyst 3700/3800 Integrated Service Routers with the Wireless LAN Control Module. Government agencies that already have deployed Cisco Catalyst 6500 Series switches or Cisco integrated services routers can take further advantage of their investments by adding wireless LAN controller capabilities to these existing platforms.
Cisco delivers a unified approach to deploying indoor and outdoor wireless LANs. The Cisco Unified Wireless Network provides a single platform for management through Cisco wireless LAN controllers and the Cisco Wireless Control System (Figure 2).
Figure 2. A Single Management Platform for Indoor and Outdoor Wireless LANs
City and municipal buildings that deploy a wireless LAN indoors can now extend Wi-Fi coverage outdoors to their own campuses or throughout the city itself while maintaining a single interface for monitoring, updates, and troubleshooting.
Conclusion
Outdoor wireless networks based on IEEE 802.11 can be an important component of a municipality's overall wireless network strategy. Low-cost infrastructure, nearly ubiquitous clients, and a high degree of multivendor interoperability make wireless LAN technology an attractive choice. What's more, this technology's ability to segment multiple users with different security requirements makes the wireless LAN a multiuse infrastructure capable of simultaneously supporting municipal, public safety, and public use applications. While wireless LAN technology itself is common, selecting a vendor that can provide the right combination of higher-level configuration, management, and security features is essential to ensuring a resilient network with low ongoing operation costs.
1http://www.cisco.com/en/US/solutions/collateral/ns340/ns394/ns348/ns621/net_implementation_white_paper0900aecd8044059b.shtml