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Patent Issued for Gain Control Apparatus and Method in Receiver of Multiband OFDM System

2012 JUL 18 (VerticalNews) -- By a News Reporter-Staff News Editor at Telecommunications Weekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Kim, Seong-Min (Daejon, KR); Kang, Byung-Su (Daejon, KR); Jo, Gweon-Do (Daejon, KR); Jung, Jae-Ho (Daejon, KR); Kim, Joon-Hyung (Daejon, KR); Kwon, Heon-Kook (Daejon, KR); Lee, Sung-Jun (Daejon, KR); Lee, Kwang-Chun (Daejon, KR), filed on July 22, 2009, was cleared and issued on July 3, 2012.

The patent's assignee for patent number 8213891 is Electronics and Telecommunications Research Institute (Daejeon, KR).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a gain control apparatus and method in a receiver of a wireless communication system; and, more particularly, to a gain control apparatus and method in a receiver of a multiband Orthogonal Frequency Division Multiplexing (OFDM) system.

"In a wireless communication system, it is important in view of the entire system capacity to properly control the transmission power of a signal to be transmitted. Accordingly, when transmitting a signal, the wireless communication system transmits the signal at a proper transmission power. The receiver of the wireless communication system, therefore, should maximize the gain of a signal which is transmitted at a proper transmission power to restore the signal. A gain control method is typically used to properly restore a signal.

"Due to development of a wireless communication technology, the wireless communication system has evolved from a method for transmitting data through only one band into a method for transmitting signals through a plurality of bands. A representative system of the signal transmission method using the plurality of bands is a wireless communication system using an Orthogonal Frequency Division Multiplexing (OFDM) signal, and a system with the plurality of bands is called a multiband system. Controlling the gain of a received signal is more important in the receiver of a wireless communication system using an OFDM scheme and the multiband more than a system using a single band.

"The following description will be made with reference to the accompanying drawing on a method for controlling the gain of a reception signal in the receiver of the wireless communication system using the multiband.

"FIG. 1 is a block diagram illustrating a typical auto gain control apparatus in a receiver of a wireless communication system using a multiband scheme.

"A received signal is inputted to an auto gain amplifier 101. The auto gain amplifier 101 controls the gain of the received signal by a gain value according to the control of the auto gain controller 103 to output a gain controlled signal. The reception signal which is outputted through the above-described gain control operation is inputted to an analog-to-digital converter (ADC) 102. The ADC 102 converts an inputted analog signal into a digital signal and outputs the digital signal. The signal outputted from the ADC 102 is inputted to the auto gain controller (AGC) 103 and two different mixers 104 and 105.

"First, the auto gain controller 103 compares the power level of the inputted digital signal with a predetermined reference value, controls a gain according to the difference between the power level and the predetermined reference value, and outputs the gain control result to the auto gain amplifier 101. This is how the auto gain controller 103 controls the gain. The mixers 104 and 105 are constituent elements for extracting a signal based on each band. The mixers 104 and 105 also determine the gain of a received signal based on a control power received from the band gain control circuit 106 and output the gain-determined signal. The band gain control circuit 106 receives a power level for each band from the modem controller 107, compares the power level with signal levels outputted from the mixers 104 and 105, and determines the gain values of the mixers 104 and 105 according to the comparison result. As described above, a gain control method based on bands in a receiver compares the received power level with a predetermined reference value for each band and performs auto gain control according to the comparison result, compensating the gain of the reception signal.

"The above-described method should perform gain control for each band, calculate the average value of a power level for longer than a predetermined time, and compare the average value with the reference value. Consequently, an error may occur in a wireless communication system using a burst mode like the OFDM system where a state of each band rapidly changes according to time. Such an error may increase the number of retransmission times and decrease the total system throughput due to the increased retransmission. Accordingly, it is required to develop an apparatus and method capable of reducing an error when performing auto gain control for each band in a system in which a state of each band rapidly changes according to time."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "An embodiment of the present invention is directed to a gain control apparatus and method which control gain for each band in a wireless communication system using multiband.

"Another embodiment of the present invention is directed to a gain control apparatus and method in a receiver which can improve throughput in a multiband system where a state of each band rapidly changes according to time.

"Another embodiment of the present invention is directed to a gain control apparatus and method which can reduce the error of a received signal in a multiband system where a state of each band rapidly changes according to time.

"In accordance with an aspect of the present invention, there is provided a gain control apparatus in a receiver of a multiband Orthogonal Frequency Division Multiplexing (OFDM) system, the gain control apparatus including: an amplification unit configured to amplify a received signal based on a first auto gain control signal; an analog-to-digital conversion unit configured to convert the amplified signal into a digital signal; a plurality of band reception signal extraction units configured to extract a signal of a desired reception band from the converted digital signal for each reception band, and control a gain of the extracted signal according to a second auto gain control signal; a reception power detection unit configured to detect a reception power value of a whole band from the converted digital signal to output the detected value; and a multiband integration baseband processor configured to generate the first auto gain control signal by using the detected reception power value of the whole band, and generate the second auto gain control signal to be provided to the band reception signal extraction units by using power information of a whole band, resource allocation information for each band and a reception power for each reception band.

"In accordance with another aspect of the present invention, there is provided a gain control method in a receiver of a multiband Orthogonal Frequency Division Multiplexing (OFDM) system, the gain control method including: receiving a multiband signal to detect a reception power, and primarily controlling a gain of the multiband signal by using the reception power; and secondarily controlling a gain of a band for receiving a signal by using resource allocation information of a reception band and power information which is allocated to the whole of the multiband.

"Other objects and advantages of the present invention can be understood by the following description, and become apparent with reference to the embodiments of the present invention. Also, it is obvious to those skilled in the art to which the present invention pertains that the objects and advantages of the present invention can be realized by the means as claimed and combinations thereof."

For additional information on this patent, see: Kim, Seong-Min; Kang, Byung-Su; Jo, Gweon-Do; Jung, Jae-Ho; Kim, Joon-Hyung; Kwon, Heon-Kook; Lee, Sung-Jun; Lee, Kwang-Chun. Gain Control Apparatus and Method in Receiver of Multiband OFDM System. U.S. Patent Number 8213891, filed July 22, 2009, and issued July 3, 2012. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=29&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1449&f=G&l=50&co1=AND&d=PTXT&s1=20120703.PD.&OS=ISD/20120703&RS=ISD/20120703

Keywords for this news article include: Wireless Technology, Wireless Communication, Electronics And Communications, Electronics and Telecommunications Research Institute.