16.4 Manet Implementation: Related Technologies and Standards

16.4 Manet Implementation: Related Technologies and Standards

In this section, we explore related hardware, software, and networking technologies that may be used for the implementation of MANETs. These technologies provide some or all of the following ad hoc networks features:

• Distributed processing

• Collaborative computing

• Dynamic discovery of services and devices

• Mobility

• Detection of radio beacons and radio proximity

• Support for forming groups

• Support for wireless connectivity

• Self-administration

16.4.1 Software Technologies

In this section, we look at software and software framework technologies that facilitate implementation of MANETs, and we discuss how these technologies contribute to building ad hoc networks:

• Java and Jini ^[69], ^[70]

• Universal Plug and Play (UPnP) ^[71]

• Open Services Gateway Initiative (OSGI) ^[72]

• Home Audio Visual Interoperability (HAVi) ^[73]

• Peer-to-Peer (P2P) Computing ^[74]

16.4.1.1 Java and Jini

Java is more than a programming language; we explore some related Java technologies later in this section. For our purposes here, we note that the Java program paradigm consists of a set of tools and technologies that are amenable to the implementation of ad hoc networks, because Java provides:

• Code mobility: Software code implemented on one Java Virtual Machine (JVM) on one node can be moved across the network and directly run on another node without any change.

• Platform/protocol independence: Java is platform and protocol agnostic.

• Remote method invocation (RMI): Software modules can be executed remotely on a node.

• Portability: Java code is portable across all devices that support Java without any changes.

• Security: Java provides byte-code verification and other security features.

• Dynamic load of code: Java classes can be downloaded "on the fly."

Jini is a framework for distributed computing using a set of simple interfaces and protocols. Jini enables spontaneous networks of software services and devices to assemble into working groups of objects known as federations. Jini enables self-administration and self-healing when devices move dynamically from one federation to another. Jini uses RMI to pass entire Java objects and their code. In addition, RMI provides object serialization, transport, and deserialization of objects. RMI is robust and supports security protocols. Jini provides the following basic services:

• Discovery service: The discovery and join protocols can be used to join a group of services using a UDP multicast. Each service advertises capabilities and provides the required software drivers.

• Lookup service: This is a repository of available services. It stores each service as a Java object, and clients can download services on demand. The lookup service provides interfaces for registration, access, search, and removal of services.

• Lease: Leases are resource grants that are time-based between a grantor and a holder. Leases can be cancelled, renewed, and negotiated by third parties. Thus, resources are allocated only as long as needed. The network is self-healing as the resources are granted and released dynamically.

• Event: The Java network event model has been expanded in Jini to work in a distributed system. It supports several delivery models such as push, pull, and filter.

• Transaction: Jini's transaction model allows for distributed object coordination using two-phase commits.

Jini extends its architecture to allow a surrogate that is designed to deal with legacy and non-Jini devices and resource-limited Java-based devices. The Jini technology surrogate architecture specification defines interfaces and methodology by which these components, with the aid of a third party, can participate in a Jini network while still maintaining the plug-and-work model of Jini technology. Java-spaces is a Jini Service based on tuple-spaces, which uses a persistent object store for secure transactions in a simple fashion. It is a unified mechanism by which Java objects can be shared, dynamically communicated, and coordinated in the distributed object stores called spaces. This paradigm lends itself to parallel programming, distributed systems, and cooperating software entity groups.

16.4.1.2 UPnP

Universal Plug and Play is architecture for smart home networking and pervasive peer-to-peer connectivity of intelligent appliances, wireless devices, and PDAs. It is an extension of device plug and play supported by Microsoft . It supports transparent networking also, and resource and service discovery. UPnP, like all the service discovery paradigms, aims to provide all these features to be exercised automatically without any user intervention. UPnP supports standard Internet and TCP/IP-based protocols with a view to providing interoperability with existing networks and infrastructure. UPnP is an open distributed network paradigm that does not define any APIs. The standard defines device and service descriptions based on common device architecture, thus keeping the device and service specificity away from the users.

16.4.1.3 OSGi

The Open Services Gateway Initiative is supported by more than 50 companies to develop services gateway architecture. The OSGi Forum is defining a set of APIs for this purpose and providing a reference implementation of services gateway architecture. A services gateway connects the external network with home-based internal networks and devices providing the user with transparency for service discovery. The services gateway adds to the usefulness of home networks by allowing service providers to deliver real-time, new and innovative value added services to the services gateway. The OSGi based gateway will provide distribution, integration and management of new and existing services. The OSGi forum is targeting the SOHO/ROBO (Small Office/Home Office and Remote Office/Branch Office) and residential users.

16.4.1.4 HAVi

Home audio/visual interoperability is a digital consumer electronics and home appliances communications standard. HAVi is specifically focused on digital audio/video (A/V) networking for home entertainment products. HAVi provides many of the semantics required for pervasive and ad hoc networking. An important tenet of the standard is interoperability among A/V devices from the major home entertainment consumer electronics companies. HAVi defines a middleware that manages A/V streams, and provides APIs for the development of home A/V software applications. The salient selling point of HAVi is that it provides highly optimized data communication between bandwidth-hungry A/V devices. The HAVi network standard has been architected to integrate seamlessly with other home networks. HAVi provides a distributed software architecture with support for network management, device abstraction, interdevice communication, and device user interface management.

16.4.1.5 P2P Computing

Peer-to-peer is a paradigm used for sharing of computing resources (information, CPU power, processing cycles, cache storage, and disk storage for files) and services by direct exchange between peer systems. In a P2P environment, computing devices have a dual nature and act as clients/servers, assuming the appropriate role required by the network. P2P lends itself to user collaboration, edge services (moving data closer to users across large geographic distances), distributed computing and resources, and intelligent agents. The Open P2P Initiative is a forum that provides more information on P2P technologies. Examples of P2P software implementations ^[75] include Napster, Gnutella, and Morpheus.

16.4.2 Network Technologies

In this section, we study the following networking technologies that can facilitate implementation of ad hoc networks:

• Bluetooth ^[76], ^[77]

• Ultra-Wideband (UWB) ^[78]

• HiperLAN/1 and HiperLAN/2 ^[79], ^[80]

• IEEE 802.11 Wireless LAN ^[81], ^[82], ^[83]

• IEEE 802.15.3 Wireless PAN ^[84]

• HomeRF ^[85]

16.4.2.1 Bluetooth

Bluetooth is a short-range radio technology originally intended as a wireless cable replacement to connect portable computers, wireless devices, handsets, and headsets. Today, Bluetooth is being used for deploying wireless personal area networks in homes and offices. Bluetooth business requirements make it necessary to produce a pair of units that are below $10. Other requirements include low power usage for running on batteries, a lightweight and small form factor.

Bluetooth devices operate in the 2.4-GHz ISM band. There are specifications for power and spectral emissions and interference to which Bluetooth devices must adhere. ^[86] It offers three different power classes for operation. The corresponding ranges for the power classes are 10 (lowest power range), 20, and 100 m (highest power range). Bluetooth uses the concept of a piconet, which is a MANET with a master device controlling one or several slave devices; it allows scatternets wherein a slave device can be part of multiple piconets. Bluetooth has been designed to handle both voice and data traffic. Bluetooth specifications provide different application profiles which are used for fine-tuning the implementation of the various applications. Bluetooth provides a service discovery protocol for discovering Bluetooth devices.

16.4.2.2 UWB

Ultra-Wideband, also known as baseband or impulse radio, is a carrier-free radio transmission technology that uses brief, low power pulses that spread the radio energy across a wide spectrum of frequencies. UWB radio can utilize a variety of modulation techniques. In one example, pulse position modulation (PPM) transmissions consist of precisely timed pulses. In PPM, the transmitter and receiver are tightly coordinated, and information is transferred using the position of the pulses. For FCC-compliant systems, the UWB signal level is comparable to background noise, and so interference with conventional carrier-based communication systems is unlikely. To qualify as a UWB communication, the transmitted signal must have a fractional bandwidth of more than 20 percent or occupy more than 500 MHz of spectrum.

UWB is an emerging technology that has strong advantages over conventional carrier-based communications. These advantages include low susceptibility to multipath fading, higher transmission security, low power consumption, simple architecture, and low implementation cost. In addition, UWB provides ranging information, and in a network can yield position data. UWB has been used for ground penetration radar and secure communications. The recent publication of the UWB Report and Order by the FCC ^[87] has given rise to a great deal of effort focused on commercial applications. Examples of UWB applications include collision avoidance radar, RF tagging, and geolocation and data communications in personal area network (PAN) and local area network (LAN) environments.

16.4.2.3 HiperLAN/1 and HiperLAN/2

HiperLAN/1 and HiperLAN/2 are wireless LAN (WLAN) standards developed by the European Telecommunications Standards Institute (ETSI). HiperLAN/1 is a wireless equivalent of Ethernet, while HiperLAN/2 has architecture based on wireless asynchronous transfer mode (ATM). Both standards use dedicated frequency spectrum at 5 GHz. HiperLAN/1 provides a gross data rate of 23.5 Mbps and a net data rate of more than 18 Mbps, while HiperLAN/2 provides gross data rates of 6, 16, 36, and 54 Mbps, and a maximum of 50 Mbps net data rate. Both standards use 10, 100, and 1000 mW of transmit power and have a maximum range of 50 m. Also, the standards provide isochronous and asynchronous services with support for QoS. However, they differ in their channel access and modulation schemes. HiperLAN/1 uses dynamic priority-driven channel access, while HiperLAN/2 uses reserved channel access. HiperLAN/1 uses Gaussian minimum shift keying (GMSK) and HiperLAN/2 uses orthogonal frequency division multiplexing (OFDM) plus binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), and QAM (quadrature amplitude) modulation schemes. HiperLAN/1 and HiperLAN/2 support an ad hoc network mode of operation.

16.4.2.4 IEEE 802.11

This IEEE family of standards is primarily for indoor and in-building WLANs. There are several flavors of this standard. The current available versions are the 802.11a, 802.11b, and 802.11g (emerging draft standard) with other versions currently in the works. The 802.11 standards support ad hoc networking, as well as connections using an access point (AP). The standard provides specifications of the PHY and the MAC layers. The 802.11 standards have the same MAC sublayer specification, while their PHY specifications differ substantially. The MAC specified uses CSMA/CA for access and provides service discovery and scanning, link setup and tear down, data fragmentation, security, power management, and roaming facilities. The MAC provides for independent configuration (ad hoc network mode) and infrastructure configuration (using access points to increase the range). The 802.11 PHY specifications are shown in Table 16.2.

Table 16.2: PHY Specifications for IEEE 802.11

PHY	Frequency Band	Data Rates	Modulation	Comments
Frequency hopping spread spectrum	2.4-GHz ISM band	1, 2 Mbps	2-level Gaussian frequency shift keying 4-level Gaussian frequency shift keying	50 hops per second 79 channels
Direct sequence spread spectrum	2.4-GHz ISM band	1, 2 Mbps	Differential binary frequency shift keying Differential quadrature phase shift keying	11-chip barker sequence spreading
Baseband IR	Diffuse infrared	1, 2 Mbps	16 pulse position modulation 4 pulse position modulation	Uses pulse position modulation

The 802.11a PHY is similar to the HiperLAN/2 PHY. The PHY uses OFDM (orthogonal frequency division multiplexing) and operates in the 5-GHz UNII band. 802.1 la supports data rates ranging from 6 to 54 Mbps. 802.1 la currently offers much less potential for RF interference than other PHYs (e.g., 802.11b and 802.11g) that utilize the crowded 2.4-GHz ISM band. 802.11a can support multimedia applications in densely populated user environments. The 802.11b standard, proposed jointly by Harris Corporation and Lucent Technologies, extends the 802.11 direct sequence spread spectrum PHY to provide 5.5 and 11 Mbps data rates. To provide the higher data rates, 802.11b uses 8-chip CCK (complementary code keying), a modulation technique that makes efficient use of the radio spectrum. The 802.11g specification uses the same OFDM scheme as 802.11a and will potentially deliver speeds on par with 802.11a. However, 802.11g operates in the 2.4-GHz frequency band that 802.11b occupies, and for this reason it should be compatible with existing WLAN infrastructures.

16.4.2.5 IEEE 802.15.3

The standard defines MAC and PHY (2.4 GHz) layer specifications for a wireless personal area network (WPAN). The standard is based on the concept of a piconet, which is a network confined to a 10-m personal operating space (POS) around a person or object. A WPAN consists of one or more collocated piconets. Each piconet is controlled by a piconet coordinator (PNC) and may consist of devices (DEVs). The PNC's functions include the basic timing of the piconet using beacons, managing QoS, managing the power save modes, and security and authentication. The 802.15.3 PHY is defined for 2.4 to 2.4835 GHz band and has two defined channel plans. It supports five different data rates (11 to 55 Mbps). The base uncoded PHY rate is 22 Mbps. Table 16.1 provides other details of the 802.15.3 PHY specifications.

16.4.2.6 HomeRF

The HomeRF Working Group was formed to develop a standard for wireless data communications between personal computers and consumer electronics in a home environment. The HomeRF standard is technically solid, simple, secure, and easy to use. HomeRF networks provide a range of up to 150 feet, typically enough for home networking. HomeRF uses Shared Wireless Access Protocol (SWAP) to provide efficient delivery of voice and data traffic. SWAP uses digital enhanced cordless telecommunications (DECT), and the 802.11 FHSS technologies. SWAP uses a transmit power of up to 100 mW and a gross data rate of 2 Mbps. It can support a maximum of 127 devices per network. A SWAP-based system can work as an ad hoc network or as a managed network using a connection point.

16.4.3 Hardware Technologies

Following is a discussion of the hardware technologies that are helping implement ad hoc networks. These technologies offer low power/power aware hardware and miniaturization of memory, processor, and other peripherals.

16.4.3.1 Smart Wireless Sensors ^[88]

Smart wireless sensors have added substantially to the applications that MANETs execute. Sensor-based MANETs can be used in applications such as detecting chemicals, explosives, and toxins in hazardous areas; military reconnaissance; gathering geological data in difficult terrain, etc. Being able to make miniature sensors such as the ones used in Smart Dust ^[89] has shown that MANETs can be successfully scaled to deal with thousands of nodes. Sensor networks are exploring the limits of MANETs in terms of scalability, minimum resource requirements, network resilience, fault tolerance, and security. The emerging IEEE 802.15.4 (low rate WPAN) standard ^[90] has been proposed for several smart sensor applications.

16.4.3.2 Smart Batteries ^[91]

Mobile devices typically have strong battery and bandwidth constraints. Power conservation can be achieved on two different fronts: the device and the communication protocols. The power conservation of the device involves reducing the usage of the battery for all the hardware of the device, including the CPU, display, and peripherals. The communication protocols also can be power-aware designs. Smart batteries have low discharge rates, a long cycle life, a wide operating temperature range, and high energy density. Nickel cadmium (NiCad), nickel metal hydride (NiMH), and lithium ion (Li-ion) are the most commonly used for mobile devices. Li-ion batteries have the highest energy density among these technologies.

16.4.3.3 Software-Defined Radio ^[92]

Software-defined radio (SDR, or software radio) is a radio that can be controlled using software. In SDR systems, waveform generation, modulation techniques, wideband or narrowband operation, security functions, and frequency of operation can be adjusted in software based on the requirements. SDR systems, in essence, provide programmable hardware that increases the flexibility of use and development. SDR is the Holy Grail of radio design. A SDR system is designed to work with any existing or developing standard. SDR highlights the various trade-offs in the design of different radio architectures with a view to improving the radio performance, enhance the feature sets, and add new services resulting in a better user experience. SDR has a vital role in the implementation of MANETs with heterogeneous hosts that employ different radio technologies.

16.4.3.4 GPS ^[93]

Location awareness, as discussed earlier, can be valuable in establishing the routing topology. Location awareness of nodes distributed in a MANET requires the acquisition of information about each node with respect to an absolute or relative location reference. GPS has been used for obtaining location information of a node in a MANET. GPS is a global positioning system consisting of a group of satellites that continuously broadcast location and timing information while orbiting the earth. Using position triangulation, GPS receivers on Earth calculate the exact location of the receiver on an absolute global scale. The location information thus calculated is in reference to the latitude and longitude coordinate system.

^[69]Jini Community Resource Page, http://www.jini.org, Aug. 2002.

^[70]Jini Networking Technology, http://wwws.sun.com/software/jini/, Aug. 2002.

^[71]Universal Plug and Play (UPnP) Forum, http://www.upnp.org/, Aug. 2002.

^[72]OSGI Official Website, http://www.osgi.org, Sept. 2001.

^[73]HAVi: Home Audio Video Interoperability home page, http://www.havi.org/, Aug. 2002.

^[74]Open P2P Project, http://www.openp2p.com, Aug. 2002.

^[75]Open P2P Project, http://www.openp2p.com, Aug. 2002.

^[76]Bray, J. and Sturman, C.F., Bluetooth 1.1: Connect Without Cables, 2nd ed., Prentice-Hall, Englewood Cliffs, NJ, 2002.

^[77]Bluetooth Official Website, http://www.bluetooth.com, Aug. 2002.

^[78]Ultra Wideband Working Group, http://www.uwb.org, Aug. 2002.

^[79]ETSI, www.etsi.org, Aug. 2002.

^[80]HiperLAN Global Forum 2, http://www.hiperlan2.com/, Aug. 2002.

^[81]IEEE 802.11 Specifications, grouper.ieee.org/groups/802/11/index.html, Aug. 2002.

^[82]Geier, J., Wireless LANs, MacMillan, New York, 2001.

^[83]Nader, S. et al., Ad hoc networks with smart antennas using IEEE 802.11-based protocols, Proc. IEEE International Conference on Communications (ICC), New York, April 28-May 2, 2002.

^[84]IEEE 802.15 Working Group for WPAN, http://grouper.ieee.org/groups/802/15/, Aug. 2002.

^[85]HomeRF Official Website, homerf.org, Aug. 2002.

^[86]Bluetooth Official Website, http://www.bluetooth.com, Aug. 2002.

^[87]FCC home page, www.fcc.gov, Aug. 2002.

^[88]Smart Dust, Autonomous sensing and communication in a cubic millimeter, http://robotics.eecs.berkeley.edu/~pister/SmartDust/, Aug. 2002.

^[89]Smart Dust, Autonomous sensing and communication in a cubic millimeter, http://robotics.eecs.berkeley.edu/~pister/SmartDust/, Aug. 2002.

^[90]IEEE WPAN Task Group 4, IEEE 802.15.4 draft standard, http://www.ieee802.org/15/pub/TG4.html, Aug. 2002.

^[91]Smart Battery Systems Implementers Forum, www.sbs-forum.org, Aug. 2002.

^[92]Software Defined Radio Forum, www.sdrforum.org/, Aug. 2002.

^[93]Trimble: All about GPS, http://www.trimble.com/gps/, Aug. 2002.