Some medium speed smart metering modems, "Prime" and "G3" use OFDM at modest frequencies (30–100 kHz) with modest numbers of channels (several hundred) in order to overcome the intersymbol interference in the power line environment. The IEEE 1901 standards include two incompatible physical layers that both use OFDM.
Chang of Bell Labs in 1966.
OFDM was improved by Weinstein and Ebert in 1971 with the introduction of a guard interval, providing better orthogonality in transmission channels affected by multipath propagation.
COFDM was introduced by Alard in 1986 for Digital Audio Broadcasting for Eureka Project 147.
The service was discontinued on April 30, 2009. == Vector OFDM (VOFDM) == VOFDM was proposed by Xiang-Gen Xia in 2000 (Proceedings of ICC 2000, New Orleans, and IEEE Trans.
The Flash-OFDM network was switched off in the majority of Slovakia on 30 September 2015. T-Mobile Germany used Flash-OFDM to backhaul Wi-Fi HotSpots on the Deutsche Bahn's ICE high speed trains between 2005 and 2015, until switching over to UMTS and LTE. American wireless carrier Nextel Communications field tested wireless broadband network technologies including Flash-OFDM in 2005.
It was developed by Flarion, and purchased by Qualcomm in January 2006.
Sprint purchased the carrier in 2006 and decided to deploy the mobile version of WiMAX, which is based on Scalable Orthogonal Frequency Division Multiple Access (SOFDMA) technology. Citizens Telephone Cooperative launched a mobile broadband service based on Flash-OFDM technology to subscribers in parts of Virginia in March 2006.
A wireless mobile communication system without pilot signals Patent PCT/Il N 2006000926, Patent PCT International Application N0 PCT/IL 2006000926.
As an example, 450 MHz frequency bands previously used by NMT-450 and C-Net C450 (both 1G analogue networks, now mostly decommissioned) in Europe are being licensed to Flash-OFDM operators. In Finland, the license holder Digita began deployment of a nationwide "@450" wireless network in parts of the country since April 2007.
The service was discontinued on April 30, 2009. == Vector OFDM (VOFDM) == VOFDM was proposed by Xiang-Gen Xia in 2000 (Proceedings of ICC 2000, New Orleans, and IEEE Trans.
It was purchased by Datame in 2011.
In February 2012 Datame announced they would upgrade the 450 MHz network to competing CDMA2000 technology. Slovak Telekom in Slovakia offers Flash-OFDM connections with a maximum downstream speed of 5.3 Mbit/s, and a maximum upstream speed of 1.8 Mbit/s, with a coverage of over 70 percent of Slovak population.
The Flash-OFDM network was switched off in the majority of Slovakia on 30 September 2015. T-Mobile Germany used Flash-OFDM to backhaul Wi-Fi HotSpots on the Deutsche Bahn's ICE high speed trains between 2005 and 2015, until switching over to UMTS and LTE. American wireless carrier Nextel Communications field tested wireless broadband network technologies including Flash-OFDM in 2005.
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