**6.2.1 Wireless Personal Area Network (WPAN)**

Personal networks make a small area networking for a variety of devices. The most popular WPAN has been Bluetooth, which was firstly developed by the Sweden Ericsson. Bluetooth operates in unlicensed 2.4 GHz spectrum, which is also used by Wi-Fi. IEEE 802.15.1 standard for Bluetooth allows data rates up to 3 Mbps and at a range of up to 100 meters.

In addition to the Bluetooth, two industrial technologies, namely UWB (Ultra Wide Band) and Zigbee, make high data rate and low cost WPAN, respectively (Fourty et al., 2005).

Unlike OPGW, ADSS is a self supporting cable and it does not include any metal component. In fact, they are designed to be fastened into towers or poles underneath the power conductors. Moreover, ADSS is ideal for installation in distribution poles as well as transmission towers, even when live-line installations are required (Marihart, 2001; Nordell,

Historically, leased telephone circuits have been widely used in electric utilities to create a point-to-point or point-to-multipoint communications (Marihart, 2001). The leased lines only provide a share medium for communication and some technologies should be implemented in order to transmit signals through this media. Digital Subscriber Line (DSL) is a group of technologies, which provides digital data transmission over leased telephone circuits. The first version of DSL was defined in 1988 and called ISDN (Integrated Services Digital Network). ISDN provides a maximum of 128 Kbps in both uplink and downlink directions (Hrasnica et al., 2004). Other DSL versions have appeared in different forms, such as high-data-rate DSL (HDSL), single-line DSL (SDSL), asymmetric DSL (ADSL), rateadaptive DSL (RADSL), and very high-data-rate DSL (VDSL), all of which utilize copper lines. The differences between xDSL technologies are their data rates and directionality of transmission, distances to which those rates can be supported, and the size of the wire.

Wireless transmission is used when we have several challenges such as environmental or financial limitations for utilization of guided media. However, as transmitted signals using wireless communication can be accessed by anyone, the security of wireless communication is naturally low. On the other hand, various signals, which are transmitted by different sources, may be broadcast on the same frequency and thereby, collision may happen. Thus, it can be concluded that the reliability of wireless communication is less than the reliability of transmission through a guided media. In wireless transmission, signal can take the form of waves in the radio spectrum, including very high frequency (VHF) and microwaves, or it can be light waves including infrared or visible lights such as laser (Shahraeini et al., 2010). The first important parameter in wireless communication is its range. In accordance with

Personal networks make a small area networking for a variety of devices. The most popular WPAN has been Bluetooth, which was firstly developed by the Sweden Ericsson. Bluetooth operates in unlicensed 2.4 GHz spectrum, which is also used by Wi-Fi. IEEE 802.15.1 standard for Bluetooth allows data rates up to 3 Mbps and at a range of up to 100 meters.

In addition to the Bluetooth, two industrial technologies, namely UWB (Ultra Wide Band) and Zigbee, make high data rate and low cost WPAN, respectively (Fourty et al., 2005).

wireless ranges, four wireless types may be defined (Fourty et al., 2005):

 Wireless Personal Area Network (WPAN) Wireless Local Area Network (WLAN)

Wireless Wide Area Network (WWAN)

Wireless Metropolitan Area Network (WMAN)

**6.2.1 Wireless Personal Area Network (WPAN)** 

2008).

**6.1.3 Leased line** 

**6.2 Unguided media** 

UBW, which is standardized under the name IEEE 802.15.3, can use frequencies from 3.1 GHz to 10.6 GHz. UBW allows data rate up to 480 Mbps at the range of several meters and a rate of 110 Mbps at a range of up to 10 meters (Fourty et al., 2005).

Zigbee has been created to become a wireless standard for remote control in industrial fields. It makes very low-cost WPAN for applications that are not too much bandwidth hungry (Fourty et al., 2005). Zigbee allows data rate of 250 Kbps at 2.4 GHz at the range of up to 10 meters (IEEE 802.15.4) and data rate of 20 Kbps at 900 kHz at the range of up to 75 meters (IEEE 802.15.4a). Recently, Zigbee is widely used to create home area communications between smart meters and smart home equipments (Shahraeini et al., 2010).
