International Journal of Electronics and Computer Science Engineering 897 Available Online at www.ijecse.org ISSN- 2277-1956 Analysis of xdsl Technologies Dimple Saproo 1, Megha Goyal 2, Asha Bhagashra 3, A.N.Mahajan 4 1, 2, 3, 4 Department of Electronics and Communication Engineering 1,2,4 Dronacharya College of Engineering, Gurgaon, India Email- 1 dimplesaproo@gmail.com, 2 meghagoyal2010@gmail.com, 4 aparnanmahajan@yahoo.co.in, 3 Shekhawati Engineering College, Dundlod, India Email- 3 a_balara@rediffmail.com Abstract- The Rapid development in the field of information technologies has led to the appearance of new services that requires high speed data transmission technologies. For example VoIP, online education, online video gaming etc, uses high speed internet access for efficient operation. This paper explores the information carrying capabilities of different types of DSL technologies along with the limitations of various high speed data services like ISDN, Dial-up and Cable modem. Keywords ADSL, DSL, DSLAM, SDSL, VDSL I. INTRODUCTION Digital subscriber line (DSL, originally digital subscriber loop) is a family of technologies that provide internet access by transmitting digital data over the wires of a local telephone network. Other technologies are ISDN, dialup, cable modem etc. In telecommunication marketing, term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology. The bit rate of consumer DSL services typically ranges from 256Kbps to 40 Mbps in the direction to the customer, depending on line conditions, DSL technology and service level implementation. Bandwidth in DSL is dedicated to all subscribers i.e. speed doesn t drop when other users uses it at same time. The advances in electronics have largely made DSL a successful, faster and cheaper while using new copper or fiber optical cables. There are several variations in DSL technology known as xdsl where x is variable. The main advantage of using DSL over other technologies is the cost, speed and bandwidth. DSL can be used on the wires that are already installed into homes or businesses [1]. Whereas ISDN lines need to be installed and connection charges vary depending upon the connection you choose. In case of dedicated or, "always on" connections you will have to pay more as some ISDN packages are charged on per minute basis. Fig. 1 shows the comparison of various high speed data services.
IJECSE,Volume2,Number 3 Dimple Saproo et al. 898 Figure 1. Comparison of DSL over other technologies II. PRINCIPLE OF DSL TECHNOLOGIES DSL technology is a modern technology that uses existing twisted pair, telephone lines to transport high bandwidth data such as multimedia and video to service subscriber. DSL is dedicated to point to point communication. DSL connections are provided by using the same telephones lines and network element called DSLAM (Digital subscriber line access multiplexer).it is installed at the central office / telephone exchange along with a modem placed in a subscriber home or work place. The connection to the subscriber is given from DSLAM via copper lines. The pair from the DSLAM is terminated into the main distribution frame from where connections are provided to subscriber r through twisted copper wires. The twisted pair lines terminate at DP box placed near a subscriber home as shown in fig.2.dsl technology divides the frequency used in a single phone line into two primary bands. The higher frequency band is used for data services and lower frequency band below 4 KHz is utilized for voice [2].
Analysis of xdsl Technologies 899 Figure 2: XDSL setup III. VARIOUS DSL TECHNOLOGIES 3.1 ADSL ADSL is popular of all DSL types. It is called asymmetric because the download speed is greater than upload speed. ADSL provides high speed transmission of information at high bandwidth over regular phone lines. Unlike dial up phone, ADSL gives permanent internet connectivity.adsl can contain both the analog and digital information on the same telephone line. ADSL gives speed up to 8Mbps which translates into over 100 times faster the speed of regular dial-up. Up-stream speed can be up to 800Kbps. ADSL uses dedicated bandwidth so multiple connection to several home will not affect its performance or speed. Rather speed will depend on how far you are from DSL provider. Homes and small business find ADSL easy to use [3]. 3.2 SDSL Symmetric DSL technology offers symmetric bandwidth of upstream and downstream. It supports data on a single line. It can offer speed up to 2.3 Mbps. It s mainly used in teleconferencing and uploading of heavy data such as multimedia to remote sensors. 3.3 HDSL High rate DSL is symmetrical technology that provides the same amount of bandwidth for uploading and downloading. Its speed is up to 2.048 Mbps over two copper pair wires with operating distance of 3.6 to 4.6 Km. It s mainly used for connecting PBX system, digital local loops, internet servers and campus based networks. 3.4 HDSL-II HDSL-II offers the performance of HDSL. It can transmit data up to speeds of 1.5 Megabits per second (Mbps) across a single pair of copper wires and covers distances of up to 20,000 feet.. HDSL-II supports voice, data, video using synchronous transfer mode (ATM), private-line T1 service and frame relay.
IJECSE,Volume2,Number 3 Dimple Saproo et al. 900 3.5 IDSL Integrated Services Digital Network (ISDN), IDSL is slower than most other forms of DSL, operating at fixed rate of 144 Kbps in both directions. The advantage for ISDN customers is that they can use their existing equipment, but the actual speed gain is typically only 16 Kbps (ISDN runs at 128 Kbps). 3.6 SHDSL Symmetric high-speed DSL (SHDSL) is another version of SDSL, which attempts to improve on both HDSL and SDSL by only requiring a single line and by integrating low-level services of interest to small businesses. SHDSL generates speeds of 2.3 Mbps upstream and downstream. SHDSL gives providers a platform to deliver improved services at a much lower cost than traditional T1/E1. SHDSL offers the benefits of T1/E1 and can be used in the same bundled cable loop as ADSL, without causing interference. SHDL also operates in a fixed rate mode at 784 kbps and 1.544Mbps [4]. 3.7 VDSL Very high bit rate digital subscriber line (VDSL) is one of the newest developments in DSL. VDSL delivers fast data rates across short distances - the shorter the distance, the faster the connectivity. VDSL can produce speeds up to 13 to 52 Megabits per second (Mbps) for downloading and 1.5 to 2.3 Mbps for uploading over a distance of 300 m to 1.4 Km. VDSL can deliver interactive video, video on demand and high definition TV [5]. Table 1 shows the comparative analysis of DSL technologies in terms of downstream, upstream, distance and phone support. Table 1. Comparison of various DSL technologies DSL Type Download Speed Upload Speed Distance in Feet Phone Support ADSL 8Mbps 800 Kbps 18000 Yes SDSL 2.3 Mbps 2.3 Mbps 22000 No HDSL 2.048 Mbps 2.048 Mbps 12000-15000 No HDSL-II 1.5 Mbps 1.5 Mbps 20000 No IDSL 144 Kbps 144 Kbps 35000 No SHDSL 2.3 Mbps 2.3 Mbps 22000 No VDSL 13 to 52 Mbps 1.5 to 2.3 Mbps 1000-4500 Yes
Analysis of xdsl Technologies 901 Figure 3: Comparison of various DSL technologies in terms of downstream data rate Figure 4: Comparison of various DSL technologies in terms of upstream data rate
IJECSE,Volume2,Number 3 Dimple Saproo et al. 902 IV.CONCLUSION DSL has the ability to deliver high speed data transmission over existing infrastructure with relatively small changes. XDSL provides data and voice services on the cooper wires at the same time. Data services are provided on higher frequency bands and regular voice services on lower frequency range. In India, ADSL is widely used. It is depicted from the graph 2& 3 that VDSL is fastest technology amongst the all mentioned above. REFERENCE [1] http://www.tech-faq.com/difference-between-isdn-and-dsl.html [2] xdsl configuration, Alcatel lucent university [3] http://computer.howstuffworks.com/vdsl3.htm [4] http://www.dsl-isp-info.com/type_dsl.htm [5] http://www.telebyteusa.com/dslprimer/dslch2.htm