JP5206390B2 - Wireless device sharing method, multiplexing device, and wireless device - Google Patents

Description

  The present invention relates to a radio apparatus sharing method, a multiplexing apparatus, and a radio apparatus, and more particularly to a method for sharing an asynchronous baseband signal of a plurality of radio control apparatuses by one radio apparatus, and the multiplexing apparatus and the radio apparatus. It is.

  In recent years, the progress of wireless technology has been rapid, and even before the transition from the current generation wireless method to the next generation wireless method, a new method that has advanced the current method often appears, and the wireless control device (REC) of the current method has appeared. : Radio equipment controller (RE) and radio equipment (RE: Radio Equipment) add a new wireless control device, share the wireless device, or use the new wireless control device and wireless device It is conceivable to connect devices and share wireless devices.

  A radio device (RE) is a radio device of a radio base station, and is a device that modulates and demodulates a baseband signal and performs radio transmission and reception. The radio control device (REC) is a device that controls the radio device (RE), sets parameters necessary for the radio device (RE), and controls input / output of baseband signals.

  FIG. 8 is a connection configuration diagram between a single radio control apparatus and a radio apparatus according to the prior art. In the figure, a radio control device 1 (REC: Radio Equipment Controller) and a radio device 2 (RE: Radio Equipment) are connected one-to-one.

  REC1 transmits a baseband signal to RE2 via a transmission line 3 compliant with a standard such as CPRI (Common Public Radio Interface) in synchronization with its own baseband clock, and RE2 is a base transmitted from REC1. The baseband clock is extracted from the band signal by the clock extraction circuit 24 and operates in synchronization with the extracted baseband clock.

  The CPRI (Common Public Radio Interface) divides a radio base station into a radio unit (RE) and a radio control unit (REC), and arranges only the radio unit (RE) directly below the antenna. This is a transmission path standard for connecting a radio control unit (REC).

  The baseband signal is transmitted from REC1 to RE2 in synchronization with the baseband clock, and RE2 extracts the baseband clock from the received baseband signal, uses it for the operation of the internal circuit, multiplies it by α and sets the RF frequency. To do. Further, the baseband signal is converted from a digital signal to an analog signal through the filter 22, and is RF-modulated and transmitted by radio.

  The signal received wirelessly via the antenna 4 is RF demodulated and synchronized with the baseband clock by the sampling circuit 23. After synchronization, the baseband signal is transmitted to REC1 as a baseband signal.

FIG. 9 is a connection configuration diagram between a plurality of radio control apparatuses and radio apparatuses according to the prior art. In the figure, the base for the band clock connects asynchronous multiple REC1 _1, 1 ₂ to RE2 one, each REC1 _1, 1 ₂ transmission path in synchronism with the (cable) 3 REC1 _1, 1 _It is necessary to connect to RE2 for _two units.

In this connection method, the antenna 4 and the housing of RE2 can be shared as compared with the case where a plurality of configurations shown in FIG. 8 are prepared. However, the transmission path (cable) 3 between REC1 _1, 1 ₂ and RE2 is expensive because it is a high-speed signal. Furthermore, the distance between REC1 _1, 1 ₂ and RE2 may be a long distance (several tens of kilometers), which is very expensive even considering facility construction.

As the connection using the CPRI interface, for example, the content of connecting the first unit (BB1, BB2) and the third unit (RE1, RE2) with the CPRI (Common Public Radio Interface) interface is disclosed. (For example, refer to Patent Document 1).
JP-T-2007-523577

  As described above, since the radio apparatus (RE) synchronizes the RF frequency with the baseband clock, information on the baseband clock from the radio control apparatus (REC) is necessary.

  In order to connect a plurality of radio control devices (REC) to one radio device (RE), the radio devices (RE) can be connected to one radio control device (REC) using one cable. ) Need to send a baseband clock.

  However, there may be a long distance (several tens of kilometers) between the wireless control device (REC) and the wireless device (RE). Since optical cables are connected, it is enormous to lay a plurality of optical cables over a long distance. I need it.

  To reduce this cost, even if the clock is sent with a separate cable, there is only one high-speed cable for baseband signals, but it is necessary to lay the clock cable.

  When transmission becomes long distance, synchronization of baseband signals becomes difficult due to the difference in transmission delay between the two types of cables.

  An object of the present invention is to provide a wireless device sharing method by a plurality of wireless control devices in which signals from a plurality of wireless control devices (REC) whose baseband clocks are asynchronous are connected to the wireless device (RE) with a single cable. It is to provide a multiplexing device and a wireless device.

  In order to solve the above problems, the present invention provides a wireless control apparatus that serves as a reference in a wireless apparatus sharing method in which baseband signals of a plurality of wireless control apparatuses having asynchronous baseband clocks are modulated and demodulated by one wireless apparatus. Extracting the clock difference information of the baseband clock and the baseband clock of the wireless control device other than the reference, transmitting the clock difference information to the wireless device, and in the wireless device, from the clock difference information A step of restoring a baseband clock of a radio control device other than the reference, a step of performing RF modulation with an RF frequency synchronized with the restored baseband clock, and a radio output, and the radio device receiving via an antenna All radio controller signals at an RF frequency synchronized to the restored baseband clock F-demodulating step, transmitting the demodulated baseband signals of all radio control apparatuses to the plurality of radio control apparatus sides using the reference baseband clock, and basebands of all radio control apparatuses received from the radio apparatuses The method includes a step of transmitting a signal to each radio control apparatus using a baseband clock of each radio control apparatus.

  According to the present invention, baseband signals of a plurality of radio control apparatuses are transmitted by transmitting difference information of baseband clocks between a plurality of radio control apparatuses to the radio apparatus and restoring the original baseband clock by the radio apparatus. Can be provided by a plurality of asynchronous wireless control devices that can transmit and receive data to and from the wireless device through a single transmission line.

In addition, the present invention provides a radio apparatus that is connected to a plurality of radio control apparatuses and restores a baseband clock of a radio control apparatus other than the reference from a signal obtained by multiplexing baseband signals from the plurality of radio control apparatuses. in the multiplexing device for outputting a signal obtained by multiplexing the base band signal, a difference extracting circuit for extracting the difference between baseband clock of the radio controller apparatus baseband clock and other than the reference in relation to the standard radio controller, The baseband signal of each of the reference wireless control device and the wireless control device other than the reference and the clock difference information extracted by the difference extraction circuit are multiplexed and transmitted to the wireless device using the reference clock. Means .

  According to the present invention, it is possible to provide a multiplexing apparatus that multiplexes / demultiplexes baseband signals of a plurality of radio control apparatuses and extracts difference information between a reference clock of the plurality of radio control apparatuses and a clock other than the reference. .

  Furthermore, the present invention provides a clock extraction circuit for extracting one reference radio control apparatus baseband signal input from a plurality of radio control apparatus sides, an output of the clock extraction circuit, and a plurality of radio control apparatuses in the radio apparatus A clock restoration processing circuit for restoring the baseband clock of the other radio control device based on the clock difference information between the baseband clock of one reference radio control device inputted from the side and the baseband clock of the other radio control device other than the reference Means for performing RF modulation with an RF frequency synchronized with the baseband clock of all the radio control devices restored by the output of the clock restoration processing circuit, and outputting the radio signal all radio control device signals received from radio The base station of all radio control devices that have been RF demodulated at an RF frequency synchronized with the baseband clock of the radio control device. The baseband signal and means for transmitting to said plurality of wireless control device.

  According to the present invention, the baseband signal of all the radio control devices can be restored using the clock difference information, and can be wirelessly output by RF modulation at an RF frequency synchronized with each restored baseband clock, and each restored A radio apparatus capable of performing RF demodulation at an RF frequency synchronized with a baseband clock can be provided.

  As described above, according to the disclosed technique, the difference information of the baseband clock between the radio control devices (REC) is transmitted to the radio devices (RE) to the radio devices (REC). Thus, by restoring the original baseband clock, it is not necessary to transmit each baseband clock to the radio equipment (RE) through a separate line, and one baseband signal of a plurality of radio control equipment (REC) is transmitted. Since it becomes possible to transmit / receive to / from the radio equipment (RE) on the road, the cost of the transmission path itself and the transmission path can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a connection configuration diagram between a plurality of radio control devices 1 _{1 and} 1 ₂ and a radio device _{2 according} to an embodiment of the present invention. This configuration diagram shows an example in which two radio control units (REC) 1 _{1 and} 1 ₂ are connected to one radio unit (RE) 2, and α and β in FIG. coefficient, alpha = reference radio controller (REC) _{1 1} RF frequency / reference clock frequency, beta = other radio control apparatus (REC) _{1 2} RF frequency / other radio control apparatus for synchronizing the (REC) 12 Baseband clock frequency.

  Hereinafter, a procedure of a wireless device (RE) sharing method by a plurality of asynchronous wireless control devices (REC) will be described with reference to FIG.

S1. A multiplexer / demultiplexer (hereinafter referred to as MUX5) is connected to connect a plurality of REC1 _1, 1 ₂ and RE2. The MUX 5 is a device for connecting to a plurality of REC1 _1, 1 ₂ , multiplexing these REC1 _1, 1 ₂ baseband signals on one cable and connecting to one RE 2.

S2. MUX5 is a REC1 ₁ of single among certain multiple REC1 _1, 1 ₂ as a reference (hereinafter, reference REC1 _1), the baseband clock (hereinafter, a reference clock) of the reference REC1 ₁ and the remaining REC1 ₂ ( Thereafter, a clock difference extraction circuit 13 is provided for extracting a difference (hereinafter referred to as clock difference information) from the baseband clock of other REC1 ₂ ), and this difference is extracted.

S3. The MUX 5 transmits baseband signals of all the REC1 _{1 and} 1 ₂ (reference REC1 ₁ and other REC1 ₂ ) and clock difference information to the RE 2 using the reference clock.

S4. In RE2, extracting a reference clock from the baseband signal received from MUX5, using clock difference information, the clock recovery processing circuit 28 to recover the baseband clock of the other REC1 ₂ provided, all REC1 _1, 1 ₂ of the base Restore the band clock.

S5. In RE2, the baseband signals of all the REC1 _{1 and} 1 ₂ received from the REC are RF-modulated with an RF frequency synchronized with the restored baseband clock, and are wirelessly output via the antenna 4.

S6. In RE2, all REC signal received via the antenna 4, the RF-demodulated at the RF frequency synchronized with the restore respective baseband clock, all REC1 _1, 1 ₂ of the baseband signal demodulated in the reference clock MUX5 Send to.

S7. MUX5 are all REC1 _1, 1 ₂ of the baseband signal received by the reference clock from the RE2, each REC1 _1, 1 _2, respectively of the baseband clock is sent to each REC1 _1, 1 _2.

  FIG. 2 is a clock difference extraction circuit according to an embodiment of the present invention. In FIG. 2, the clock difference extraction circuit 13 samples one clock of the difference extraction clock with, for example, a clock obtained by multiplying the reference clock by 32, and observes that the number of times of sampling sometimes becomes other than 32. If the number of times of sampling is 31, the clock for extracting the difference is faster, and if it is 33, it is slower.

  Difference extraction is performed continuously. This is an operation in which the difference between the reference clock and the other clocks is very small. Actually, 32 continues for a long time, and the clock is shifted little by little, so that sometime it becomes other than 32.

  Therefore, the clock difference information is 32, 32,..., 32, 32, 31, 32, 32,... 32, 32,. Become.

  FIG. 3 is a time chart of clock difference extraction according to FIG. In FIG. 3, one clock other than the reference clock is counted by 32 times the reference clock, and if the count value is 31, it is advanced and if the count value is 33, it is delayed.

  FIG. 4 is a clock restoration processing circuit according to an embodiment of the present invention. In FIG. 4, a clock restoration processing circuit 28 has a PLL circuit 281 and a timing generation circuit 282, and the timing generation circuit 282 is generated from clock difference information (phase information indicating how the phase is shifted). Generate a clock for synchronization. Specifically, when the clock difference information notifies the delay, the phase information is delayed, and when the frequency of the delay information is high, the phase information is delayed quickly. The timing generation circuit can output finer phase information to the PLL circuit 281 by multiplying the reference clock by, for example, 1024 inside. When the PLL circuit 281 quickly follows the phase information, it is necessary to output finer phase information to the PLL circuit 281 in order to output a smooth clock.

  In the figure, integrating the clock phase information means continuing to add past information. For example, when the current addition result is 2 and the clock difference information (+1) is sent, the addition result is It becomes 3. As a result, the phase information (basically the clock) is changed from 2 lags to 3 lags with respect to the reference clock. However, when delaying from 2 to 3, the next of 2 is not necessarily 3. In consideration of the performance of the PLL circuit 281, the wireless clock standard, the sampling speed, and the like, when it is necessary to change gradually, such as 2, 2.5 and 3, the timing generation circuit is designed as such.

  FIG. 5 is a time chart of clock recovery according to FIG. In this example, the phase information indicates to the PLL circuit 281 that the difference extraction side clock is slower than the reference clock. The PLL circuit 281 shifts the phase little by little so as to match this phase information. In this case, the phase information lags behind the reference clock, and the corrected clock has a frequency slower than the reference clock.

  FIG. 6 is a circuit example of an FIR filter used in the present invention. As shown in FIG. 6, the FIR (Finite Impulse Response) filter 22 has a circuit configuration in which a delay unit 221, an accumulator 222, and an adder 223 that delay an input signal by one clock are combined in a cascaded form. Is a filter that converges the output signal to 0 in a finite time.

  The baseband signal is converted from a digital signal to an analog signal through the FIR filter 22, and is RF-modulated and transmitted by radio. In practice, this circuit upsamples the baseband signal (3.84 MHz) to an RF frequency (such as 2 GHz).

  FIG. 7 is a format diagram of information transmitted through the transmission path according to the embodiment of the present invention. FIG. 7 is a format example of information transmitted through a transmission line when transmitting baseband signals of two RECs. In the figure, it is necessary to secure the band of the clock difference information of other RECs in addition to the baseband signal band of the two RECs.

  In FIG. 7, W (horizontal axis) and Y (vertical axis) indicate the transmission order of the CPRI standard data. Data is W = 0: Y = 0, W = 0: Y = 1,... W = 1: Y = 0, W = 1: Y = 1,..., W = 15: Y = 3 are transmitted in this order.

  In the CPRI standard, the time required from the head of W = 0 to the head of W = 1 is determined. The number of Y is currently defined as 1, 2, 4, and 5, and the larger the number of Y, the faster the transmission path. Note that W = 0: Y = 0 normally transmits 8-bit data.

  In the figure, the other REC clock difference information indicates the information of the clock difference between the reference REC and the other REC, and is a band for transmitting the clock difference information (specifically, the phase shift information) according to the required accuracy. Secure.

  The other REC clock difference countermeasure band is an area (band) for incrementing “1Q data” on the other REC side necessary for the clock difference, that is, a “data area”.

  The difference in clock is the difference in data amount as it is, and if the other REC is increased by one clock from the reference REC, the data is also increased by one data. Therefore, an area for transmitting this one data is required.

  If the reference clock is slower than the baseband clock of the other REC, the baseband signal of the other REC cannot be sent if the clock is slow. Therefore, it is possible to transmit / receive all the baseband signals of the other REC by securing the corresponding band. It is a band for Note that this band is not always used, but is used when necessary. Since the used / unused information is synchronized with the clock difference information, it is not necessary to secure a new signal. On the other hand, when the reference clock is earlier than the baseband clock of the other REC, a predetermined portion of the baseband signal band needs to be freed. Also in this case, the vacancy can be determined in synchronization with the clock difference information.

  The present invention adds a new wireless control device between the wireless control device of the current method and the wireless device to share the wireless device, or replaces the wireless control device of the current method between the new wireless control device and the wireless device. It can be used when additional wireless devices are shared.

It is a connection block diagram between the some radio | wireless control apparatus and radio | wireless apparatus in one Embodiment of this invention. 3 is a clock difference extraction circuit according to an embodiment of the present invention. 3 is a time chart of clock difference extraction according to FIG. 2. 2 is a clock restoration processing circuit according to an embodiment of the present invention. FIG. 5 is a time chart of clock restoration according to FIG. 4. FIG. It is an example of a circuit of an FIR filter. It is a format figure of the information transmitted on the transmission line in one Embodiment of this invention. It is a connection block diagram between a single radio control device and a radio device according to the prior art. It is a connection block diagram between a some radio | wireless control apparatus and radio | wireless apparatus by a prior art.

Explanation of symbols

1 _1, 1 ₂ Radio control unit (REC)
2 Radio equipment (RE)
3 Transmission line (cable)
4 Antenna 5 Multiplexer / Demultiplexer (MUX)
11 _1, 11 ₂ clock extraction circuit 12 multiplexer / demultiplexer (mux)
13 clock differential extraction circuit 21 _1, 21 ₂ D / A circuit 22 _1, 22 ₂ filter 221 delay unit 222 accumulator 223 adder 23 _1, 23 ₂ sampling circuit 24 clock extraction circuit 25 RF modulator / demodulator 26 _1, 26 ₂ times multiplication 27 Multiplexer / Demultiplexer (mux)
28 Clock recovery processing circuit 281 PLL circuit 282 Multiplier

Claims (5)

A wireless device sharing method in a wireless base station having a plurality of wireless control devices and wireless devices,
Extracting clock difference information between a baseband clock of a wireless control device serving as a reference and a baseband clock of a wireless control device other than the reference; and
Transmitting the clock difference information to the wireless device;
Restoring the baseband clock of the wireless control device other than the reference from the received clock difference information in the wireless device;
Modulating and wirelessly outputting at a radio frequency synchronized with the restored baseband clock;
Demodulating a signal received via an antenna into a baseband signal at a radio frequency synchronized with the restored baseband clock in the wireless device;
Transmitting the demodulated baseband signal of the wireless control device to the plurality of wireless control devices with the reference baseband clock;
Transmitting a baseband signal of a radio control device received from the radio device to each radio control device with a baseband clock of each radio control device;
A wireless device sharing method comprising the steps of: In the step of extracting the clock difference information, when the clock difference information is extracted, a band for transmitting the clock difference information is secured in a transmission band for transmitting a baseband signal of a radio control device other than the reference. The wireless device sharing method according to claim 1. In the step of extracting the clock difference information, when the case where the reference baseband clock is slower than the baseband clock other than the reference is extracted, data is transmitted using the clock difference countermeasure band, and the reference baseband clock is other than the reference. 2. The wireless device sharing method according to claim 1, wherein when a case earlier than the baseband clock is extracted, the last part of the baseband signal band is made empty. The baseband signal is multiplexed to a radio device that is connected to a plurality of radio control devices and restores a baseband clock of a radio control device other than the reference from a signal obtained by multiplexing the baseband signals from the plurality of radio control devices. In the multiplexing device that outputs the digitized signal ,
A difference extracting circuit for extracting the difference between baseband clock of the radio controller apparatus other than the base band clock and the reference in relation to the standard radio controller,
The baseband signal of each of the reference wireless control device and the wireless control device other than the reference and the clock difference information extracted by the difference extraction circuit are multiplexed and transmitted to the wireless device using the reference clock. Means,
A multiplexing apparatus comprising: A clock extraction circuit that extracts a clock from a baseband signal of a reference wireless control device input from a plurality of wireless control devices;
The other radio is based on the output of the clock extraction circuit and the clock difference information between the baseband clock of the reference radio control apparatus input from a plurality of radio control apparatuses and the baseband clock of the radio control apparatus other than the reference. A clock restoration processing circuit for restoring the baseband clock of the control device;
Means for performing radio output by modulating at a radio frequency synchronized with a baseband clock of each of the plurality of radio control devices restored by the output of the clock restoration processing circuit;
A baseband signal of each of the plurality of radio control devices obtained by radio demodulation of a radio received signal at a radio frequency synchronized with a baseband clock of each of the restored radio control devices is transmitted to the plurality of radio control devices. Means,
A wireless device comprising:

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