Modulation schemes have not changed much in 802.11, since the early days we used OFDM (Orthogonal Frequency Division Multiplexing). 802.11b was really the only notable 802.11 PHY (physical layer) standard that did not use OFDM but then again it did only get 11Mbps using DSSS (Direct-Sequence Spread Spectra). OFDM is the primary modulation suite used for today’s technology. This is because of the super extensible QAM (Quadrature Amplitude Modulation) with BPSK (Binary Phase Shift Keying), and QPSK (Quadrature Phase Shift Keying) handling the simpler modulation.
IOL Blog Entries for May 2014
Comparing Measurements of High Speed Serial Interfaces
By Paul Willis - May 19, 2014
The priorities and specifics of physical limitations differ between standards. For instance Mobile Industry Processor Interface (MIPI) physical layer (PHY) specifications prioritize low power consumption and low electromagnetic interference (EMI) whereas an enterprise storage specification such as Serial Attached SCSI (SAS) focuses on high bandwidth and reliability. The MIPI protocols that are tested at the UNH-IOL are designed for video streaming while SATA is for transmission of Block Storage data. Both send bursts of data with headers and footers to manage erroneous bits. In MIPI the breaks between bursts are relatively short because one line of pixels is usually contained in one burst. After each MIPI burst there is also a break where the transmitter stops sending data, and the receiver stops terminating the signal line, to save on power. The MIPI PHY Specification specifies the timings and voltage levels necessary for entering and exiting this low power mode. SATA on the other hand, does not take breaks between bursts. Once one frame is finished, another is sent. If no data needs to be sent, idle data is shared to maintain the connection.
Wireless Reliability
By Jackson Corson - May 14, 2014
The IEEE 802.11 specification has proven to be a very reliable way to do networking. Wireless LANs (Local Area Networks) are capable of achieving Gigabits of speed with little to no effort. This makes wireless a competitor with Ethernet and many other networking technologies. But is it as reliable and will it continue to be so?