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ATM and IP Integration
Published in Naoaki Yamanaka, High-Performance Backbone Network Technology, 2020
The rapid growth in demand for new telecommunication services, such as WWW access through the Internet, has led to a need for subscriber lines with broadband access. The asymmetric digital subscriber line (ADSL) [1] was developed to convert an ordinary telephone subscriber line into a broadband access subscriber line. In North America, for example, ADSL provides 8 Mbps downstream and 640 kbps upstream. Universal ADSL, which is a simplified ADSL that the ITU-T [2] and UAWG (Universal ADSL working group) [3] are aiming to achieve through their standardization efforts, provides 1.5 Mbps downstream and 512 kbps upstream. ADSL is an attractive approach to implementing broadband access for existing telecommunication network operators because it uses their existing ordinary telephone subscriber lines.
Communication Systems
Published in John Watkinson, The Art of Digital Video, 2013
One of the difficulties of the AMI coding used in N-ISDN is that the data rate is limited and new cabling to the exchange is needed. ADSL (asymmetric digital subscriber line) is an advanced coding scheme that obtains high bit rate delivery and a back channel down existing subscriber telephone wiring. ADSL works on frequency-division multiplexing using 4 kHz-wide channels, and 249 of these provide the delivery or downstream channel and another 25 provide the back channel. Figure 10.23a shows that the existing bandwidth used by the traditional analog telephone is retained. The back channel occupies the lowest-frequency channels, with the downstream channels above. Figure 10.23b shows that at each end of the existing telephone wiring a device called a splitter is needed. This is basically a high-pass/low-pass filter that directs audio-frequency signals to the telephones and high-frequency signals to the modems.
9 The Importance of Bandwidth
Published in Wes Simpson, Howard Greenfield, IPTV and Internet Video:, 2012
Wes Simpson, Howard Greenfield
To keep overall speeds reasonable and to enable other services (such as Internet access) on the ADSL link, it is normal to find only one, or at most two, video signals on a single ADSL circuit. However, ADSL2+ has become more prevalent for IPTV because, for one thing, its downlink speed is twice that of ADSL. Also, ADSL2+ is capable of 24 Mbps performance (in theory) and supports port bonding, which doubles bandwidth again wherever the DSLAM supports it. Performance is dependent on the proximity of the home to the exchange. ADSL2+ provides a smoother performance roll-off than ADSL as this distance increases, but has the disadvantage of not being compatible across all existing copper cable and modem devices.
Joint CFO and channel estimation using pilot aided interpolation for high performance MIMO-OFDM
Published in International Journal of Electronics, 2023
S. Chitra, S. Ramesh, Ramya Vijay, G. Jegan, T. Samraj Lawrence
Orthogonal frequency division multiplexing (OFDM) has gained more attention in fourth and fifth generation (4 G and 5 G) wireless standards due to its high throughput, spectral efficiency, robustness to multipath fading and simple implementation with inverse fast Fourier transform (IFFT) and FFT algorithms. The principle of OFDM is dividing the total bandwidth into a number of orthogonal subcarriers, each with a narrow bandwidth. Since the subcarrier bandwidth is less than the coherence bandwidth of the channel, flat fading is possible in each subcarrier. As the frequency selective fading is converted to flat fading, OFDM system has reduced intersymbol interference (ISI), which simplifies the equaliser’s design. OFDM finds applications in digital video broadcasting, digital audio broadcasting, asymmetric digital subscriber line (ADSL) and IEEE 802.11 wireless LAN standards. The performance of 4 G and 5 G wireless services over multipath frequency selective fading channels can be improved by combining MIMO and OFDM algorithms.
The Changing Face of Public Broadcasting in India
Published in IETE Journal of Education, 2023
The internet connection is provided to a telephone subscriber with the help of an ADSL (Asymmetric Digital Subscriber Line) connection to the telephone exchange, or else, a fiber optic modem. The data bit-stream is decoded in a proprietary set-top box (STB), to recover video as well as audio information. The STB needs to have adequate processing power to accomplish signal reconstruction as well as data decompression. The user watches only one program at a time, but the link to the telephone exchange is two way. The user can select any program by sending a command via the remote control. The service provider, in turn, directs the user selected data to the particular STB. The OTT service operates as an interface layer, for the pay channel, and facilitates selection from a variety of video recordings as well as live programs.
Factors attracting online consumers to choose e-Malls for e-procurement in Saudi Arabia
Published in Enterprise Information Systems, 2018
Adel A. Bahaddad, Steve Drew, Luke Houghtoni, Osama Abdulaziz Alfarraj
The following is a summary of the e-Mall target audience: They include Internet users who use high bandwidth connections (broadband and Asymmetric Digital Subscriber Line (ADSL)); the survey results show that 51% of those who buy products and services online use digital lines or broadband.About 66% of those who bought products over the Internet had a monthly income of SR 6000 or more.Women with bachelor’s degrees or higher are also part of the target audience. About 43% of these women shop on the Internet. The majority of this segment is the target audience of e-Malls, since the custom in Saudi society is for women to stay home while men work and serve the family outside the home. Therefore, women may be unable to go shopping on their own, especially in non-urban areas that do not have big markets.Finally, those between 25 and 40 years old represent 80% of the total participants. This segment tends to own and use the latest computer technologies including e-Malls.