Transmission system with interference avoidance capability and method thereof

[0001] The present invention relates generally to a transmission system, and particularly to a transmission system with interference avoidance capability and a method thereof.

[0002] Modern technologies make progresses day by day. Technological products continuously weed through the old to bring forth the new, particularly in wireless technological products such as cell phones or Bluetooth earphone. The Institute of Electrical and Electronics Engineers (IEEE) regulates many wireless network standards for avoiding interference, which would affect communication qualities, while using wireless products.

[0003] Besides, the Federal Communications Commission (FCC) has issued the First Report and Order on Ultra Wide Band (UWB) technology. The publication approved UWB technology in commercial deployment. A spectral mask is announced for ensuring UWB signals will not interfere frequency bands of other protocols, such as sensitive devices in Global Positioning System (GPS), and the Worldwide Interoperability for Microwave Access (WiMAX) protocol. In the spectral mask, there is a wide continuous bandwidth, in which the UWB communication technology adopts the bandwidth from 3.1GHz to 10.6 GHz with the effective isotropic radiated power (EIRP) emission limit being −41.25 dBmi/MHz.

[0004] However, because one of the frequency bands used by WiMAX includes the frequency of 3.6 GHz, the spectrum used by the WiMAX and the UWB protocols overlap. Thereby, the paper ECC/TG3 TG3#10_XX, “UWB Interference Mitigation”, 10^thECC/TG3 meeting , Copenhagen, Jul. 2005 published by TI, which is related to interference avoidance technology, used Active Interference Cancellation (AIC) technology to achieve the purpose of interference avoidance. The capability of the notch filter for interference avoidance proposed by TI can reach approximately 30 dB. Nevertheless, such capability is still prone to interference.

[0005] Accordingly, a novel transmission system with interference avoidance and a method thereof that can improve the drawbacks of interference due to spectrum overlap are highly needed.

[0006] The purpose of the present invention is to provide a transmission system with interference avoidance capability and a method thereof, which prevent signal interference by means of an interference-processing module for avoiding spectrum overlap regions.

[0007] Another purpose of the present invention is to provide a transmission system with interference avoidance capability and a method thereof, which avoid spectrum overlap for preventing signal interference by adding an extension unit for increasing extension data as well as a multiplexer.

[0008] The transmission system with interference avoidance capability according to the present invention includes a transmission apparatus and a receiving apparatus. The transmission apparatus includes a first inverse fast Fourier transform unit, an interference-processing module, and a transmission-processing module. The receiving apparatus includes a receiving-processing module, a removal unit, and a fast Fourier transform unit. The transmission method according to the present invention includes receiving input data and transforming the input data to first data by the first inverse fast Fourier transform unit, receiving the first data and adding a plurality of extension data to the first data by the interference-processing module to produce second data for replacing a plurality of data corresponding to an interfered band in the second data with zero data and then producing transmission data, converting the transmission data to a radio-frequency signal by the transmission-processing module, and transmitting the radio-frequency signal.

[0009] The transmission method according to the present invention further includes receiving the radio-frequency signal by the receiving-processing module of the receiving apparatus and converting the radio-frequency signal to received data, removing the plurality of extension data from the received data by the removal unit to producing recovered data, and transforming the recovered data by the fast Fourier transform unit to produce output data.

[0013] In order to make the structure and characteristics as well as the effectiveness of the present invention to be further understood and recognized, the detailed description of the present invention is provided as follows along with preferred embodiments and accompanying figures.

[0014] The transmission system with interference avoidance capability according to the present invention is applied in an orthogonal frequency division multiplexing (OFDM) system of UWB for avoiding the frequency band used the WiMAX protocol. Thereby, signal interference in the frequency band can be prevented. However, the present invention is not limited to the application. The application is only a preferred embodiment of the present invention.

[0015] FIG. 1 shows the block diagram of a transmission apparatus according to a preferred embodiment of the present invention. As shown in the figure, the transmission apparatus 1 of the transmission system with interference avoidance capability according to the present invention includes a serial-to-parallel converter 110, a first inverse fast Fourier transform unit 120, an interference-processing module 130, a parallel-to-serial converter 140, a filter 150, and a transmission-processing module 160. The serial-to-parallel converter 110 receives input data, coverts the serial input data to parallel input data, and transmits the parallel input data to the first inverse fast Fourier transform unit 120. The first inverse fast Fourier transform unit 120 receives the parallel input data and transforms the frequency-domain parallel input data to first data, which is time-domain input data.

[0016] The interference-processing module 130 receives the first data and adds a plurality of extension data to the first data for increasing resolution of the first data, and thereby produces second data. Then a plurality of data corresponding to an interfered band in the second data is replaced with zero data to produce transmission data. Where while adding the plurality of extension data, which is a plurality of zero data, and replacing the plurality of data corresponding to an interfered band in the second data with zero data, the accuracy of the first data is enhanced, and thereby interfered band can be avoided accurately.

[0017] The parallel-to-serial converter 140 converts the parallel transmission data to serial transmission data. The filter 150 receives the serial transmission data and filters unnecessary noises. The filter 150 can be a square-root raised cosine filter. The transmission-processing module 160 receives the transmission data, converts it to a radio-frequency signal, and then transmits the radio-frequency signal.

[0018] In addition, the interference-processing module 130 further includes an extension unit 132, a second fast Fourier transform unit 134, a selection unit 136, and a second inverse fast Fourier transform unit 138. The extension unit 132 adds the plurality of extension data to the first data for increasing its resolution and thus producing the second data, wherein the plurality of extension data can be a plurality of zero data. Besides, the larger the number of the plurality of extension data is, the higher the resolution of the first data is. The second fast Fourier transform unit 134 receives the second data and transforms the time-domain second data to frequency-domain second data, which is third data. The selection unit 136 identifies the plurality of data corresponding to an interfered band and replaces it with zeros with the other data remained unchanged for producing fourth data. The second inverse fast Fourier transform unit 138 transforms the frequency-domain fourth data to time-domain fourth data to produce the transmission data. The selection unit 136 can be a multiplexer, and according to a zero-tone selection signal, identifies the plurality of data corresponding to an interfered band in the third data and replaces it with zeros.

[0019] Besides, the transmission-processing module 160 further includes a digital-to-analog converter 162, a radio-frequency transmitter 164, and a transmission antenna 166. The digital-to-analog converter 162 converts the transmission data to analog transmission data. The radio-frequency transmitter 164 receives the analog transmission data as a radio-frequency signal, and then transmits the radio-frequency signal via the transmission antenna 166.

[0020] FIG. 2 shows the block diagram of a receiving apparatus according to a preferred embodiment of the present invention. As shown in the figure, the receiving apparatus 2 of the transmission system with interference avoidance capability according to the present invention includes a receiving-processing module 210, a filter 220, a serial-to-parallel converter 230, a removal unit 240, a first fast Fourier transform unit 250, a equalizer 260, a parallel-to-serial converter 270, and a decoder unit 280. The receiving-processing unit 210 receives the radio-frequency signal transmitted by the transmission apparatus, and converts the radio-frequency signal to received data. The filter 220, which can be a square-root raised cosine filter, filters noises of the received data. The serial-to-parallel converter 230 converts the received data to a parallel received data, and transmits it to the removal unit 240. The removal unit 240 removes the plurality of extension data from the received data, which means removing the added extension data to the first data by the extension unit 132 of the transmission apparatus 1, and thereby produces recovered data. The first fast Fourier transform unit 250 transforms the recovered data and produces output data. The equalizer 260 receives the output data and equalizes the output data for compensating the channel effects during data transmission. The parallel-to-serial converter 270 converts the parallel output data to serial output data. The decoder unit 280 decodes the output data and thus data transmission is completed.

[0021] Moreover, the receiving-processing module 210 further includes a receiving antenna 212, a radio-frequency receiver 214, and an analog-to-digital converter 216. The receiving antenna 212 receives the radio-frequency signal to the radio-frequency receiver 214. The radio-frequency receiver 214 converts the radio-frequency signal to received data. The analog-to-digital converter 216 converts the analog received data to digital received data.

[0022] FIG. 3 shows the spectrum diagram according to a preferred embodiment of the present invention. As shown in the figure, the application is OFDM used in UWB. The frequency band used by the UWB technology is between 3.1 GHz and 10.6 GHz, which is overlapped with the frequency 3.6 GHz used by WiMAX. Besides, the maximum bandwidth used by WiMAX is 20 MHz, thereby UWB has to avoid transmitting signals within the 20 MHz bandwidth of WiMAX for preventing signal interference. The present invention increases resolution of the input data of the transmission apparatus by adding the extension data. For example, the resolution of the input data is five, which divides the 20 MHz bandwidth into five frequency bands with 4 MHz-bandwidth each. When the extension data is added to the input data, the resolution of the input data is increased to ten, which divides the 20 MHz bandwidth into ten frequency bands with 2 MHz-bandwidth each. Thus, the resolution of the input data is increased and thereby the accuracy of the UWB technology is enhanced accordingly. That is, it is more capable of avoiding the 20 MHz-bandwidth.

[0023] Furthermore, because each data is a sinc-waveform in spectrum, when the resolution of the input data is increased, the sinc-waveform narrowed and the signal intensity of the sidelobes thereof decreases. Consequently, when the interference-processing module shuts necessary signals down, because of lower signal intensity of the sidelobes of the sinc-wave, the interference avoidance capability of the present invention is enhanced. As shown in FIG. 3, the interference avoidance capability of the present invention reaches 42 dB, which can prevent signal interference effectively.

[0024] To sum up, the transmission system with interference avoidance capability and the method thereof according to the present invention receives first data by means of an interference-processing module of a transmission apparatus and adds a plurality of extension data to the first data to produce second data for replacing a plurality of data corresponding to an interfered band in the second data with zero data, and then producing transmission data. The transmission data is converted to a radio-frequency signal by a transmission-processing module and transmitted to a receiving apparatus for receiving the radio-frequency signal. A removal unit of the receiving apparatus removes the extension data of input data for recovering the corresponding input data. Thereby, signal interference can be prevented by avoiding spectrum overlap regions.

[0025] Accordingly, the present invention conforms to the legal requirements owing to its novelty, unobviousness, and utility. However, the foregoing description is only a preferred embodiment of the present invention, not used to limit the scope and range of the present invention. Those equivalent changes or modifications made according to the shape, structure, feature, or spirit described in the claims of the present invention are included in the appended claims of the present invention.