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Unstructured Supplementary Service Data (USSD), sometimes referred to as "quick codes" or "feature codes", is a communications protocol used by GSM cellular telephones to communicate with the mobile network operator's computers.
Signal Comments 1 state 0 state NRZ–L: Non-return-to-zero level. This is the standard positive logic signal format used in digital circuits. forces a high level
Some malls will be left without the free WIFI hotspots. [ 3 ] On 1 April 2013, StarHub and Y5Zone were added to the list of Wireless@SG operators, while iCELL was dropped as the company's proposal did not meet IDA's requirements for the next deployment phase of the programme [ 4 ] [ 5 ] and will remain support until 30 June 2013.
IEEE 802.11d-2001 is an amendment to the IEEE 802.11 specification that adds support for "additional regulatory domains". This support includes the addition of a country information element to beacons, probe requests, and probe responses.
Low-density parity-check (LDPC) codes are a class of highly efficient linear block codes made from many single parity check (SPC) codes. They can provide performance very close to the channel capacity (the theoretical maximum) using an iterated soft-decision decoding approach, at linear time complexity in terms of their block length.
Space–time block coding is a technique used in wireless communications to transmit multiple copies of a data stream across a number of antennas and to exploit the various received versions of the data to improve the reliability of data transfer.
TETRA networks use the mobile country code from ITU-T Recommendation E.212 together with a 14-bit binary mobile network code (T-MNC) where only values between 0 and 9999 are used. [2] However, a TETRA network may be assigned an E.212 network code as well. [3] Some network operators do not have their own radio access network at all.
IEEE 802.11n is an amendment to IEEE 802.11-2007 as amended by IEEE 802.11k-2008, IEEE 802.11r-2008, IEEE 802.11y-2008, and IEEE 802.11w-2009, and builds on previous 802.11 standards by adding a multiple-input multiple-output (MIMO) system and 40 MHz channels to the PHY (physical layer) and frame aggregation to the MAC layer.