Chapter 2: Standards for Hotspots

While we are just starting to see the use of 802.11b wireless local area networks (WLANs) as a widespread broadband connectivity method in the United States, wireless carriers in Korea and Japan are reportedly ramping up massive deployments of hotspot networks. These deployments punctuate the importance of the topic at hand. This chapter starts with an assessment of key standards that have applicability to hotspot services and it then looks at quality of service (QoS). QoS itself has an extensive body of literature, but given its discussion in the wireless standards bodies and its need in applications such as voice over Internet Protocol (VoIP) and video streaming, a short synopsis of this topic is provided at the end of the chapter. Some standards that have a special significance to hotspots are discussed in more detail in following chapters.

Standards

A major issue facing wireless-system designers is the fact that quite a number of wireless protocols exist (as shown in Table 2-1). There are standards for WLANs, wireless personal area networks (WPANs), and wireless wide area networks (WWANs). For hotspot networks built from WLANs and WPANs, the major standards of interest are the Institute of Electrical and Electronics Engineers (IEEE) standards. IEEE 802.11-based technology assists wireless device roaming through buildings and IEEE 802.15-based technology supports short-range links among computers, mobile telephones, peripherals, and other consumer electronics that are worn or carried. IEEE 802.16 supports high-rate broadband-wireless access services to buildings through rooftop antennas from central base stations.

Table 2-1. Wireless standards*

Standard	Significance
Bluetooth/IEEE 802.15	Derivative of Bluetooth 1.x spec and more meaningful standards developments relate to Bluetooth application profiles.
Code Division Multiple Access (CDMA) 2000 1x	2.5 G standard for wireless WANs, this provides more efficient voice and packet-switched data services with peak data rates of 153 Kbps.
CDMA 2000 1xEV	Qualcomm is pushing 1xEV as an evolution of 1x technology. It uses a 1.25 MHz CDMA radio channel dedicated to and optimized for packet data, and has throughputs of more than 2 Mbps.
CDMA 2000 3x	Third-generation (3G) standard for WWANs, this uses the same architecture as 1X. It offers 384 Kbps outdoors and 2 Mbps indoors, but operators will likely need to wait for new spectrum.
Enhanced Data rates for Global Evolution (EDGE)	Pushes the General Packet Radio Service (GPRS) data rate to 384 Kbps, but upgrades may be costly for carriers.
General Packet Radio Service (GPRS)	The 2.5G standard for WWANs based on Global System for Mobile Communications (GSM) systems deployed throughout Europe and in other parts of the world. GPRS is an IP-based, packet-data system providing theoretical peak data rates of up to 160 Kbps.
IEEE 802.1x	Security framework for all IEEE 802 networks, this is one of the key components of future multivendor interoperable wireless security systems, but implementation will not be simple.
IEEE 802.11	Basic standard for WLANs which was developed in the late 1990s supporting speeds up to 2 Mbps.
IEEE 802.11b	Basic standard for WLANs. An extension of the IEEE 802.11 specifications, supporting speeds of 1, 2, 5.5, aand 11 Mbps. Operates at 2.4 GHz.
IEEE 802.11a	High-speed WLAN (6 Mbps through 54 Mbps ranges), operating at 5 GHz.
IEEE 802.11e	Revision of 802.11 Media Access Control (MAC) standards, this provides QoS capabilities needed for real-time applications like IP telephony and video.
IEEE 802.11g	A new standard for 2.4 GHz WLANs, this provides a bump in the data rate to 20 _ Mbps, but backward-compatible products will not arrive soon.
IEEE 802.11i	Mired in technical debate and politics, this is critical to WLAN market expansion, but delays and indecisiveness may make it meaningless if de facto standards emerge.
IEEE 802.16	Its goal is to define physical and MAC standards for fixed point-to-multipoint broadband wireless access (BWA) systems.
Java 2 Platform, Micro Edition (J2ME)	Provides application-development platform for mobile devices, including cell phones and personal digital assistant (PDAs).
Mobile Management Forum (MMF)	The Open Group’s initiative aimed at defining standards for mobile-device management, including session management, synchronization, device-independent content, security, and accounting.
Wideband-CDMA (W-CDMA)	3G standard similar to CDMA 2000 but uses wider 5 MHz radio channels. It provides data rates up to 2 Mbps, but more spectrum needs to be allocated in some areas.
Wireless Internet Service Provider Roaming (WISPR)	Driven by the Wireless Ethernet Compatibility Association (WECA), this represents the industry’s first effort to provide transparent roaming and billing across public WLANs.
*www.networkcomputing.com

IEEE 802 and Related Activities

WLANs appeared in the early to mid-1990s, but the technology was proprietary to the various vendors in that space. In the mid-1990s, the IEEE sought to produce an industry-wide standard (the committee, however, had been in existence since 1990, handling preliminary activities related to wireless).

IEEE 802.11  Table 2-2 (from IEEE sources) provides a recent view of the standardization activities underway or recently completed in the 802.11 space. IEEE 802.11b is an extension to IEEE 802.11 to support higher data rates. Both standards (initially) used the Wired Equivalent Privacy (WEP) algorithm to address security.

Table 2-2. IEEE wireless standardization activities

Group	Label	Description
IEEE 802.11 Working Group	WG	The Working Group is comprised of all of the Task Groups together.
Task Group	TG	The committee(s) that is tasked by the WG as the author(s) of the standard or subsequent amendments.
MAC Task Group	MAC	Scope of project	The scope of the project is to develop one common MAC for WLANs applications in conjunction with the Physical Layer (PHY) Task Group.
		Status	Work has been completed and is now part of the original standard published as IEEE Std. 802.11-1997.
		Update Status	Work has been completed on the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) version of the original standard published as 8802-11: 1999 (ISO/IEC) (IEEE Std. 802.11, 1999 Edition).
PHY Task Group	PHY	Scope of Project	The scope of the project is to develop three PHYs for WLAN applications using Infrared (IR), 2.4 GHz Frequency Hopping Spread Spectrum (FHSS), and 2.4 GHz Direct Sequence Spread Spectrum (DSSS) in conjunction with the common MAC Task Group.
		Status	Work has been completed and is now part of the original standard published as IEEE Std. 802.11-1997.
		Update Status	Work has been completed on the ISO/IEC version of the original standard published as 8802-11: 1999 (ISO/IEC) (IEEE Std. 802.11, 1999 Edition).
Task Group a	TGa	Scope of Project	The scope of the project is to develop a PHY to operate in the newly allocated Unlicensed National Information Infrastructure (UNII) band.
		Status	Work has been completed and is now part of the standard as an amendment published as IEEE Std. 802.11a-1999.
		Update Status	Work has been completed on the ISO/IEC ﷓version of the original standard as an amendment published as 8802-11: 1999 (E)/Amd 1: 2000 (ISO/IEC) (IEEE Std. 802.11a-1999 Edition).
Task Group b	TGb	Scope of Project Status	The scope of the project is to develop a standard for a higher-rate PHY in the 2.4 GHz band.
		Status	Work has been completed and is now part of the standard as an amendment published as IEEE Std. 802.11b-1999.
Task Group b-cor1	TGb-Cor1	Scope of Project	The scope of this project is to correct deficiencies in the Management Information Base (MIB) definition of 802.11b.
		Purpose of Project	As the MIB is currently defined in 802.11b, it is not possible to compile an interoperable MIB. This project will correct the deficiencies in the MIB.
		Status	Ongoing.
Task Group c	TGc	Scope of Project	This adds a subclause under 2.5 support of the Internal Sublayer Service by specific MAC procedures to cover bridge operations with IEEE 802.11 MACs. This supplement to ISO/IEC 10038 (IEEE 802.1D) will be developed by the 802.11 Working Group in cooperation with the IEEE 802.1 Working Group.
		Purpose inforof Project	To provide the required 802.11-specific information to the ISO/IEC 10038 (IEEE 802.1D) standard.
		Status	Work has been completed and is now part of the ISO/IEC 10038 (IEEE 802.1D) standard.
Task Group d	TGd	Scope of Project	This supplement will define the physical-layer requirements (channelization, hopping patterns, and new values for current MIB attributes) and other requirements to extend the operation of 802.11 WLANs to new regulatory domains (countries).
		Purpose of Project	The current 802.11 standard defines operation in only a few regulatory domains (countries). This supplement will add the requirements and definitions necessary to enable 802.11 WLAN equipment to operate in markets not served by the current standard.
		Status	Ongoing.
Task Group e	TGe	Scope of Project	Enhance the 802.11 MAC to improve and manage QoS, provide classes of service, and enhanced security and authentication mechanisms. Consider efficiency enhancements in the areas of the distributed coordination function (DCF) and point coordination function (PCF).
		Purpose of Project	To enhance the current 802.11 MAC to expand support for LAN applications with QoS requirements and to provide improvements in security as well as in the capabilities and efficiency of the protocol. These enhancements, in combination with recent improvements in PHY capabilities from 802.11a and 802.11b, will increase overall system performance and expand the application space for 802.11. Example applications include the transport of voice, audio, and video over 802.11 wireless networks, video conferencing, media stream distribution, enhanced security applications, and mobile and nomadic access applications.
		Status	Ongoing. Note that the Security portion of the TGe project authorization request (PAR) was moved to the TGi PAR as of May 2001.
Task Group f	TGf	Scope of Project	To develop recommended practices for an Interaccess Point Protocol (IAPP) that provides the necessary capabilities to achieve multivendor access point interoperability across a distribution system supporting IEEE P802.11 WLAN links. This IAPP will be developed for the following environment(s): 1. A distribution system consisting of IEEE 802 LAN components supporting an IETF IP environment. 2. Others as deemed appropriate. This Recommended Practices Document shall support the IEEE P802.11 standard revision(s). IEEE P802.11 specifies the MAC and PHY layers of a WLAN system and includes the basic architecture of such systems, including the concepts of access points and distribution systems. Implementation of these concepts was purposely not defined by P802.11 because there are many ways to create a WLAN system. Additionally, many of the possible implementation approaches involve concepts from higher network layers. Although this leaves great flexibility in distribution systems and access point functional design, the associated cost is that physical access point devices from different vendors are unlikely to interoperate across a distribution system due to the different approaches taken to distribution system design. As P802.11-based systems have grown in popularity, this limitation has become an impediment to WLAN market growth. At the same time, it has become clear that a small number of distribution system environments comprise the bulk of the commercial WLAN system installations.
		Purpose of Project	This project proposes to specify the necessary information that needs to be exchanged between access points to support the P802.11 distribution system functions. The information exchanges required will be specified for one or more distribution systems in a manner sufficient to enable the implementation of distribution systems containing access points from different vendors that adhere to the recommended practices.
		Status	Ongoing.
Task Group g	TGg	Scope of Project	The scope of this project is to develop a higher-speed PHY extension to the 802.11b standard. The new standard shall be compatible with the IEEE 802.11 MAC. The maximum PHY data rate targeted by this project shall be at least 20 Mbps. The new extension shall implement all mandatory portions of the IEEE 802.11b PHY standard. The project will take advantage of the provisions for rate expansion that are in place on the current standard PHY. The 802.11 MAC defines a mechanism for the operation of stations supporting different data rates in the same area. The current 802.11b standard already defines the basic rates of 1, 2, 5.5, and 11 Mbps. The proposed project targets further developing the provisions for enhanced data rate capabilities of 802.11b networks. The 802.11 MAC currently incorporates the interpretation of data rate information and the computation of expected packet duration even if the specific station does not support the rate at which the packet was sent.
		Purpose of Project	To develop a new PHY extension to enhance the performance and the possible applications of the 802.11b-compatible networks by increasing the data rate achievable by such devices. This technology will be beneficial for improved access to fixed network LANs and internetwork infrastructures (including access to other WLANs) via a network of access points as well as the creation of higher-performance ad hoc networks.
		Status	Ongoing.
Task Group h	TGh	Scope of Project	To enhance the 802.11 MAC standard and 802.11a high-speed PHY in the 5 GHz band supplement to the standard, to add indoor and outdoor channel selection for 5 GHz license-exempt bands in Europe, and to enhance channel energy measurement and reporting mechanisms to improve spectrum and transmit power management (per the Conference of European Postal and Telecommunications Administrations [CEPT] and the subsequent European Union [EU] committee or the body ruling the incorporating CEPT Recommendation ERC 99/23 ).
		Purpose of Project	To enhance the current 802.11 MAC and 802.11a PHY with network management and control extensions for spectrum and transmit power management in 5 GHz license-exempt bands, enabling regulatory acceptance of 802.11 5 GHz products. Its purpose is also to provide improvements in channel energy measurement and reporting, channel coverage in many regulatory domains, and to provide dynamic channel selection and transmit power control mechanisms.
		Status	Ongoing.
Task Group i	TGi	Scope of Project	To enhance the current 802.11 MAC to provide improvements in security.
		Purpose of Project	Ongoing.
		Status	Note that the Security portion of the TGe PAR was moved to the TGi PAR as of May 2001.
Study Group	SG	Investigates the interest of placing something in the
Study Group 5GSG	5GSG	Presently investigating the globalization and harmonization of the 5 GHz band jointly with European Telecommunications Standards Institute-Broadband Radio Access Networks (ETSI-BRAN), and Multimedia Mobile Access Communication Systems Promotion Council (MMAC). The
Ad-Hoc Publicity	PC	Looks at how IEEE 802.11 can better “publicize” the standard by collecting data related to its use and operation.
Ad-Hoc Regulatory	R-REG	Tracks the regulatory bodies and administrations of various worldwide countries and makes sure the standard is in compliance with their rules, or lobbies for future implementations or extensions.

IEEE 802.11 is focused on the Physical layer (PHY) and Medium Access Control (MAC) sublayer. The MAC is consistent with the IEEE 802.3 Ethernet standard. The IEEE WLAN standard developed by Working Group 802.11 was accepted by the IEEE board during the summer of 1997 and became IEEE Standard 802.11-1997 (see Table 2-3). The standard defines three different physical implementations (signaling techniques and modulations), a MAC function, and a management function. All of the implementations support data rates of 1 Mbps and, optionally, 2 Mbps. Security, roaming, and QoS are also considered. The three physical implementations are as follows:

• Direct sequence spread spectrum radio (DSSS) in the 2.4 GHz band

• Frequency hopping spread spectrum radio (FHSS) in the 2.4 GHz band

• Infrared light (IR)

Table 2-3. IEEE 802.11 standards: the “workhorses” of hotspot networks today

Standard	Description
IEEE 802.11, 1999 Edition (ISO/IEC 8802-11: 1999)	IEEE Standard for Information Technology—Telecommunications and Information Exchange between Systems—Local and Metropolitan Area Network—Specific Requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical (PHY) Layer Specifications
IEEE 802.11a-1999 (8802-11:1999/Amd 1:2000(E))	IEEE Standard for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications—Amendment 1: High-speed Physical Layer in the 5 GHz band
IEEE 802.11b-1999	Supplement to 802.11—1999,Wireless LAN MAC and PHY specifications: Higher-speed Physical Layer (PHY) extension in the 2.4 GHz band

After the initial promulgation of the standard, the 802.11 Working Group then considered additions to the standard to provide higher data rates (5.5 and 11 Mbps) in the 2.4 GHz band and to allow WLANs to operate in a 5 GHz band at 54 Mbps. 802.11a uses the 5 GHz band called the Unlicensed National Information Infrastructure (UNII) in the United States; it supports 54 Mbps thanks to the higher frequency and greater bandwidth allocation. The IEEE 802.11a specification progressed toward standardization more rapidly than expected (it uses the orthogonal frequency division multiplexing [OFDM] modulation), and chipmakers quickly brought out chipsets (in early 2001). However, the higher density of hubs and the high price on early equipment still make 802.11b, and soon 820.11g, the more affordable choice for the majority of enterprise and hotspot applications at this time. In summary:

• 802.11a supports 6, 12, and 24 Mbps (mandatory), 9, 18, 36, 48, and 54 Mbps (optional) using 5 GHz OFDM.

• 802.11b supports 1, 2, 5.5, and 11 Mbps using 2.4 GHz complimentary code keying (CCK).

The differentiation with Bluetooth technology is that the latter is a low-cost, low-power, short-range radio link, while IEEE technology has higher throughput and range. The DSSS and FHSS PHY options were designed specifically to conform to FCC regulations for operation in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band, which has worldwide allocation for unlicensed operation. Both FHSS and DSSS PHYs support 1 and 2 Mbps; all 11 Mbps radios are DSSS.

Table 2-4 shows global spectrum allocation around 2.4 GHz. Table 2-5 identifies some of the spectrum regulatory bodies. WLANs implemented in accordance with the IEEE standards are subject to equipment certification and operating requirements established by regional and national regulatory administrations. The Physical Medium Dependent (PMD) specs establish technical requirements for interoperability, based upon established regulations at the time this standard was issued.

Table 2-4. Global spectrum allocation at 2.4 GHz

Region	Allocated Spectrum
U.S.	2.4—2.4835 GHz
Europe	2.4—2.4835 GHz
Japan	2.471—2.497 GHz
France	2.4465—2.4835 GHz
Spain	2.445—2.475 GHz

Table 2-5. Regulatory entities

Geographic area	Approval standards	Documents
Japan United States	Federal Communications Commission (FCC) Ministry of Post and Telecommunication (MPT)	CFR47, Part 15, sections 15.205 and 15.209; and Subpart E, sections 15.401—15.407 MPT Ordinance for Regulating Radio Equipment, Article 49.20

The IEEE does not get involved with the marketing and promotion of the technology, which as noted in Chapter 1, “Introduction to Wireless Personal Area Networks, Public Access Locations, and Hotspot Services,” is addressed by WECA’s Wireless Fidelity (WiFi) efforts. IEEE 802.11b has been a successful technology with a large base, good user experience, and tested interoperability. IEEE 802.11a offers higher throughput, but there are issues related to range, battery life, cost, and spectrum. In any event, backward compatibility is a requirement (see Figure 2-1).

Figure 2-1: Standardization efforts

802.11g extends 802.11b to speeds greater than 20 Mbps for WLAN. 802.11g was under development at press time. IEEE 802.11 Task Group G reached an important milestone late in 2001 by approving its first draft. When complete, this spec will extend the IEEE 802.11 family of standards, with data rates up to 54 Mbps in the 2.4 GHz band (not the 5.0 GHz band). This draft is based on CCK, OFDM, and packet binary convolutional code (PBCC) technologies. The 802.11 Task Group G initially considered a number of spread-spectrum modulations schemes to achieve higher speeds. Texas Instruments has promoted PBCC, which could offer better backward compatibility with 802.11b, while Intersil has been advocating OFDM. Both of these technologies are actually preexisting modulation schemes reinvigorated by the arrival of faster, smaller, and cheaper chips that make them practical for wireless networking.^[1] The 802.11 Task Group G eventually discarded Texas Instruments’ proposal of PBCC from consideration for the 802.11g protocol.^[2] The Working Group expects publication by the second half of 2002. IEEE 802.11 standards are covered in more detail in Chapters 5, “IEEE 802.11,” and 6, “IEEE 802.11b and IEEE 802.11a.”

IEEE 802.15  The 802.15 WPAN effort aims at developing consensus standards for WPANs or short-distance wireless networks. These WPANs address the wireless networking of portable and mobile computing devices such as PCs, PDAs, peripherals, cell phones, pagers, and consumer electronics, enabling these devices to communicate and interoperate with one another. The goal of the Working Group is to publish standards, recommended practices, or guides that have broad market applicability and deal effectively with the issues of coexistence and interoperability with other wired and wireless networking solutions. IEEE 802.15 (building on Bluetooth) is a 10-meter-radius, low-power technology. The IEEE 802.15 Working Group is part of the 802 Local and Metropolitan Area Network Standards Committee of the IEEE Computer Society.

IEEE 802.15 Task Group 1 (TG1) is deriving a WPAN standard based on the Bluetooth v1.x Foundation Specification’s. Approval by the Standards Board was expected by press time (2002). The scope and purpose are as follows:

1. To define PHY and MAC specifications for wireless connectivity with fixed, portable, and moving devices within or entering a Personal Operating Space (POS). A goal of the WPAN Group is to achieve a level of interoperability that could allow the transfer of data between a WPAN device and an 802.11 device. A POS is the space around a person or object that typically extends up to 10 meters in all directions and envelops the person whether stationary or in motion. The proposed WPAN standard will be developed to ensure coexistence with all 802.11 networks.

2. To provide a standard for low-complexity, low-power-consumption wireless connectivity to support interoperability among devices within or entering the POS. This includes devices that are carried, worn, or located near the body. The proposed project will address QoS to support a variety of traffic classes. Examples of devices, that can be networked, include computers, PDAs/handheld personal computers (HPCs), printers, microphones, speakers, headsets, bar code readers, sensors, displays, pagers, and cellular and personal communications service (PCS) phones.

See Figure 2-2 for a view of the protocol model.^[3]

Figure 2-2. 802.15 protocol view

A number of technical challenges exist in regards to wireless services under discussion:

• Both IEEE 802.11 and Bluetooth operate in the same 2.4 GHz ISM band.

• Bluetooth-enabled devices will likely be portable and will need to operate in an IEEE 802.11 WLAN environment.

• There will be some level of mutual interference.

The IEEE 802.15 Coexistence Task Group 2 (TG2) for WPANs is developing recommended practices to facilitate the coexistence of WPANs (802.15) and WLANs (802.11). The Task Group is developing a coexistence model to quantify the mutual interference of a WLAN and a WPAN. The Task Group is also developing a set of coexistence mechanisms to facilitate the coexistence of WLAN and WPAN devices.

The IEEE P802.15.3 High Rate (HR) Task Group 3 (TG3) for WPANs is chartered to draft and publish a new standard for high-rate (20 Mbps or greater) WPANs. Besides a high data rate, the new standard will provide for low-power, low-cost solutions addressing the needs of portable consumer digital imaging and multimedia applications. In addition, when approved, the new WPAN-HR standard may provide compatibility with the TG1 draft standard based upon the Bluetooth specification.

The IEEE 802.15 Task Group 4 (TG4) is chartered to investigate a low data rate solution with multimonth to multiyear battery life and very low complexity. It is intended to operate in an unlicensed, international frequency band. Potential applications are sensors, interactive toys, smart badges, remote controls, and home automation.

IEEE 802.16  The activities of this Working Group are summarized later, directly from IEEE sources. These standards are more applicable to fixed wireless applications and may support the interconnection of hotspot cells (such as picocells and microcells). They also have more general applicability.

The 802.16-2001 standard^[4] specifies the PHY and MAC layer of the air interface of interoperable, fixed, point-to-multipoint broadband wireless access (BWA) systems. The specification enables the transport of data, video, and voice services. It applies to systems operating in the vicinity of 30 GHz but is broadly applicable to systems operating between 10 and 66 GHz. The project purpose is to enable the rapid worldwide deployment of innovative, cost-effective, and interoperable multivendor BWA products. The goal is to facilitate competition in broadband access by providing alternatives to wireline broadband access. Another goal is to facilitate coexistence studies, encourage consistent worldwide allocation, and accelerate the commercialization of BWA spectrum.

The 802.16.1b^[5] standard specifies the MAC layer and PHYs of the air interface of interoperable, fixed point-to-multipoint BWA systems. The specification enables the transport of data, video, and voice services. Physical layers are specified for both licensed and license-exempt bands. The amendment expands the scope of the original project by extending it to license-exempt bands (thereby defining the Wireless High-Speed Unlicensed Metropolitan Area Network [WirelessHUMAN^TM] Standard). It specifies the PHY and MAC layer of the air interface of interoperable fixed broadband wireless metropolitan area network (MAN) systems, including point-to-multipoint. The standard enables access to data, video, and voice services with QoS in unlicensed (license-exempt) bands designated for public network access. It focuses on the 5 to 6 GHz range and may be applied to unlicensed bands between 2 and 11 GHz. It will address strategies for coexistence with other unlicensed applications. The project utilizes or modifies applicable elements from the following: MAC: IEEE 802.16; PHY: IEEE 802.11a; and ETSI Broadband Radio Access Networks (BRAN) High-Performance Radio Local Area Network type 2 (HIPERLAN/2).^[6]

The project purpose is to enable the rapid worldwide deployment of innovative, cost-effective, and interoperable multivendor BWA products. The goal is to facilitate competition in broadband access by providing alternatives to wireline broadband access. Other goals are to facilitate coexistence studies, encourage consistent worldwide allocation, and accelerate the commercialization of BWA spectrum. It will identify techniques to tolerate interference in the unlicensed bands and facilitate strategies for coexistence with other unlicensed band systems such as 802.11 and 802.15. It will also encourage consistent worldwide spectrum allocation and accelerate the commercialization of unlicensed BWA spectrum. The utilization of unlicensed frequencies will address a market that includes residences, small offices-home offices (SOHOs), telecommuters, and small and medium enterprises (SME).

The 802.16.2a^[7] project is aimed at developing extensions and modifications to IEEE 802.16.2-2001 addressing two distinct topics. The first topic is the coexistence between multipoint systems and point-to-point systems in the frequency range 10 to 66 GHz, which were planned to focus on the range 23.5 to 43.5 GHz. Two types of point-to-point systems will be considered: those used by fixed BWA operators and those used as individually assigned links, commonly licensed on a first-come, first-served basis.

The second topic is coexistence among fixed BWA systems operating in licensed bands within the frequency range 2 to 11 GHz. The project purpose is to provide additional coexistence guidelines to license holders, service providers, deployment groups, and system integrators, covering coexistence with point-to-point systems (primarily from 23.5 to 43.5 GHz) and coexistence among licensed, fixed BWA systems operating in the 2 to 11 GHz frequency range. The equipment parameter values contained within this amended practice will benefit license holders, equipment and component vendors, and industry associations by facilitating the deployment and operation of fixed BWA systems while minimizing the need for case-by-case coordination. Another purpose is to encourage voluntary procedures that facilitate a simpler licensing process for systems operating below 11 GHz, particularly in the 2.5 GHz MMDS/ITFS bands in the United States.

The 802.16.2-2001^[8] project covers the development of a recommended practice for the design and coordinated deployment of fixed systems operating from 10 to 66 GHz (with a focus on 23.5 to 43.5 GHz). This is done to minimize interference and to maximize system performance and/or service quality. The spec provides for coexistence using frequency and spatial separation and will cover three areas. First, it will recommend limits of in-band and out-of-band emissions from BWA transmitters through parameters, including radiated power, spectral masks, and antenna patterns. Second, it will recommend receiver-tolerance parameters, including noise floor degradation performance, for interference received from other BWA systems. Third, it will provide coordination parameters, including separation distances and power flux density limits, to enable the successful deployment of BWA systems with tolerable interference. The scope includes interference between systems deployed across geographic boundaries in the same frequency band and systems deployed in the same geographic area in different frequency bands (including different systems deployed by a single license-holder in subbands of the licensees’ authorized bandwidth).

The purpose of this spec is to provide coexistence guidelines to license holders, service providers, deployment groups, and system integrators. The equipment parameters contained within this spec will benefit equipment and component vendors as well as industry associations by providing design targets. The benefits of this spec include the following:

• Coexistence of different systems with higher assurance that system performance objectives will be met.

• Minimal need for case-by-case interference studies and coordination between operators to resolve interference issues.

• Preservation of a favorable electromagnetic environment for the deployment and operation of BWA systems, including future systems compliant to IEEE 802.16 interoperability standards.

• Improved spectrum utilization.

• Cost-effective system deployment.

The 802.16.3^[9] standard specifies the PHY and MAC layer of the air interface of interoperable, fixed point-to-multipoint BWA systems (those supporting data rates of DS1/E1 or greater). The specification enables access to data, video, and voice services with a specified QoS in licensed bands designated for public network access. It applies to systems operating between 2 and 11 GHz. The goal is to enable the rapid worldwide deployment of innovative, cost-effective, and interoperable multivendor BWA products. This is done to facilitate competition in broadband access by providing wireless alternatives to wireline broadband access and to facilitate coexistence studies, encourage worldwide allocation, and accelerate the commercialization of spectrum. The utilization of frequencies from 2 to 11 GHz will address a market that includes residences, SOHO, telecommuters, and SMEs.

The 802.16a^[10] standard specifies the PHY and MAC layer of the air interface of interoperable fixed point-to-multipoint BWA systems (those supporting data rates of DS1/E1 or greater). The specification enables access to data, video, and voice services with a specified QoS in licensed bands designated for public network access. The spec applies to systems operating between 2 and 11 GHz. The project’s purpose is to enable the rapid worldwide deployment of innovative, cost-effective, and interoperable multivendor BWA products. This is done to facilitate competition in broadband access by providing wireless alternatives to wireline broadband access and to facilitate coexistence studies, encourage consistent worldwide allocation, and accelerate the commercialization of BWA spectrum. The utilization of frequencies from 2 to 11 GHz will address a market that includes residences, SOHOs, telecommuters, and SMEs.

Finally, the 802.16b^[11] standard specifies the MAC layer and PHYs of the air interface of interoperable, fixed, point-to-multipoint BWA systems. The specification enables the transport of data, video, and voice services. PHYs are specified for both licensed and license-exempt bands. The spec expands the scope of the original project by extending it to license-exempt bands (thereby defining the WirelessHUMAN™ standard). It specifies the PHY and MAC layer of the air interface of interoperable, fixed, broadband wireless MAN systems, including point-to-multipoint. The standard enables access to data, video, and voice services with QoS in unlicensed (license-exempt) bands designated for public network access. It focuses on the 5 to 6 GHz range and may be applied to unlicensed bands between 2 and 11 GHz. It also addresses strategies for coexistence with other unlicensed applications.

The project will utilize or modify applicable elements from the following layers: MAC, IEEE 802.16 PHY, IEEE 802.11a, and ETSI BRAN HIPERLAN/2. The project purpose is (i) to enable the rapid worldwide deployment of innovative, cost-effective, and interoperable multivendor BWA products; (ii) to facilitate competition in broadband access by providing alternatives to wireline broadband access; and (iii) to facilitate coexistence studies, encourage consistent worldwide allocation, and accelerate the commercialization of BWA spectrum. The undertaking enhances the original project by extending it to license-exempt bands. It identifies techniques to tolerate interference in the unlicensed bands and facilitate strategies for coexistence with other unlicensed band systems such as 802.11 and 802.15. It encourages consistent worldwide spectrum allocation and accelerates the commercialization of unlicensed BWA spectrum. The utilization of unlicensed frequencies will address a market that includes residences, SOHOs, telecommuters, and SMEs.

2G/2.5G/3G  Table 2-6 depicts some of the existing WWAN 2G/2.5G/3G standards, while Table 2-7 provides a more detailed listing of key standards. Generally speaking, 3G seeks to provide up to 2 Mbps of data (for example, on the Internet) to cell phones. Multiple groups are involved in standards development: Third-Generation Partnership Project (3GPP), Third-Generation Partnership Project 2 (3GPP2), and so on. Eventually, there will be some interplay with 802.11. Two of the groups are as follows:

• Third-Generation Partnership Project (3GPP)  This is a GSM-originated standards group. 3GPP is a collaboration agreement that was established in 1998 to bring together a number of telecommunications standards bodies such as ARIB, CWTS, ETSI, T1, TTA, and TTC in one single body.^[12] ETSI, T1P1, ARIB/TTC, TTA, CWTS aim at all IP-based mobile networks (GSM focus). Originally, the 3GPP was to produce globally applicable technical specifications and technical reports for 3G based on evolved GSM core networks. This was amended to include the maintenance and development of GSM and evolved into radio access technologies (GPRS and EDGE).^[13]

• Third Generation Partnership Project 2 (3GPP2)  This is a CDMA-oriented 3G standards group. It is an American National Standards Institute (ANSI)-based effort.

Table 2-6. Key technologies for 2G, 2.5G, and 3G

Technology	Generation	Description	Notes
Time Division Multiple Access (TDMA)	2G	The standard used by AT&T Wireless services. In North America, CDMA subscribers currently outnumber TDMAs. The TDMA variant GSM is deployed in Europe and has the largest number of subscribers worldwide.
EDGE	3G	Enhances TDMA for data rates between 384 Kbps and 2 Mbps.	North America is one of the few markets where EDGE services are likely to appear.
CDMA	2G	The leading air interface in North America, patented by Qualcomm.	Key CDMA carriers include Verizon, Sprint, and Bell Mobility.
CDMA2000 1X	2.5G	Provides CDMA users with data rates as fast as 307 Kbps. Qualcomm’s pre-3G evolution of its CDMA.	Sprint PCS, BellSouth, and Verizon were planning to introduce CDMA2000 1X data service in North America.
CDMA2000 2X	3G	Provides data services to CDMA devices at bit rates as fast as 2 Mbps. Qualcomm’s technology.	Has more momentum in North America than W-CDMA and could still lose the race in North America but, given the success of CDMA2000 1X, it has a lead.
W-CDMA	3G	ITU’s official 3G migration path for TDMA networks, including the subscriber-rich GSM networks in Europe and Asia. It is a major competitor to CDMA2000 and is likely to become the world’s leading wireless data standard.	W-CDMA, now an international standard, has a lock on most non-U.S. markets.
GSM	2G	The most widely used wireless standard in Europe, based on TDMA.	To provide global roaming for wireless data subscribers, North American carriers will need to support GSM devices. Qualcomm was reportedly planning to create a chip that enables wireless devices to communicate on both GSM and CDMA networks.
GPRS	2.5G	Supports midrange data service to TDMA subscribers, including those using GSM devices. The maximum bit rate is 115 Kbps (less than half that of CDMA2000 1X.) GRPS is a stepping-stone to EDGE, a 3G alternative to W-CDMA for TDMA wireless carriers.	AT&T Wireless (while it upgrades its network for EDGE), Cingular Wireless, and Voice Stream were expected to expand their GPRS offerings in the United States.

Table 2-7. Detailed listing of key 1G/2G/3G standards

Standard’s Family	Detailed Standard
TDMA Systems	EIA Standard IS-54-B, “Cellular System Dual-Mode Mobile Station — Base Station Compatibility Standard,” 1992.
	EIA Interim Standard IS-136.2, “800 MHz TDMA — Radio Interface — Mobile Station — Base Station Compatibility — Traffic Channels and FSK Control Channels,” 1994.
GSM	GSM Specifications 2.01, Version 4.2.0, Issued by ETSI, January 1993. Also, ETSI/GSM Specifications 2.01, “Principles of Telecommunications Services,” January 1993.
	GSM Specifications 3.60, Version 6.4.1, “General Packet Radio Service (GPRS); Service Description, Stage 2,” 1997.
	GSM Specifications 4.60, Version 7.2.0, “General Packet Radio Service (GPRS); Mobile Radio-Base Station Interface, Radio Link Control/Medium Access Control (RLC/MAC) Protocol,” 1998.
	ETSI GSM 03.60: GPRS Service Description, Stage 2.
	ETSI GSM 03.64: Overall Description of the GPRS Radio Interface, Stage 2.
	ETSI GSM 04.60: GPRS, Mobile Station — Base Station System (BSS) Interface, Radio Link Control/Medium Access Control (RLC/MAC) Protocol.
	ETSI GSM 04.64: GPRS, Logical Link Control.
	ETSI GSM 04.65: GPRS, Subnetwork Dependent Convergence Protocol (SNDCP).
	ETSI GSM 07.60: Mobile Station (MS) Supporting GPRS.
	ETSI GSM 08.08: GPRS, Mobile Switching Center — Base Station Subsystem (MSC-BSC) Interface: Layer 3 Specification.
	ETSI GSM 08.14: Base Station Subsystem — Serving GPRS Support Node (BSS-SGSN) Interface; Gb Interface Layer 1.
	ETSI GSM 08.16: Base Station Subsystem — Serving GPRS Support Node (BSS-SGSN) Interface; Network Service.
	ETSI GSM 08.18: Base Station Subsystem — Serving GPRS Support Node (BSS-SGSN); Base Station Subsystem GPRS Protocol (BSSGP).
	ETSI GSM 09.60: GPRS Tunneling Protocol (GTP) Across the Gn and Gp Interface.
	ETSI GSM 09.61: General Requirements on Interworking Between the Public Land Mobile Network (PLMN) Supporting GPRS and Packet Data Network (PDN).
	ETSI GSM 2.01, Version 4.2.0, January 1993.
	ETSI GSM Section 4.0.2, “European Digital Cellular Telecommunication System (Phase 2); Speech Processing Functions: General Description,” April 1993.
CDMA One	EIA Interim Standard IS-95, “Mobile Station — Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,” 1998.
IMT-2000	ITU-R M.1034-1, “International Mobile Telecommunications-2000 (IMT-2000),” 1997.
	ITU-R M.816-1, “ Framework for Services Supported on International Mobile Telecommunications-2000 (IMT-2000),” 1997.
	ITU-R M.687-2, “International Mobile Telecommunications-2000 (IMT-2000),” 1997.
	IMT-2000: Recommendations ITU-R M.687-2, 1997.
	3G TS 22.105 Release 1999, Services and Service Capabilities.
	EIA/TIA/IS-41.1-B, Cellular Radio — Telecommunications Intersystem Operations: Functional Overview, 1991.
	EIA/TIA/IS-634-A, MSC-BS Interface (A-Interface) for Public 800 MHz, 1998.
	GSM 03.60: GPRS Service Description, Stage 2.
	GSM 03.64: Overall Description of the GPRS Radio Interface, Stage 2.
	3GPP TS 25.401: UTRAN Overall Description, 2000.
	3GPP TR 23.922: Architecture for an All IP Network, 1999.
PCS	TIA TR-45.4, Microcellular/PCS.
	TIA TR-46, Mobile and Personal Communications 1800.
	TIA TR-46.1, Services and Reference Model.
	TIA TR-46.2, Network Interfaces.
	TIA TR-46.3, Air Interfaces.
	EIA/TIA-553 Cellular System Mobile Station — Land Station Compatibility Specification.
Universal Mobile	3G TS 22.105, Service Aspects; Services and Service Capabilities.
Telecommunications	3GPP TS 23.107, QoS Concept and Architecture.
System (UMTS)	3GPP TS 25.401, UTRAN Overall Description
	3GPP TS 25.101, UE Radio Transmission and Reception.
	3GPP TS 25.104, UTRA (BS) FDD, Radio Transmission and Reception.
	3GPP TS 25.105, UTRA (BS) TDD, Radio Transmission and Reception.
	3GPP TS 25.301, Radio Interface Protocol Architecture.
	3GPP TS 25.201, Physical Layer — General Description.
	3GPP TS 25.211, Physical Channels and Mapping of Transport Channels onto Physical Channels (FDD).
	3GPP TS 25.212, Multiplexing and Channel Coding.
	3GPP TS 25.213, Spreading and Modulation (FDD).
	3GPP TS 25.214, Physical Layer Procedures.
	3GPP TS 25.215, Physical Layer — Measurements.
	3GPP TS 25.302, Services Provided by the Physical Layer.
	3GPP TS 25.321, MAC Protocol Specification.
	3GPP TS 25.322, RLC Protocol Specification.
	3GPP TS 25.323, Packet Data Convergence Protocol (PDCP) Specification.
	3GPP TS 25.324, Broadcast/Multicast Control (BMC) Protocol Specification.
	3G TS 25.331, RRC Protocol Specification.
	3G TS 25.303, Interlayer Procedures in Connected Mode.
	3GPP TS 25.410, UTRAN Iu Interface: General Aspects and Principles.
	3GPP TS 25.411, UTRAN Iu Interface: Layer 1.
	3GPP TS 25.412, UTRAN Iu Interface: Signaling Transport.
	3GPP TS 25.413, UTRAN Iu Interface: RANAP Signaling.
	3GPP TS 25.414, UTRAN Iu Interface: Data Transport and Transport Signaling.
	3GPP TS 25.415, UTRAN Iu Interface: CN-RAN User Plane Protocol.
	3GPP TS 25.420, UTRAN Iur Interface: General Aspects and Principles.
	3GPP TS 25.421, UTRAN Iur Interface: Layer 1.
	3GPP TS 25.422, UTRAN Iur Interface: Signaling Transport.
	3GPP TS 25.423, UTRAN Iur Interface: RNSAP Signaling.
	3GPP TS 25.424, UTRAN Iur Interface: Data Transport and Transport Signaling for CCH Data Streams.
	3GPP TS 25.425, UTRAN Iur Interface: User Plane Protocols for CCH Data Streams.
	3GPP TS 25.426, UTRAN Iur and Iub Interface Data Transport and Transport Signaling for DCH Data Streams.
	3GPP TS 25.427, UTRAN Iur and Iub Interface User Plane Protocols for DCH Data Streams.
	3GPP TS 25.430, UTRAN Iub Interface: General Aspects and Principles.
	3GPP TS 25.431, UTRAN Iub Interface: Layer 1.
	3GPP TS 25.432, UTRAN Iub Interface: Signaling Transport.
	3GPP TS 25.433, UTRAN Iub Interface: NBAP Signaling.
	3GPP TS 25.434, UTRAN Iub Interface: Data Transport and Transport Signaling for CCH Data Streams.
	3GPP TS 25.435, UTRAN Iub Interface: User Plane Protocols for CCH Data Streams.
	3G TR 23.922, Architecture of an All IP Network.
	3G TR 25.990, Vocabulary.

3GPP supports efforts for Europe and Asia, while 3GPP2 supports efforts for North America. Table 2-8 lists some recent Internet Engineering Task Force (IETF) Request for Comments (RFCs) that focus on wireless and/or mobile systems.

Table 2-8. Recent wireless/mobile IETF RFCs

RFC	Title
3141	CDMA2000 Wireless Data Requirements for AAA. T. Hiller, P. Walsh, X. Chen, M. Munson, G. Dommety, S. Sivalingham, B. Lim, P. McCann, H. Shiino, B. Hirschman, S. Manning, R. Hsu, H. Koo, M. Lipford, P. Calhoun, C. Lo, E. Jaques, E. Campbell, Y. Xu, S. Baba, T. Ayaki, T. Seki, A. Hameed (June 2001).
3115	Mobile IP Vendor/Organization-Specific Extensions. G. Dommety, K. Leung (April 2001, obsoletes RFC3025.)
3024	Reverse Tunneling for Mobile IP, Revised. G. Montenegro, Editor (January 2001, obsoletes RFC2344).
2977	Mobile IP Authentication, Authorization, and Accounting Requirements. S. Glass, T. Hiller, S. Jacobs, C. Perkins (October 2000).
2501	Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations. S. Corson, J. Macker (January 1999).
2284	PPP Extensible Authentication Protocol (EAP). L. Blunk, J. Vollbrecht (March 1998).
2002	IP Mobility Support. C. Perkins, Editor (October 1996).

IETF IP Over Bluetooth (BOF)  The BOF^[14] advocates the creation of an IETF Working Group to investigate the most open and efficient way to place IP over the Bluetooth Host Controller. Current work in this area within the Bluetooth Special Interest Group (SIG) concentrates on defining IP over a set of other lower-layer stacks. Currently, the Bluetooth SIG defines two options:

• Option 1: IP/PPP/RFCOM/L2CAP/Host Controller

• Option 2: IP/PAN Profile/L2CAP/Host Controller (where the PAN Profile is a Bluetooth SIG work in progress)

The IETF Working Group seeks to define a more efficient way of running IP over Bluetooth. In particular, IP would run over an IETF protocol over the Host Controller without L2CAP. This option may be adopted by the Bluetooth SIG at a later date as a profile. Since all Bluetooth SIG profiles are optional, a customer may choose any combination of profiles in a final product. Further, since Bluetooth Working Groups have it in their mandate to adopt protocols from other standards-making bodies such as the IETF, a clear path exists for IETF work to be adopted by the Bluetooth SIG. The objective of the BOF is to foster innovation and speed progress by placing IP-related protocol development within the IETF and Bluetooth-specific protocol development within the Bluetooth SIG by developing an IP over Bluetooth IETF Working Group. This effort will define its own way of running IP over Bluetooth by carefully selecting a set of Bluetooth protocols (freely available from published specifications at www.bluetooth.com/ developer/specification/specification.asp) on which to build IP.

Mobile IP

IETF RFC 2002 specifies protocol enhancements that enable the transparent routing of IP datagrams to mobile nodes on the Internet. Mobility does not necessarily imply a wireless situation, but often it does, hence our brief coverage of this technology. In a mobile environment, each mobile node is always identified by its home address, regardless of its current point of attachment to the Internet. Although situated away from its home, a mobile node is also associated with a care-of address, which provides information about its current point of attachment to the Internet. The protocol of RFC 2002 provides for registering the care-of address with a home agent. The home agent sends datagrams destined for the mobile node through a tunnel to the care-of address. After arriving at the end of the tunnel, each datagram is then delivered to the mobile node.^[15]

IP^[16] Version 4 assumes that a node’s IP address uniquely identifies the node’s point of attachment to the Internet. Therefore, a node must be located on the network indicated by its IP address in order to receive datagrams destined to it; otherwise, datagrams destined to the node would be undeliverable. For a node to change its point of attachment without losing its capability to communicate, currently one of the two following mechanisms must typically be employed:

• The node must change its IP address whenever it changes its point of attachment.

• Host-specific routes must be propagated throughout much of the Internet routing fabric.

Both of these alternatives are often unacceptable. The first makes it impossible for a node to maintain transport and higher-layer connections when the node changes location. The second has obvious and severe scaling problems, which are especially relevant considering the explosive growth in sales of notebook (mobile) computers. A new, scalable, mechanism is required for accommodating node mobility within the Internet. The RFC defines such a mechanism, which enables nodes to change their point of attachment to the Internet without changing their IP address.

Protocol Requirements

• A mobile node must be able to communicate with other nodes after changing its link-layer point of attachment to the Internet yet without changing its IP address.

• A mobile node must be able to communicate with other nodes that do not implement these mobility functions. No protocol enhancements are required in hosts or routers that are not acting as any of the new architectural entities introduced in the “New Architectural Entities” section.

• All messages used to update another node as to the location of a mobile node must be authenticated in order to protect against remote redirection attacks.

Goals  The link by which a mobile node is directly attached to the Internet may often be a wireless link. This link may thus have substantially lower bandwidth and a higher error rate than traditional wired networks. Moreover, mobile nodes are likely to be battery powered, and minimizing power consumption is important. Therefore, the number of administrative messages sent over the link by which a mobile node is directly attached to the Internet should be minimized, and the size of these messages should be kept as small as reasonably possible.

Assumptions

• The protocols defined in this document place no additional constraints on the assignment of IP addresses. That is, a mobile node can be assigned an IP address by the organization that owns the machine.

• The RFC 2002 protocol assumes that mobile nodes will generally not change their point of attachment to the Internet more frequently than once per second.

• The RFC 2002 protocol assumes that IP unicast datagrams are routed based on the destination address in the datagram header (and not, for example, by the source address).

Applicability  Mobile IP is intended to enable nodes to move from one IP subnet to another. It is just as suitable for mobility across homogeneous media as it is for mobility across heterogeneous media. That is, Mobile IP facilitates node movement from one Ethernet segment to another and it accommodates node movement from an Ethernet segment to a wireless LAN as long as the mobile node’s IP address remains the same after such a movement.

Think of Mobile IP as solving the macromobility management problem. It is less suited for more micromobility management applications such as handoffs amongst wireless transceivers, each of which covers only a small geographic area. As long as node movement does not occur between points of attachment on different IP subnets, link-layer mechanisms for mobility (that is, a link-layer handoff) may offer faster convergence and far less overhead than Mobile IP.

New Architectural Entities  Mobile IP introduces the following new functional entities:

• Mobile node  A host or router that changes its point of attachment from one network or subnetwork to another. A mobile node may change its location without changing its IP address; it may continue to communicate with other Internet nodes at any location using its (constant) IP address, assuming that link-layer connectivity to a point of attachment is available.

• Home agent  A router on a mobile node’s home network that tunnels datagrams for delivery to the mobile node when it is away from home. A home agent also maintains current location information for the mobile node.

• Foreign agent  A router on a mobile node’s visited network that provides routing services to the mobile node while registered. The foreign agent detunnels and delivers datagrams to the mobile node that were tunneled by the mobile node’s home agent. For datagrams sent by a mobile node, the foreign agent may serve as a default router for registered mobile nodes.

A mobile node is given a long-term IP address on a home network. This home address is administered in the same way as a permanent IP address is provided to a stationary host. When away from its home network, a care-of address is associated with the mobile node and reflects the mobile node’s current point of attachment. The mobile node uses its home address as the source address of all IP datagrams that it sends, except where otherwise described in this document for datagrams sent for certain mobility management functions.

Terminology  The RFC frequently uses the terms shown in Table 2-9.

Table 2-9. Key mobile IP terms

Term	Definition
Agent advertisement	An advertisement message constructed by attaching a special extension to a router advertisement message.
Care-of address	The termination point of a tunnel toward a mobile node for datagrams forwarded to the mobile node while it is away from home. The protocol can use two different types of care-of addresses: a foreign agent care-of address is an address of a foreign agent with which the mobile node is registered, and a co-located care-of address is an externally obtained local address with which the mobile node has associated one of its own network interfaces.
Correspondent correnode	A peer with which a mobile node is communicating. A spondent node may be either mobile or stationary.
Foreign network	Any network other than the mobile node’s home network.
Home address	An IP address that is assigned for an extended period of time to a mobile node. It remains unchanged regardless of where the node is attached to the Internet.
Home network	A network, possibly virtual, having a network prefix matching that of a mobile node’s home address. Note that standard IP routing mechanisms will deliver datagrams destined to a mobile node’s home address to the mobile node’s home network.
Link	A facility or medium over which nodes can communicate at the link layer. A link underlies the network layer.
Link-layer address	The address used to identify an endpoint of some communication over a physical link. Typically, the link-layer address is an interface’s Media Access Control (MAC) address.
Mobility agent	Either a home agent or a foreign agent.
Mobility binding	The association of a home address with a care-of address, along with the remaining lifetime of that association.
Mobility security association	A collection of security contexts between a pair of nodes that may be applied to Mobile IP protocol messages exchanged between the nodes. Each context indicates an authentication algorithm and mode, a secret (a shared key or appropriate public/private key pair), and a style of replay protection in use.
Node	A host or a router.
Nonce	A randomly chosen value, different from previous choices, inserted in a message to protect against replays.
Security Parameter Index (SPI)	An index identifying a security context between a pair of nodes among the contexts available in the mobility security association. SPI values 0 through 255 are reserved and must not be used in any mobility security association.
Tunnel	The path followed by a datagram while it is encapsulated. The model is that, while it is encapsulated, a datagram is routed to a knowledgeable decapsulating agent, which decapsulates the datagram and then correctly delivers it to its ultimate destination.
Virtual network	A network with no physical instantiation beyond a router (with a physical network interface on another network). The router (a home agent) generally advertises reachability to the virtual network using conventional routing protocols.
Visited network	A network other than a mobile node’s home network, to which the mobile node is currently connected.
Visitor list	The list of mobile nodes visiting a foreign agent.

Protocol Overview  The following support services are defined for Mobile IP:

• Agent discovery  Home agents and foreign agents may advertise their availability on each link for which they provide service. A newly arrived mobile node can send a solicitation on the link to learn if any prospective agents are present.

• Registration  When the mobile node is away from home, it registers its care-of address with its home agent. Depending on its method of attachment, the mobile node will register either directly with its home agent or through a foreign agent that forwards the registration to the home agent.

The following steps provide a rough outline of operation of the Mobile IP protocol:

1. Mobility agents (foreign agents and home agents) advertise their presence via agent advertisement messages. A mobile node may optionally solicit an agent advertisement message from any locally attached mobility agents through an agent solicitation message.

2. A mobile node receives these agent advertisements and determines whether it is on its home network or a foreign network.

3. When the mobile node detects that it is located on its home network, it operates without mobility services. If returning to its home network from being registered elsewhere, the mobile node deregisters with its home agent through the exchange of a registration request and a registration reply message with it.

4. When a mobile node detects that it has moved to a foreign network, it obtains a care-of address on the foreign network. The care-of address can either be determined from a foreign agent’s advertisements (a foreign agent care-of address) or by some external assignment mechanism such as the Dynamic Host Configuration Protocol (DHCP), a co-located care-of address.

5. The mobile node operating away from home then registers its new care-of address with its home agent through the exchange of a registration request and a registration reply message with it, possibly via a foreign agent.

6. Datagrams sent to the mobile node’s home address are intercepted by its home agent, tunneled by the home agent to the mobile node’s care-of address, received at the tunnel endpoint (either at a foreign agent or at the mobile node itself), and finally delivered to the mobile node.

7. In the reverse direction, datagrams sent by the mobile node are generally delivered to their destination using standard IP routing mechanisms, not necessarily passing through the home agent.

When away from home, Mobile IP uses protocol tunneling to hide a mobile node’s home address from intervening routers between its home network and its current location. The tunnel terminates at the mobile node’s care-of address. The care-of address must be an address to which datagrams can be delivered via conventional IP routing. At the care-of address, the original datagram is removed from the tunnel and delivered to the mobile node.

Mobile IP provides two alternative modes for the acquisition of a care-of address:

• Foreign agent care-of address  A care-of address provided by a foreign agent through its agent advertisement messages. In this case, the care-of address is an IP address of the foreign agent. In this mode, the foreign agent is the endpoint of the tunnel and, upon receiving tunneled datagrams, decapsulates them and delivers the inner datagram to the mobile node. This mode of acquisition is preferred because it allows many mobile nodes to share the same care-of address and therefore does not place unnecessary demands on the already limited IPv4 address space.

• Co-located care-of address  A care-of address acquired by the mobile node as a local IP address through some external means, which the mobile node then associates with one of its own network interfaces. The address may be dynamically acquired as a temporary address by the mobile node such as through DHCP, or it may be owned by the mobile node as a long-term address for its use only while visiting some foreign network. Specific external methods of acquiring a local IP address for use as a co-located care-of address are beyond the scope of this document. When using a co-located care-of address, the mobile node serves as the endpoint of the tunnel and itself performs decapsulation of the datagrams tunneled to it.

The mode of using a co-located care-of address has the advantage of allowing a mobile node to function without a foreign agent, for example, in networks that have not yet deployed a foreign agent. It does, however, place an additional burden on the IPv4 address space because it requires a pool of addresses within the foreign network to be made available to visiting mobile nodes. It is difficult to efficiently maintain pools of addresses for each subnet that may permit mobile nodes to visit.

It is important to understand the distinction between the care-of address and the foreign agent functions. The care-of address is simply the endpoint of the tunnel. It might indeed be an address of a foreign agent (a foreign agent care-of address), but it might instead be an address temporarily acquired by the mobile node (a co-located care-of address). A foreign agent, on the other hand, is a mobility agent that provides services to mobile nodes.

A home agent must be able to attract and intercept datagrams that are destined to the home address of any of its registered mobile nodes. Using the proxy and gratuitous Address Resolution Protocol (ARP) mechanisms, this requirement can be satisfied if the home agent has a network interface on the link indicated by the mobile node’s home address. Other placements of the home agent relative to the mobile node’s home location may also be possible using other mechanisms for intercepting datagrams destined to the mobile node’s home address. Such placements are beyond the scope of the RFC.

Similarly, a mobile node and a prospective or current foreign agent must be able to exchange datagrams without relying on standard IP routing mechanisms, that is, those mechanisms that make forwarding decisions based upon the network prefix of the destination address in the IP header. This requirement can be satisfied if the foreign agent and the visiting mobile node have an interface on the same link. In this case, the mobile node and foreign agent simply bypass their normal IP routing mechanism when sending datagrams to each other, addressing the underlying link-layer packets to their respective link-layer addresses. Other placements of the foreign agent relative to the mobile node may also be possible using other mechanisms to exchange datagrams between these nodes, but such placements are beyond the scope of this chapter.

If a mobile node is using a co-located care-of address (as described previously), the mobile node must be located on the link identified by the network prefix of this care-of address. Otherwise, datagrams destined to the care-of address will be undeliverable.

For example, Figure 2-3 illustrates the routing of datagrams to and from a mobile node away from home once the mobile node has registered with its home agent. In the figure, the mobile node is using a foreign agent care-of address. Figure 2-4 provides another pictorial example.

Figure 2-3: Routing datagrams

Figure 2-4: Mobile IP

Message Format and Protocol Extensibility  Mobile IP defines a set of new control messages, sent with User Datagram Protocol (UDP) using well-known port number 434. Currently, the following two message types are defined:

• 1 Registration request

• 3 Registration reply

Up-to-date values for the message types for Mobile IP control messages are specified in the most recent “Assigned Numbers.”

In addition, for agent discovery, Mobile IP makes use of the existing router advertisement and router solicitation messages defined for ICMP router discovery.

Mobile IP defines a general extension mechanism to enable optional information to be carried by Mobile IP control messages or by ICMP router discovery messages. Each of these extensions (with one exception) is encoded in the following type-length-value format:

    0                   1                   2     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-    |     Type      |    Length     |    Data ...    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

• Type  Indicates the particular type of extension.

• Length  Indicates the length (in bytes) of the data field within this extension. The length does not include the type and length bytes.

• Data  The particular data associated with this extension. This field may be zero or more bytes in length. The format and length of the data field is determined by the type and length fields.

Extensions enable varying amounts of information to be carried within each datagram. The end of the list of extensions is indicated by the total length of the IP datagram.

Two separately maintained sets of numbering spaces, from which extension type values are allocated, are used in Mobile IP:

• The first set consists of those extensions that may appear only in Mobile IP control messages (those sent to and from UDP port number 434). Currently, the following types are defined for extensions appearing in Mobile IP control messages:

  • 32 mobile-home authentication

  • 33 mobile-foreign authentication

  • 34 foreign-home authentication

• The second set consists of those extensions that may appear only in ICMP router discovery messages. Currently, Mobile IP defines the following types for extensions appearing in ICMP router discovery messages:

  • 0 one-byte padding (encoded with no Length or Data field)

  • 16 mobility agent advertisement

  • 19 prefix-lengths

Each individual extension is described in detail in a separate section later in this chapter. Up-to-date values for these extension type numbers are specified in the most recent “Assigned Numbers”.

Due to the separation (orthogonality) of these sets, it is conceivable that two extensions that are defined at a later date could have identical type values. This could be true as long as one of the extensions is used only in Mobile IP control messages and the other is used only in ICMP router discovery messages.

When an extension numbered in either of these sets within the range 0 through 127 is encountered but not recognized, the message containing that extension must be silently discarded. When an extension numbered in the range 128 through 255 is encountered but not recognized, that particular extension is ignored, but the rest of the extensions and message data must still be processed. The Length field of the extension is used to skip the Data field in searching for the next extension.

Protocol Details  The interested reader should refer to the RFC for the detailed protocol machinery.

^[1]Glenn Fleishman, “New Wireless Standards Challenge 802.11b,” www.oreillynet.com/pub/a/wireless/2001/05/08/standards.html, June 8, 2001.

^[2]Subsequently, Texas Instruments indicated it would likely pursue the technology and sell it as a wireless networking chipset compatible with 802.11b up to 11 Mbps. PBCC was already approved for use by the IEEE with 802.11b at 11 Mbps (however, manufacturers have not implemented the technology).

^[3]Figure partially based on IBM materials by V. Malhotra, “Checking on IEEE 802.15,” www-106.ibm/developerworks/library/wi-checking/?dwzone=wireless, September 2001.

^[4]Designation: 802.16-2001. “Standard for Local and Metropolitan Area Networks — Part 16: Air Interface for Fixed Broadband Wireless Access Systems.” Status: Approved Publication of IEEE. PAR APP: January 30, 2000, BD APP: December 6, 2001.

^[5]Designation: 802.16.1b. “Telecommunications and Information Exchange Between Systems — LAN/MAN Specific Requirements — Air Interface for Fixed Broadband Wireless Access Systems Including License-Exempt Frequencies.” Status: Changed Designation to P802.16b. PAR APP: December 7, 2000.

^[6]ETSI Project BRAN is developing a new generation of standards that will support both asynchronous data and time-critical services (packetized voice and video) that are bounded by specific time delays to achieve an acceptable QoS. One of these standards is HIPERLAN/2, which will provide high-speed multimedia communications between different broadband core networks and mobile terminals. HIPERLAN/2 provides a platform for a variety of business and home multimedia applications that can support a set of bit rates up to 54 Mbps. In a typical business application scenario, a mobile terminal gets services over a fixed corporate/public network infrastructure. In addition to QoS, the network will provide mobile terminals with security and mobility management services when moving. In an exemplary home application scenario, a low-cost and flexible networking system is supported to interconnect wireless digital consumer devices (www.etsi.org/frameset/home.htm?/technicalactiv/Hiperlan/ hiperlan2tech.htm).

^[7]Designation: 802.16.2a. “Local and Metropolitan Area Networks — Amendment to Recommended Practice for Coexistence of Fixed Broadband Wireless Access Systems.” Status: Amendment. PAR APP: August 17, 2001.

^[8]Designation: 802.16.2-2001. “Local and Metropolitan Area Networks — IEEE Recommended Practice for Coexistence of Fixed Broadband Wireless Access Systems.” Status: Approved Publication of IEEE. PAR APP: September 16, 1999, BD APP: July 6, 2001, ANSI APP: November 1, 2001.

^[9]Designation: 802.16.3. “Telecommunications and Information Exchange Between Systems — LAN/MAN Specific Requirements — Air Interface for Fixed Broadband Wireless Access Systems in Licensed Bands from 2 to 11 GHz.” Status: Changed Designation to P802.16a. PAR APP: March 30, 2000.

^[10]Designation: 802.16a. “Local and Metropolitan Area Networks — Amendment to Standard Air Interface for Fixed Broadband Wireless Access Systems — Media Access Control Modifications and Additional Physical Layer for 2-11 GHz RP.” History: PAR APP: March 30, 2000.

^[11]Designation: 802.16b. “Local and Metropolitan Area Networks — Amendment to Standard Air Interface for Fixed Broadband Wireless Access Systems — Media Access Control Modifications and Additional Physical Layer for License-Exempt Frequencies RP.” History: PAR APP: December 7, 2000.

^[12]www.3gpp.org.

^[13]Oliver Thylmann, www.infosync.no/show.php?id=1246, February 2, 2002.

^[14]Kulwinder Atwal, www.imc.org/ietf-sacred/mail-archive/msg00152.html, February 9, 2001.

^[15]C. Perkins (ed.), Request for Comments 2002, “IP Mobility Support,” IETF, October 1996.

^[16]This section is based on RFC 2002. Copyright© The Internet Society (1996). This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published, and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works.