Reduction Of Unmodulated Ambient Blockers In Reflected Data Links Through Manipulation Of Replication Of The Illuminating Signal Source

Tech ID: 29673 / UC Case 2015-170-0


Researchers at the UCLA Department of Electrical and Computer Engineering have developed a new method to eliminate a power amplifier from the transmitter chain in a wireless data link, while overcoming the effects of ambient reflections.


WiFi and WLAN technology is broadly adopted in the mobile market. However, the high power consumption of existing WiFi transceiver technology limits its use for the emerging wearable device market because the WLAN transceiver requires a power amplifier device to generate power levels suitable for transmitting a WiFi signal to a base-station or router. Currently available amplifiers can only achieve 10-15% efficiency, meaning that in order to generate the typical 100-250 mW required to send a WiFi signal, the device must consume ten times greater amount of power, which is not compatible with battery on wearable products. Previously, the same group of UCLA researchers developed a reflective link that eliminates the need of using power amplifiers while enabling implementation of a WLAN or WiFi link that consumes 10-100 times less power. However, the overall communication performance is still heavily limited by receipt of ambient carrier reflections, which appear as an in-band signal blocker or jammer.


Researchers at UCLA have developed a novel method to enhance the communication between a wireless base-station and a microwave reflector link by feeding back a portion of the transmitter signal, adjusted for phase and amplitude, to cancel ambient reflection blocker signals being received at the base-station. More specifically, an additional circuit pathway is introduced between the illumination TX and RX within the base-station. The pathway contains a programmable phase delay from 0 to 360° in cascade with a variable attenuator, thus allowing the base-station to adjust phase delay and attenuation in the circuit pathway to compensate for ambient reflections captured by the receiving antenna. With removal of the large blocking signal, the receiver is able to amplify modulated reflection signals from reflective modulation and readily extract data sent by the microwave reflector link.


  • Wireless connectivity market: WLAN, WiFi, Bluetooth, and Cellular devices 
  • 5G cellular standards (15 or 30 GHz) 
  • The mm-wave standards (i.e. and 802.15.3c) 
  • UHF and the pager band (433 MHz)


Overcomes the adverse effects of the ambient reflection, allowing a 100 times improvement in either data communication rates or in communication transmission distance

State Of Development

Have completed proof of concept experiments.

Patent Status

Country Type Number Dated Case
United States Of America Issued Patent 10,305,606 05/28/2019 2015-170

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  • Chang, Mau-Chung Frank

Other Information


Ambient reflection, wireless, WiFi, WLAN, 5G, Bluetooth, power amplifier, wearable device, reflector link, cellular antenna

Categorized As