WO2011089860A1 - Wireless relay device and wireless relay method - Google Patents

Abstract

Equipped with an RF-digital conversion unit (801) that obtains a digital IQ signal by converting an input RF signal into a digital signal after directly converting the RF signal into an I and Q baseband signal; digital signal processing units (802, 804) that separate the digital IQ signal, which was obtained in a donor unit by means of the aforementioned conversion, into the carrier unit of each antenna, respectively perform gain adjustment and/or delay adjustment on the separated digital signal, and re-synthesize the digital IQ signal after adjustment; digital IQ signal transmission/reception units (803, 806) that transmit and receive the digital IQ signal between the donor unit and a service unit; and a digital-RF conversion unit (805) that converts the input digital IQ signal into an analog signal, and directly converts the I and Q baseband signal that was obtained into an RF signal.

Description

Radio relay apparatus and radio relay method

The present invention relates to a radio relay apparatus and a radio relay method for relaying signals transmitted and received between a mobile communication radio base station and a mobile terminal.

The radio relay apparatus is an area in which a radio signal transmitted from a radio base station for mobile communication cannot reach a mobile communication service due to attenuation in a propagation path (an environment where a sufficient SINR for a mobile terminal cannot be obtained. For example, indoors This is a device installed for relaying to the shadow of a building or in a rural area), receiving a carrier signal attenuated in a radio propagation path (a radio signal transmitted from a radio base station), amplifying and retransmitting it. To the area.

In general, a radio signal relay method in a radio relay device is a method of down-converting a signal received by a donor unit to an intermediate frequency (IF) (frequency conversion to a low frequency) to a service unit using a coaxial cable. The method to relay is taken. Here, the service unit refers to a unit that performs wireless communication with a mobile terminal in a wireless relay device. On the other hand, a unit that performs radio communication with a service unit with a radio base station is called a donor unit.

FIG. 18 is an explanatory diagram illustrating a general configuration example of a wireless relay device. The example shown in FIG. 18 shows a configuration in which one or more service units are connected to one donor unit via a distributor using a coaxial cable. In the donor unit, when a downlink RF signal is received from a radio base station via an antenna duplexer (DUP: duplexer), a low noise amplification circuit (LNA: Low Noise Amplifier) is received for the received RF signal, By passing through an RF out-of-band filter (RF-BPF: RF-Band-Pass filter), noise other than the RF signal is removed and down-converted to an IF signal. The obtained IF signal is passed through an IF out-of-band filter (IF-BPF: IF-Band-Pass filter) to remove noises other than the IF signal, and then on the coaxial cable via the antenna duplexer (here, the service unit). (Toward). When the insertion loss due to the IF signal out-of-band filter is large, an amplifier (IF-AMP) is inserted before sending the IF signal as well as before sending the RF signal.

In the service unit, the downstream IF signal from the donor unit is received via the antenna duplexer, and the received IF signal is removed to the RF signal after removing noise other than the IF signal by the IF out-of-band filter. Conversion (frequency conversion to high frequency). Then, after removing the noise other than the RF signal through the RF out-of-band filter, the obtained RF signal is further amplified by an amplifier (RF-AMP) and directed from the antenna to the mobile terminal through the antenna duplexer. Sending out.

In the service unit, when an uplink RF signal is received from the mobile terminal from the antenna via the antenna duplexer, the received RF signal is similar to the downlink RF signal from the radio base station in the donor unit. In addition, noise other than the RF signal is removed using a low-noise amplifier circuit and an RF out-of-band filter, then down-converted to an IF signal, and the obtained IF signal is removed through the IF out-of-band filter to remove noise other than the IF signal. After that, it is sent out on the coaxial cable (in this case toward the donor unit) via the antenna duplexer.

The upstream IF signal (the signal obtained by converting the upstream RF signal from the mobile terminal into the IF band) transmitted from the service unit onto the coaxial cable is received via the antenna duplexer in the donor unit. In the donor unit, the received IF signal is up-converted to an RF signal after noise other than the IF signal is removed by an IF out-of-band filter in the same manner as the downlink IF signal from the donor unit in the service unit. After removing the noise other than the RF signal through the RF out-of-band filter, the obtained RF signal is further amplified by an amplifier (RF-AMP) and transmitted from the antenna to the radio base station through the antenna duplexer. is doing.

However, in the method of converting into an IF signal and relaying it using a coaxial cable in this way, attenuation due to the cable length and the influence of the thermal noise generated in the service unit on the SIR are problematic. Further, when the neighborhood noise is removed by BPF, the insertion loss is large, so that there is a problem that many amplifiers (RF-AMP and IF-AMP) are required.

By the way, in recent years, a method of digitizing IF signals and transmitting them using optical cables has also been adopted. However, when an IF signal is digitized, a high-speed digital processing signal is required, and there is a problem that gain and delay control cannot be performed in units of carriers simply by digitizing, and a fine area design cannot be performed. . In the future, wireless relay devices are expected to be able to perform gain and delay control in units of carriers, considering the case where the service is shifted from 3G (3rd Generation: 3rd generation mobile phone system) to LTE (Long Term Evolution). It is given as.

Patent Documents 1 and 2 are prior art documents related to a signal relay method in a wireless relay device. For example, in Patent Document 1, all radio waves from base stations arranged by a plurality of operating entities are received and amplified, branched into the number of operating entities, individually selected and amplified for each operating entity, and then combined and amplified. A wireless relay amplifying apparatus for sending to each operating entity mobile device is described.

Further, for example, in Patent Document 2, a high-frequency signal received from a base station or a communication system is converted into a digital signal by wired or wireless connection, and then unnecessary interference waves included in the high-frequency signal are removed by a digital signal processing unit. A private wireless distribution relay system is described in which an extension unit or a remote unit is connected to the output end.

JP 2000-031879 A JP 2006-186997 A

The radio relay device is used to relay radio signals from a radio base station to an area where the mobile communication service does not reach in this way. Since the amount of propagation attenuation differs depending on the frequency, the input of the donor unit of the wireless relay device has different levels and C / N carrier groups for each carrier. Many of the radio relay apparatuses perform power control so that the total power value of the carrier signal group is constant at the service unit output end. That is, it operates with a fixed amplification gain.

For example, when the reception level of the input carrier signal group is −50 dBm at the end of the donor unit, amplification of 60 dB is performed so as to be +10 dBm. Similarly, the signal from the terminal is subjected to constant amplification and is output from the donor unit and sent to the base station.

FIG. 19 is an explanatory diagram showing an installation example of the wireless relay device. FIG. 19 shows an example of a radio relay apparatus that relays a carrier signal from a base station A for mobile communication and a carrier signal from a base station B in a building. FIG. 19 shows an example of a radio relay apparatus including one donor unit 901 and three service units 902-1 to 902-3. FIG. 20 is an explanatory diagram showing the level relationship in the radio relay apparatus when carrier signals for different services are mixedly transmitted from different base stations. In FIG. 20, one carrier signal for the purpose of service B is transmitted from the base station A, and a total of two carrier signals, a carrier signal for the purpose of service A and a carrier signal for the purpose of service C, are transmitted from the base station B. An example of transmission is shown. FIG. 20A is an explanatory diagram illustrating the relationship among the radio relay device, the base station, and the terminal. FIG. 20B is an explanatory diagram showing the input level (reception level) of each carrier signal in the wireless relay device. Moreover, FIG.20 (c) is explanatory drawing which shows the output level (transmission level) of each carrier signal in a radio relay apparatus.

In the example shown in FIG. 20, since the service A has a long distance from the base station and a wide bandwidth, the gain control for the C / N required by the terminal is larger than that of the service B and the service C. Suppose there is. Many radio relay apparatuses have a problem that radio capacity deteriorates due to interference with terminals other than the service unit because constant amplification is performed on a plurality of carrier groups. In addition, when there is a carrier signal that can be received at a relatively high level (for example, a carrier signal for service B), a necessary carrier signal (for example, for performing amplification so that the carrier signal does not exceed the peak level). Further, there is a problem that sufficient gain control is not performed on the carrier signal of service A and the terminal may not reach the terminal.

In addition, when amplifying in units of carriers that are used for different purposes such as data and voice, a plurality of relay apparatuses for relaying the respective carrier signals have been installed.

Regarding such a problem, for example, if the wireless relay amplification device described in Patent Document 1 is used, it can be selected and amplified individually for each operating entity. However, the wireless relay amplification device described in Patent Document 1 has a configuration in which a carrier signal is branched, amplified, combined, and relayed as an analog signal.

In general, a radio signal from a mobile base station is greatly attenuated in a propagation path, and the attenuation amount is expressed by the following equation (1). Here, d represents the distance [m], f represents the frequency [Hz], and c represents the speed of light (3.0 × 10 ⁸ ).

Loss = 20 log (4πdf / c) (1)

For example, when it is 10 km away from the base station to be communicated, it arrives after being attenuated by 111.5 dB in the 2 GHz band. For example, if the base station that is not the target is 100 m away, the radio signal is 78.5 dB. Reach with a decay of. This 40 dB level difference is a major interference for mobile communication wireless relay. In the wireless relay device, a filter having a steep out-of-passband attenuation is required in order to remove interference signals from different base stations. In general, when the filter is required to be steep, attenuation of the desired wave increases, so that a multistage amplifier is required, resulting in a problem that the scale of the analog circuit increases.

In Patent Document 2, after converting a received high-frequency signal into a digital signal, an unnecessary interference wave included in the high-frequency signal is removed by a digital signal processing unit, and an extension unit or a remote unit is connected to the output end thereof A local wireless distribution relay system is described. However, the local wireless distribution relay system described in Patent Document 2 is a cable with a high frequency (bit rate) when digital signals are transmitted between a donor unit and a service unit (an extension unit or a remote unit). No consideration is given to degradation due to transmission. For example, when converting to a digital signal, it is required to send at a bit rate as low as possible in cable transmission, but by simply converting a received high-frequency signal downconverted to an intermediate frequency into a digital signal by an A / D converter Since the signal bandwidth for digital conversion is wasted, the amount of transmission data is increased. Also, the processing capability of the conversion unit is required. For this reason, degradation due to cable transmission may occur.

Therefore, an object of the present invention is to make it possible to obtain a stable received signal on the terminal side without installing a different radio relay apparatus for each carrier used for different purposes. More specifically, with a single wireless relay device, a plurality of carrier groups used for different purposes transmitted from a single or a plurality of base stations are amplified while suppressing deterioration of wireless capacity due to amplification and relay distance. An object of the present invention is to enable relaying so that a stable received signal can be obtained on the terminal side.

A radio relay apparatus according to the present invention is a radio relay apparatus installed between a single or a plurality of mobile communication base stations and terminals, a donor unit that performs radio communication with a base station side, One or a plurality of service units that perform communication, and the donor unit and the service unit are connected via a cable, and the donor unit directly converts the input RF signal into I and Q baseband signals. An RF-to-digital converter that obtains a digital IQ signal by converting it into a digital signal, and a downlink digital IQ signal are separated into carrier units for each antenna, and gain or delay with respect to the separated digital signal, or both, respectively. A downlink digital signal processing unit that re-synthesizes a digital IQ signal from the adjusted separated digital signal, and a service Digital IQ signal transmission / reception unit that transmits / receives digital IQ signals to / from the unit, and uplink digital IQ signals are separated in units of carriers for each antenna, and gain and / or delay for each separated digital signal An uplink digital signal processing unit that re-synthesizes the digital IQ signal from the adjusted separated digital signal, converts the input digital IQ signal into an analog signal, and converts the obtained I and Q baseband signals The service unit includes a digital IQ signal transmission / reception unit that transmits / receives a digital IQ signal to / from the donor unit and is input. Converts digital IQ signals to analog signals and directly converts the resulting I and Q baseband signals to RF signals A digital-RF converter for obtaining an RF signal, and an RF-digital converter for obtaining a digital IQ signal by directly converting the input RF signal into an I and Q baseband signal and then converting the digital signal to a digital signal It is characterized by including.

A radio relay method according to the present invention is a radio relay method applied to a radio relay device installed between a single or a plurality of mobile communication base stations and a terminal. RF-to-digital conversion step for direct conversion to a baseband signal of Q and Q, and conversion to a digital signal, and a digital IQ signal obtained by the conversion by a donor unit that communicates with the mobile communication base station side for each antenna A digital signal processing step of separating the digital signal into individual carrier units, adjusting the gain and / or delay of each of the separated digital signals, and re-synthesizing the digital IQ signal from the separated separated digital signal; A digital-to-RF conversion step that converts an IQ signal to an analog signal and directly converts the resulting I and Q baseband signals to an RF signal. Characterized in that it comprises and.

According to the present invention, it is possible to obtain a stable received signal on the terminal side without installing a different radio relay device for each carrier used for different purposes.

It is a block diagram which shows the structural example of the radio relay apparatus of 1st Embodiment. 3 is a block diagram illustrating a configuration example of a donor unit 100. FIG. 3 is a functional block diagram illustrating a configuration example of a downlink digital processing unit 10. FIG. 2 is a block diagram illustrating an embodiment of a digital filter 9 and a downlink digital processing unit 10. FIG. It is explanatory drawing which shows the difference in the transmission amount (transmission signal bandwidth) by a modulation system. 2 is a block diagram illustrating a configuration example of a service unit 200. FIG. 3 is a functional block diagram illustrating a configuration example of an uplink digital processing unit 13. FIG. FIG. 3 is a block diagram illustrating an example of an uplink digital processing unit 13 and a digital filter 12. It is explanatory drawing which shows the example of a carrier leak jamming wave and an I and Q image jamming wave. It is explanatory drawing which shows the example of the gain adjustment in a carrier unit. It is explanatory drawing which shows the example of the gain adjustment in a carrier unit. It is explanatory drawing which shows the relationship between the gain adjustment of a carrier unit, and the downlink digital process part. 4 is an explanatory diagram illustrating an example of signal processing in a delay adjustment unit 104 of a downlink digital processing unit 10. FIG. FIG. 3 is a block diagram illustrating an example of a donor unit 100. It is a block diagram which shows the other structural example of a radio relay apparatus. FIG. 3 is a block diagram illustrating a configuration example of a signal synthesis / distribution unit 300. It is explanatory drawing which shows the characteristic of this invention. It is explanatory drawing which shows the general structural example of a radio relay apparatus. It is explanatory drawing which shows the example of installation of a radio relay apparatus. It is explanatory drawing which shows the level relationship in a radio relay apparatus in case the carrier signal aiming at a different service is mixed and transmitted from a different base station.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of a wireless relay device according to the present embodiment. The radio relay apparatus shown in FIG. 1 includes a donor unit 100 that performs radio communication with a base station side and one or a plurality of service units 200 that perform radio communication with a terminal side. The donor unit 100 and each service unit 200 are connected by an optical cable, a LAN cable, or the like. With such a configuration, the radio signal from the base station received by the donor unit 100 is relayed to the area where each service unit 200 is installed.

The donor unit 100 performs radio communication with a single or a plurality of base stations, digitizes the received radio signal (RF signal) and relays (transmits) it to the service unit 200. Also, the donor unit 100 demodulates (converts) the RF signal received after being synthesized into the I and Q baseband signals without converting them into IF frequencies, and converts them into digital signals. The digital signal thus obtained (hereinafter referred to as digital I / Q signal) is separated for each carrier, and the gain and delay are adjusted according to the traffic amount and capacity on the service unit side, and again. The digital I / Q signal is combined and relayed as a digital carrier signal.

The service unit 200 converts the digital carrier signal received from the donor unit 100 into an RF signal and sends it to a terminal under the service. The service unit 200 modulates the I and Q baseband signals obtained by converting the digital carrier signals into analog signals into RF signals.

FIG. 2 is a block diagram illustrating a configuration example of the donor unit 100. The donor unit 100 shown in FIG. 2 includes one or more antennas 1, an antenna duplexer (duplexer) 2, a low noise amplifier (LNA) 3, out-of-band filters (BPF) 4, 5, and an amplifier (PA ) 6, quadrature demodulation unit 7, quadrature modulation unit 8, digital filters 9 and 12, downlink digital processing unit (DL digital processing unit) 10, uplink digital processing unit (UL digital processing unit) 12, Serial converters 11 and 14. In the case where a plurality of antennas 1 are provided due to diversity or MIMO (Multi-Input Multi-Output) configuration, the antenna duplexer 2, the low noise amplifier 3, the out-of-band filter 4, the quadrature modulation unit 7, and the out-of-band filter 5 are provided. A plurality of amplifiers 6 and quadrature demodulation units 8 may be provided in accordance with the antenna configuration.

In the example shown in FIG. 2, for signal transmission in the downlink (link from base station to terminal), antenna 1, antenna duplexer 2, low noise amplifier 3, out-of-band filter 4, orthogonal demodulator 7, These are connected in the order of the digital filter 9, the downlink digital processing unit 10, and the serial conversion unit 11. In order to perform signal transmission in the uplink (link from the terminal to the base station), the serial conversion unit 14, the uplink digital processing unit 13, the digital filter 12, the quadrature modulation unit 8, the amplifier 6, the out-of-band filter 5, The antenna duplexer 2 and the antenna 1 are connected in this order. The antenna 1 is shared by the antenna duplexer 2 for transmission and reception.

First, each part will be described regarding signal transmission in the downlink. The antenna 1 receives a radio signal from the base station. The duplexer 2 is an antenna duplexer for sharing the antenna 1 for transmission and reception, and electrically separates the transmission path and the reception path. The low noise amplifier 3 is a low noise amplifier that selects and amplifies an input signal. The out-of-band filter 4 is a filter circuit that passes only a specific frequency band and attenuates other frequencies. The received radio signal (RF signal) is amplified by the low noise amplifier 3, and the interference wave (such as a radio wave of another operator or a radio signal in another band) is removed by the out-of-band filter 4.

The orthogonal demodulator 7 directly demodulates (down-converts) the RF signal into I and Q baseband signal bands, and converts the obtained I and Q signals into digital signals. The quadrature demodulator 7 includes, for example, a frequency oscillator 71, multipliers 72 and 73 and low-pass filters (LPF) 74 and 75 corresponding to the I and Q signals, and an analog-digital converter (ADC) 78, for example. The Although not shown, an orthogonal correction circuit may be further provided after the analog-digital converter 78. The orthogonal correction circuit removes an image (I, Q image interference wave) generated due to a mismatch in amplitude and phase of the I and Q signals by the direct demodulation method.

The digital filter 9 removes noise other than the baseband from the digital I / Q signal digitized by the orthogonal demodulation unit 7. Here, the aliasing interference wave having the sampling frequency generated in the downlink digital processing unit 10 is mainly removed. The digital I / Q signal can be handled separately as a digital signal I signal and a Q signal or collectively as a complex number.

The downlink digital processing unit 10 separates the input digital I / Q signal into carrier units to be relayed to the service unit, and adjusts the carrier-separated signal for each antenna according to the situation under the service antenna. The gain is adjusted, the delay is adjusted, and the digital I / Q signal is synthesized again and output as a digital carrier signal.

FIG. 3 is a functional block diagram illustrating a configuration example of the downlink digital processing unit 10. In the example shown in FIG. 3, the downlink digital processing unit 10 includes a digital carrier / antenna separation unit 101, a separated carrier-specific digital filter 102 (102-1 to 102-n), and a gain adjustment unit 103 (103- 1 to 103-n), a delay adjusting unit 104 (104-1 to 104-n), and a digital carrier / antenna combining unit 105.

The digital carrier / antenna separation unit 101 separates the input digital I / Q signal into carrier units for each antenna. Note that the information on the carrier to be separated may be arbitrarily set to a deviation (Fa) from 0 Hz and a bandwidth (Fb), for example, F0 (0 Hz) + Fa, + Fb. The digital filter 102 removes unnecessary signals from the separated carrier unit signals. Thereby, a desired carrier component is taken out. Each gain adjusting unit 103 changes the gain of the digital signal corresponding to the input one carrier component. Depending on the gain change performed by the gain adjusting unit 103, the presence / absence of relaying is set. Each delay adjustment unit 104 performs delay adjustment on the input digital signal corresponding to one carrier component. The delay adjustment unit 104 performs delay adjustment by inserting a delay time (multiplying an arbitrary time delay) into the input digital signal as necessary. The digital carrier / antenna combining unit 105 multiplexes the digital signals separated in units of carriers, recombines the digital I / Q signals, and outputs them as digital carrier signals that are relayed to the service unit 200.

FIG. 4 is a block diagram showing an embodiment of the digital filter 9 and the downlink digital processing unit 10. In the embodiment shown in FIG. 4, the digital filter 9 and the downlink digital processing unit 10 are realized by an FPGA (Field Programmable Gate Array) 40.

In the example shown in FIG. 4, first, FIR filters (FIR1: Finite Impulse Response Filter) 401 and 402 corresponding to I and Q are provided to remove the return wave from the ADC. The signals that have passed through the FIR filters 401 and 402 are input to the subsequent multipliers 403 and 404. Offset signals (signals for digitally offsetting the frequency) from NCO (Numerically Controlled Oscillators) 405 and 406 are input to the multipliers 403 and 404, respectively. A desired carrier component is extracted by the sum calculation (carrier separation calculation) by the multipliers 403 and 404. Subsequent FIR filters (FIR2, FIR3) 407 and 408 remove unnecessary signals, respectively. Thereafter, the signals are input to gain controllers (Gain) 409 and 410 as carrier unit signals, respectively, and gain adjustment is performed. The gain controllers 409 and 410 each adjust the gain by changing the amplitude of the input signal. The amplitude is changed by, for example, arithmetic processing on a digital signal. After such gain adjustment, the signals are again passed through the multipliers 411 and 412, and then input to a delay insertion unit (Delay Insertion) 413, and delay adjustment is performed as necessary. For example, when the cable length between the donor unit and the service unit is different, the delay insertion unit 512 may insert a delay for correcting a delay difference due to the cable length. Further, for example, a delay may be individually inserted into a carrier unit signal that requires a delay, such as MIMO and antenna diversity transmission. Note that the delay time to be inserted may be variable by setting, for example. Thereafter, the multiplexer (MUX) 414 multiplexes the digital signals corresponding to the respective carrier components, re-synthesizes the digital I / Q signal, and outputs it as a digital carrier signal to be relayed to the service unit 200. Note that signal processing for each carrier may be performed by parallel processing of programs.

The serial conversion unit 11 converts the input digital carrier signal into a serial signal and sends it to the service unit 200 which is a connection destination. The serial signal may be a Gigabit Ethernet (registered trademark) signal (gigabit Ethernet signal) as long as it is 1 Gbit / sec or less, for example. In this case, a physical interface (such as GpE-PHY in FIG. 4) that transmits a Gigabit Ethernet signal may be used for signal transmission.

FIG. 5 is an explanatory diagram showing the difference in transmission amount (transmission signal bandwidth) depending on the modulation method. FIG. 5A is an explanatory diagram illustrating an example of a transmission amount when transmission is performed in the RF frequency band without conversion (RF frequency relay). FIG. 5B is an explanatory diagram showing an example of the transmission amount when converted to the IF frequency band (IF frequency conversion). FIG. 5C is an explanatory diagram illustrating an example of a transmission amount when converted by a direct modulation method (also referred to as Zero IF method, direct conversion method, or I / Q conversion). As shown in FIG. 5 (a), when the RF frequency band is 2 GHz and the bandwidth is 20 MHz, if an RF signal is transmitted as it is, the signal band that must be transmitted is 0 to 2 GHz + 10 MHz. An extra signal band is included with respect to the bandwidth of 20 MHz. Further, as shown in FIG. 5B, when the IF frequency band is converted to 140 MHz and transmitted, it is 0 to 140 MHz + 10 MHz, and the signal band that must be transmitted is narrower than that in FIG. 5A. But still includes extra signal bandwidth. On the other hand, as shown in FIG. 5C, in the direct modulation method employed in the present invention, the signal band that must be transmitted is 20 MHz, which is the same as the actual signal bandwidth, and the extra signal band is Not included. In this manner, by minimizing the signal band for digital conversion, transmission at a low bit rate is possible while reducing the processing capability required for the conversion unit.

Next, the configuration on the service unit side regarding signal transmission in the downlink will be described. FIG. 6 is a block diagram illustrating a configuration example of the service unit 200. The service unit 200 includes serial conversion units 21 and 22, digital filters 23 and 24, quadrature modulation units 25 and 26, an amplifier 27, out-of- band filters 28 and 29, a low noise amplifier 30, and an antenna duplexer 31. And an antenna 32.

In the example shown in FIG. 6, in order of signal transmission in the downlink, the serial conversion unit 21, the digital filter 23, the quadrature modulation unit 25, the amplifier 27, the out-of-band filter 28, the antenna duplexer 31, and the antenna 32 are arranged in this order. These are connected. In order to perform signal transmission in the uplink, the antenna 32, the antenna duplexer 31, the low noise amplifier 30, the out-of-band filter 29, the orthogonal demodulation unit 26, the digital filter 24, and the serial conversion unit 22 are connected in this order. ing. The antenna 32 is shared by the antenna duplexer 31 for transmission and reception.

The serial conversion unit 21 receives the digital serial signal transmitted from the donor unit 100 and assembles it into a digital carrier signal. Thereafter, the digital filter 23 and the quadrature modulation unit 25 directly convert the input digital carrier signal into an RF signal (more specifically, the analog signal is converted into an I and Q baseband signal and then directly converted into the RF signal. Convert). The amplifier 27 amplifies the RF signal obtained by the quadrature modulation unit 25. The out-of-band filter 28 removes out-of-band signals. The RF signal obtained in this way is transmitted from the antenna 32 through the antenna duplexer 31.

Thus, in each service unit 200, the digital carrier signal sent from the donor unit 100 may be converted into an analog signal and then orthogonally modulated again before being transmitted. This is because the digital carrier signal sent from the donor unit has already been gain-adjusted to the power required for service and diversity-combined after delay adjustment between antennas. For this reason, the circuit on the service unit side can be simplified. Further, since gain adjustment includes control of presence / absence of relaying, noise and interference can be minimized by relaying only necessary carriers.

Next, each part will be described regarding signal transmission in the uplink. The signal processing in the uplink is basically the same as that obtained by inverting the relationship between the donor unit 100 and the service unit 200 in the downlink. However, the gain adjustment and delay adjustment for each carrier are performed by the donor unit 100 as in the downlink. That is, the signal from the terminal is converted into a digital signal (digital I / Q signal) corresponding to the I and Q baseband signals by each service unit 200 and then transmitted to the donor unit 100 by cable as a digital carrier signal.

More specifically, each service unit 200 receives a radio signal (RF signal) from the terminal by the antenna 32 and then divides it into transmission and reception by the antenna duplexer 31. The received RF signal is amplified by the low noise amplifier 30 and the interference wave (radio signal of other business operator, radio signal such as TV band) is removed by the out-of-band filter 29. Then, the signal is directly converted into I and Q baseband signals by the orthogonal demodulator 26 and digitized. At that time, the I / Q image generated by the orthogonal demodulation may be removed by the correction circuit. The digitized I / Q baseband signal is input to the digital filter 24, and the digital filter 24 removes interference waves (here, mainly sampling frequency aliasing). The digital I / Q signal thus obtained is converted into a serial format (for example, a Gigabit Ethernet signal) by the serial conversion unit 22 and transmitted as a digital carrier signal to the donor unit 100 which is a connection destination.

In the donor unit 100, a digital carrier signal received from each service unit, that is, a digital I / Q signal is separated into carrier units, gain adjustment and delay adjustment are performed, and a digital I / Q signal obtained by synthesizing the signals again. Is converted into an analog signal, converted directly into an RF signal, and transmitted to the base station.

More specifically, the donor unit 100 receives a digital carrier signal (that is, a digital I / Q signal) serially transmitted from each service unit 200 by the serial conversion unit 14. Thereafter, the uplink digital processing unit 13 separates the digital I / Q signal into carriers, adjusts the signal level to be relayed to the base station by performing delay adjustment and gain adjustment, and then synthesizes again. For the digital I / Q signal obtained by synthesis, the digital filter 12 removes unnecessary waves outside the transmission band (in this case, mainly the folding of the sampling frequency), while the quadrature modulation unit 8 converts it to an analog signal. Directly converted to RF signal after conversion. Then, after being amplified by the amplifier 6, unnecessary signals are removed through the out-of-band filter 5 and transmitted from the antenna 1 to the base station through the antenna duplexer 2.

FIG. 7 is a functional block diagram illustrating a configuration example of the uplink digital processing unit 13. As shown in FIG. 7, the digital carrier / antenna separation 131, the separated carrier-specific digital filters 132 (132-1 to 132-n), the delay adjustment unit 133 (133-1 to 133-n), and the gain adjustment Unit 134 (134-1 to 134-n), power clipping unit 135 (135-1 to 135-n), and digital carrier / antenna combining unit 136.

The digital carrier / antenna separation unit 131, the digital filter 132, the delay adjustment unit 133, the gain adjustment unit 134, and the digital carrier / antenna combination unit 136 are the digital carrier / antenna separation unit 101 and the digital filter 102 in the downlink processing unit 10, respectively. The delay adjustment unit 104, the gain adjustment unit 103, and the digital carrier / antenna combination unit 105 are the same.

The uplink has a power clipping unit 135 to suppress distortion due to peak power during synthesis. The carrier unit signal is subjected to gain adjustment, reduced in peak power by power clipping 135, and then recombined into a digital I / Q signal by a digital carrier / antenna combining unit 136. The I / Q digital signal obtained by the synthesis is directly converted into an RF analog signal by the quadrature modulation unit 8 after unnecessary waves outside the transmission band are removed by the digital filter 12. Then, after being amplified by the amplifier 6, unnecessary signals are removed through the out-of-band filter 5 and transmitted from the antenna 1 to the base station through the antenna duplexer 2.

FIG. 8 is a block diagram showing an embodiment of the uplink digital processing unit 13 and the digital filter 12. In the embodiment shown in FIG. 8, the uplink digital processing unit 13 and the digital filter 12 are realized by an FPGA.

In the example shown in FIG. 8, firstly, multipliers 502 and 503 for inputting a digital carrier signal (digital I / Q signal) input from the serial conversion unit 14 are provided in the previous stage. The multipliers 502 and 503 receive the offset signals from the NCOs 504 and 505, respectively. A desired carrier component is extracted by the sum calculation (carrier separation calculation) by the multipliers 504 and 505. Subsequent FIR filters (FIR2, FIR3) 506 and 507 remove unnecessary signals, respectively. Thereafter, the signals are input to gain controllers (Gain) 508 and 509 as carrier unit signals, respectively, and gain adjustment is performed. After the gain adjustment, the signals are again passed through the multipliers 510 and 511, and then input to the delay insertion unit 512, and the delay adjustment is performed as necessary. After delay adjustment is performed, a multiplexer (MUX) 513 multiplexes digital signals corresponding to each carrier component, and re-synthesizes the digital I / Q signal. In the subsequent stage, FIR filters (FIR1) 514 and 515 corresponding to I and Q are provided, and a digital I / Q signal from which unnecessary waves are removed is output to the quadrature modulation unit 8. A peak controller (Peak Controller) that performs peak control may be provided before the delay insertion unit 512.

Next, the digitization of the wireless carrier signal in this embodiment will be described more specifically. In this embodiment, in order to greatly reduce the analog circuit scale, the radio signal is directly based on the orthogonal demodulator 7 of the donor unit 100 in the downlink and the orthogonal demodulator 26 of the service unit 200 in the uplink. Demodulate to band I and Q signals. Such a method is generally used for a mobile terminal as a direct modulation method (direct conversion method) or a Zero-IF method. However, carrier leaks and IQ image interference waves caused by the orthogonal error of the orthogonal demodulation unit become problems, and the required specifications. Have been shunned by harsh wireless repeaters and base stations. In the present embodiment, the out-of-band signal generated after demodulation in the quadrature demodulator is first digitized after being removed by an analog LPF ( LPF 74, 75, 264, 265), and the out-of-band signal generated after the digitization is digitally filtered ( It is removed by digital filters 9, 24). This problem is avoided by adopting a filter system in which the digital filters (digital filters 9 and 24) provided in the subsequent stage of the quadrature demodulation unit are complex multiplied by I and Q, respectively.

FIG. 9 is an explanatory diagram showing examples of carrier leak jamming waves and I and Q image jamming waves. In FIG. 9, an arrow indicated by a is a carrier leak interference wave, and an arrow indicated by b is an IQ image interference wave. The carrier leak is also called a DC leak, and is a DC noise component in which a local signal leaks to the IQ baseband in I / Q conversion (demodulation). The IQ image is an interference wave that appears as shown in FIG. 9 according to the amount of deviation when the phase difference (90 degrees) and the amplitude difference between the local signals of I and Q are deviated from zero in quadrature demodulation. Since these interference waves appear as an image in the pass band, the band elimination filter cannot take measures. In the present embodiment, not only has a correction circuit for removing an I / Q image generated by quadrature demodulation in the subsequent stage of the analog-digital converter, but also a filter system that feeds back I and Q and performs complex multiplication in the digital filter. By adopting it, it is possible to perform signal multiplication to erase each other's image.

Thus, by adopting an orthogonal modulation method that avoids carrier leaks and IQ image interference waves, the signal band for digital conversion is minimized. Thereby, the processing capability of the digital conversion unit can be reduced, and the transmission rate with the service unit 200 can be set to a low bit rate.

Next, an example of gain adjustment and delay adjustment for each carrier will be described. 10 and 11 are explanatory diagrams illustrating an example of gain adjustment in units of carriers. 10 and 11 show the frequency spectrum (relationship between frequency and level) of the input and output from the wireless relay device.

FIG. 10 shows an example of installation in an environment in which base station A transmits CDMA-1X system 7 carriers and base station B transmits CDMA-EVDO system 3 carriers. As shown in the graph at the time of input in FIG. 10A, the input level of the radio signal in the radio relay apparatus is higher than the CDMA-1X system 7 carrier from the base station A, compared with the CDMA-EVDO system from the base station B. Suppose 3 carriers were low.

In such a case, as shown in the graph at the time of output in FIG. 10 (a), as the interference reduction and level adjustment of the EVDO signal from the base station B, the adjacent carrier from the base station A is relayed OFF. The gain of each carrier of the EVDO system signal from the base station B may be increased and relayed to each service unit.

FIG. 11 shows an example in which an LTE system 1 carrier is transmitted from the base station A and a CDMA system 3 carrier is transmitted from the base station B. As shown in the graph at the time of input in FIG. 11B, the radio signal reception level in the radio relay apparatus is lower in the LTE system 1 carrier from the base station A than in the CDMA system 3 carrier from the base station B. Suppose.

In such a case, as shown in the graph at the time of output of FIG. 11B, the adjacent carrier of the base station A is relayed OFF as interference reduction and level adjustment from the base station B to the LTE signal. The gain of the EVDO signal from the base station B may be increased and relayed to each service unit.

FIG. 12 is an explanatory diagram showing the relationship between the example of gain adjustment for each carrier shown in FIG. 11 and the downlink digital processing unit 10. FIG. 12 illustrates an example of signal processing in the gain adjustment unit 103 of the downlink digital processing unit 10 in the donor unit 100. In the example shown in FIG. 12, the CDMA3 carrier is transmitted from the base station A and the LTE1 carrier is transmitted from the base station B. In the downlink digital processing unit 10, the digital filter 102 corresponding to each carrier, the gain An adjustment unit 103 and a delay adjustment unit 104 are provided. In the digital carrier / antenna separation 101, a desired signal is extracted by the subsequent digital filter 102 by performing up-down conversion of one of 0 Hz by digital processing.

In this example, it is assumed that the CDMA carrier 1 is associated with the digital filter 102-1, the gain adjusting unit 103-1, and the delay adjusting unit 104-1. The CDMA carrier 2 is associated with the digital filter 102-2, the gain adjustment unit 103-2, and the delay adjustment unit 104-2. Further, it is assumed that the CDMA carrier 3 is associated with the digital filter 102-3, the gain adjustment unit 103-3, and the delay adjustment unit 104-3. In addition, it is assumed that LTE is associated with the digital filter 102-4, the gain adjustment unit 103-4, and the delay adjustment unit 104-4.

In such a case, in order to obtain an output as shown in FIG. 11B, for example, the gain adjusting unit 103-1 sets the gain to 0 with respect to the digital signal corresponding to the CDMA carrier 1 component. Control to turn off (erase). Further, for example, the gain adjusting unit 103-2 and the gain adjusting unit 103-2 perform control to reduce the gain by 1 dB for the input digital signal corresponding to the carrier 2 or carrier 3 component of CDMA. Further, for example, the gain adjustment unit 103-4 performs control to increase the gain by 3 dB with respect to the digital signal corresponding to the LTE carrier component.

The adjustment value of the gain may be determined by setting, or at the input of the donor unit 100, the pilot signal quality of the base station is measured, and the gain calculation for keeping the level at the service output constant is performed by the CPU or the like. Automatic gain control can also be performed based on this.

As another example of the adjustment case, when a plurality of carriers of the same system are relayed, it is also possible to control to select only a certain carrier and increase the gain. For example, when there are four W-CDMA signals, only the carrier used for HSDPA (high-speed data communication) may be selected and controlled to increase (amplify) the gain.

Also, the adjustment method may be fixed adjustment by external setting or automatic adjustment. When performing the fixed adjustment, the gain value may be held in advance in each gain adjustment unit, or the gain value may be set (input) from the outside. When performing automatic adjustment, the donor unit 100 may have a quality measurement unit (not shown) that receives a radio signal from the base station and measures reception quality. Based on the pilot signal multiplexed on the radio signal from the base station, it is determined whether or not the signal is a signal to be relayed. If the signal is a relay target (a signal that is permitted to be relayed), the Ec of the pilot signal is determined. / No (signal-to-noise ratio) and the input level may be used to determine the gain range for control.

Further, the status under the service antenna is determined by measuring the amount of uplink traffic or by notification from the service unit 200, and when it is determined that there are many subscribers (mobile stations) under the service unit, the gain is increased. Such control may be performed.

In addition, when it is desired to improve the throughput of the data service, the LTE gain may be increased and the CDMA gain may be decreased. Further, the gain can be varied according to the presence or absence of data.

Also, gain adjustment can be performed based on the output value at the antenna output end on the service unit side. For example, if the service unit output is less than the maximum value after gain adjustment by the above method, the gain adjustment value may be increased. The service unit 200 periodically measures the output level and notifies the result to the donor unit 100. Based on the notified output level, the donor unit 100 may perform control such as increasing the gain value if it is below the threshold value or decreasing the gain value if it is above the threshold value.

The gain adjustment can be performed not only by the donor unit 100 but also by the service unit 200 individually. If the service unit 200 measures the input level and statistically processes the input level and determines that the level is high, the service unit 200 may perform control such as changing the individual gain assuming that the traffic amount is large.

Also, for example, when a MIMO signal is relayed with two antennas, delay adjustment as shown in FIG. 13 may be performed. FIG. 13 is an explanatory diagram illustrating an example of signal processing in the delay adjustment unit 104 of the downlink digital processing unit 10. In the example shown in FIG. 13, delay diversity (a system that intentionally transmits buses having different delay times) is used as an SIR improvement of a non-MIMO CDMA signal in the LTE MIMO signals received by antenna # 1 and antenna # 2. This is an example of transmission.

In the example shown in FIG. 13, the antenna # 1 receives an LTE MIMO signal and a CDMA3 carrier, and the antenna # 2 receives an LTE MIMO signal. The downlink digital processing unit 10 receives each carrier for each antenna. A corresponding digital filter 102, gain adjustment unit 103, and delay adjustment unit 104 are provided.

In this example, it is assumed that the CDMA carrier 1 is associated with the digital filter 102-1, the gain adjusting unit 103-1, and the delay adjusting unit 104-1. The CDMA carrier 2 is associated with the digital filter 102-2, the gain adjustment unit 103-2, and the delay adjustment unit 104-2. Further, it is assumed that the CDMA carrier 3 is associated with the digital filter 102-3, the gain adjustment unit 103-3, and the delay adjustment unit 104-3. Further, it is assumed that LTE1 (LTE MIMO signal received by antenna # 1) is associated with digital filter 102-4, gain adjustment unit 103-4, and delay adjustment unit 104-4. Further, it is assumed that LTE2 (LTE MIMO signal received by antenna # 2) is associated with the digital filter 102-5, the gain adjustment unit 103-5, and the delay adjustment unit 104-5.

In such a case, in order to delay-divide the CDMA signal of the non-MIMO signal, for example, the delay adjustment unit 104-1, the delay adjustment unit 104-2, and the delay adjustment unit 104-3 input each CDMA carrier component. Delay processing for inserting a predetermined delay time may be performed on the digital signal corresponding to the above.

Note that the delay adjustment can be performed not only for delay diversity of a CDMA signal of a non-MIMO signal but also for adjustment of a delay amount generated from a cable length between a donor unit and a service unit. In such a case, the delay amount may be set according to the cable length with the service unit as the transmission destination. For example, when a plurality of service units are connected and the distance between the service unit and the donor unit is different from 10 m, 1 km, and 2 km, the delay on the service unit side is set so that the delay difference due to this distance becomes zero. insert. In the case of this example, a delay equivalent to 1990 m is inserted for a signal to a service unit 10 m away, a delay equivalent to 1000 m is inserted for a signal to a service unit 1 km away, and a service unit 2 km away The delay adjustment may be performed so that the delay to zero is zero. Such a delay amount may be set in the service unit based on the setting from the donor unit or the result of measuring the cable length by a signal synthesis / distribution unit described later.

In the above example, gain adjustment and delay adjustment in the downlink have been described, but the same adjustment may be performed for the uplink.

FIG. 14 is a block diagram showing an example of the donor unit 100 of this embodiment. The donor unit 100 shown in FIG. 14 includes an RF front end unit 1001, an RF-digital modem 1002, a broadband-digital processor 1003, and an interface / power supply unit 1003.

The RF front end unit 1001 includes an antenna 1, an antenna duplexer 2, a low noise amplifier 3, out-of-band filters 4 and 5, an amplifier 6, and a pulse density modulator (PDM) 1005. The RF-digital modem 1002 includes components of the quadrature demodulator 7, a quadrature correction processing unit 77, components of the quadrature modulation unit 8, a quadrature correction processing / peak control unit 87, and a PLL (Phase Locked Loop). Circuit 1006. The baseband-digital processor 1003 includes a digital up / down converter 1007, a downlink filter / gain control / delay control unit 1008, a digital signal multiplexing / demultiplexing / serial conversion unit 1009, and a digital up / down converter 1010. A link filter / gain control / delay control unit 1011 and a CPU 1012 are included. The interface / power supply unit 1013 includes a cable modem driver 1013, a cable power supply (PoE) 1014, and a DC power supply 1015.

This example is an example in which quadrature correction is incorporated in the quadrature demodulation unit 7 and an example in which quadrature correction processing and peak control are incorporated in the quadrature modulation unit. In the example shown in FIG. 14, the digital up / down converter 1007 and the filter / gain control / delay control unit 1008 of the baseband-digital processor 1003 realize the functions of the digital filter 9 and the downlink digital processing unit 10. . Also, the digital up / down converter 1010 and the filter / gain control / delay control unit 1011 of the baseband-digital processor 1003 realize the functions of the digital filter 12 and the uplink digital processing unit 12 (except for peak control). ing. This embodiment can also be realized by such a configuration.

As described above, in this embodiment, the radio signal from the base station is orthogonally demodulated by the direct modulation method, digitized, and relayed between the donor unit and the service unit by the digital signal. Therefore, the scale of the RF analog circuit can be reduced, the cost can be suppressed, and deterioration due to long-distance cable transmission can be suppressed because it does not include useless bandwidth information as the transmission amount.

Moreover, since gain adjustment and delay adjustment are performed on the digitized signal, it is possible to easily cope with a change in the carrier bandwidth with the same hardware. Further, since the delay can be made variable in units of service units, a multipath combined gain can be obtained.

Also, since the gain can be adjusted for each carrier, it is possible to stably relay different types of radio carrier signals from different base stations. Also, when non-MIMO signals are relayed by two antennas, such as LTE MIMO format signals and CDMA format signals, non-MIMO signals can be maintained while delaying and multiplexing the non-MIMO signals while maintaining the effects of the MIMO signals. The gain effect of the signal can be increased.

Note that this wireless relay device can also be applied to multi-system wireless relay devices such as GSM and W-CDMA. It is also possible to directly connect the base station with a coaxial cable or an optical cable without using a radio (antenna).

FIG. 15 is a block diagram showing another configuration example of the wireless relay device. As shown in FIG. 15, instead of directly connecting the donor unit 100 and the service unit 200, a signal synthesis / distribution unit 300 may be provided between the donor unit 100 and the service unit 200. The signal synthesis / distribution unit 300 is a unit that synthesizes and distributes digital signals between the donor unit 100 and the service unit 200.

FIG. 16 is a block diagram showing a configuration example of a signal synthesis / distribution unit (referred to as HUB in the figure) 300. A signal synthesis / distribution unit 300 shown in FIG. 16 includes a cable modem transceiver / cascade control unit 301, a digital signal synthesis / separation / serial conversion unit 302, a donor unit (DU) transmission rate control unit 303, a dynamic range control 304, , Uplink signal control unit 305, downlink signal control unit 306, service unit (SU) state monitoring / ON / OFF control unit 307, maintenance / monitoring unit (O & M) 308, cable model transceiver 309, cable A power supply (PoE) 310 and a power supply unit 311 are provided.

The cable modem transceiver / cascade control unit 301 is a transceiver for transmitting and receiving signals from a cable on the donor unit side. In the case of supporting the cascade connection, as cascade control, a process of amplifying and converting the cascade signal separated by the digital signal synthesis separation / serial conversion unit 302 described later and transmitting it to another port is also performed.

The digital signal synthesis / separation unit 302 synthesizes and separates digital signals, converts a digital carrier signal to be relayed to the donor unit into a digital serial signal, or receives a digital serial signal received from the donor unit. Performs conversion from signal to digital carrier signal. In cascade connection composed of a plurality of HUBs, the cascade signals are separated and multiplexed.

The downlink signal control unit 306 generates a digital carrier signal to be transmitted to each connected service unit based on the digital signal transmitted from the donor unit 100 input from the digital signal synthesis / separation / serial conversion unit 302. , Output to the service unit state monitoring / ON / OFF control unit 307. At that time, in accordance with the service unit status notification from the service unit status monitoring / ON / OFF control unit 307, individual control according to the service unit of the transmission source can be performed. In the individual control, for example, the gain of a certain carrier signal may be set to zero.

The service unit status monitoring / ON / OFF control unit 307 monitors the status of the connection destination service unit, and determines whether or not to transmit the signal input from the downlink signal control unit 306 to the connection destination service unit. Make a decision. Further, it is determined whether or not to accept a digital signal from the service unit 200 input from a cable modem transceiver 309 described later. Further, it may have a function of deriving (measuring) the cable length with the service unit from the delay amount. By notifying the service unit of the derived cable length, the service unit may perform delay insertion for cable length correction.

The cable modem transceiver 309 is a driver for transmitting and receiving signals from the cable on the service unit side. The cable power supply 310 is a device that supplies power to the Ethernet cable. The maintenance / monitoring unit 308 performs maintenance and monitoring of the signal synthesis / distribution unit 300.

The uplink signal control unit 305 generates a digital carrier signal to be transmitted to the connected donor unit based on the digital signal transmitted from the service unit 200 input via the service unit state monitoring / ON / OFF control unit 307. Addition (multiplexing) is performed and output to the dynamic range control unit 304.

The dynamic range control unit 304 performs power limiter control so that the signal power transmitted to the donor unit 100 does not become too large. For example, the peak value is predicted by statistical calculation, and the filter process is performed. The donor unit transmission rate control unit 303 adjusts the rate according to the size of the dynamic range. For example, when the dynamic range is large, control such as increasing the communication speed may be performed.

By providing such a signal synthesis / distribution unit 300 in between, the number of donor units 100 and the number of service units 200 that can be relayed (the number of connections) can be increased.

Next, features of the present invention will be described. FIG. 17 is an explanatory diagram showing features of the present invention. As shown in FIG. 17, the radio relay apparatus according to the present invention is a radio relay apparatus installed between a single or a plurality of mobile communication base stations and terminals, and is a donor that performs radio communication with the base station side. A unit 701 and one or a plurality of service units 702 that perform wireless communication with the terminal side are provided. The donor unit 701 and the service unit 702 are connected via a cable.

The donor unit 701 includes an RF-digital conversion unit 801, a downlink (DL) digital signal processing unit 802, a digital IQ signal transmission / reception unit 803, an uplink (UL) digital signal processing unit 804, and a digital-RF conversion unit. 805.

The service unit 702 includes a digital IQ signal transmission / reception unit 804, a digital-RF conversion unit 805, and an RF-digital conversion unit 801.

The RF-digital conversion unit 801 and the digital-RF conversion unit 805 may be the same in the donor unit 701 and the service unit 702.

The RF-digital converter 801 (for example, the quadrature demodulator 7 and the digital filter 9, the quadrature demodulator 26 and the digital filter 24) directly converts the input RF signal into I and Q baseband signals, and then converts the digital signal. To obtain a digital IQ signal.

The downlink digital signal processing unit (eg, the downlink digital processing unit 10) separates the downlink digital IQ signal into carrier units for each antenna, and performs gain and / or delay on the separated digital signal, respectively. Adjust and re-synthesize the digital IQ signal from the adjusted separated digital signal.

The digital IQ signal transmission / reception unit 803 (for example, the serial conversion units 11 and 14) transmits / receives a digital IQ signal to / from the service unit 702.

The uplink digital signal processing unit 804 (for example, the uplink digital processing unit 13) separates the uplink digital IQ signal into carrier units for each antenna, and gain or delay with respect to the separated digital signal or both, respectively. The digital IQ signal is re-synthesized from the adjusted separated digital signal.

The digital-RF conversion unit 805 (for example, the quadrature modulation unit 8 and the quadrature modulation unit 25) converts the input digital IQ signal into an analog signal, and directly converts the obtained I and Q baseband signals into an RF signal. Then, an RF signal is obtained.

The digital IQ signal transmission / reception unit 806 (for example, the serial conversion units 21 and 22) transmits / receives a digital IQ signal to / from the donor unit 701.

With such a configuration, a plurality of carrier groups used for different purposes transmitted from a single or a plurality of base stations can be amplified by one radio relay device while suppressing deterioration of radio capacity due to amplification and relay distance. Thus, it is possible to relay so that a stable received signal can be obtained on the terminal side.

The RF-digital conversion unit converts the I signal and the Q signal to the I signal and the Q signal of the digital signal obtained by the conversion when the I and Q baseband signals are changed to the digital signal. Unnecessary signals may be removed by a digital filter (for example, digital filters 9 and 24) employing a filter system that performs complex multiplication.

Further, the RF-digital conversion unit directly outputs a desired signal from the quadrature demodulation unit (eg, the quadrature demodulation units 7 and 26) that directly demodulates the RF signal into I and Q baseband signals, and the analog signal obtained by the quadrature demodulation unit. An analog filter circuit (for example, LPF 74, 75 or LPF 264, 265) corresponding to the I signal and Q signal that removes out-of-band signals, and the analog signal I signal and Q signal output from the analog filter circuit are digital signals, respectively. An analog-to-digital converter that converts the signal to the digital signal, and an I signal and a Q signal that are digital signals output from the analog-to-digital converter, and the I signal and Q signal of the input digital signal A digital filter (for example, digital filters 9 and 24) that employs a filter system that performs complex multiplication with the Q signal. It can have.

Further, the downlink digital signal processing unit may perform delay adjustment on each separated digital signal based on a delay time determined according to a cable length between the donor unit and the service unit. .

Further, the wireless relay device is installed in a wireless environment that receives an RF signal in which a MIMO signal and a non-MIMO signal are combined, and the downlink digital signal processing unit corresponds to a specific carrier component that is a non-MIMO signal. You may perform the delay adjustment which inserts predetermined delay time with respect to the isolate | separated digital signal.

The donor unit includes a reception quality measurement unit that measures the quality of the received RF signal, and the downlink digital signal processing unit calculates a gain range based on the reception quality measured by the reception quality measurement unit, Gain adjustment may be performed on each separated digital signal.

Also, the uplink digital signal processing unit may perform gain adjustment and delay adjustment similar to those of the downlink signal processing unit.

Also, a signal distribution / combination unit that distributes a signal addressed to the service unit received from the connected donor unit and combines a signal addressed to the donor unit received from the connected service unit between the donor unit and the service unit. (For example, a signal synthesis / distribution unit 300) may be provided.

In the wireless relay method according to the present invention, in the RF-digital conversion step, the I signal and the Q signal of the digital signal obtained by converting the analog signal into the digital signal are respectively obtained. A filter method for complex multiplication may be implemented to remove unnecessary signals.

Also, in the digital signal processing step, delay adjustment may be performed on each separated digital signal based on a delay time determined according to the cable length between the donor unit and the service unit.

A wireless relay method applied to a wireless relay device installed in a wireless environment that receives an RF signal in which a MIMO signal and a non-MIMO signal are combined, and is a specific method that is a non-MIMO signal in a digital signal processing step. You may perform the delay adjustment which inserts predetermined delay time with respect to the isolate | separated digital signal corresponding to a carrier component.

The donor unit measures the quality of the received RF signal, and the digital signal processing step calculates a gain range based on the measured reception quality and performs gain adjustment on each separated digital signal. May be.

For transmission and reception of digital IQ signals between the donor unit and the service unit, the signal addressed to the service unit received from the connected donor unit is distributed, and the signal addressed to the donor unit received from the connected service unit is synthesized. This may be done via a signal distribution and synthesis unit.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims priority based on Japanese Patent Application 2010-11903 filed on January 22, 2010, the entire disclosure of which is incorporated herein.

The present invention can be suitably applied to a purpose of relaying a signal of wireless communication performed between a mobile communication base station and a terminal.

100 Donor unit 1 Antenna 2 Antenna duplexer (duplexer)
3 Low noise amplifier (LNA)
4, 5 Out-of-band filter (BRF)
6 Amplifier (PA)
7 Quadrature demodulation unit 8 Quadrature modulation unit 9,12 Digital filter 10 Downlink (DL) digital processing unit 101 Digital carrier / antenna separation unit 102-1 to 102-n Digital filter 103-1 to 103-n Gain adjustment unit 104- 1 to 104-n delay adjustment unit 105 digital carrier / antenna combining unit 11, 14 serial conversion unit 13 uplink (UL) digital processing unit 131 digital carrier / antenna separation unit 132-1 to 132-n digital filter 133-1 to 133-n Delay adjustment unit 134-1 to 134-n Gain adjustment unit 135-1 to 135-n Power clipping unit 136 Digital carrier / antenna combination unit 200 Service unit 21, 22 Serial conversion unit 23, 24 Digital filter 25 Quadrature modulation Part 26 orthogonal Demodulator 27 Amplifier (PA)
28, 29 Out-of-band filter (BPF)
30 Low noise amplifier (LNA)
31 antenna duplexer 32 antenna 300 signal synthesis / distribution unit 301 cable modem transceiver / cascade control unit 302 digital signal synthesis / separation unit 303 donor unit (DU) transmission rate control unit 304 dynamic range control 305 uplink signal control unit 306 Downlink signal control unit 307 Service unit (SU) status monitoring / ON / OFF control unit 308 Maintenance / monitoring unit (O & M)
309 Cable model transceiver 310 Cable power supply (PoE)
311 Power supply unit 701 Donor unit 702 Service unit 801 RF-digital conversion unit 802 Downlink digital signal processing unit 803, 806 Digital IQ signal transmission / reception unit 804 Uplink digital signal processing unit 805 Digital-RF conversion unit

Claims (14)

1. A wireless relay device installed between a single or multiple mobile communication base stations and a terminal,
   A donor unit that performs wireless communication with the base station side, and one or a plurality of service units that perform wireless communication with the terminal side,
   The donor unit and the service unit are connected via a cable,
   The donor unit is
   An RF-to-digital converter that directly converts an input RF signal into an I and Q baseband signal and then converts it into a digital signal to obtain a digital IQ signal;
   A downlink digital IQ signal is separated into carrier units for each antenna, gain and / or delay is adjusted for each separated digital signal, and the digital IQ signal is recombined from the adjusted separated digital signal. A link digital signal processing unit;
   A digital IQ signal transmission / reception unit for transmitting / receiving a digital IQ signal to / from the service unit;
   Uplink digital IQ signal is separated into carrier units for each antenna, gain and / or delay is adjusted for each separated digital signal, and digital IQ signal is re-synthesized from the separated separated digital signal A link digital signal processing unit;
   A digital-RF converter that converts an input digital IQ signal into an analog signal, directly converts the obtained I and Q baseband signals into an RF signal, and obtains an RF signal;
   Service unit
   A digital IQ signal transmission / reception unit that transmits / receives a digital IQ signal to / from a donor unit,
   A digital-RF converter that converts an input digital IQ signal into an analog signal, directly converts the obtained I and Q baseband signals into an RF signal, and obtains an RF signal;
   A radio relay apparatus comprising: an RF-digital conversion unit that directly converts an input RF signal into an I and Q baseband signal and then converts the RF signal into a digital signal to obtain a digital IQ signal.
2. The RF-digital conversion unit converts the I signal and the Q signal into complex signals with respect to the I signal and the Q signal of the digital signal obtained by the conversion when the I and Q baseband signals are changed to the digital signal. The wireless relay apparatus according to claim 1, wherein an unnecessary signal is removed by a digital filter that employs a filter method for multiplication.
3. The RF-digital converter is
   An orthogonal demodulator that directly demodulates the RF signal into I and Q baseband signals;
   An analog filter circuit corresponding to the I signal and the Q signal for removing a desired out-of-band signal from the analog signal obtained by the quadrature demodulation unit;
   An analog-to-digital converter that converts each of the I signal and Q signal of the analog signal output from the analog filter circuit into a digital signal;
   A filter that receives an I signal and a Q signal of a digital signal output from the analog-digital conversion unit, and performs complex multiplication of the input I signal and the Q signal with the I signal and the Q signal, respectively. The wireless relay device according to claim 1, further comprising a digital filter that employs a system.
4. The downlink digital signal processing unit performs delay adjustment on each separated digital signal based on a delay time determined according to a cable length between the donor unit and the service unit. Item 4. The wireless relay device according to any one of items 3 to 3.
5. A wireless relay device installed in a wireless environment for receiving an RF signal in which a MIMO signal and a non-MIMO signal are combined,
   The downlink digital signal processing unit performs delay adjustment by inserting a predetermined delay time for the separated digital signal corresponding to a specific carrier component that is a non-MIMO signal. The wireless relay device according to any one of the above.
6. Donor units
   A reception quality measuring unit for measuring the quality of the received RF signal;
   6. The downlink digital signal processing unit calculates a gain range based on the reception quality measured by the reception quality measurement unit, and performs gain adjustment on each separated digital signal. The wireless relay device according to any one of the above.
7. The radio relay apparatus according to any one of claims 1 to 6, wherein the uplink digital signal processing unit performs the same gain adjustment and delay adjustment as the downlink signal processing unit.
8. Provided between the donor unit and the service unit is a signal distribution / combination unit that distributes the signal addressed to the service unit received from the connected donor unit and combines the signal addressed to the donor unit received from the connected service unit. The wireless relay device according to any one of claims 1 to 7.
9. A wireless relay method applied to a wireless relay device installed between a single or multiple mobile communication base stations and a terminal,
   An RF-digital conversion step for directly converting an input RF signal into an I and Q baseband signal and then converting the digital signal into a digital signal;
   The digital IQ signal obtained by the conversion is separated into carrier units for each antenna in a donor unit that communicates with the mobile communication base station side, and gain or delay or both are respectively applied to the separated digital signal. A digital signal processing step of adjusting and recombining the digital IQ signal from the adjusted separated digital signal;
   A radio relay method comprising: a digital-RF conversion step of converting an input digital IQ signal into an analog signal, and directly converting the obtained I and Q baseband signals into an RF signal.
10. In the RF-to-digital conversion step, a filter method for performing complex multiplication of the I signal and the Q signal on the I signal and the Q signal of the digital signal obtained by converting the analog signal into the digital signal, respectively, The wireless relay method according to claim 9, wherein unnecessary signals are removed.
11. The delay adjustment is performed on each separated digital signal based on a delay time determined according to a cable length between the donor unit and the service unit in the digital signal processing step. The wireless relay method described in 1.
12. A wireless relay method applied to a wireless relay device installed in a wireless environment that receives an RF signal in which a MIMO signal and a non-MIMO signal are combined,
    The digital signal processing step performs delay adjustment for inserting a predetermined delay time for the separated digital signal corresponding to a specific carrier component which is a non-MIMO signal. The wireless relay method according to item 1.
13. The donor unit measures the quality of the received RF signal,
    The digital signal processing step calculates a gain range based on the measured reception quality, and performs gain adjustment for each separated digital signal. The wireless relay method described.
14. Send and receive digital IQ signals between the donor unit and the service unit, distribute the signal addressed to the service unit received from the connected donor unit, and synthesize the signal addressed to the donor unit received from the connected service unit The wireless relay method according to claim 9, wherein the wireless relay method is performed via a signal distribution / combination unit.

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