KR100882358B1 - Method and apparatus for creating link quality indicator in mb-ofdm uwb system - Google Patents

Abstract

The present invention drives the algorithm of the automatic gain controller to form an efficient piconet in a multi-band orthogonal frequency division ultra wideband (MB-OFDM UWB) system comprising a receiver having a dynamic gain regulator and an automatic gain controller. After the automatic gain control index is extracted, the CCA state is determined by using the extracted automatic gain control index, and if the determined CCA state is high, the request for each data rate is received using the automatic gain control index. By simply generating link quality indication (LQI) information to be provided from the physical layer to the MAC layer based on the power, it is possible to intuitively determine whether transmission power control or data rate mode conversion of the current data rate mode is required.

MB-OFDM UWB system, LQI, RSSI, CCA, AGC algorithm, AGC index, DGC, MAC layer, physical layer, ADC, DAC

Description

TECHNICAL AND APPARATUS FOR CREATING LINK QUALITY INDICATOR IN MB-OFDM UWB SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for generating link quality indication information in a multiband orthogonal frequency ultra wideband system. A method and apparatus for generating information.

In general, a multi-band quadrature ultra-wideband (MB-OFDM UWB) system consists of many piconet networks connecting many devices in a narrow space with very low transmission power and limited frequency resources, minimizing mutual interference in this limited environment. In order to transfer as much data as possible, transmission output control and data rate mode conversion are required. Therefore, in order to construct such an efficient piconet network, meaningful information on the received signal level should be uploaded from the physical layer to the media access control (MAC) layer. To this end, existing wireless system technologies mainly include the following techniques for setting a received signal strength indication (hereinafter referred to as RSSI).

Korean Laid-Open Patent Publication (10-1998-057727) discloses an RSSI generator for generating RSSI, which is a voltage representing a signal strength received at a radio frequency, a reference voltage generator for generating a reference voltage, and a voltage and reference generated from the RSSI generator. Comprising comparators comparing voltages generated by voltage generators, this paper proposes a method of changing the reference voltage according to the transmission output to prevent an error from occurring when RSSI appears largely due to noise.

In the Republic of Korea Patent Application Publication No. 10-2004-0060307, the fixed device measures the RSSI of the signal transmitted from the portable device, and transmits the variable by changing the modulation degree of the transmitted character data according to the strength of the measured RSSI, thereby transmitting the portable device to the portable device. It proposes a method to remove a large part of noise caused by a character data signal.

In addition, the Republic of Korea Patent Publication (10-2006-0045865) detects the received signal error at the RSSI limit value currently set in the significant change in the radio wave environment, and if there is an error, the difference between the estimated received power and the currently set RSSI limit value We propose a method of estimating the noise power to change the RSSI limit that guarantees signal reception according to the estimated noise power.

As described above, in the conventional technologies, the RSSI setting method and the set RSSI value are used to adjust the transmission data modulation degree, or the RSSI limit value in the RSSI reception is varied, and the optimum RSSI limit value is selected and set even in a noisy environment. . However, the system specification suggests CCA (hereinafter referred to as CCA), RSSI, and link quality indication status (hereinafter referred to as Link Quality Indicator, referred to as LQI), and the existing technologies consider LQI only for RSSI configuration. In order to consider LQI, hardware devices must be additionally configured in an existing wireless system.

Accordingly, an object of the present invention is to provide a method and apparatus for generating link quality indication information provided from a physical layer to a media access control layer in order to implement an efficient piconet network in an MB-OFDM UWB system.

In addition, the problem to be solved by the present invention is to facilitate the transmission power control and data rate mode switching in the medium access control while minimizing additional hardware devices by using the information on the automatic gain control algorithm implemented in the receiver of the MB-OFDM UWB system The present invention provides a method and apparatus for generating link quality indication information.

A method for achieving these objects of the present invention is to generate link quality indication information in a multi-band orthogonal frequency ultra-wideband (MB-OFDM UWB) system comprising a receiver having a dynamic gain regulator and an automatic gain controller. A method for extracting an automatic gain control index after driving an algorithm of the automatic gain controller; Determining a channel state by using the extracted automatic gain control index; And generating link quality indication information to be provided from the physical layer to the media access control layer by using the automatic gain control index when the channel state is high.

An apparatus for achieving the objects of the present invention comprises: a dynamic gain adjuster, driven by an automatic gain control algorithm, for controlling the power gain of a received signal; And outputting a signal for controlling the dynamic gain regulator through an automatic gain control algorithm, extracting an automatic gain control index using the automatic gain controller algorithm to determine a channel state, and if the identified channel state is high And an automatic gain controller for generating link quality indication information to be provided from a physical layer to a media access control (MAC) layer using the automatic gain control index.

As described above, the present invention simply obtains CCA and RSSI by using AGC index and RF design specification obtained from AGC algorithm for controlling received signal with appropriate input range of ADC in MB-OFDM UWB system, and for each data rate. By generating the LQI based on the required received power, the MAC can intuitively determine whether transmission power control or data rate mode conversion of the current data rate mode is required.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, if it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The multi-band orthogonal frequency ultra-wideband (MB-OFDM UWB) system uses a time frequency hopping scheme which is being standardized by IEEE802.15.3a Alt-PHY, and as shown in FIG. Media Access Control (hereinafter referred to as MAC) transmits and receives information through an interface between a layer and a physical layer (PHY). In the embodiment of the present invention, the channel state (CCA (Clear Channel Assessment) _STATUS) is mainly described in the MAC-PHY interface, and the CCA_STATUS information is transmitted from the physical layer 20 to the MAC layer 10. In addition to the information transmitted through the CCA_STATUS, a received signal strength indication (hereinafter referred to as RSSI) and a link quality indication (hereinafter referred to as Link Quality Indicator (LQI)) have a structure as shown in FIG. It may be provided to the MAC layer 10 by the received frame format having.

Next, a receiver structure of the MB-OFDM UWB system will be described with reference to the accompanying drawings.

FIG. 3 is a diagram illustrating a structure of a reception synchronizer of a multiband quadrature ultra wideband system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, a receiver of the MB-OFDM UWB system includes a low noise amplifier (LNA) 101, a mixer 102, an oscillator 103, and a low frequency. Low pass filter (LPF) 104, dynamic gain controller (hereinafter referred to as DGC) 105, analog-to-digital converter (ADC) 106, and digital-to-analog converter (DAC) ( 108, an auto gain controller (hereinafter referred to as AGC) 107, and a demodulator (DEMOD) 109. Only some of the devices in such a receiver play an important role according to an embodiment of the present invention in detail. The remaining devices are generally well known and will not be described.

Such a receiver typically drives the algorithm of the AGC 107 to determine the received power level through the received RF, because the input range of the analog-to-digital converter (hereinafter referred to as ADC) 106 is determined by the ADC specification. 106) Adjust to fit the input range. In addition, it is determined whether the received power level (signal level) is suitable for the ADC 106 in comparison with the reference value by the demodulator 109 at the rear of the ADC 108, and the AGC 107) to design the algorithm.

The DGC 105 operates under the control of the AGC 107 to adjust the power gain of the received signal, and may be implemented as an amplifier or attenuator.

The ADC 106 converts the gain-controlled received signal from the DGC 105 into a digital signal, and the digital analog converter (DAC) 108 converts the digital control signal output from the AGC 107 into an analog signal. It converts and transmits the data to the DGC 105.

The AGC 107 receives the digital received data converted by the ADC 106 and outputs a signal for controlling the DGC 105 through an automatic gain control algorithm. The AGC 107 extracts an automatic gain control index using the automatic gain controller algorithm, and identifies the channel state through the extracted automatic gain control index, and the channel is crowded when the identified channel state is busy. Set it to the state, and if it is low, set it to the state where the channel is free. In addition, the AGC 107 obtains the RSSI and the LQI to be provided from the physical layer to the MAC layer using the automatic gain control index.

On the other hand, the data rate mode of the MB-OFDM UWB system varies from 53.3 Mbps mode to 480 Mbps mode, as shown in Table 1 below, and for maintaining the received signal quality above a certain level because of the transmission characteristics of each data rate mode The required SNR value also varies by data rate mode. In other words, even with the same reception power, in some data rate modes, it may be determined that the reception power is very large, so that the transmission output may be lowered or a higher data rate mode may be required. In addition, in other data rate modes, the received power is very low, requiring higher transmission power or switching to a more stable data rate mode.

In the accompanying FIG. 4, the AGC index for each received power presented in the MB-OFDM UWB system standard is shown, and the AGC estimated by the AGC algorithm for driving the DGC 105 as the DGC input (DAC output) voltage also increases. It can be seen that the index value is increased. For example, if the AGC index value is set in units of 1 dB and the RF reception limit level is designed to be -80.8 dBm, the lowest of the minimum received power for each data rate, as shown in Table 1, the AGC index is set to 60 steps. Therefore, the dynamic range of the RF receiver that can be received by adjusting the DGC 105 is -80.8 dBm to -21.8 dBm. Accordingly, the reception power correlation may be represented as shown in Table 2 when the DGC 105 is designed as an amplifier, and as shown in Table 3 when the DGC 105 is designed as an attenuator.

Here, the AGC index value may be generated by the AGC algorithm in comparison with a reference value in order to match the appropriate output voltage of the ADC 106. Therefore, if the correlation between the AGC index and the RF reception design specification is known, the reception power level can be easily determined from the AGC index. Therefore, if the data rate modes selected by simulation or actual measurement are compared with the target minimum received field, it is possible to directly check whether the current received signal power is excessive or insufficient compared to the set data rate mode while minimizing additional hardware (H / W). LQI information that can be determined by the MAC can be generated.

Next, a method for generating LQI information provided from the physical layer to the MAC layer in the MB-OFDM UWB system will be described in detail with reference to the accompanying drawings. First, the LQI information generation process when the DGC is an RF receiver designed as an amplifier according to an embodiment of the present invention will be described.

FIG. 5 is a diagram illustrating a link quality indication generation process when a dynamic gain controller (DGC) in a reception synchronizer of a multiband quadrature ultra-wideband system is configured as an amplifier according to an embodiment of the present invention.

Referring to FIG. 5, the receiver of the MB-OFDM UWB system drives the AGC algorithm of the AGC 107 after analog-to-digital conversion through the ADC 108 in step 201. Thereafter, in step 202, the receiver extracts the AGC index in the stabilization step after driving the AGC algorithm. Then, in step 203, it is checked whether the extracted AGC index of CCA_STATUS is less than or equal to 60.

On the other hand, if the AGC index is 60 or less, it is determined that the RF reception power is received at -80.8 dBm or more. In step 204, the receiver converts the reception power from the AGC index using Equation 1 below. At this time, the receiver sets CCA_STATUS as the channel is busy.

Received Power (dBm) =-20.8-AGC Index

Then, in step 205, the receiver calculates the RSSI by using Equation 2 below.

RSSI (dB) = 60-AGC Index

With the RSSI obtained from Equation 2, the MAC can determine how much the RF received power is greater than the minimum received power level. However, only the RSSI value can be used to control transmission output or change the data rate mode. Since it may be difficult to determine, the receiver uses LQI information to facilitate this determination. Accordingly, in order to generate such LQI information, in step 206, the receiver calculates a link quality estimate (hereinafter referred to as LQE) using Equation 3 below. In this case, the LQI information should be set according to the currently set data rate mode. For example, if the required received power for each data rate of the MB-OFDM UWB system designed by simulation and measurement in consideration of the channel environment is given as in <Table 4>, it is compared with the received power calculated from Equation 1 above. To obtain the LQE suitable for the data rate.

LQE (dB) = RF Received Power Obtained by AGC Index-Required Received Power

Then, in step 207, the receiver calculates an LQI using the calculated LQE value using Equation 4 below.

LQI (dB) = LQE + 7

For example, if the AGC index is calculated as 35, the RF received power is calculated as -55.8 dBm by Equation 1, and the RSSI value is calculated as 25 by Equation 2. The LQE is calculated as 10.7 in the 200Mbps mode and 2.8 in the 480Mbps mode according to the following <Table 4> and <Equation 3>. Accordingly, when the AGC index is 35, it may be determined that sufficient power is received in both the 200 Mbps and the 480 Mbps modes. In addition, both modes may request lower transmission power, and in the case of 200 Mbps mode, may require switching the data rate mode to a higher data rate mode.

Next, a process of generating LQI information when the DGC is an RF receiver designed as an attenuator according to another embodiment of the present invention will be described.

FIG. 6 is a diagram illustrating a process of generating a link quality indication when a dynamic gain adjuster (DGC) is configured as an attenuator in a reception synchronizer of a multiband orthogonal frequency ultra wideband system according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the receiver of the MB-OFDM UWB system drives the AGC algorithm in the AGC 107 after analog-to-digital conversion through the ADC 106 in step 301. Thereafter, in step 302, the receiver extracts the AGC index in the stabilization step after driving the AGC algorithm. Then, in step 303, it is checked whether the extracted AGC index of CCA_STATUS is greater than 1, and if it is 1 or less, it is determined that CCA_STATUS is low and the operation is terminated as it is.

On the other hand, when the AGC index is greater than 1, it is determined that the RF reception power is received at -80.8 dBm or more, and in step 304, the receiver converts the reception force from the AGC index using Equation 5 below. At this time, the receiver sets CCA_STATUS to be busy.

Received Power (dBm) =-81.8 + AGC Index

Then, in step 305, the receiver calculates the RSSI using Equation 6 below.

RSSI (dB) = AGC Index-1

With the RSSI obtained from Equation 6, the MAC can determine how much the RF received power is greater than the minimum received power level. However, only the RSSI value can be used to control transmission output or change the data rate mode. Since it may be difficult to determine, the receiver uses LQI information to facilitate this determination. Accordingly, in order to generate such LQI information, in step 306, the receiver calculates an LQE using Equation 3, and in step 307, the receiver calculates an LQI using the calculated LQE value using Equation 4. do.

On the other hand, in the detailed description of the present invention has been described with respect to specific embodiments, various modifications are possible without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating a MAC-PHY interface state in a multiband quadrature ultra-wideband system according to an embodiment of the present invention;

2 is a view illustrating a structure of an RX frame in a multiband quadrature ultra-wideband system according to an embodiment of the present invention;

3 is a diagram illustrating a structure of a reception synchronizer of a multiband quadrature frequency ultra wideband system according to an embodiment of the present invention;

4 is a graph illustrating a correlation graph between an input and an output voltage of a digital-to-analog converter (DAC) by an automatic gain control (AGC) index for driving the dynamic gain controller (DGC) of FIG.

5 is a diagram illustrating a link quality indication generation process when a dynamic gain adjuster (DGC) is configured as an amplifier in a receiver of a multiband quadrature ultra-wideband system according to an embodiment of the present invention;

FIG. 6 illustrates a process of generating a link quality indication when a dynamic gain adjuster (DGC) is configured as an attenuator in a receiver of a multiband quadrature ultra-wideband system according to an embodiment of the present invention. FIG.

Claims (18)

CLAIMS 1. A method for generating link quality indication information in a multiband- quadrature ultra-wideband (MB-OFDM UWB) system comprising a receiver having a dynamic gain adjuster and an automatic gain controller; Extracting an automatic gain control index after driving the algorithm of the automatic gain controller; Determining a channel state by using the extracted automatic gain control index; And Generating link quality indication information to be provided from the physical layer to the media access control layer using the automatic gain control index when the channel state is high. How to generate quality indication information. The method of claim 1, wherein the determining of the channel state comprises: Comparing the extracted automatic gain control index with a preset first threshold value when the dynamic gain adjuster is implemented as an amplifier; Determining the channel state as a high state if the extracted automatic gain control index is less than the first threshold value; And determining the channel state as a low state if the extracted automatic gain control index is equal to or greater than the first threshold value. The method of claim 1, wherein the determining of the channel state comprises: Comparing the extracted automatic gain control index with a second preset threshold when the dynamic gain adjuster is implemented as an attenuator; Determining the channel state as a high state if the extracted automatic gain control index is greater than the second threshold value; And determining the channel state as a low state if the extracted automatic gain control index is less than or equal to the second threshold value. The method of claim 1, wherein the generating of the link quality indication information to be provided from the physical layer to the media access control layer using the automatic gain control index includes: Converting received power from the automatic gain control index; Obtaining received signal strength indication (RSSI) information using the automatic gain control index; Obtaining link quality estimate (LQE) information suitable for a data rate using the converted received power and the required received power for each data rate; Obtaining the link quality indication (LQI) information using the obtained link quality estimate (LQE) information. The method of claim 4, wherein And the received power is converted by subtracting the automatic gain control index from a high received power threshold when the dynamic gain adjuster is implemented as an amplifier. The method of claim 4, wherein The received signal strength indication (RSSI) information is obtained by subtracting the automatic gain control index from a first threshold value when the dynamic gain adjuster is implemented as an amplifier. How information is generated. The method of claim 4, wherein And the link quality estimate (LQE) information is obtained by subtracting the required received power from the converted received power. The method of claim 4, wherein The link quality indication information (LQI) is obtained by adding 7 to the link quality estimate (LQE). The method of claim 4, wherein The received power is converted by adding the automatic gain control index at a low received power threshold when the dynamic gain adjuster is implemented as an attenuator. The method of claim 4, wherein The received signal strength indication (RSSI) information is obtained by subtracting a second threshold value from the automatic gain control index when the dynamic gain adjuster is implemented as an attenuator. How information is generated. A dynamic gain adjuster, driven by an automatic gain control algorithm, for controlling the power gain of the received signal; And Outputs a signal for controlling the dynamic gain controller through an automatic gain control algorithm, extracts an automatic gain control index using the automatic gain controller algorithm to determine a channel state, and if the identified channel state is high, Multi-band orthogonal frequency ultra-wideband (MB-OFDM UWB), characterized in that it comprises an automatic gain controller for generating link quality indication information to be provided from the physical layer to the media access control (MAC) layer using the automatic gain control index. Receiving device in the system. delete The method of claim 11, The automatic gain controller compares the extracted automatic gain control index with a preset first threshold when the dynamic gain adjuster is implemented as an amplifier, and if the extracted automatic gain control index is smaller than the first threshold, Determining a channel state as high and obtaining received signal strength indication (RSSI) and link quality indication (LQI) information which are information to be provided to the medium access control layer. Receiver in OFDM UWB) system. The method of claim 13, The reception signal strength indication (RSSI) information is obtained by subtracting the automatic gain control index from the first threshold value. The method of claim 13, The link quality indication (LQI) information is obtained by subtracting the automatic gain control index from a high reception power threshold to obtain link quality estimation (LQE) information by subtracting the required reception power for each data rate from the converted reception power. A reception apparatus in a multi-band orthogonal frequency ultra-wideband (MB-OFDM UWB) system, characterized by adding 7 to the obtained link quality estimate (LQE). The method of claim 11, The automatic gain controller compares the extracted automatic gain control index with a second preset threshold when the dynamic gain adjuster is implemented as an attenuator, and if the extracted automatic gain control index is greater than the second threshold, the channel state. Is determined to be high, and the received signal strength indication (RSSI) and the link quality indication (LQI) information, which are information to be provided to the medium access control layer, are obtained. ) Receiving device in the system. The method of claim 16, The receiving signal strength indication (RSSI) information is obtained by subtracting the second threshold value from the automatic gain control index in a multi-band orthogonal frequency ultra wideband (MB-OFDM UWB) system. The method of claim 16, The link quality indication (LQI) information is obtained by subtracting the required received power for each data rate from the converted received power by adding the automatic gain control index at a low received power threshold to obtain link quality estimate (LQE) information. A reception device in a multi-band orthogonal frequency ultra-wideband (MB-OFDM UWB) system, characterized by adding 7 to the link quality estimate (LQE).

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