Multichannel multipoint distribution service (MMDS), formerly known as broadband radio service (BRS) and also known as wireless cable, is a wireless telecommunications technology, used for general-purpose broadband networking or, more commonly, as an alternative method of cable television programming reception. MMDS is used in Australia, Barbados, Belarus, Bolivia, Brazil, Cambodia, Canada, Czech Republic, Dominican Republic, India, Iraq ( Asiacell Only ) , Kazakhstan, Kyrgyzstan, Lebanon, Mexico, Nepal, Nigeria, Pakistan, Panama, Portugal (including Madeira), Russia, Slovakia, Sri Lanka, Sudan, Thailand, Ukraine, United States, Uruguay and Vietnam. It is most commonly used in sparsely populated rural areas, where laying cables is not economically viable, although some companies have also offered MMDS services in urban areas, most notably in Ireland, until they were phased out in 2016.
Technology The BRS band uses microwave frequencies from 2.3 to 2.5 GHz. Reception of BRS-delivered television and data signals is done with a rooftop microwave antenna. The antenna is attached to a down-converter or transceiver to receive and transmit the microwave signal and convert them to frequencies compatible with standard TV tuners (much like on satellite dishes where the signals are converted down to frequencies more compatible with standard TV coaxial cabling), some antennas use an integrated down-converter or transceiver. Digital TV channels can then be decoded with a standard cable set-top box or directly for TVs with integrated digital tuners. Internet data can be received with a standard DOCSIS cable modem connected to the same antenna and transceiver. The MMDS band is separated into 33 (31 in USA) 6 MHz "channels", which may be licensed to cable companies offering service in different areas of a country. The concept was to allow entities to own several channels and multiplex several television, radio, and later Internet data onto each channel using digital technology. Just like with digital cable channels, each channel is capable of 30.34 Mbit/s with 64QAM modulation, and 42.88 Mbit/s with 256QAM modulation. Due to forward error correction and other overhead, actual throughput is around 27 Mbit/s for 64QAM and 38 Mbit/s for 256QAM. The newer BRS Band Plan makes changes to channel size and licensing in order to accommodate new WIMAX TDD fixed and mobile equipment, and reallocated frequencies between 2150 and 2162 MHz to the AWS band. These changes may not be compatible with the frequencies and channel sizes required for operating traditional MMDS or DOCSIS based equipment. MMDS has been used to provide internet access.
MMDS and DOCSIS+ Local multipoint distribution service (LMDS) and BRS have adapted the DOCSIS (Data Over Cable Service Interface Specification) from the cable modem world. The version of DOCSIS modified for wireless broadband is known as DOCSIS+. Data-transport security is accomplished under BRS by encrypting traffic flows between the broadband wireless modem and the WMTS (wireless modem termination system) located in the base station of the provider's network using Triple DES. DOCSIS+ reduces theft-of-service vulnerabilities under BRS by requiring that the WMTS enforce encryption, and by employing an authenticated client/server key-management protocol in which the WMTS controls distribution of keying material to broadband wireless modems. LMDS and BRS wireless modems utilize the DOCSIS+ key-management protocol to obtain authorization and traffic encryption material from a WMTS, and to support periodic reauthorization and key refresh. The key-management protocol uses X.509 digital certificates, RSA public-key encryption, and Triple DES encryption to secure key exchanges between the wireless modem and the WMTS. MMDS provided significantly greater range than LMDS. MMDS may be obsoleted by the newer 802.16 WiMAX standard approved since 2004. MMDS was sometimes expanded to multipoint microwave distribution system or multi-channel multi-point distribution system. All three phrases refer to the same technology.
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