08-08-2012, 02:53 PM
an identifier based architecture for native vertical handover support
[attachment=30600]
INTRODUCTION
The growing demand for ubiquitous computing lead manufactures to develop devices with multiple network interfaces to access different wireless networks. As a consequence, users have a broader range of options to choose the best available network to connect based on the users’ current needs such as higher data rates for a file download or wider area coverage for mobile devices.
Different Types of Networks
This section gives a brief introduction on some of the networks that are part of an overlay network.
802.11:
This is known as Wi-Fi (Wireless Fidelity) or WLAN (Wireless LAN). This is a set of standards IEEE to form Local Area Network. This includes 802.11a, 802.11b and 802.11g. The initial release in this set is 802.11b, which is a low cost solution for LAN working at 2.4 GHz and supporting a data rate of 11 mbps. This uses DSSS and covers upto 100 meters. 802.11a works at 5 GHz channel to give 20 mbps data rate. But this standard is not popular. works at 2.4 GHz and supports 54 mbps data rate. 802.11a and 802.11g uses OFDM and has coverage up to 150 and 300 meters, respectively. Usually, now a days support for 802.11b and 802.11g comes together
802.15/16/20: 802.15 or Bluetooth:
It is a low cost, low data rate solution for home network, where small volume of data is transmitted. This shares channel with 802.11 and uses DSSS. On the other hand, 802.16 or Broadband Wireless Access for high speed data communication over a vast coverage. This uses OFDM and supports upto 70 mbps over almost 50 km of area. It works at 10-66 GHz. 802.20 is called Mobile Broadband Wire-less Access, a specific technology to enable mobile devices to access the a network over a large area. This is a high cost solution based on OFDM with data rate up 9 mbps.
GPRS(General Packet Radio Service):
It is a packet based communication service for mobile devices that allows data to be sent and received across a mobile telephone network. GPRS is a step towards 3G and is often referred to as 2.5G. GPRS is packet switched. Higher connection speeds are attainable at around 56-118 kbps, a vast improvement on circuit switched networks of 9.6 kbps. By combining standard GSM time slots theoretical speeds of 171.2 kbps are attainable. However in the very short term, speeds of 20-50 kbps are more realistic.
IMT2000/UMTS:
IMT2000/UMTS are FDD and TDD based technologies for 3G mobile systems. They are very high cost solution with wide coverage area of up to 20 km. They run at 2 GHz channel and support data transmission up to 2mpbs. UMTS is the combination of the 3G nature of the technology and the GSM standard which it was designed to succeed. IMT2000 is a set of five radio interfaces that defines the global standard for 3G and design to succeed the current CDMA cellular systems.
DVB/DAB:
Digital video broadcasting (DVB) and digital audio broadcasting (DAB) both are designed for digital multimedia data transmission over a large coverage of 100 km. Both of them uses OFDM modulation and low cost technologies. DAB operates at 1.5 mbps data rate while DVB can provide a data rate of around 30 mbps. These difference in data rate is obvious because of their different type of service.
Satellite:
Communication satellites can provide very wide coverage of low data rate. Its a costly but effective solution for global communication. Usually communication satellites are used between remote points on the earth. It is also useful for data transmission from hostile environment. Satellite usually works at up to 14 GHz with data rate upto 144 kbps
Out of all these mainly two classes of wireless technology are mainly supported by these devices: IEEE 802.11 ( Wi-Fi ) and Global System for Mobile Communications (GSM). The first one offers higher data rates (up to54 Mbps in the 802.11ag modes) but provides small coverage area, restricted to Wi-Fi hotspots. The second one offers wider area coverage with high mobility, but with lower data rates.
[attachment=30600]
INTRODUCTION
The growing demand for ubiquitous computing lead manufactures to develop devices with multiple network interfaces to access different wireless networks. As a consequence, users have a broader range of options to choose the best available network to connect based on the users’ current needs such as higher data rates for a file download or wider area coverage for mobile devices.
Different Types of Networks
This section gives a brief introduction on some of the networks that are part of an overlay network.
802.11:
This is known as Wi-Fi (Wireless Fidelity) or WLAN (Wireless LAN). This is a set of standards IEEE to form Local Area Network. This includes 802.11a, 802.11b and 802.11g. The initial release in this set is 802.11b, which is a low cost solution for LAN working at 2.4 GHz and supporting a data rate of 11 mbps. This uses DSSS and covers upto 100 meters. 802.11a works at 5 GHz channel to give 20 mbps data rate. But this standard is not popular. works at 2.4 GHz and supports 54 mbps data rate. 802.11a and 802.11g uses OFDM and has coverage up to 150 and 300 meters, respectively. Usually, now a days support for 802.11b and 802.11g comes together
802.15/16/20: 802.15 or Bluetooth:
It is a low cost, low data rate solution for home network, where small volume of data is transmitted. This shares channel with 802.11 and uses DSSS. On the other hand, 802.16 or Broadband Wireless Access for high speed data communication over a vast coverage. This uses OFDM and supports upto 70 mbps over almost 50 km of area. It works at 10-66 GHz. 802.20 is called Mobile Broadband Wire-less Access, a specific technology to enable mobile devices to access the a network over a large area. This is a high cost solution based on OFDM with data rate up 9 mbps.
GPRS(General Packet Radio Service):
It is a packet based communication service for mobile devices that allows data to be sent and received across a mobile telephone network. GPRS is a step towards 3G and is often referred to as 2.5G. GPRS is packet switched. Higher connection speeds are attainable at around 56-118 kbps, a vast improvement on circuit switched networks of 9.6 kbps. By combining standard GSM time slots theoretical speeds of 171.2 kbps are attainable. However in the very short term, speeds of 20-50 kbps are more realistic.
IMT2000/UMTS:
IMT2000/UMTS are FDD and TDD based technologies for 3G mobile systems. They are very high cost solution with wide coverage area of up to 20 km. They run at 2 GHz channel and support data transmission up to 2mpbs. UMTS is the combination of the 3G nature of the technology and the GSM standard which it was designed to succeed. IMT2000 is a set of five radio interfaces that defines the global standard for 3G and design to succeed the current CDMA cellular systems.
DVB/DAB:
Digital video broadcasting (DVB) and digital audio broadcasting (DAB) both are designed for digital multimedia data transmission over a large coverage of 100 km. Both of them uses OFDM modulation and low cost technologies. DAB operates at 1.5 mbps data rate while DVB can provide a data rate of around 30 mbps. These difference in data rate is obvious because of their different type of service.
Satellite:
Communication satellites can provide very wide coverage of low data rate. Its a costly but effective solution for global communication. Usually communication satellites are used between remote points on the earth. It is also useful for data transmission from hostile environment. Satellite usually works at up to 14 GHz with data rate upto 144 kbps
Out of all these mainly two classes of wireless technology are mainly supported by these devices: IEEE 802.11 ( Wi-Fi ) and Global System for Mobile Communications (GSM). The first one offers higher data rates (up to54 Mbps in the 802.11ag modes) but provides small coverage area, restricted to Wi-Fi hotspots. The second one offers wider area coverage with high mobility, but with lower data rates.