November 14, 2012
New Wireless Technology To Double 3G, 4G Network Efficiency
redOrbit Staff & Wire Reports - Your Universe Online
Researchers at the University of California at Riverside have developed a way to double the efficiency of wireless networks, something they say could help alleviate the ℠spectrum crunch´ as consumers migrate from traditional cell phones to smartphones and tablets that use services which consume higher bandwidth.
Without increasing network efficiency, customers are likely to drop more calls, pay more money for service, suffer with slower data speeds and see the end of unlimited data plans, the researchers said.
Current radios for wireless communications are half-duplex, meaning signals are transmitted and received in two separate channels. Full duplex radios, which transmit signals at the same time in the same frequency band, can double the efficiency of the spectrum.
The problem is that in order to make a full duplex radio, the interference between the transmitting and receiving functions must be mitigated, and the technology to do that with 3G and 4G networks is not yet ready. Without it, the interference caused by signals from cell towers, which can be billions of times more powerful than the ones towers are trying to pick up from a user´s smartphone, drown out the incoming signals.
The UC Riverside researchers developed a solution they call “time-domain transmit beamforming,” which digitally creates a time-domain cancellation signal and couples it to the radio frequency frontend to allow the radio to detect much weaker incoming signals while transmitting strong outgoing signals at the same frequency and same time.
The technology has a sound theoretical proof and a lower cost as well as the benefit of offering faster and more accurate channel estimation for effective cancellation, the researchers said.
“We believe the future applications of full duplex radios are huge, ranging from cell towers, backhaul networks and wireless regional area networks to billions [of] handheld devices for data intensive application such as FaceTime,” said study co-author Ping Liang, professor of electrical engineering at the UC Riverside Bourns College of Engineering.
Liang said he and his colleagues have already had discussions with several major wireless telecommunication equipment companies about their solution.
The solution has commercial potential in part because most of the central components required are digital and would not require any costly hardware to be added to existing wireless infrastructure, Liang explained.
The researchers said cell towers are one of the most likely places to begin rolling out full-duplex radios because they are less constrained by existing standards.
Liang and fellow co-author Yingbo Hua also see applications in cognitive radio, a type of wireless communication in which a transceiver can detect which communication channels are in use and which are not, and move signals into vacant channels while avoiding occupied ones.
For instance, if cellular frequency bands are overloaded, other bands, such as military, amateur radio and TV, which are often underutilized, can be used instead.
The researchers described their work in a paper entitled “A Method for Broadband Full-Duplex MIMO Radio,” which was published online in the journal IEEE Signal Processing Letters.