Inclusivity Essentials_ Creating Accessible Websites for Nonprofits .pdf
Wireless review
1. An Overview of Wireless Data Communications Wide Area Cellular Services Wireless LANs Satellite Integrated Wireless Services Richard Perlman Lucent Technologies [email_address]
31. 3G Systems Overview 3G Migration SOURCE: CDMA Development Group (CDG) CDG Migration Diagram
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34. Standards Evolution to 3G Worldwide Japan Europe/Parts of Asia Americas/Parts of Asia Instead of solving the 2G network differences via 3G, we will continue to have W-CDMA and cdma2000 as separate networks. Both will be “optional implementation modes” in one 3G standard specification. Basic 3G phones will support one or the other. “Global phones” will be able to roam from one to the other. cdma2000 1st Gen TACS NMT/TACS/Other AMPS 2nd Gen PDC GSM TDMA CDMA 3rd Gen EDGE cdma2000 W-CDMA/UMTS
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39. Evolution of messaging Rich Call Browsing Messaging Versatility of Content and User Benefits Time Text SMS Text & Graphics Picture Messaging Digital image input Multimedia Message Service New content types Mobile Multimedia
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41. SMS growth in Europe 0 10 20 30 40 50 60 0% 10% 20% 30% 40% 50% 60% 70% 80% Mobile Penetration SMSs/subs/month Finland Norway Germany Italy Portugal Greece UK France Sweden Spain
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45. New Phones Have MMS, WAP, Java (GSM) or BREW (CDMA) – 400 million plus in 2003
The Groups relate the speed and sophistication of the fax machine. The standards were developed by the ITU-T (International Telecommunications Union-Telecommunication Standardization Sector) in order that fax machines from different manufactures could communicate. Group 3 fax is the most common type of fax machine transmitting on A4 paper. The machine scanning format is digital and operates at rates between 9.6Kbps and 14.4Kbps. Asynchronous A method of transmitting data whereby each byte is clocked separately. One start bit is added to the beginning, and one or more stop bits to the end, of each character. Asynchronous transmission is the most rudimentary form of data communication, as the originating and recipient machines do not have to be in sync. It is commonly used for low speed transmission, as with a PC’s serial port. Synchronous Transmission Digital transmission in which the time interval between any two similar significant instants in the overall bit stream is always an integral number of unit intervals
USSD - offers an open cimmunication link for use between network and operatot and user for operator defined services operator barring restrictions of different services, vall types by the operator
The Mobile Station (MS) consists of the Mobile Equipment (ME) and the Subscriber Identity Module (SIM). · The Mobile Equipment (ME), commonly referred to as a terminal or handset, comes in two varieties: fixed and portable. A fixed MS is usually installed in a vehicle while portable MSs are normally carried by subscribers. Due to size limitations and power requirements, fixed MSs were originally predominant though this situation has changed dramatically in recent years as the portable MS is by now almost ubiquitous and even regarded as a fashion accessory. The ME is uniquely identified by its International Mobile Equipment Identity (IMEI) number, which is primarily used for security purposes. · A Subscriber Identity Module (SIM) is a smart card that is inserted into the ME to provide personal mobility. Each SIM card contains an International Mobile Subscriber Identity (IMSI) number that uniquely identifies the subscriber to the network thereby allowing access to subscribed services. To prevent unauthorised access, the SIM card can be protected using a Personal Identification Number (PIN). Only emergency calls can be made from a terminal without a SIM card. While the SIM card currently facilitates a number of services including the standard Short Message Service (SMS), advances in smart card technologies will ensure that the SIM card becomes a cornerstone for any new services deployed in the future.
The Base Station Subsystem is composed of two parts: the Base Transceiver Station (BTS) and the Base Station Controller (BSC). The Base Transceiver Station (BTS), or simply the Base Station, is the interface for the MS to the network. It handles all communications with the MS via the air interface (technically referred to as the Um interface in the GSM specifications). Essentially, the transmitting power of a BTS defines the cell size i.e. its coverage area. In large urban areas, the number of BTSs deployed is large so the corresponding cell size is small. In contrast, there is usually a far smaller number deployed in rural areas so the cell size can be quite large. The Base Station Controller (BSC) manages the radio resources for multiple BTSs, the number of which varies but could be up to several hundred. As well as the allocation and release of radio channels, the BSC is responsible for handover management when the MS roams into an area covered by another BSC. Similar to all other interfaces in GSM, the interface between the BSC and a BTS is standardised and is referred to as the Abis interface.
The Mobile Switching Centre (MSC) performs almost identical functions to that of a normal switching node in a fixed network. In addition, it provides the functionality needed to handle mobile subscribers including registration, authentication, location updating etc. Depending on size, a GSM network may contain a number of MSCs or just one. All GSM networks must connect to fixed networks at some point. This interconnection always takes place through an MSC in which case the MSC is called a Gateway MSC (GMSC). The interface between the MSC and a BSC is called the A interface
The Home Location Register (HLR) contains all the administrative information for each subscriber registered in the corresponding GSM network. This includes both the IMSI number and actual phone number as well as details of a subscriber’s permitted supplementary services e.g. call forwarding. The current location i.e. which Visitor Location Register (VLR) the subscriber is currently registered with, is also stored in the HLR as, without this, the MSC could not route any calls to the subscriber. Logically, there is one HLR for each GSM network, although it can be implemented as a distributed database.
Three new types of terminal have been defined in the GPRS standard: . Class A terminals, which support simultaneous circuit-switched and packet-switched traffic. For example, a subscriber can initiate or receive a voice call without interrupting data transmission or reception activity. . Class B terminals, which supports simultaneous connections to GSM and GPRS but cannot support both types of traffic at the same time. If a GPRS data call is in progress and an incoming voice call is received, the data call is suspended for the duration of the voice call. However, when the voice call is terminated, the GPRS data call will resume. . Class C terminals, which can handle either data or voice calls but can only be connected to either GSM or GPRS at any given time. The GPRS MS itself has two components: a Mobile Terminal (MT) which consists of a handset and SIM card, and a Terminal Equipment (TE) component which is typically a laptop or a Personal Digital Assistant (PDA).
The most important changes take place in the NSS with the introduction of two new nodes for the handling of packet data: . The Serving GPRS Support Node (SGSN) is responsible for handling packet data traffic in a geographic area. It monitors GPRS users, performs security procedures and handles access control. An SGSN may be regarded as doing for packet-switched data services what the MSC does for normal circuit-switched services. . The Gateway GPRS Support Node (GGSN) provides the internetworking functionality for external packet data networks e.g. the Internet. It can act as an access server and is responsible for routing incoming data traffic to the correct SGSN. To facilitate communication between different networks, it can translate between various different signalling protocols and data formats. The introduction of these nodes required that several new interfaces be defined to handle interactions between them and other NSS components. For example, the Gb interface is required between the BSC and the SGSN while queries are sent to the HLR by the SGSN over the Gr interface. To support GPRS subscribers, the HLR database must be upgraded to include details about which data services the subscriber is registered for.
While the implementation of GPRS will improve GSM network data capacities substantially, the individual subscriber experience may vary quite considerably. The theoretical maximum speed of 171.2 kb/s (eight timeslots by 21.4 kb/s) will never be achieved in a real network, as in practice, the available data rate will ultimately depend on the network configuration, which is defined by the network operator. Another factor that will influence the subscriber’s experience is what class of handset the operator supports. Even though GPRS specifies three classes, a particular network operator may only support one. Nevertheless, the situation will have improved considerably. Set-up time will be less than a second while data transfers will be less susceptible to errors and delays. The "always-on" nature of GPRS means that emails can be received without making an explicit connection. Also, the charging rate will favour the consumer who will be billed based on the amount of data transported by the network rather than on the amount of time connected to the network.
At present, GPRS is being rolled out in Europe whereas in Japan full 3G tests are being conducted with full deployment almost imminent. EDGE is currently being evaluated by various network operators with a view to deploying it as an interim step to 3G. However it is unlikely that EDGE will be deployed widely if operators believe that implementing a full 3G solution may be more economical. Recalling that the deployment of 3G requires new spectrum, it may be that those operators who fail to obtain 3G licences will use EDGE. Indeed this was one of the motivations for the development of EDGE originally.
Replacing the existing GSM air interface is the final and most important step in the evolution of GSM to UMTS i.e. 3G. Recall that one of the criteria for a system to be IMT2000 compliant is that it implements an air interface standard defined by the ITU. In the case of UMTS, the communication over the air interface, or UMTS Terrestrial Radio Access (UTRA) as it is technically known, is achieved using W-CDMA and TD-CDMA. The access parts of the network, called the UMTS Terrestrial Radio Access Network (UTRAN), are based on ATM and it is here that the major changes in upgrading will occur, which of course will also be reflected on the handsets (figure 4).
UMTS BSS The UMTS equivalent of the BSS, the Radio Network Subsystem (RNS) introduces two new network elements: Node B is responsible for radio transmission between subscribers. It may be regarded as fulfilling the same role as the BTS in standard GSM. The Radio Network Controller (RNC) supports a number of Node Bs and may be regarded as the UMTS BSC equivalent. A UTRAN will support a set of RNSs. Obviously, the introduction of new nodes into the networks means a corresponding increase in interface standards e.g. the Iur interface between two RNCs.
"2.5G customers" refer to those customers who have joined the service plans for 2.5G services (including GPRS and IS-95B services) or used the 2.5G services
The importance of standardisation is crucial. For example, SMS has not experienced such a success in the US and Japan where the operators have competing technologies that are not interoperable. MMS is THE ONLY standardised messaging technology for 3G and that's what guarantees its success as an evolution from the SMS success. MMS is standardised by 3GPP and the WAP forum. SMS has acted as a bridge between voice and data traffic. It has changed the users' perception about the mobile phone: they are beginning to see it as a communication and information media rather than just a telephone. --- Given the converging market and technology space, what is the right way to develop successful new services? To identify and build on a natural application migration path... The first crucial step in MMS market development is getting consumers accustomed to using their mobile phones for purposes other than voice communication, i.e. making current SMS applications more commonly used. Focusing on creating awareness and acceptance for the concept of SMS as well as on educating the market on how specific services work. SMS messaging = mobile email =' Gmail' => discretion, efficiency, fun; anytime, anywhere. MMS = 'enhanced SMS', with full content versatility => fun, sharing, rational utility. Nokia's migration path in multimedia messaging builds on the well-established SMS paradigm by adding new functionality and new content types in consumer-understandable steps. This will reduce the barriers for MMS adoption, leading to rapid take-up and high penetration, paving the way towards personal mobile multimedia. Picture Messaging: Combines the ease of use of SMS with the enjoyment of expressing oneself with pictures. Spec is now available at www.forum.nokia.com - no longer proprietary. Digital image input: Enables the electronic postcard based on instant photographs and text. Multimedia Message Service (MMS) and Mobile Multimedia: A complete end-to-end solution for person-to-person mobile messaging, from terminal to terminal, terminal to internet, internet to terminal. With full content versatility, including images, audio, video, data, text. Delivers a location independent, total communication experience - combined with ease of use that is a simple, logical extension of SMS and Picture Messaging.
And we believe the WAP content will continue to expand, much in a similar fashion as the popularity of text messaging and SMS based services has exploded. The exponential growth typically starts when the 20-40% mobile phone penetration window has been reached, as is evident from these figures from various European markets.
Just some of the phones available now or soon Samsung SGH-S100 (not T100, which is available now) Siemens SX45 (coming now) Nokia 7210 (expected mid October) Ericsson P800 (unknown, should be out now) Motorola A388 (unknown when available) Nokia 3650 (Unknown, Symbian Series 60) Nokia 3410 (Price: 1500 NOK, can get it for NOK 90 with subscription) Siemens M50 Siemens (6 phones) C55, MT50, SL42, M50, SL45i, SX45 Nokia (7 phones) 3410 (On picture), 3510i (Color Series 30!), 3650 (On picture – Series 60), 6310i (World phone), 6610 (Series 40), 7210 (On picture – Series 40), 9210 + 9210i Communicator (Series 80) Samsung SGH-S100 Motorola (8 phones) A820 (?) (September), Accompli 008, Accompli 009, A388, T280i, T720, V60i, V66i Sony Ericsson (2 phones) P800, Z700
WiFi (Wireless Fidelity) [HL02] is the popular name for the WLANs based on the IEEE 802.11b standard [ICS99]. As well as being deployed in businesses and homes, WiFi is also being deployed in open areas to create what are termed "hotspots". It is hoped within the industry that WiFi will bring broadband Internet access to the general population. WiFi has a range of about 50 meters and supports a theoretical throughput of 11Mb/s. In practice, 7 Mb/s is a more realistic figure. WiFi operates in the unlicensed 2.4 GHz spectrum. Unfortunately, thick walls can reduce both the range and the throughput considerably. However, by using high gain external antennae, and under line-of-sight conditions, WiFi offers a very attractive alternative to leased lines or conventional microwave systems. A newer version of the protocol – 801.11a offer throughputs of up to 54Mb/s and operate in the 5GHz band. However, it may be less useful in offices and buildings as walls absorb the higher frequencies more than the 2.4GHz signals of 802.11b.
Two problems continue to affect WiFi in an adverse manner. WiFi is essentially an insecure system principally because it was not designed with robust security as a priority. However, this issue continues to receive urgent attention within the WiFi community. The second problem concerns interference. As it operates in unlicensed spectrum, it could find itself competing with other products. For example, a microwave oven operating in the neighbourhood and at a similar frequency would cause problems, as could another business’s WLAN. As WiFi installations are relatively rare, such issues are not of concern today. However, should WiFi be deployed as its advocates wish, such issues will become increasingly important and the need for solutions more urgent.
Bluetooth [URL15] is a universal radio interface that enables portable electronic devices connect and communicate wirelessly via short-range ad-hoc networks [Haa98]. One of the objectives of Bluetooth is to eliminate the need for the cabling and connectors that plagues modern computing systems. For example, if somebody received an email on their Bluetooth-enabled mobile phone and a hard copy was required, they could approach a Bluetooth-enabled printer and print the message directly without resorting to installing device drivers or connecting via a LAN etc. To enable visions like this, Ericsson, Nokia, Toshiba, IBM and Intel formed the Bluetooth SIG in 1998 with the specific objective of defining a suitable specification. This specification would then be used by various companies to implement their own products thereby ensuring interoperability.
From a technical perspective, Bluetooth operates in the international 2.4 GHz frequency band with a gross data rate of 1Mbit/s. The nominal range of a Bluetooth device is 10 meters. Two or more Bluetooth devices can form a piconet. To regulate traffic between devices, one must become a master – usually the device that establishes the piconet. The others are termed slaves. A group of piconets is termed a scatternet. A device may be a member of a number of piconets at the same time. One of the advantages of the piconet-scatternet architecture is that it can increase both the range and the data throughput of individual devices.
One of the primary objectives of satellite telephony is to extend access to people in remote areas where terrestrial fixed line and cellular services do not exist. By regarding a satellite as a base station in orbit, the principles behind satellite telephony are very similar to those underpinning cellular communications. However, subscribers to a satellite service enjoy global roaming, a feature not yet available to their terrestrial cellular counterparts. Satellite telephony systems can be classified according to the height of their orbits (table 2). The success of satellite based telephony systems has been varied. While the technology is proven, nevertheless, there have been some high profile spectacular commercial failures. Both Iridium and ICO were rescued from bankruptcy. Naturally, the reasons given vary. However it is thought that events on the ground, namely the success of 2G networks contributed. For example, Iridium was conceived in the early 1990s, but by the time it was deployed (almost a decade later), it could not compete competitively with GSM. However, its revised business model is geared towards serving industrial and institutional subscribers rather than the personal communications market.
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