News Column

Patent Issued for Device and Method for Configurable Transmit and Receive Antennas

March 5, 2014



By a News Reporter-Staff News Editor at Telecommunications Weekly -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Li, Jia-Ru (San Jose, CA); Lee, Yueh-Ju (Saratoga, CA), filed on October 28, 2011, was published online on February 18, 2014.

The assignee for this patent, patent number 8654743, is Lilee Systems, Ltd (Santa Clara, CA).

Reporters obtained the following quote from the background information supplied by the inventors: "In a wireless Positive Train Control (PTC) system, a fast-travelling locomotive communicates with a wayside or track-side base station through a radio link. A spectrum at 220 MHz has been allocated for the wireless PTC application to provide a reliable communication link between a locomotive and base stations. It is well known for digital radio systems that there are various channel impairments due to noise, multipath fading and the time-varying channel. A manifest of the net effects of the later two channel impairments is fast and deep fading, where the signal strength of received signal may be attenuated substantially in a very short period of time within the same packet. The attenuation may be more than 25 dB within 1 ms time during deep fading and the normal operation of the communication link may be temporarily interrupted.

"In the PTC system, the weather damage and vandalism are the most frequent reasons that cause the service interruption since the antennas are usually installed outdoors. Often times, railroad uses dual antennas to overcome the performance problem by using an antenna splitter. Without careful impedance matching for cables, this mechanism usually causes serious performance degradation. The circuit block according to the present invention can optimize the system performance and provides matched impedance, maximizes the transmit power and receive sensitivity, and maintains the reliability of dual antenna systems against weather damage. With minimal cost added by the invented circuit, it allows to reuse existing dual antennas tower to achieve optimal performance.

"There are several methods to overcome the fast fading issue. Block-based channel coding is one method that may be used to correct short burst errors associated with the fast fading. Nevertheless, the technique may require a block size sufficiently large to correct the burst errors and the large block size may not be desirable due to long latency and large memory required to store the block. Specifically, in a fast fading channel, smaller block size is highly preferable. On the other hand, multiple parallel receivers may also be used, where one receiver may be subject to deep fading at a time while the other one may still receive a good signal. However, the use of multiple parallel receivers will increase system cost. The circuit block incorporating an embodiment according to the present invention allows the receivers to use a secondary receive antenna when the primary antenna enters deep fade. In a time division multiple access (TDMA) channel, it is advantageous to configure the separate transmit and receive antennas as multiple receive antennas during the receiving period to overcome the fast fading problem."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "A configurable multiple antennas for a time division multiple access (TDMA) radio system between a base station and a locomotive are disclosed. The configurable multiple antennas comprise a first antenna, a second antenna, a first control circuit and a second control circuit. The first antenna is connected to a transmit signal port through a first electrical path, where the first electrical path has substantially zero loss. The second antenna is connected to a receive signal port through a second electrical path, where the second electrical path has substantially zero loss. The first control circuit is coupled between the first antenna and the receive signal port, where a first control signal is operable on the first control circuit to cause the first control circuit in an ON state or an OFF state. When the first control circuit is in the ON state, the first control circuit provides a third electrical path from the first antenna to the receive signal port. The second control circuit is coupled between the second antenna and a ground node, where a second control signal is operable on the second control circuit to cause the second control circuit in the ON state or the OFF state. When the second control circuit is in the ON state, the second antenna is grounded. The configurable multiple antennas can be configured to a selected antenna operation mode according to the first control signal and the second control signal. For example, if the selected antenna operation mode corresponds to a transmit mode, the first control signal and the second control signal can be configured to cause the first control circuit in the OFF state and the second control circuit in the ON state so that a transmit signal is fed from the transmit signal port to the first antenna through the first path and the second antenna is grounded. If the selected antenna operation mode corresponds to a primary received mode, the first control signal and the second control signal can be configured to cause the first control circuit in the OFF state and the second control circuit in the OFF state so that only the second antenna through the second path provides received signals to the receive signal port. If the selected antenna operation mode corresponds to a secondary receive mode, the first control signal and the second control signal can be configured to cause the first control circuit in the ON state and the second control circuit in the OFF state so that the first antenna through the third electrical path and the second antenna through the second electrical path both provide received signals to the receive signal port.

"A method of configuring multiple antennas to a transmit mode, a primary receive mode or a secondary receive mode for a time division multiple access (TDMA) radio system between a base station and a locomotive is disclosed, where the multiple antennas comprises a first antenna connected to a transmit signal port through a first electrical path having substantially zero loss, a second antenna connected to a receive signal port through a second electrical path having substantially zero loss, a first control circuit coupled between the first antenna and the receive signal port, and a second control circuit coupled between the second antenna and a ground node. If the transmit mode is selected, the method applies a first control signal to the first control circuit to cause the first electrical control circuit in an OFF state and applies a second control signal to the second control circuit to cause the second electrical control circuit in an ON state so that a transmit signal is fed from the transmit signal port to the first antenna through the first path and the second antenna is grounded. If the primary receive mode is selected, the method applies the first control signal to the first control circuit to cause the first electrical control circuit in the OFF state and applies the second control signal to the second control circuit to cause the second electrical control circuit in the OFF state so that only the second antenna through the second electrical path provides received signals to the receive signal port. If the secondary receive mode is selected, the method applies the first control signal to the first control circuit to cause the first electrical control circuit in the ON state and applies the second control signal to the second control circuit to cause the second electrical control circuit in the OFF state so that the first antenna through the third electrical path and the second antenna through the second electrical path both provide the received signals to the receive signal port."

For more information, see this patent: Li, Jia-Ru; Lee, Yueh-Ju. Device and Method for Configurable Transmit and Receive Antennas. U.S. Patent Number 8654743, filed October 28, 2011, and published online on February 18, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=46&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2274&f=G&l=50&co1=AND&d=PTXT&s1=20140218.PD.&OS=ISD/20140218&RS=ISD/20140218

Keywords for this news article include: Lilee Systems Ltd.

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Source: Telecommunications Weekly


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