Chapter 10. The Future
Predicting the future is always a little dangerous, especially for technology intensive systems and services such as telecommunications. This handbook was written over a two year period that saw major developments in the way that telecommunication services are provided, and in their supporting technologies. The intent of this chapter is to provide a look at some of the telecommunications technologies that may have an impact on the development of Transportation Management Centers, Traffic Signal Systems, and Freeway Management Systems. The following information is provided based on technology developments at the time of publication of this document.
Circuit Switched vs. Packet Switched
Prior to 2004, most industry analysts were indicating that the major telecommunication carriers would continue to invest most of their money in the maintenance and upgrade of existing circuit switched voice based networks – the general consensus being that the significant investment in those types of networks would continue through 2050. In January 2004, several major telecommunication carrier companies announced that they were shifting the investment of those dollars to implementation of packet switched internet telephony networks. They indicated that the shift would be aggressive, looking to make services based on those systems available network wide by 2010.
The overall effect of these changes will make the transmission of digital data via these networks less expensive and require less hardware. Departments of Transportation will derive significant benefits from the changes. Traffic signal systems that traditionally used dedicated leased telephone lines will be able to use packet switched circuits. Instead of paying for a leased line on a 24/7 basis (even when the line is not in use) they will pay for the amount of data actually transmitted (the number of packets used). Hardware for these systems will be less complex, and lower in cost. DOTs will see a reduction in the overall complexity and cost of hardware required in the TMC together with a reduction of the cost to operate and maintain this equipment.
Between 1998 and 2004, the IEEE 802 committees developed a number of standards for the efficient transmission of data using both wireline (including fiber) and wireless. These new standards help to provide for the "seamless" transmission of data from one medium to another. All of these new standards will be easier to implement via the new packet switched networks. The new standards allow for relatively simple transition from wireline to wireless, and back, with minimal degradation of data quality and bandwidth.
A major problem created by the transition from circuit switched to packet switched is the requirement to identify the origin and destination of the communication. Currently, telephone numbers are used. The caller simply enters the telephone number of the called and the system recognizes the hierarchal (a thirteen digit code) order to route the call. Each circuit can be identified via the:
- Country Code (3 digits)
- Area Code (3 digits)
- Exchange Code (3 digits)
- Circuit Code (4 digits)
The pair of wires connected to each telephone instrument can ultimately be identified (and called) by a telephone number.
The Cellular Telephone system simply replicated the circuit switch method by providing each wireless handset with a traditional telephone number. The system works for voice connectivity, but is problematic for broadband data networking. The emerging requirement for wireless handsets to be mobile computers (rather than mobile telephones) has created a need for a new switching and connection protocol.
"Session Initiated Protocol" (SIP) is an emerging communication protocol that improves the ability of packet switched networks to identify origin and destination points within a network. SIP uses the universal resource locator (URL) protocol to provide connections. These are the same identifiers used to browse web pages. A URL is a type of address that describes the location of information on the World Wide Web, e.g., www.fhwa.dot.gov. With SIP, even phone numbers are converted to URLs. Reaching an individual can be as simple as entering his or her e-mail address. The similarity of SIP to HTTP not only makes it ideally suited for the IP environment, but it's easy for HTTP experts to program it without learning a new language
A number of new telecommunication technologies will begin to be used on a broad scale by Departments of Transportation and Tolled Facilities operations. Some of these are:
- High speed Ethernet
- Resilient Packet Ring (RPR)
- Broadband Wireless
- Radio Frequency Identification (RFID)
High Speed Ethernet
Ethernet is generally considered as a high speed telecommunication topology, but for purposes of this discussion one (1) gigabit (GigE) and ten (10) gigabit (10GigE) are considered as high speed. There are (as this handbook is being written) discussions of higher speeds (beyond 10 Gig) for Ethernet.
Many devices used in Traffic Signal and Freeway Management systems are being manufactured with Ethernet communication ports. This will allow for direct connection of the devices without the need to use protocol converters (serial to Ethernet).
GigE will provide significant capabilities for transporting video and other data from field devices to the TMC. Most desktop computers and work stations started shipping with GigE capability embedded into the "motherboard" by the fourth quarter of 2003. Eventually, GigE will become the standard for LAN for desk-top to desk-top communication within the center. Two processes, voice and video over IP, will be greatly facilitated by the use of GigE.
Chapters 2, 5, and 7 presented the concept of VIP (video over IP). CCTV cameras are designed with built-in video CODECS and Ethernet transmission ports. The use of these devices will simplify the deployment of visual observation systems for traffic and transportation management. The following is a comparison of traditional CCTV systems and VIP systems:
Fewer pieces of hardware reduces the overall complexity of the system, and reduces the total cost of deployment and maintenance. This is one example of how new telecommunications standards and systems will help provide economies and efficiencies in the development of Freeway and Traffic Management systems.
Voice-over-IP (VoIP) will provide an ability to reach individuals regardless of the type of communication system being used. Dispatchers at a desktop work station will be able to reach field personnel by selecting an individual's personal identification number in an application such as Microsoft Outlook. The dispatcher won't have to worry about pushing buttons on a communication console, or which communication network to use. A software application will take care of the process.
A primary objective of the 802.3ae working group was to develop a 10 Gbps communication protocol with a transmission link distance of up to 40km over single mode fiber (14). The 10 Gbps 802.3 solution was developed to extend Ethernet capabilities providing higher bandwidth for multimedia, distributed processing, imaging, medical, CAD/CAM, by improving the performance of:
- LAN Backbone and Server and Gateway Connectivity
- Switch aggregation
- the MAN, WAN, Regional Area Network (RAN), and Storage Area Network (SAN) (15)
10GigE is (as of the publication of this handbook) only starting to be deployed. Its initial use is as a backbone transport system. There is no (current) plan to use this type of system for desktop-to-desktop communication.
Department of transportation could take advantage to 10GigE for Center-to-Center communications, and connecting major field communication hubs to a TMC.
Resilient Packet Ring (RPR)
Fiber optic networks are widely deployed throughout the world. They are normally deployed in a ring architecture. These rings are currently using protocols that are neither optimized nor scalable to the demands of packet networks. An RPR networks standard (IEEE 802.17) is being developed to provide for the optimization of bandwidth allocation and throughput, resiliency to faults. This will also result in reduced equipment and operational costs.
The current SONET standard was developed to provide for the efficient operation of fiber optic ring networks. However, its primary goal was to support circuit switched networks. Moving data in and out of a SONET network is very cumbersome, and requires significant investment in multiplexing equipment. Additionally, SONET is bandwidth inefficient. That's because it is a traditional TDM protocol that provides fixed bandwidth for data circuits – even those that are unused. The biggest advantage of SONET is its ability to restore circuits within a ring architecture. Communication circuits are provided an alternate path within 50ms of an outage due to physical damage.
RPR is being developed to support Packet Switched networks and utilize the 802.3 series of communication protocols. Bandwidth is provided when needed. RPR also provides for circuit restoration as efficiently as SONET.
Engineering personnel responsible for the design and development of Traffic and Freeway management systems should learn more about RPR. There is a strong likelihood that RPR will play a significant role in communication networks of the future. You can learn more by visiting the following web sites:
- The IEEE 802.17 Working Group – http://grouper.ieee.org/groups/802/17/
- The RPR Alliance – http://www.rpralliance.org/
IEEE published the 802.16 standard in April, 2002. The standard was developed to provide for broadband internet access and to meet the demand for low cost (by comparison to trenching) deployment of services. The standard is designed to support spectrum in the 10 to 66 GHz range. A modified standard, 802.16a has also been approved to support both licensed and un-licensed spectrum in the 2 to 11 GHz range.
The new standards are actually referred to as the "air interface" for broadband services. They are designed to complement the 802.3 wireline standards and provide for efficient media transitions in a mixed system. There is a need to be able to extend the reach of broadband internet access beyond the wireline infrastructure. DSL for example has a limited distance (typically 18,000 feet from a central office). Wireless systems are seen as the answer. An IP based wireline system can be extended using a wireless broadband link without changing the communication protocol. The transition from one media to the next is seamless.
Wireless communication links have been used by many Departments of Transportation to connect remote devices to a main system on a limited basis. The City of Irving Texas decided to upgrade its entire traffic signal communications infrastructure to an 802.16a standards based system. The City was originally looking at a fiber communications network that was estimated at more than $10 million. The broadband wireless system is being implemented (as this handbook is being written) for less than $750,000.
Dedicated Short Range Communications Systems (DSRC) are part of the broadband wireless services. However, current system development is based on the 802.11a standard. There is a difference between the two standards. 802.11 was developed as a wireless local area network (LAN) and 802.16 was developed to support "fixed" broadband access. Both complement and work together within the overall series of 802 standards.
DOTs will continue to look at wireless as part of an overall telecommunication strategy. Broadband wireless will play a key role in the development of future systems.
More information can be found at the following web sites:
- IEEE 802.16 Committee – http://grouper.ieee.org/groups/802/16/
- Worldwide Interoperability for Microwave Access – http://www.wimaxforum.org
- Wireless Communication Association – http://wcai.com/
Radio Frequency Identification (RFID)
RFID systems first appeared in the 1980s for tracking and access applications. RFID has been used to track containers moving from ships to dock storage to land transportation. Manufacturing has used RFID to track major parts (such as automobile axles) through a warehouse and onto an assembly line. RFID devices are used to open gates to a parking lot. The "tags" used by Toll Collection Authorities are a type of RFID.
Technology advancements over the past 20 years have seen the development of RFID into a universally accepted means of asset tracking and data collection. RFID Tags have been reduced in size from their original inception. Manufacturers are beginning to embed the tags in many items, and major retailers are starting to require the tags to help prevent theft. In the not too distant future, tags may replace bar-coding as the universal form of product identification. Theoretically, a shopping cart full of groceries could be scanned without having to remove the items from the cart. A shopper could pack items into bags in the cart. The cart would have an active reader that would display a running total. When finished, the shopper could charge the purchase to an account and leave the store without having to wait in a checkout lane.
A major advantage of RFID devices is that they can be embedded within the structure of an item. The tag activates on receipt of a radio signal from a reader device. A drivers license could have an embedded tag for instant identification.
RFID Tags could be placed in sections of roadway. Maintenance crews could be directed to locations that need repair or restoration. Their vehicle would have a tag reader that reports the completion of the repair. A police officer at the scene of an accident could scan in an identification tag in a damaged section of guardrail. The information would be directly reported to a DOT District maintenance office to schedule repairs.
A number of organizations are working to develop standards for RFID. More information is available at the following locations:
- RFID Standards – http://www.aimglobal.org/standards/rfidstds/RFIDStandard.htm
- RFID Journal – http://www.rfidjournal.com/
Between 1876 and 1986 the most that could be said about telecommunication technology and process was that it is consistent. In the laboratory, change was dramatic, in the field, change was very slow. Since 1986, new technology and process has been introduced almost as rapidly as it was developed.
Carriers are being forced by the new technologies to change the way they do business. The traditional telephone companies are now forced to compete with cable companies and wireless companies. Time-Warner Cable company is effectively competeing with Verizon for traditional telephone services. With the introduction of VoIP, many individuals are now using wireless carriers for their primary voice telephone services.
All of these changes will have a profound impact on how departments of transportation deploy and use technology for management of traffic signal and freeway management systems. The use of Gigabit Ethernet and broadband wireless technologies will provide significant implementation savings over current systems technologies. These same technologies will make it easier to provide for interoperability between transportation agencies, as well as public safety and other municipal and state agencies.
14. http://grouper.ieee.org/groups/802/3/ae/objectives.pdf – IEEE 802.3ae committee, July 2001.
15. http://grouper.ieee.org/groups/802/3/ae/criteria.pdf – IEEE 802.3 High Speed Study Group, Criteria.