**3.2 WiMAX (IEEE 802.16)**

WiMAX is a high bandwidth technology designed to provide broadband wireless access over large areas to home and business and to a large number of users. WiMAX is an implementation of the IEEE 802.16 standard and was created by the WiMAX Forum4 in 2001 (Ghosh & Wolter, 2005). To date more than 500 companies are members of the WiMAX Forum. Some of the potential usages of WiMAX include: mobile broadband connectivity across cities, last mile broadband access, VOIP, Internet connectivity, in-building coverage, temporary coverage and coverage on a mobile vehicle, among others (Peters & Heath, 2009). WiMAX maximum operating range of coverage is 100 Km and supports speeds of up to 1 Gbps (on fixed stations). WiMAX speed depends on the distance covered, the closer the

 4 http://www.wimaxforum.org

Emerging Technologies for Urban Traffic Management 71

Examples of vehicular applications includes wireless control and communication with

Successful of vehicular networks will depend upon the definition of sensing platforms that allow providing a means of collecting/processing/accessing sensor data. Comprehensive and accurate data are the primary requirement of vehicular networks. Various technologies have been enhanced/developed in recent years to improve this data collection quantity and quality though two main categories can be identified: urban sensing technologies, where field infrastructure is needed and intra vehicular sensors technologies in which a vehicle needs to be equipped. This section describes the most relevant sensing platforms for

Advances in vehicular communications make it possible to implement vehicular sensor networks, i.e., collaborative environments where mobile vehicles that are equipped with sensors of different nature (from toxic detectors to video cameras) interworking to implement monitoring applications. Vehicles continuously collect sensor data from urban streets (e.g., images, accelerometer data, among others), which are then processed to search for information of interest (e.g., recognizing license plates, or inferring trafc patterns). This challenging environment requires novel solutions with respect to those of more-traditional wireless sensor nodes. Additionally, vehicles can be used by the VSN to improve its performance, for example, vehicles have much higher power reserves than a typical mobile computer, power can be drawn from on-board batteries, and recharged as needed from a gasoline or alternative fuel engine, vehicles are orders of magnitude larger in size and weight compared to traditional wireless clients, and can therefore support significantly




systems allow for easy localization of the vehicle (Lim et al., 2009).

mobile phones, multimedia and entertainment devices.

collecting information about traffic conditions.

heavier computing (and sensorial) components.

vehicle performance (Birnbam, & Truglia, 2000).

Some intra vehicular sensors are:

**4. Sensing platforms** 

**4.1 Intra vehicular sensors** 

WiMAX station the higher the speed and the farther the station the lower the speed. Table 2 summarizes the mobility performance of WiMAX (Cudak, 2010).


Table 2. WiMAX mobility support.

#### **3.3 Cellular technology (3G)**

The third-generation (3G) system comprehends a set of standards that aim to support global communication for mobile telecommunication services such as mobile Internet, video calls and mobile TV. These standards are defined in the IMT-2000 vision of the International Telecommunications Union. The most popular implementations of 3G are: UTMS or 3GPP which is widely utilized in Europe, Japan and some parts of Asia and CDMA2000 also referred as 3GPP2 which has been deployed in the United States, South Korea, Belarus, Romania, and some parts of Russia, Japan and China (Etoh, 2005). The IMT-2000 standard aims to provide minimum transmission rates of 2 Mbps for stationary or walking users, and 348 kbps in a moving vehicle (ITU, 2011).

#### **3.4 Zigbee**

This technology is built upon the IEEE 802.15.4 standard which defines the physical and MAC layers for low cost and low rate personal area networks. Zigbee has a coverage range of up to 400 meters and a maximum data rate of 250 kbps with network latency between 15 and 30 ms (Backer, 2005). It operates in three different radio bands: 868 Mhz in Europe, 915 Mhz in the USA and Australia, and 2.4 Ghz worldwide. The Zigbee Alliance defines 7 application profiles including building automation, remote control, smart energy, health care, home automation among others. Besides, the research community is also investigating the usage of Zigbee in vehicular applications such as intra-car wireless sensor networks (Tsai et al., 2007), wireless vehicular identification and authentication system (Dissanayake et al., 2008), wireless sensor networks for CO2 monitoring (Hu et al., 2009).

#### **3.5 Bluetooth**

Bluetooth is a low power consumption and short-range communication system (powerclass-dependent: 1 meter, 10 meters, 100 meters) originally designed to replace cables connecting electronic devices. Bluetooth devices can communicate with up to 7 slave devices forming a piconet network (1 master + 7 slaves), where a piconet is an ad-hoc computer network of interconnected Bluetooth devices. Piconets can communicate with each other forming a scatternet, in which some devices act as bridges to provide communication between piconets. The Bluetooth core system utilizes a protocol stack consisting of a radio protocol, a link control protocol, a link manager protocol and a logical link control and adaptation protocol. It operates in an unlicensed band at 2.4 to 2.485 Ghz. The list of Bluetooth applications includes wireless headsets, printers, keyboards, game controllers (e.g. Nintendo's Wii and Sony's PlayStation), medical equipment, bar code scanners. -

Examples of vehicular applications includes wireless control and communication with mobile phones, multimedia and entertainment devices.
