Chapter 14: Recent Advances in Wireless Networks

1. Introduction • Ultra-Wide-Band Radio Communication (UWB) and WiMedia • Wireless Fidelity System (WiFi) and WiMax • Optical Wireless Networks • Advances in 802.11 • The Meghadoot Architecture Chapter 14: Recent Advances in Wireless Networks

2. Ultra-Wide-Band Radio Communication • UWB is a technology developed to transfer large amounts of data wirelessly over short distances over a very wide spectrum of frequencies in a short period of time. • The amount of spectrum occupied by a UWB signal, i.e. the bandwidth of the UWB signal is at least 25% of the center frequency. For example, a UWB signal centered at 2 GHz would have a minimum bandwidth of 500 MHz and the minimum bandwidth of a UWB signal centered at 4 GHz would be 1 GHz. The most common technique for generating a UWB signal is to transmit pulses with durations less than 1 nanosecond. • UWB technology has the capacity to handle the very high bandwidths required to transport multiple audio and video streams. • UWB will be ideally suited for transmitting data between consumer electronics (CE), PC peripherals, and mobile devices within short range at very high speeds while consuming little power. • This technology operates at a level that most systems interpret as noise and, as a result, does not cause interference to other radios such as cell phones, cordless phones or broadcast television sets.

3. Ultra-Wide-Band Radio Communication

4. UWB Advantages • Extremely Difficult to Intercept - LPI/LPD. Wideband pulsed radar spreads the signal and allows more users access to a limited amount of scarce frequency spectrum. • Multipath Immunity - A low path loss and low energy density minimizes interference to other services. UWB is very tolerant of interference, enabling operation within buildings, urban areas, and forests. • Precision Network-wide timing - Real-time, continuous position location down to a centimeter of resolution results in precision geolocation systems. • Low Cost - Requires minimal components resulting in small size and weight • Low Power - Typical consumption is in microwatts

5. UWB Applications • Communications - High Speed WLANs, Mobile Ad-Hoc wireless networks, Groundwave Communications, Handheld and Network Radios, Intra-home and Intra-office communication. Stealthy communications provide significant potential for military, law enforcement, and commercial applications. • Sensor Networks - Ground penetrating Radar that detects and identifies targets hidden in foliage, buildings or beneath the ground. Intrusion Detection Radars, Obstacle Avoidance Radars, and Short-range motion sensing. • Tracking/Positioning - Precision Geolocation Systems and high-resolution imaging. Indoor and outdoor tracking down to less than a centimeter. Good for emergency services, inventory tracking, and asset safety and security.

6. WiMedia • WiMedia refers to high data-rate, wireless multimedia networking applications operating in a wireless personal area network (WPAN). • The WiMedia brand is defined and supported by the WiMedia Alliance. • The initial WiMedia radio technology will be based on ultrawideband (UWB) as defined by the MultiBand OFDM Alliance (MBOA) SIG's PHY and MAC specifications. • The primary goals of the WiMedia Alliance are • to enable coexistence of multi-protocol applications (UWB, 1394 and TCP/IP among others) and • to enable true multi-vendor interoperability by establishing procedures for ensuring devices from different manufacturers coexist within the common UWB radio platform.

7. UWB Standards • 802.15.3a is a group working on UWB standards but could not decide between the two approaches – multiband OFDM (MOFDM) from the TI/Intel-led MBOA group, or direct sequence code division multiple access (DS-CDMA) from Motorola. • Multiband OFDM Alliance SIG (MBOA-SIG) and WiMedia Alliance have merged to create UWB industry specifications and certification programs for consumer electronics, mobile and PC applications. • Advantages of the MultiBand OFDM proposal: • based on proven OFDM technology: used in IEEE 802.11a and 802.11g • Achieves data rates of 53 to 480 Mbps • Support for 4 to 16 simultaneous piconets • Spectrum easily sculpted for international regulatory domain compliance • easily extensible for future range/rate improvements • Refer to MBOA at http://www.multibandofdm.org/.

8. Objectives of MBOA • To develop, publish, and promote the best overall solution for global UWB standardization • As a formal SIG, publish detailed system specification in May 2004 • To support the development of a robust UWB ecosystem • Support industry efforts to develop upper layer protocols and interfaces • Provide a forum for vendors of antennas, RF modules, and test and measurement equipment • Work in harmony with IEEE, WiMedia, CEA, 1394-TA, Wireless-USB WG • To ensure the standardization of UWB solutions with the best coexistence characteristics possible and to continue work with worldwide regulatory agencies to provide education and seek specific approval of MBOA-based technology • To enable a single worldwide standard for high bit rate UWB applications with optimum time-to-market and maximum benefit to the broadest number of end consumers

9. Wireless Fidelity Systems (WiFi) • Wireless Fidelity (WiFi) is the standard for the high-speed wireless LAN. • A Wi-Fi network can be used to connect computers to each other, to the Internet, and to wired networks (which use IEEE 802.3 or Ethernet). • Wi-Fi networks operate in the unlicensed 2.4 and 5 GHz radio bands, with an 11/54 Mbps (802.11b/g) or 54 Mbps (802.11a) data rate Any Wi-Fi product uses the same radio frequency (for example, 2.4GHz for 802.11b/g, 5GHz for 802.11a). • The Wi-Fi Alliance (http://www.wi-fi.org/) • A global, non-profit industry association of more than 200 member companies devoted to promoting the growth of wireless Local Area Networks (WLANs). • With the aim of enhancing the user experience for mobile wireless devices, the Wi-Fi Alliance's testing and certification programs ensure the interoperability of WLAN products based on the IEEE 802.11 specification.

10. WiMax • WiMAX is an acronym that stands for Worldwide Interoperability for Microwave Access. • The WiMAX Forum is an industry-led, non-profit corporation formed to promote and certify compatibility and interoperability of broadband wireless products. • The WiMax forum supports the industry-wide acceptance of the IEEE 802.16 and ETSI HiperMAN wireless MAN standards.

11. Optical Wireless Networks • Optical wireless communication enables communication using infrared ray. • Operates outdoor up to 5 Km and indoor a few meters. • Advantages: • Abundance of unregulated bandwidth: 200 THz in the 700 – 1500 nm range • No multipath fading: Intensity modulation and direct detection • Higher capacity per unit volume • Cost effective at rates near 100 Mbps • Small cell size • At 800 – 890 nm and 1550 nm absorption effects are minimal. • Disadvantages: • Multipath dispersion • Limited range • Difficult to operate outdoor • High power requirement • SNR can vary significantly with the distance • costly

12. Advances in IEEE 802.11 • Multimode 802.11 enables dynamically to use 802.11a/b/g. • The 802.11e defined an extension of the 802.11 standard for quality of service (QoS). • The 802.11f developed specifications for implementing access points and distribution systems. • The 802.11h developed the MAC layer standard that comply with European regulations for 5 GHz wireless LAN. • The 802.11i group is working on mechanisms for enhancing security in the 802.11 standard. • The 802.11j task group is working on mechanisms for enhancing security in the 802.11 MAC physical layer protocols to additionally operate in the newly available Japanese 4.9 GHz and 5 GHz bands. • The 802.11n defines standardized modifications to the 802.11 MAC and physical layers to allows at least 100 Mbps.

13. Meghadoot • The meghadoot architecture is a packet-based wireless network architecture for low-cost rural community networks. • The major goals of the Meghadoot project are • Develop a fully distributed packet-based hybrid wireless network that can carry voice and data traffic • Provide a low-cost communication system in the rural regions • Provide a low-cost communication network for urban environment • Meghadoot uses a routing protocol called infrastructure-based ad hoc routing protocol (IBAR). • The end user equipment in Meghadoot is an IEEE 802.11 enabled device. • Meghadoot is aimed at deploying an 802.11 phone in rural areas, using Voice over Wireless IP (VoWIP) that promises to free them from their telephone handsets. • VoWIP is an emerging technology that enables IP voice to be sent over an 802.11 wireless LAN.

14. Final Thoughts • Wireless networks are widespread in our daily life. • Fourth generation (4G) WWAN communications systems that are characterized by high-speed data rates at 20+ Mbps, suitable for high-resolution movies and television. It describes two different but overlapping ideas. • High-speed wireless access with a very high data transmission speed, of the same order of magnitude as a local area network connection (20 Mbps and up). It can integrate wireless LAN technologies like Wi-Fi, as well as other potential successors of the current 3G mobile telephone standards. • Pervasive networks. A user is simultaneously connected to several wireless access technologies and can seamlessly move between them. These access technologies can be Wi-Fi, UMTS, EDGE or any other future access technology. Included in this concept is also smart-radio technology to efficiently manage spectrum use and transmission power as well as the use of mesh routing protocols to create a pervasive network . • A cell phone could be an integral part of all wireless standards.