KR100431202B1 - A Baseband Modem Apparatus Suitable for Bluetooth System by using OFDM Modem - Google Patents

Abstract

The present invention provides a baseband modulation and demodulation using OFDM modulation and demodulation in a Bluetooth system that performs baseband modulation and demodulation using Orthogonal Frequency Division Multiplexing (OFDM) modulation to enable high-speed, variable data rates in a Bluetooth system. Relates to a device. To this end, the present invention, in the baseband modulation and demodulation apparatus using orthogonal frequency division multiplexing (OFDM) in a Bluetooth system for transmitting and receiving data at a high variable data rate, the data transmitted from the link manager at a variable data rate to the orthogonal frequency An OFDM modulator for modulating in division multiplex (OFDM); An OFDM modulation controller for controlling the OFDM modulation unit and controlling an output power of radio frequency (RF) according to a variable data rate designated by the link manager; An OFDM demodulator extracting a variable data rate from an OFDM signal received at a radio frequency, demodulating the data received at the variable data rate by the OFDM scheme, and transmitting the demodulated data to the link manager; And an OFDM demodulation control unit for controlling the OFDM demodulator according to the extracted variable data rate and reducing the power consumption of the OFDM demodulator by comparing the data rate with the data rate used in the OFDM modulator.

Description

Baseband modulation and demodulation device using OFM M modulation in a Bluetooth system {A Baseband Modem Apparatus Suitable for Bluetooth System by using OFDM Modem}

The present invention relates to a baseband modulation and demodulation apparatus using OFDM modulation and demodulation in a Bluetooth system, and more particularly, orthogonal frequency division multiplexing (OFDM) modulation and demodulation scheme to support a high speed variable data rate in a Bluetooth system. The present invention relates to a baseband modulation and demodulation device in a Bluetooth system for performing baseband modulation and demodulation.

Conventionally, in the Bluetooth system, a frequency hopping (FH) method of an RF (radio frequency) modem method, a frequency shifting keying (FSK) method of a baseband modem method, or a Gaussian Frequency Shifting Keying (GFSK) method is used in a Bluetooth system. However, these methods have low bandwidth and low data transmission rate, which does not meet the demand for high-speed data transmission and reception. In addition, since baseband modulation and demodulation is performed at a fixed data rate, it is impossible to support a variable data rate.

Various wireless data communication methods have been disclosed. As an example, Korean Patent Application No. 1999-0035610 discloses a short range wireless communication method using Bluetooth. Although the method relates to short-range wireless communication, which is preferably applied to a wireless interface between a computer using Bluetooth and its peripheral device, it does not solve the demand for high-speed data transmission.

In addition, Korean Patent Application No. 2000-0066524 discloses a communication control apparatus and method for transmitting and receiving data between a plurality of devices included in a short-range wireless communication network or between the communication network and an external communication network. The Bluetooth technology disclosed in the above apparatus and method uses a radio frequency (RF) in the 2.4 GHz frequency band and executes a process corresponding to a frequency hopping (FH) system to transmit and receive data between devices. The need for support was not met.

Accordingly, an object of the present invention is to provide a baseband modulation and demodulation device that supports a high speed variable data rate using an OFDM modulation and demodulation method in a Bluetooth system.

It is a further object of the present invention to provide a baseband modulation and demodulation device that supports dynamic bandwidth allocation and dynamic subcarrier number allocation to enable high-speed data transmission and reception in Bluetooth.

1 is a block diagram of an embodiment of an OFDM modulation and demodulation system of the present invention.

Figure 2 is a block diagram according to an embodiment of the mixer and inverse mixer of the present invention.

3 is a block diagram according to an embodiment of a convolutional encoder of the present invention.

4 is a configuration diagram of the synchronization shown in FIG. 1;

FIG. 5 is a configuration diagram of the Viterbi decoder shown in FIG. 1. FIG.

6 is a conceptual diagram of a dynamic bandwidth allocation scheme according to the present invention.

7 is a conceptual diagram of a dynamic subcarrier number allocation scheme according to the present invention.

Explanation of symbols on the main parts of the drawings

1: link manager 2: OFDM modulator

3: OFDM demodulation section 4: Radio frequency (RF) section

200: OFDM modulation controller 201: mixer

202: weaving encoder 203: interleaver

204: mapper 205: IFFT block

206: guard section insertion section 300: OFDM demodulation section

301: synchronizer 302: FFT block

303: Equalizer 304: Pilot power estimation unit

305: demapper 306: deinterleaver

307 Viterbi decoder 308 Reverse mixer

401: OFDM symbol synchronization acquisition unit 402: Frequency offset compensation unit

As a technical configuration for achieving the above object, the present invention is a baseband modulation and demodulation device using Orthogonal Frequency Division Multiplexing (OFDM) in a Bluetooth system for transmitting and receiving data at a high variable data rate,

An OFDM modulator for modulating data transmitted from the link manager at a variable data rate in an orthogonal frequency division multiplex (OFDM) scheme;

An OFDM modulation controller for controlling the OFDM modulation unit and controlling an output power of radio frequency (RF) according to a variable data rate designated by the link manager;

An OFDM demodulator extracting a variable data rate from an OFDM signal received at a radio frequency, demodulating the data received at the variable data rate by the OFDM scheme, and transmitting the demodulated data to the link manager; And

And an OFDM demodulation control unit for controlling the OFDM demodulator according to the extracted variable data rate and reducing the power consumption of the OFDM demodulator by comparing the data rate with the data rate used in the OFDM modulator.

Here, the baseband modulation / demodulation device supports variable data rates by dynamically allocating bandwidth to each slave terminal according to the increase and decrease of the number of slave terminals forming the piconet in the link manager. In addition, the apparatus controls the power of the slave terminals according to the connection state of the slave terminals forming the piconet and supports a dynamic subcarrier number allocation scheme that can transmit and receive variable data by changing the number of subcarriers of OFDM.

Advantages and features of the present invention will become more apparent from the following detailed description. Hereinafter, a baseband modulation and demodulation device including an OFDM modulation control unit for controlling an OFDM modulation and demodulation unit to support a high speed variable data rate according to the present invention with reference to the accompanying drawings of a preferred embodiment of the present invention and a bandwidth dynamically in the device. Allocating and dynamically allocating subcarrier numbers is described in detail.

1 is a configuration diagram according to an embodiment of an OFDM modulation and demodulation system of the present invention. As shown in FIG. 1, the OFDM modulation and demodulation system according to the present invention includes a link manager (1), an OFDM modulator (2), an OFDM modulation controller (200), an OFDM demodulator (3), and an OFDM demodulation controller. 300 and a radio frequency (RF) unit 4. The OFDM modulator 2 is composed of a mixer 201, a convolutional encoder 202, an interleaver 203, a mapper 204, an IFFT block 205, and a guard interval insertion unit 206. The demodulator 3 includes a synchronizer 301, an FFT block 302, an equalizer 303, a pilot power estimator 304, a demapper 305, a deinterleaver 306, and a Viterbi decoder 307. And a backmixer 308.

The link manager 1 sets a data rate of data to be transmitted and transfers the data to the mixer 201 of the OFDM modulator 2. The data mixed in the mixer 201 is input to the interleaver 203 via the convolutional encoder 202 and interleaved the data in the interleaver 203, and then at a data rate determined by the link manager 1. Accordingly, the mapper 204 maps to Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (16QAM), and 64QAM. The data mapped through the above process is sent to the RF unit 4 via the IFFT block 205 and the guard interval insertion unit 206.

Table 1 and Table 2 below show one embodiment of parameters used in a Bluetooth system using OFDM modulation and demodulation. Table 1 is a parameter according to data rate and Table 2 is a parameter related to time. The OFDM symbol is obtained by adding the number of output values of the N IFFT blocks 205 and the number of sample values corresponding to the guard interval.

Data rate (Mbps) Mapping Code rate Number of bits coded per subcarrier Coded bits per OFDM symbol Number of data bits per OFDM symbol Bandwidth (MHz) 2.5 QPSK 1/2 2 20 10 5 5 16QAM 1/2 4 40 20 7.5 64QAM 1/2 6 60 30

parameter value N _SD : Number of data subcarriers 10 N _SP : Pilot subcarrier number 2 N _ST : total number of subcarriers 12 (N _SD + N _SP ) ΔF: subcarrier frequency spacing 0.3125 MHz (= 10 MHz / 32) T _FFT : IFFT / FFT period 3.2 μs (1 / ΔF) T _SIGNAL : Signal field period 4.0 μs (T _GI + T _FFT ) T _GI : Protection Period 0.8 μs (T _FFT / 4) T _SYM : Symbol Period 4 μs (T _GI + T _FFT )

An operation of the apparatus illustrated in FIG. 1 will be described with reference to specific embodiments.

The admixture 201 is used to prevent the data received from the link manager 1 from continuously having the same value, and an embodiment of the generated polynomial is shown in Equation 1 below. 2 is shown.

S (X) = X ⁷ + X ⁴ + 1

The data mixed through the mixer 201 passes through the convolutional encoder 202 and an embodiment of the generated polynomial is shown in Equation 2 below and shown in FIG. 3.

Least Significant Bits (LSBs) = 133 ₈

MSB (Most Significant Bit) = 171 8

In the baseband modulation and demodulation device according to the present invention, an interleaver 203 is used to convert a burst error generated by a channel into a random error. The data that has passed through the interleaver 203 is mapped according to the data rate in the mapper 204 at a later stage, which is shown in Tables 3, 4, and 5 below. First, Table 3 shows one embodiment of QPSK mapping, Table 4 shows one embodiment of 16QAM mapping, and Table 5 shows one embodiment of 64QAM mapping.

In addition, the mapped data is divided into an in-phase component and a quadrature component, and the normalization factor is multiplied by the mapped data to normalize the transmitted power, respectively, and one embodiment of the value is shown in Table 6 below.

Input bit b0 Inphase component Input bit b1 Quadrature components 0 -One 0 -One One One One One

Input bit b0b1 Inphase component Input bit b2b3 Quadrature components 00 -3 00 -3 01 -One 01 -One 11 One 11 One 10 3 10 3

Input bit b0b1b2 Inphase component Input bit b3b4b5 Quadrature components 000 -7 000 -7 001 -5 001 -5 011 -3 011 -3 010 -One 010 -One 110 One 110 One 111 3 111 3 101 5 101 5 100 7 100 7

Mapping KMOD QPSK 1 / sqrt (2) 16QAM 1 / sqrt (10) 64QAM 1 / sqrt (42)

The mapped data is allocated to the ten subcarrier frequencies of the IFFT block 205 and the pilot signal is allocated to the third and third subcarrier frequencies of the IFFT block 205. Data passing through the IFFT block 205 comes out as 16 in-phase components and quadrature components, and the guard interval is inserted by copying the last four values among the 16 values and copying them before the data passing through the IFFT block 205 ( 206). Therefore, one OFDM symbol interval is 4 microseconds, and the number of samples per OFDM symbol is 20.

The OFDM modulation controller 200 controls blocks required for variable data transmission in the OFDM modulation unit 2. The OFDM modulation controller 200 transmits a control signal tx_ready for receiving data to the link manager 1. The control signal tx_ready has values of '1' and '0', and the link manager 1 sends data to the OFDM modulator 2 only while the control signal tx_ready is '1'. The OFDM modulation controller 200 generates tx_ready to have a value of '1' only for the number of data bits per OFDM symbol according to the data rate. In addition, the OFDM modulation controller 200 informs the mapper 204 and the interleaver 203 about the data rate so that the OFDM modulator 2 operates according to a variable data rate. Therefore, the OFDM modulation controller 200 controls the operation of the OFDM modulator 2 according to the variable data rate set by the link manager 1 to perform OFDM modulation on the data having the variable data rate. Accordingly, it is possible to support high speed variable data rates.

Hereinafter, the OFDM demodulator 3 shown in FIG. 1 will be described.

The received OFDM signal passes through the RF unit 4 and is input to the synchronizer 301 of the OFDM demodulator 3. The data passing through the synchronization unit 301 passes through the FFT block 302 and then passes through the equalizer 303 of the rear stage. The data passing through the equalizer 303 is demapped by the demapper 305 according to the data rate and deinterleaved by the deinterleaver 306. The data that has passed through the deinterleaver 306 passes through the Viterbi decoder 307 and is input to the demixer 308. Demixed data is transmitted to the link manager 1. The above processes are described in more detail as follows.

Since the frequency offset occurs because of the independent oscillator of the RF unit 4, the frequency offset of the received OFDM signal should be compensated. The configuration of the synchronization unit 301 of the OFDM demodulator 3 is shown in FIG. As shown in FIG. 4, the configuration of the synchronizer 301 includes a frequency offset compensator 402 for compensating for frequency offset and an OFDM symbol synchronizer acquirer 401 for acquiring an OFDM symbol synchronizer.

As described above, the frequency offset-compensated data performs a Fast Fourier Transform after removing the guard interval from the Fast Fourier Transform (FFT) block 302. The FFT data is input to the equalizer 303. The equalizer 303 estimates a channel corresponding to the frequency of each subcarrier. The channel is compensated by multiplying the input signal of the equalizer 303 using the estimated channel value. The data passed through the equalizer 303 is sent to the demapper 305 and the pilot symbol is sent to the pilot power estimator 304. The pilot power estimator 304 estimates the environment of the current radio channel by calculating the power of the received pilot symbol and determines the link quality based on the estimated power. Data demapped by the demapper 305 is input to the deinterleaver 306. The demapper 305 and the deinterleaver 306 operate according to the received data rate. Data passing through the deinterleaver 306 is input to the Viterbi decoder 307. The configuration of the Viterbi decoder 307 is shown in FIG. As shown in FIG. 5, the Viterbi decoder 307 detects and corrects an error on a channel, and is composed of a hard decision and a soft decision. The configuration is a branch metric (BM) unit 502 and an ACS (Add). It includes a Compare Select (503) unit, a TB (Trace Back) unit 505, a memory unit 504, a LIFO (Last In First Out) unit 506, and a control unit 501. Data passed through the Viterbi decoder 307 passes through a demixer 308. An embodiment of the generated polynomial of the inverse mixer 308 is shown in Equation 1 above.

The OFDM demodulation control unit 300 controls the OFDM demodulation unit 3 and receives the start signal rx_start indicating the start of the OFDM symbol from the synchronization unit 301 and informs the FFT block 302. The FFT block 302 receives the start signal rx_start and performs an FFT with the remaining 16 sample values except the 4 sample values of the protection interval. In addition, the OFDM demodulation control unit 300 controls the demapper 305 and the deinterleaver 306 operated according to the data rate. In addition, the OFDM demodulation controller 300 may reduce the power consumption of the OFDM demodulator 3 when the data rate of the received OFDM signal does not correspond to the data rate used by the OFDM modulator 2. It serves to inform the link manager 1 of a control signal for stopping the operation of the remaining blocks except for the synchronization unit 301 in (3). The synchronizer 301 should always be operated for detection of the next packet.

The data demixed by the demultiplexer 308 is input to the OFDM demodulation control unit 300, and the OFDM demodulation control unit 300 has a value of '1' only for the number of data bits per OFDM symbol according to the data rate. Generate a control signal (rx_ready). The OFDM demodulation control unit 300 transmits a control signal rx_ready and a data bit together to the link manager 1, and the link manager 1 transmits the control signal rx_ready from the OFDM demodulation control unit 300 only while the control signal rx_ready is '1'. Get a bit. Accordingly, the OFDM demodulation control unit 300 controls the operation of the OFDM demodulation unit 3 according to the data rate of the received OFDM signal to demodulate data having a variable data rate, thereby supporting a high speed variable data rate. Done.

6 illustrates an embodiment of a conceptual diagram of a dynamic bandwidth allocation scheme according to the present invention. FIG. 6 (a) shows the bandwidth allocation of seven slave terminals in Bluetooth and FIG. 6 (b) shows the bandwidth allocation of three slave terminals. This will be described in detail below.

In the Bluetooth according to the present invention, two or more terminals form a wireless personal area network (WPAN) called a piconet. One piconet consists of one master terminal and seven slave terminals, and the master terminal assigns a unique address called AM_ADDR (Active Member Address) to each slave terminal. Therefore, the link manager of the master terminal can grasp the number of slave terminals forming the piconet, and when the number of slave terminals forming the piconet increases, the link manager of the master terminal reduces the bandwidth of the slave terminals. All slave terminals can transmit and receive data, and if the number of slave terminals decreases, the bandwidth of the remaining slave terminals is increased to support a dynamic bandwidth allocation method for high speed data transmission and reception. As the number of slave terminals increases and decreases, the bandwidth of the remaining slave terminals is dynamically allocated, thereby enabling high-speed data transmission.

7 illustrates an embodiment of a conceptual diagram of a dynamic subcarrier number allocation scheme according to the present invention. Fig. 7 (a) shows the dynamic subcarrier number allocation when the connection state is good and Fig. 7 (b) shows the dynamic subcarrier number allocation when the connection state is bad. In more detail, in the state where the slave terminals according to the present invention form the piconet, the power size of the pilot symbol received from each slave terminal can be obtained from the equalizer 303. The link quality between the slave terminals is determined using the power size of the pilot symbol extracted from the equalizer 303, and then the power of the slave terminals is controlled by sending the information back to the slave terminals. By changing the number of OFDM subcarriers according to the connection state of a slave terminal, a dynamic subcarrier number allocation method capable of transmitting and receiving variable data is supported. As shown in FIG. 7A, when the connection state is good, a large number of subcarriers are allocated, and when the connection state is bad as shown in FIG. Allocates a dynamic subcarrier number so that variable data can be transmitted.

The detailed description and drawings described above are for the embodiments of the present invention and do not limit the present invention. Therefore, one of ordinary skill in the art to which the present invention pertains may be substituted, changed or modified without departing from the spirit of the present invention, and the scope of the present invention shall be determined by the appended claims.

As described above, the present invention can support a high speed variable data rate in a Bluetooth system and can be applied to a Bluetooth system that requires a high data rate in the future.

In addition, as the number of slave terminals forming the piconet increases and decreases in the Bluetooth system, the bandwidth of the slave terminals is dynamically allocated, thereby enabling high-speed data transmission and reception and determining the connection state of the slave terminals to dynamically adjust the number of subcarriers of OFDM. By allocating to a variable data transmission / reception is possible.

Claims (9)

In the baseband modulation and demodulation device using Orthogonal Frequency Division Multiplexing (OFDM) in a Bluetooth system for transmitting and receiving data at a high variable data rate, An OFDM modulator for modulating data transmitted from the link manager at a variable data rate in an orthogonal frequency division multiplex (OFDM) scheme; An OFDM modulation controller for controlling the OFDM modulation unit and controlling an output power of radio frequency (RF) according to a variable data rate designated by the link manager; An OFDM demodulator extracting a variable data rate from an OFDM signal received at a radio frequency, demodulating the data received at the variable data rate by the OFDM scheme, and transmitting the demodulated data to the link manager; And And an OFDM demodulation controller for controlling the OFDM demodulator according to the extracted variable data rate and reducing the power consumption of the OFDM demodulator by comparing the data rate with the data rate used in the OFDM modulator. A baseband modulation and demodulation device using OFDM modulation and demodulation in a system. The method of claim 1, wherein the OFDM modulator, A mixer to prevent the data received from the link manager from continuously outputting the same value; A convolutional encoder for performing channel coding to correct an error of data mixed by the mixer generated by the channel; An interleaver for converting a burst error generated by the channel into a random error; A mapper for mapping an in-phase component and a quadrature component corresponding to input bits of data output from the interleaver; An IFFT block for allocating the mapped data to a plurality of subcarrier frequencies; And A baseband modulation and demodulation device using OFDM modulation and demodulation in a Bluetooth system, characterized in that it comprises a guard interval inserting unit for copying a plurality of in-phase components and quadrature components and inserts the guard interval by inserting it into the allocated data. The method of claim 2, wherein the mapper and the interleaver, A baseband modulation and demodulation device using OFDM modulation and demodulation in a Bluetooth system, characterized in that for performing matching and interleaving according to the specified variable data rate. The method of claim 1, wherein the OFDM modulation control unit, The control unit for receiving data is transmitted to the link manager, data is received, and information about the data transmission rate is transmitted to the OFDM modulator, thereby controlling the operation of the OFDM modulator according to a variable data rate. Baseband Modulation Demodulation Device using OFDM Modulation Demodulation in Bluetooth System. The method of claim 1, wherein the OFDM demodulation unit, A synchronizer configured to compensate for a frequency offset of the received OFDM signal; An FFT block for performing fast Fourier transform by removing the guard interval of the offset-compensated data; An equalizer for receiving data output from the FFT block, estimating a channel corresponding to a frequency of each subcarrier, compensating a channel using the estimated channel value, and outputting a pilot symbol; A pilot power estimator for estimating a current wireless channel environment by calculating power of the pilot symbol and determining a link quality using the pilot symbol; A demapper for demapping inphase components and quadrature components of data output from the equalizer with input bits; A deinterleaver for converting a burst error into a random error generated by the channel; A Viterbi decoder for detecting and correcting errors on the channel for the deinterleaved data; And A baseband modulation and demodulation device using OFDM modulation and demodulation in a Bluetooth system, characterized in that it comprises a demixer for receiving the data output from the Viterbi decoder to perform the reverse mixing. The method of claim 5, wherein the synchronization unit, A frequency offset compensator for compensating the frequency offset of the received OFDM signal; And A baseband modulation and demodulation device using OFDM modulation and demodulation in a Bluetooth system, characterized in that it comprises an OFDM symbol synchronization acquisition unit for obtaining OFDM symbol synchronization. The method of claim 1, wherein the OFDM demodulation control unit, Store and transmit information indicating the received data rate to the OFDM demodulator and control the operation of the OFDM modulator according to the received data rate, and when the received data rate is different from the transmitted data rate, power consumption of the OFDM modulator. A baseband modulation and demodulation device using OFDM modulation and demodulation in a Bluetooth system, characterized in that to generate a signal to reduce the. The method of claim 1, The link manager of the master terminal forming the piconet supports a variable data rate by dynamically allocating bandwidth to each slave terminal according to the increase or decrease of the number of slave terminals. Band modulation and demodulation device. The method of claim 1, In a Bluetooth system, the power of the slave terminals is controlled according to a connection state of a slave terminal forming a piconet, and a dynamic subcarrier number allocation method capable of transmitting and receiving variable data by changing the number of subcarriers of OFDM is provided. A baseband modulation and demodulation device using OFDM modulation and modulation.