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    Asifuzzaman (061846556) Asifuzzaman (061846556) Document Transcript

    • VoIP in Mobile communication Prepared By Asifuzzaman ID: 061 846 556 Course: ETE605 Sec-2 Prepared For Dr. Mashiur Rahman Assistant Professor Department of Electronics & Tele Communication North South University 1
    • 1. Introduction: Nowadays VoIP (Voice Over Internet Protocol) is one of the hot topics in our country and it is also a new technology in our country. VoIP is the name of a new communications technology that changes the meaning of the phrase telephone call. VoIP stands for voice over Internet protocol, and it means “voice transmitted over a computer network.” Internet protocol (IP) networking is supported by all sorts of networks: corporate, private, public, cable, and even wireless networks. Don’t be fooled by the “Internet” part of the acronym. VoIP runs over any type of network. Currently, in the corporate sector, the private dedicated network option is the preferred type. For the telecommuter or home user, the hands-down favorite is broadband. With VoIP, one can literally pick up his things and move to another location, within office building or around the world, without having to forward calls to a new telephone. VoIP’s entirely portable! One can access the Web from your IP phone, enabling you to get important (or not so important) announcements and e-mail on the go. It’s like having a pocket PC and a cell phone rolled into one, specifically designed for your network. VoIP is a win-win for everyone. The added flexibility and quicker response times translate into greater customer satisfaction and increased productivity throughout the organization. In this report I want to explore how VoIP and mobile are related to each other , VoIP subscriber growth trends and is it possible VoIP migrate to mobile carriers? 2
    • 2. How VoIP works: Before we discover How Does VoIP Work let me give you a quick non-technical definition of VoIP. Firstly we need a quick idea of how phones work now, so we can compare. Our ordinary phone which is analog uses circuit switching to transport calls. This means that a large two-way connection is opened between phones for the entire duration of the phone call. During the conversation thousands of miles of switching equipment and copper have to be maintained. This causes a very long chain of devices between the two parties and can result in many problems - low voltage, poor electrical connections, older equipment etc. VoIP uses packet switching, which basically means that instead of an open line it only sends information when there is something to send. It breaks the voice into tiny portions - each packet being a separate item. Each package is sent via a one way connection in the correct order and addressed to the same recipient. The packages pass through the internet routing system and servers in all directions. Each package will be given the least congested route to travel. The end result of all this is clearer, less echo and more efficient calls. It also means that computer can be surfing the net, downloading files, receiving email and receive a call at the same time. 3
    • 3. Mobile Communication GSM (Global System for Mobile communication) is a digital mobile telephony system that is widely used in Europe and other parts of the world. GSM uses a variation of time division multiple access (TDMA) and is the most widely used of the three digital wireless telephony technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at either the 900 MHz or 1800 MHz frequency band. Mobile services based on GSM technology were first launched in Finland in 1991. Today, more than 690 mobile networks provide GSM services across 213 countries and GSM represents 82.4% of all global mobile connections. According to GSM World, there are now more than 2 billion GSM mobile phone users worldwide. GSM World references China as "the largest single GSM market, with more than 370 million users, followed by Russia with 145 million, India with 83 million and the USA with 78 million users." Since many GSM network operators have roaming agreements with foreign operators, users can often continue to use their mobile phones when they travel to other countries. SIM cards (Subscriber Identity Module) holding home network access configurations may be switched to those will metered local access, significantly reducing roaming costs while experiencing no reductions in service. Bearer Services a unique feature of GSM compared to older analog systems is the Short Message Service (SMS). SMS is a bidirectional service for sending short alphanumeric messages (up to 160 bytes) in a store-and-forward manner. For point-to-point SMS, a message can be sent to another subscriber to the service, and an acknowledgment of receipt is provided to the sender. SMS also can be used in cell broadcast mode for sending messages such as traffic updates or news updates. Messages can be stored in a smart card called the "Subscriber Identity Module" (SIM) for later retrieval. Since GSM is based on digital technology, it allows synchronous and asynchronous data to be transported as a bearer service to or from an Integrated Services Digital Network (ISDN) 4
    • terminal. The data rates supported by GSM are 300, 600, 1200, 2400, and 9600 bps. Data can use either the transparent service, which has a fixed delay but no guarantee of data integrity, or a nontransparent service, which guarantees data integrity through an automatic repeat request (ARQ) mechanism but with variable delay. GSM has much more potential in terms of supporting data. The GSM standard for high-speed circuit- switched data (HSCSD) enables mobile phones to support data rates of up to 38.4 kbps, compared with 9.6 kbps for regular GSM networks. Transmission speeds of up to 171.2 kbps are available with mobile phones that support the GSM standard for Global System for Mobile communication. General Packet Radio Service (GPRS). The high bandwidth is achieved by using eight timeslots, or voice channels, simultaneously. GPRS facilitates several new applications, such as Web browsing over the Internet. The Mobile Station: The mobile station (MS) consists of the radio transceiver, display and digital signal processors, and the SIM. The SIM provides personal mobility so that the subscriber can have access to all services regardless of the terminal's location or the specific terminal used. By removing the SIM from one GSM cellular phone and inserting it into another GSM cellular phone, the user is able to receive calls at that phone, make calls from that phone, or receive other subscribed services. The SIM card may be protected against unauthorized use by a password or personal identification number (PIN). Base Station Subsystem: The base station subsystem consists of two parts: the base transceiver station (BTS) and the base station controller (BSC). These communicate across the A-bis interface, enabling operation between components made by different suppliers. The base transceiver station contains the radio transceivers that define a cell and handles the radio link protocols with the mobile stations. In a large urban area, there typically will be a number of BTSs to support a large subscriber base of mobile service users. The base station controller provides the connection between the mobile stations and the mobile service switching center (MSC). It manages the radio resources for the BTSs, handling such functions as radio channel setup, frequency hopping, and handoffs. 5
    • The BSC also translates the 13-kbps voice channel used over the radio link to the standard 64-kbps channel used by the land-based Public Switched Telephone Network (PSTN) or ISDN. Mobile Services Switching Center: The mobile services switching center (MSC) acts like an ordinary switching node on the PSTN or ISDN and provides all the functionality needed to handle a mobile subscriber, such as registration, authentication, location updating, handoffs, and call routing to a roaming subscriber. These services are provided in conjunction with several other components, which together form the network subsystem. The MSC provides the connection to the public network (PSTN or ISDN) and signaling between various network elements that use Signaling System 7 (SS7). The MSC contains no information about particular mobile stations. This information is stored in two location registers that are essentially databases. The Home Location Register (HLR) and Visitor Location Register (VLR), together with the MSC, provide the call routing and roaming (national and international) capabilities of GSM. The HLR contains administrative information for each subscriber registered in the corresponding GSM network, along with the current location of the mobile device. The current location of the mobile device is in the form of a Mobile Station Roaming Number (MSRN), which is a regular ISDN number used to route a call to the MSC where the mobile device is currently located. Only one HLR is needed per GSM network, although it may be implemented as a distributed database. The Visitor Location Register (VLR) contains selected administrative information from the HLR that is necessary for call control and provision of the subscribed services for each mobile device currently located in the geographic area controlled by the VLR. There are two other registers that are used for authentication and security purposes. The Equipment Identity Register (EIR) is a database that contains a list of all valid mobile equipment on the network, where each mobile station is identified by its IMEI. An IMEI is marked as invalid if it has been reported stolen or is not type approved. The authentication center is a protected database that stores a copy of the secret key stored in each subscriber's SIM card,which is used for authentication. 6
    • Authentication and security since radio signals can be accessed by virtually anyone. Authentication of users to prove their identity is a very important feature of a mobile network. Authentication involves two functional entities, the SIM card in the mobile unit and the authentication center (AC). Each subscriber is given a secret key, one copy of which is stored in the SIM card and the other in the AC. During authentication, the AC generates a random number that it sends to the mobile unit. Both the mobile unit and the AC then use the random number, in conjunction with the subscriber's secret key and an encryption algorithm called A3, to generate a number that is sent back to the AC. If the number sent by the mobile unit is the same as the one calculated by the AC, the subscriber is authenticated. The calculated number is also used, together with a TDMA frame number and another encryption algorithm called A5, to encrypt the data sent over the radio link, preventing others from listening in. Encryption provides an added measure of security, since the signal is already coded, interleaved, and transmitted in a TDMA manner , thus providing protection from all but the most technically astute eavesdroppers. Another level of security is performed on the mobile equipment, as opposed to the mobile subscriber. As noted, a unique IMEI number is used to identify each GSM terminal. A list of IMEIs in the network is stored in the EIR. The status returned in response to an IMEI query to the EIR is one of the following: . Authentication of users to prove their identity is a very important feature of a mobile network. Authentication involves two functional entities, the SIM card in the mobile unit and the authentication center (AC). Each subscriber is given a secret key, one copy of which is stored in the SIM card and the other in the AC. During authentication, the AC generates a random number that it sends to the mobile unit. Both the mobile unit and the AC then use the random number, in conjunction with the subscriber's secret key and an encryption algorithm called A3, to generate a number that is sent back to the AC. If the number sent by the mobile unit is the same as the one calculated by the AC, the subscriber is authenticated. The calculated number is also used, together with a TDMAframe number and another encryption algorithm called A5, to encrypt the data sent over the radio link, preventing others from listening in. Encryption provides an 7
    • added measure of security, since the signal is already coded, interleaved, and transmitted in a TDMAmanner , thus providing protection from all but the most technically astute eavesdroppers. Another level of security is performed on the mobile equipment, as opposed to the mobile subscriber. As noted, a unique IMEI number is used to identify each GSM terminal. Alist of IMEIs in the network is stored in the EIR. The status returned in response to an IMEI query to the EIR is one of the following: White listed. Indicates that the terminal is allowed to connect to the network. Gray listed. Indicates that the terminal is under observation from the network for possible problems. Black listed. Indicates that the terminal either has been reported as stolen or is not type approved (i.e., not the correct type of terminal for a GSM network). Such terminals are not allowed to connect to the network. 4. VoIP Wireless Phones Several types of wireless phones are available. The first type are IP wireless phones, which have a limited range and are strictly tied to corporate networks. For example, a hospital or a large construction site may have wireless networking and VoIP available over that network. VoIP wireless phones hook into the network and do VoIP within their specified range. Features on these types of phones are generally limited. One thing to watch for in IP wireless phones is whether they are WiSIP compatible.If they are, the phones can include quite a few features not normally available, such as the ability to connect to WiFi networks and IP-PBXs without the no-peak or off-peak minute charges. These types of phones cost a bit more, but they make calling other WiSIP phones very easy. Finally, it can be argued that a pocket PC with VoIP capability is, indeed, a wireless phone. These types of computers do everything that a cell phone can do. If the pocket PC 8
    • has built-in WiFi capability, you can use it to make VoIP calls in addition to regular cell calls. 5. Will VoIP migrate to mobile carriers? Mobile VoIP has undoable become one of the hottest topics in the communication field. It has also become one of the misunderstood. While the use of VoIP back in cellular networks is nothing new for voice traffic to be defined as mobile VoIP, a mobile originated or a mobile terminated call must originate or terminate using exclusively the wireless carrier IP data network. VoIP operators choose to peruse mobile VoIP themselves or will they be force to complete with the third parties who offer disruptive services on their networks? We belive the answer is neither. The proliferation of Mobile VoIP is unlikely because: • Wireless carries can and will block assess fees for any third-party service that is transmitted on their network. • End to end VoIP does not present any completing technological advantage for wireless carriers to implement themselves, Wireless carriers have full control on their networks: Wireless carriers own and control all network elements from handsets to switching to spectrum to towers. Wireless carries have paid billions of dallers worldwide for lisence.This means that on other carrier provider can use the spectrum. Furthermore, consider the three main reasons why VoIP has made inroads in fixed telephony market. • VoIP as a transmission medium is more different than POTS • Band width is abundant in the wired world. • Broadband service providers cannot control what travels on their networks. None of these driving forces are present in the mobile telephony world: 9
    • • VoIP is less efficient than the leading digital wireless communication technologies- mainly GSM and CDMA. • Bandwidth is very scare and mobile phones are primarily used to make voice calls. • Wireless carries have full control of their networks within regulatory body forcing operators to open access to other service provider. The scarcity of wireless frequencies and limited capacity of cellular networks has favored the development and deployment of technologies that make the best use of the scant resources.The current dominant wireless technologies GSM and CDMA are clearly superior to VoIP for voice transmission. Currently there are two billion mobile subscribers in the world making mobile communication the largest prevailing method of making phone calls today. With no economic or technological benefits for VoIP to migrate to mobile networks, all the hope, hype and anticipation associated with such migration will mostly remain unfulfilled. 6. VoIP subscriber growth enters the US mainstream: • More telephone services are being offered over the Internet through VoIP (Voice Over Internet protocol) and its steady growth this year will see a spillover into mainstream US residential households and businesses by 2006, according to a new eMarketer report. Currently, the number of US VoIP subscribers is small, with varying estimates predicting between 2.8 million and 6.7 million residential VoIP lines in use by the end of 2005. In five years' time, even the most optimistic forecast predicts just 27.0 million residential VoIP subscribers, accounting for 19.6% of the 137.4 million US consumer and small business wireline subscribers at the end of 2003. "There is still a long road ahead for consumer and business migration to VoIP," says Steve Butler, eMarketer Senior Analyst and author of the report. "But it is on the verge of moving out of the early adoption phase and into the mainstream. The next two years will mark the turning point when widespread VoIP use finally 10
    • begins to take off." eMarketer's new report, VoIP: Spending and Trends, released today, examines the rapidly developing IP telephony market and the impact its growth will have on businesses, consumers and the entire communications industry. As of late last year, several leading VoIP service providers were beginning to see strong VoIP subscription growth. And a wave of new forecasts for the residential VoIP market indicates similar growth. Telecom consultancy Atlantic-ACM estimates that US retail VoIP services revenues will increase by a compound annual growth rate of 64% between 2003 and 2009, reaching $20.4 billion in five years' time. Gartner Group predicts that consumer VoIP services spending will jump from $1.9 billion in 2005 to $9.5 billion in 2008. Butler notes that the explosive growth of broadband Internet access in US households is driving the adoption of higher US residential VoIP usage. eMarketer estimates that 42.3 million homes, or 36.2% of US households, will be using broadband by the end of this year. 7.Conclusion: GSM is the most commonly used wireless technology in the world with over 78% market share, followed by CDMA. On the other hand VoIP is far less efficient when compared to GSM and CDMA technologies. Considering the above situation we can say that VoIP can play an important role in our communication technology in near future. 11
    • References: • VoIP for Dummies • MTI MicroFuel Cells Announces Collaboration With Korean Partner • Cell Phones - Spain's competition authority probes mobile fee increase • Abandoned SunRocket Customers Find Risk-Free Accommodation at OneSuite • 'Pistachio Heart Health Recipes' Yield Enjoyment and Health Benefits, St... • Leading Irish VoIP Provider Chooses Wowza Media Server Pro to Power Aggressive Expansion of Streamin • Free International Mobile Calling • iPhone Repair Kits Available • Brekeke Software Confirmed OnDO PBXs Interoperability with VoIP USER • You have a book. The entire world has an iPhone. Lulu.com has the Answer. • 370 Free to Air Sat TV channels in the Arab World. • http://en.wikipedia.org/wiki/VoIP • http://www.fcc.gov/voip/ • http://www.voip.com/ 12