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Personal Digital Cellular
Personal Digital Cellular (PDC) was a 2G mobile telecommunications standard used exclusively in Japan. After a peak of nearly 80 million subscribers to PDC, it had 46 million subscribers in December 2005, and was slowly phased out in favor of 3G technologies like W-CDMA and CDMA2000. At the end of March 2012, the count had dwindled down to almost 200,000 subscribers. NTT Docomo shut down their network, mova, on April 1, 2012 at midnight. Technical overview Like D-AMPS and GSM, PDC uses TDMA. The standard was defined by the RCR (later became ARIB) in April 1991, and NTT DoCoMo launched its Digital mova service in March 1993. PDC uses 25 kHz carrier, pi/4- DQPSK modulation with 3-timeslot 11.2 kbit/s (full-rate) or 6-timeslot 5.6 kbit/s (half-rate) voice codecs. PDC is implemented in the 800 MHz (downlink 810–888 MHz, uplink 893–958 MHz), and 1.5 GHz (downlink 1477–1501 MHz, uplink 1429–1453 MHz) bands. The air interface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Computing
Mobile computing is human–computer interaction in which a computer is expected to be transported during normal usage, which allows for the transmission of data, voice, and video. Mobile computing involves mobile communication, mobile hardware, and mobile software. Communication issues include ad hoc networks and infrastructure networks as well as communication properties, protocols, data formats, and concrete technologies. Hardware includes mobile devices or device components. Mobile software deals with the characteristics and requirements of mobile applications. Main principles * Portability: Devices/nodes connected within the mobile computing system should facilitate mobility. These devices may have limited device capabilities and limited power supply but should have a sufficient processing capability and physical portability to operate in a movable environment. * Connectivity: This defines the quality of service (QoS) of the network connectivity. In a mobile computing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDC-HR
Personal Digital Cellular (PDC) was a 2G mobile telecommunications standard used exclusively in Japan. After a peak of nearly 80 million subscribers to PDC, it had 46 million subscribers in December 2005, and was slowly phased out in favor of 3G technologies like W-CDMA and CDMA2000. At the end of March 2012, the count had dwindled down to almost 200,000 subscribers. NTT Docomo shut down their network, mova, on April 1, 2012 at midnight. Technical overview Like D-AMPS and GSM, PDC uses TDMA. The standard was defined by the RCR (later became ARIB) in April 1991, and NTT DoCoMo launched its Digital mova service in March 1993. PDC uses 25 kHz carrier, pi/4- DQPSK modulation with 3-timeslot 11.2 kbit/s (full-rate) or 6-timeslot 5.6 kbit/s (half-rate) voice codecs. PDC is implemented in the 800 MHz (downlink 810–888 MHz, uplink 893–958 MHz), and 1.5 GHz (downlink 1477–1501 MHz, uplink 1429–1453 MHz) bands. The air interface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunication Technology Committee
The Telecommunication Technology Committee (TTC; ja, 情報通信技術委員会) is a standardization organization established in 1985 and authorized by Japan's Ministry of Internal Affairs and Communications to conduct research and to develop and promote standards for telecommunications in Japan. The TTC is a founding partner organization of the Global Standards Collaboration The Global Standards Collaboration (GSC) started life as The "Inter-regional Telecommunications Standards conference (ITSC) in 1990. This was an initiative of the T1 Committee of the United States who invited the other founding partner organization ... initiative and an organizational partner of the 3rd Generation Partnership Project (3GPP). External links *http://www.ttc.or.jp/e/index.html Telecommunication Technology Committee website Telecommunications in Japan Mass media companies Companies established in 1985 1985 establishments in Japan {{Org-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Association Of Radio Industries And Businesses
The , commonly known as , is a standardization organization in Japan. ARIB is designated as the center of promotion of the efficient use of the radio spectrum and designated frequency change support agency. Its activities include those previously performed by the Research and Development Center for Radio Systems (RCR) and Broadcasting Technology Association (BTA). ARIB is a participating standards organization of the Global Standards Collaboration initiative and an organizational partner of the 3rd Generation Partnership Project (3GPP). See also *ISDB Integrated Services Digital Broadcasting (ISDB; Japanese: , ''Tōgō dejitaru hōsō sābisu'') is a Japanese broadcasting standard for digital television (DTV) and digital radio. ISDB supersedes both the NTSC-J analog television system and ... References https://www.arib.or.jp/english/arib/about_arib.html - Establishment of ARIB External links * ISDB Trade associations based in Japan Radio organization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Au (mobile Phone Operator)
au, or au by KDDI, is a Japanese mobile phone operator. au is a brand marketed by KDDI in the main islands of Japan and by Okinawa Cellular in Okinawa for their mobile cellular services. au is the second-largest wireless carrier in Japan, with 60.398 million subscribers as of March 2021. Naming According to the brand creator, the name 'au' is based on the Japanese verbs for 'meet' (会う) and 'unite' (合う) (both pronounced 'au'). However, KDDI explains that au comes from two letters which stand for few words. 'A' is for access, always and amenity, and 'U' is for unique, universal and user. There is also a phrase, 'access to u(you)' that goes along the brand name. History The network that would eventually become Au was originally set up as two networks: DDI and IDO. IDO's network was based upon the NTT Hi-cap analog cellular system, and began operations in December 1988 in the Kanto and Tokai regions. DDI's network was run by independent phone companies, and began service ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KDDI
() is a Japanese telecommunications operator formed on October 1, 2000 through the merger of DDI Corp. (Daini-Denden Inc.), KDD (Kokusai Denshin Denwa) Corp. (itself a former listed state-owned enterprise privatized in 1998), and IDO Corp. It has its headquarters in the Garden Air Tower in Iidabashi, Chiyoda, Tokyo. KDDI provides mobile cellular services using the " au by KDDI" brand. ISP network services are provided under the au one net brand, while "au Hikari" is the name under which long-distance and international voice and data communications services and Fiber to the Home (FTTH) services are marketed. ADSL broadband services carry the brand name "ADSL One", and IP telephony over copper is branded as "Metal Plus". History On April 1, 2002, au by KDDI launched 3G networks using CDMA2000 1x technology. On November 28, 2003, au by KDDI launched EV-DO Rev 0 service in the "CDMA 1X WIN" brand, and revolutionized Japan's mobile telecommunication industry by introducin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CELP
Code-excited linear prediction (CELP) is a linear predictive speech coding algorithm originally proposed by Manfred R. Schroeder and Bishnu S. Atal in 1985. At the time, it provided significantly better quality than existing low bit-rate algorithms, such as residual-excited linear prediction (RELP) and linear predictive coding (LPC) vocoders (e.g., FS-1015). Along with its variants, such as algebraic CELP, relaxed CELP, low-delay CELP and vector sum excited linear prediction, it is currently the most widely used speech coding algorithm. It is also used in MPEG-4 Audio speech coding. CELP is commonly used as a generic term for a class of algorithms and not for a particular codec. Background The CELP algorithm is based on four main ideas: * Using the source-filter model of speech production through linear prediction (LP) (see the textbook "speech coding algorithm"); * Using an adaptive and a fixed codebook as the input (excitation) of the LP model; * Performing a search in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adaptive Multi-rate Compression
The Adaptive Multi-Rate (AMR, AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbit/s with toll quality speech starting at 7.4 kbit/s. AMR was adopted as the standard speech codec by 3GPP in October 1999 and is now widely used in GSM and UMTS. It uses link adaptation to select from one of eight different bit rates based on link conditions. AMR is also a file format for storing spoken audio using the AMR codec. Many modern mobile telephone handsets can store short audio recordings in the AMR format, and both free and proprietary programs exist (see Software support) to convert between this and other formats, although AMR is a speech format and is unlikely to give ideal results for other audio. The common filename extension is .amr. There also exists another stor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institute Of Electronics, Information And Communication Engineers
The is a Japanese institute specializing in the areas of electronic, information and communication engineering and associated fields. Its headquarters are located in Tokyo, Japan. It is a membership organization with the purpose of advancing the field of electronics, information and communications and support activities of its members. History The earliest predecessor to the organization was formed in May 1911 as the ''Second Study Group'' of the Second Department of the Japanese Ministry of Communications Electric Laboratory. In March 1914 the Second Study Group was renamed the ''Study Group on Telegraph and Telephone''. As the adoption of the telegraph and telephone quickly mounted, there was increased demand for research and development of these technologies, which prompted the need to create a dedicated institute for engineers working in this field. Thus the ''Institute of Telegraph and Telephone Engineers of Japan'' was established in May 1917. Soon after its formation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SoftBank Mobile
is a Japanese multinational conglomerate holding company headquartered in Minato, Tokyo which focuses on investment management. The Group primarily invests in companies operating in technology, energy, and financial sectors. It also runs the Vision Fund, the world's largest technology-focused venture capital fund, with over $100 billion in capital. Fund investors include sovereign wealth funds from countries in the Middle East. The company is known for the leadership of its controversial founder and largest shareholder Masayoshi Son. It operates in broadband, fixed-line telecommunications, e-commerce, information technology, finance, media and marketing, and other areas. SoftBank Corporation, its spun-out affiliate and former flagship business, is the third-largest wireless carrier in Japan, with 45.621 million subscribers as of March 2021. SoftBank was ranked in the 2017 Forbes Global 2000 list as the 36th largest public company in the world and the second-largest publicly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
