Wireless communication system
By using attenuators or broadband amplifiers to manage interference in channel bonding, the wireless communication system maintains signal quality and prevents SNR degradation, addressing the challenges of wide bandwidth communication.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NTT DOCOMO INC
- Filing Date
- 2022-10-26
- Publication Date
- 2026-06-01
AI Technical Summary
Existing wireless communication systems face degradation in communication quality due to inter-channel interference and self-interference caused by channel bonding, particularly in wide bandwidth applications like subterahertz communication, which is exacerbated by the limitations of current isolators and band-pass filters.
The wireless communication system employs attenuators or broadband amplifiers with wider operating bandwidths than the channel bonding signal to suppress interference, replacing isolators in the configuration, thereby maintaining signal-to-noise ratio (SNR) across a broader frequency range.
This approach effectively reduces interference, ensuring stable and error-free communication by maintaining an adequate SNR, even in wide bandwidth scenarios, by minimizing the impact of reflected waves on direct signals.
Smart Images
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Abstract
Description
[Technical Field]
[0001] This disclosure relates to a wireless communication system that can suppress the degradation of communication quality caused by inter-channel interference and / or self-interference due to channel bonding. [Background technology]
[0002] This document explains the background technology and a technical examination of it. The sixth-generation mobile communication system (hereinafter referred to as "6G"), which is expected to be introduced to the market around 2030, requires the realization of high-capacity wireless communication exceeding 100 Gbps (see Non-Patent Document 1). One effective method for realizing high-capacity wireless communication is securing a wide bandwidth for wireless communication. In fact, in 6G, there are plans to widen the wireless communication bandwidth by utilizing the sub-terahertz band above 100 GHz, which has not been actively used in mobile communication systems until now.
[0003] One of the problems with expanding the bandwidth of wireless communication is the difficulty in expanding the bandwidth of the baseband (hereinafter also referred to as "BB") and the intermediate frequency (hereinafter also referred to as "IF") band. The bandwidth of the BB and IF bands is limited by the bandwidth or sampling rate of the digital-to-analog converter (DAC) (or analog-to-digital converter (ADC)) used when generating (receiving) the transmission signal. When using commercially available DACs and ADCs for wireless communication, the bandwidth of the BB and IF bands is at most about 5 GHz. As a result, the bandwidth of the high frequency (hereinafter also referred to as "RF") band used for transmission is also limited to at most about 5 GHz. Therefore, in order to realize high-capacity wireless communication using the subterahertz band, technologies that expand the bandwidth of the BB and IF bands compared to the current situation (hereinafter referred to as "bandwidth expansion technologies") are important.
[0004] Channel bonding is a known existing bandwidth expansion technique. An overview of channel bonding is shown in Figure 1. Channel bonding is a technique that combines multiple radio signal bands (in other words, channels) to achieve an equivalently wider radio signal bandwidth. The wireless communication system 900 (see Figure 1) that implements channel bonding includes a transmitter 100 and a receiver 200. The transmitter 100 includes N transmitters 101TX-n, a channel combiner 103, and a transmitting antenna 105. The receiver 200 includes N receivers 201RX-n, a channel separator 203, and a receiving antenna 205. Each of the transmitters 101TX-n and receivers 201RX-n (n=1,2,···,N) handles the nth channel n of the radio signal (indicated as Ch.n in Figure 1). The bandwidth of each channel is limited to a few GHz by the bandwidth limitations of the DAC and ADC (DAC and ADC are not shown in Figure 1). The transmitting device 100 uses a channel combiner 103 to combine N channels with different center frequencies (f1, f2, ..., f N By frequency conversion to a bandwidth having ), a wideband RF signal (hereinafter referred to as the "channel bonding signal") with a bandwidth equivalent to N channels is generated, as shown in Figure 1. The channel bonding signal is radiated into the air from the transmitting antenna 105. The receiving device 200 separates this wideband channel bonding signal received by the receiving antenna 205 into the original N channels using a channel separator 203, and each receiver 201RX-n receives the signal of the corresponding channel n out of the N channels. By using channel bonding, even if the bandwidth of the channels handled by the transmitter 101TX-n and the receiver 201RX-n is narrow, the bandwidth of the channel bonding signal used for wireless communication can be widened.
[0005] To realize wireless communication using channel bonding, it is important to properly design the channel combiner and channel separator to avoid channel interference. This will be explained using Figures 2, 3, and 4. Figure 2 shows a configuration in which the channel combiner 103 and channel separator 203 include an N:1 combiner 103a and an N:1 distributor 203a, respectively, which are commonly used in channel bonding. The transmitter 100 processes the signals handled by the transmitter 101TX-n (i.e., the modulated signal obtained by modulating the carrier wave with a baseband signal, or the IF signal obtained by frequency conversion of the modulated signal) at the center frequencies (f1, f2, ..., f) for each channel. N To perform frequency conversion to ), it is equipped with local oscillators 103b-n and frequency converters 103c-n. Similarly, the receiving device 200 handles N received signals with N receivers 201RX-n, each with a different operating frequency (f1, f2, ..., f N To perform frequency conversion, the system is equipped with a local oscillator 203b and a frequency converter 203c. Generally, a broadband N:1 combiner 103a and a broadband N:1 distributor 203a can be realized, so the N:1 combiner 103a and the N:1 distributor 203a are suitable for applications that combine and distribute signals of various bandwidths, such as channel bonding.
[0006] However, the configuration shown in Figure 2 has the following problems. First, as shown in Figure 2, in the transmitting device 100, the signal from one channel i (channel 1 in Figure 2) leaks through the N:1 combiner 103a to another channel j (channel 2 in Figure 2), and is then input to the frequency converter 103c-j of that other channel j, which can result in the generation of unwanted signals (channel leakage). Also, in the receiving device 200, the received channel bonding signal is distributed to the output port of the N:1 distributor 203a, but the leaked signal from channel i (the signal with center frequency f1 in Figure 2) is input to the j-th frequency converter 203c-j (frequency converter 203c-2 in Figure 2) together with the j-th received signal (the signal with center frequency f2 in Figure 2), making it impossible to demodulate the j-th received signal (channel interference).
[0007] Generally, to avoid such problems, the configuration shown in FIG. 3 is used. In the transmitting apparatus 100, a band-pass filter (hereinafter referred to as "BPF") 103d-n that allows only the signal in the frequency band used for channel n to pass is arranged after the frequency converter 103c-n. Similarly, in the receiving apparatus 200, a BPF 203d-n that allows only the signal in the frequency band used for channel n to pass is arranged before the frequency converter 203c-n. Therefore, channel leakage in the transmitting apparatus 100 and channel interference in the receiving apparatus 200 can be prevented.
[0008] However, it should be noted that the BPF has the characteristic of reflecting signals other than the passing signal. As shown in FIG. 3, in the transmitting apparatus 100, the signal reflected by the BPF (the signal with the center frequency f1 in FIG. 2) is re-input to the N:1 synthesizer 103a. The signal re-input to the N:1 synthesizer 103a is output from the N:1 synthesizer 103a and acts as an interfering signal with respect to the channel bonding signal (that is, the RF signal), and as a result, causes a decrease in the signal-to-noise ratio (hereinafter referred to as "SNR"). Further, as shown in FIG. 3, in the receiving apparatus 200, the signal reflected by the BPF (the signal with a center frequency other than f1 in FIG. 2) is re-input to the N:1 distributor 203a. The signal re-input to the N:1 distributor 203a leaks to other output ports of the N:1 distributor 203a. For example, when the signal with a center frequency other than f1 reflected by the BPF 203d-1 (this signal includes the signal with the center frequency f2) leaks to the port of channel 2 of the N:1 distributor 203a, the signal with the center frequency f2 reflected by the BPF 203d-1 passes through the BPF 203d-2 and interferes with the signal with the center frequency f2 that is directly input to the port of channel 2 without experiencing reflection (that is, the desired signal of channel 2), resulting in a decrease in SNR.
[0009] In order to suppress the SNR degradation caused by the reflection of the BPF (more generally, the reflection by the components constituting the channel), it is important to design the N:1 synthesizer 103a and the N:1 distributor 203a to reduce leakage. For example, since the well-known Wilkinson coupler has a port-to-port isolation function, it can be used as the N:1 synthesizer 103a and the N:1 distributor 203a with less leakage. However, the frequency range in which the isolation function appears in the Wilkinson coupler is limited, and it is difficult to apply the Wilkinson coupler to the handling of broadband signals such as channel bonding.
[0010] Therefore, in order to absorb the reflected wave generated by the BPF, a configuration using isolators 103e-n, 203e-n as shown in FIG. 4 can be considered. In the transmitter 100, the isolator 103e-n is arranged after the BPF 103d-n. Similarly, in the receiver 200, the isolator 203e-n is arranged before the BPF 203d-n. Since the isolator allows the signal to pass only in one direction, the interference of the reflected signal with the desired signal can be removed. However, there are still problems with this method. This will be described below.
[0011] The isolators 103e-n, 203e-n used in the configuration shown in FIG. 4 generally have a limited operating band, and it is known that outside the operating band, the ability to block the signal passing through the isolator in the reverse direction (so-called reverse isolation) is greatly reduced. When channel bonding is used, signals of various frequencies (in this example, f1, f2, ···, f N ) are used. The realization of isolators operating at all these frequencies is generally very difficult.
[0012] When the bandwidth of wireless communication is wider than the operating bandwidth of the isolator, problems that may occur in communication using channel bonding will be explained with reference to Figures 5, 6, and 7. In Figures 5, 6, and 7, for simplicity, we consider the case where two channels (channel i and channel j) are bonded, and explain the problems that occur in the transmitting device 100. As shown in Figure 5, the signal of channel i is input to the N:1 combiner 103a, and most of it reaches the output port of the N:1 combiner 103a as a direct signal (hereinafter, this direct signal will be referred to as the "direct wave"), but a portion of the signal of channel i reaches the input port of channel j of the N:1 combiner 103a as a leak signal. Here, we assume that the frequency bandwidth of the signal of channel i is outside the operating bandwidth of the isolator 103e-j of channel j. In this case, the isolator 103e-j of channel j loses its reverse isolation characteristics and allows the leak signal from channel i to pass in the reverse direction. Leakage signals from channel i that have passed in the reverse direction through isolators 103e-j of channel j are reflected by BPFs 103d-j of channel j and re-input to N:1 combiner 103a (hereinafter, this leakage signal will be referred to as the "reflected wave"). The reflected wave is mixed with the aforementioned direct wave, and a mixed signal is output from N:1 combiner 103a. However, since the signal paths of the direct wave and the reflected wave are different, there is a phase difference between them. Therefore, it is impossible for the i-th receiver 201RX-i to extract information about the modulated signal contained in the direct wave alone or the reflected wave alone from this mixed signal. Consequently, in this case, the reflected wave acts as noise to the direct wave, degrading the SNR. This is shown in Figures 6 and 7. As shown in Figure 6, within the bandwidth of the isolator, the reflected wave is sufficiently suppressed, so a sufficiently large SNR can be ensured. However, outside the bandwidth of the isolator, the SNR decreases due to the reflected wave. Therefore, as shown in Figure 7, outside the isolator's bandwidth, the resulting SNR becomes smaller than the SNR required for communication, making communication impossible. A similar problem occurs in the receiving device 200, as shown in Figure 8, as is the case when the isolator bandwidth in the transmitting device 100 is narrow. More generally, the same problem occurs when the total number of channels is three or more.
[0013] The aforementioned problems are particularly pronounced when the wireless bandwidth (i.e., the sum of the bandwidths of all channels bonded together, as shown in Figure 9) is wide, such as in subterahertz wireless communication being considered for 6G. [Prior art documents] [Non-patent literature]
[0014] [Non-Patent Document 1] M. Giordani, M. Polese, M. Mezzavilla, S. Rangan, and M. Zorzi, “Toward 6G networks: Use cases and technologies,” IEEE Communications Magazine, vol. 58, no. 3, pp. 55-61, Mar. 2020. [Overview of the Initiative] [Problems that the invention aims to solve]
[0015] In light of the above-mentioned background technology and technical considerations, we disclose a wireless communication system that can suppress the degradation of communication quality (i.e., SNR) caused by inter-channel interference and / or self-interference due to channel bonding. [Means for solving the problem]
[0016] The technical matters described herein are provided not to explicitly or implicitly limit the invention described in the claims, nor to enable persons other than those who benefit from the invention (e.g., the applicant and the rights holder) to limit the invention described in the claims, but simply to facilitate understanding of the essential points of the invention. An overview of the invention from other perspectives can be understood, for example, from the claims of this patent application as of the filing date. Briefly speaking, the wireless communication system of this disclosure has a configuration in which the isolator included in the configuration shown in Figure 4 is replaced with an attenuator or amplifier. The operating bandwidth of the attenuator or amplifier is wider than the bandwidth of the channel bonding signal. [Effects of the Invention]
[0017] The wireless communication system of this disclosure includes an attenuator or amplifier with an operating bandwidth wider than the bandwidth of the channel bonding signal, instead of an isolator used in the prior art wireless communication system, thereby suppressing the degradation of communication quality caused by inter-channel interference and / or self-interference due to channel bonding. [Brief explanation of the drawing]
[0018] [Figure 1] A schematic diagram of a wireless communication system illustrating the basics of channel bonding. [Figure 2] A diagram illustrating inter-channel signal leakage in a transmitting device. [Figure 3] A diagram illustrating reflection and inter-channel interference caused by a band-pass filter (BPF). [Figure 4] A diagram illustrating the suppression of inter-channel interference using an isolator. [Figure 5] A diagram illustrating the mixing of direct and reflected waves in a transmitting device. [Figure 6] A diagram illustrating that the signal intensity of reflected waves is not sufficiently suppressed within the bandwidth. [Figure 7] A diagram illustrating how reflected waves degrade the signal-to-noise ratio (SNR). [Figure 8] A diagram illustrating the mixing of direct and reflected waves in a receiving device. [Figure 9] Schematic diagram of channel bonding signals. [Figure 10] Configuration diagram of the wireless communication system of the first embodiment. [Figure 11] A diagram illustrating the mixing of direct and reflected waves in a transmitting device. [Figure 12]A diagram illustrating that the signal intensity of reflected waves is sufficiently suppressed within the bandwidth. [Figure 13] A diagram to explain that the signal-to-noise ratio (SNR) does not degrade due to reflected waves. [Figure 14] Modification 1 of the first embodiment. [Figure 15] Modification 2 of the first embodiment. [Figure 16] Modification 3 of the first embodiment. [Figure 17] Configuration diagram of the wireless communication system of the second embodiment. [Figure 18] Example configuration of a distributed amplifier. [Figure 19] Modification 1 of the second embodiment. [Figure 20] Modification 2 of the second embodiment. [Figure 21] Modification 3 of the second embodiment. [Figure 22] Modification 4 of the second embodiment. [Figure 23] Modification 5 of the second embodiment. [Modes for carrying out the invention]
[0019] Embodiments of the wireless communication system of this disclosure will be described with reference to the drawings.Hereinafter, unless otherwise specified, N is a predetermined integer greater than or equal to 2, and n represents each integer between 1 and N (i.e., with Z being the set of all integers, N∈Z, N≧2, n∈{x∈Z:1≦x≦N}).Therefore, the meaning of "n" will be determined on a case-by-case basis.For example, "N transmitters 101TX-n" means "N transmitters 101TX-1, ..., 101TX-N", and "the nth transmitter 101TX-n" means "any nth transmitter 101TX-n".In addition, from the viewpoint of clarifying the essential points of the embodiments, the illustration and explanation of components that are actually necessary or may be necessary but are considered non-essential in the embodiments (such as intermediate amplifiers) will be omitted.In each figure, the symbols of some components may be omitted to avoid complexity.
[0020] <Principle> Prior to a detailed description of the embodiments, the basic principle of the embodiments will be explained. Figure 10 shows the configuration of the first embodiment of the wireless communication system 1, which will be described later. Briefly speaking, the wireless communication system 1 has the same configuration as the wireless communication system shown in Figure 4, except that N isolators 103e-n are replaced with N attenuators 103g-n, and N isolators 203e-n are replaced with N attenuators 203g-n.
[0021] In general, over a wide frequency range, the input and output impedance of an attenuator can be considered as a pure resistance (typically 50Ω). Therefore, the attenuator can operate across the total frequency band of all channels in channel bonding. Referring to Figures 11, 12, and 13, the principle by which the configuration shown in Figure 10 can solve the aforementioned problem will be explained. For simplicity, consider a transmitter when bonding two channels (channel i and channel j). As shown in Figure 11, and similar to the case shown in Figure 5, the signal of channel i is input to the N:1 combiner 103a, and most of it reaches the output port of the N:1 combiner 103a directly as a direct signal (hereinafter, this direct signal will be referred to as the "direct wave"), but a portion of the signal of channel i reaches the input port of channel j of the N:1 combiner 103a as a leak signal. A portion of the signal from channel i that reaches the input port of channel j passes in the reverse direction through the attenuator 103g-j of channel j, is reflected by the BPF 103d-j of channel j, and is re-input to the N:1 combiner 103a (hereinafter, this leakage signal will be referred to as the "reflected wave").
[0022] Here, we consider the signal loss in both the direct wave and the reflected wave paths. Below, the loss in the attenuator 103g-i of channel i and the loss in the attenuator 103g-j of channel j are both L. ATT Let L be the input port isolation of the N:1 combiner 103a (the ratio of the signal output to the input port of channel j to the signal input to the input port of channel i). iso Let L be the input port-output port coupling coefficient of the N:1 combiner 103a (the proportion of the signal input to the input port that directly reaches the output port).cpl Let it be. The unit is dB. The loss L that the signal of channel i output from BPF 103d-i of channel i experiences until it reaches the output port of the N:1 synthesizer 103a as a direct wave direct is represented by Equation (1).
Equation
[0023] Similarly, the loss L that the signal of channel i output from BPF 103d-i of channel i experiences until it reaches the output port of the N:1 synthesizer 103a as a reflected wave reflect is represented by Equation (2). The 2L in the third term on the right side of Equation (2) ATT is due to the reflected wave being reflected by the BPF 103d-j of channel j and re-entering the N:1 synthesizer 103a, passing through the attenuator 103g-j of channel j a total of 2 times in the process.
Equation
[0024] Therefore, the intensity ratio SNR of the direct wave and the reflected wave at the output port of the N:1 synthesizer 103a achieved is represented by Equation (3) as the ratio of Equation (2) to Equation (1).
Equation
[0025] As described above, generally, since the operating band of the attenuator is wideband, as shown in FIG. 12, the level of the reflected wave can be made smaller than the level of the direct wave by SNR achieved only over the entire band of the signal. As shown in FIG. 13, this SNR achievedIf the signal-to-noise ratio (SNR) is made greater than the SNR required for communication, the receiver 200 can demodulate the signal. Here are some quantitative examples of the SNR required for communication. When using forward error correction (FEC), which is commonly used in wireless communication, error-free communication can be achieved with an SNR of 9.8 dB for quadri-phase shift keying (QPSK), 16.5 dB for quadrature amplitude modulation (QAM), and 22.5 dB for 64QAM.
[0026] In a typical synthesizer or partitioner, L iso Since this is about 5 dB, for example, if you want to communicate using 16QAM, the loss will be about 6 dB (L ATT It turns out that we should use an attenuator with ).
[0027] For simplicity, the above explanation used channel bonding of two channels as an example, but the same argument holds true when bonding three or more channels. Furthermore, equation (3) also holds true for receiving devices.
[0028] <First Embodiment> The configuration of the wireless communication system 1 of the first embodiment is as shown in Figure 10. The wireless communication system 1 includes a transmitting device 100 and a receiving device 200.
[0029] The transmitting device 100 includes N transmitters 101TX-n, N local oscillators 103b-n, N frequency converters 103c-n, N transmitting bandpass filters 103d-n, N transmitting circuitry devices 103g-n, an N:1 combiner 103a, and a transmitting antenna 105. In this example, the N local oscillators 103b-n, N frequency converters 103c-n, N transmitting bandpass filters 103d-n, N transmitting circuitry devices 103g-n, and the N:1 combiner 103a constitute the channel combiner 103.
[0030] The nth transmitter 101TX-n generates the nth transmission signal, which is included in the N transmission signals corresponding to each of the N predetermined channels. The nth local oscillator 103b-n generates the oscillation frequency f corresponding to the nth channel included in the N channels. n It generates a signal with N center frequencies f1, f2, ..., f N These are different from each other. The nth transmitted signal is transmitted by the nth frequency converter 103c-n, and the oscillation frequency f generated by the nth local oscillator 103b-n is transmitted by the nth frequency converter 103c-n. n It is mixed with the signal, and as a result, the bandwidth (baseband or intermediate frequency band) of the nth transmitted signal is center frequency f n The bandwidth is increased. The nth transmitting bandpass filters 103d-n allow the nth transmitted signal from the nth frequency converter 103c-n to pass through. The nth transmitting circuitry 103g-n acts on the nth transmitted signal from the nth transmitting bandpass filter 103d-n. The N:1 combiner 103a combines one channel bonding signal from the N transmitted signals that have been acted upon by the N transmitting circuitry 103g-n. The transmitting antenna 105 radiates the channel bonding signal into the air. In the first embodiment, each of the N transmitting circuitry 103g-n is an attenuator, and the operating bandwidth of each of the N transmitting circuitry 103g-n is wider than the bandwidth of the channel bonding signal.
[0031] The receiving device 200 includes a receiving antenna 205, an N:1 splitter 203a, N receiving-side circuit devices 203g-n, N receiving-side bandpass filters 203d-n, N local oscillators 203b-n, N frequency converters 203c-n, and N receivers 201RX-n. In this example, the N:1 splitter 203a, N receiving-side circuit devices 203g-n, N receiving-side bandpass filters 203d-n, N local oscillators 203b-n, and N frequency converters 203c-n constitute the channel separator 203.
[0032] The receiving antenna 205 receives the channel bonding signal from the transmitting device 100. The N:1 distributor 203a separates the channel bonding signal received by the receiving antenna 205 into N received signals, each corresponding to one of the N channels. The nth receiving circuit devices 203g-n act on the nth received signal included in the N received signals. The nth receiving bandpass filters 203d-n allow the nth received signal, which has been acted upon by the nth receiving circuit device 203g-n, to pass through. The nth local oscillators 203b-n set the oscillation frequency f corresponding to the nth channel included in the N channels. n The nth received signal from the nth receiving bandpass filter 203d-n is converted by the nth frequency converter 203c-n to generate the oscillation frequency f generated by the nth local oscillator 203b-n. n The signal is mixed with the nth received signal, and as a result, the bandwidth of the nth received signal is reduced to the baseband or intermediate frequency band. The nth receiver 201RX-n receives the nth received signal from the down-converted nth receiving bandpass filter 203d-n. In the first embodiment, each of the N receiving circuit devices 203g-n is an attenuator, and the operating bandwidth of each of the N receiving circuit devices 203g-n is wider than the bandwidth of the channel bonding signal.
[0033] The method for determining the attenuation amount of the attenuator is described below. The SNR in the transmitting device 100 is TX , the SNR in the receiving device 200 is set to SNR RX Therefore, the signal-to-noise ratio (SNR) of the wireless communication system 1 obtained when the transmitting device 100 and the receiving device 200 are directly connected is... total This is given by equation (4). Note that the unit of equation (4) is the true value, not dB.
number
[0034] The required SNR is determined according to the communication modulation scheme, such as 9.8 dB for QPSK and 16.5 dB for 16QAM, and this is used as a variable for SNR.req This is how it will be written. In this case, for communication to be established in the wireless communication system 1 obtained by directly connecting the transmitting device 100 and the receiving device 200, equation (5) must hold true.
number
[0035] Substituting equation (4) into equation (5) yields equation (6).
number
[0036] For simplicity, SNR TX and SNR RX The same SNR value achieved If (see equation (3)) is true, then equation (6) can be rewritten as equation (7). The unit of equation (7) is true value.
number
[0037] From equation (7), for example, 16QAM (SNR req When communicating at (=16.5dB), SNR achieved is SNR req It can be seen that it is sufficient if it is 19.5 dB or more, which is twice that (i.e., +3 dB). Therefore, based on equation (3), L ATT You just need to determine the value of L. iso For (the isolation between input ports of the combiner or distributor), the catalog value or measured value of the combiner or distributor can be used. For example, L iso If = 5.5 dB, then from equation (3) L ATT =7dB is obtained.
[0038] The above discussion is applied to a wireless communication system 1 obtained by directly connecting a transmitter 100 and a receiver 200. However, the same discussion holds true when there is a general medium (e.g., wireless communication space) between the transmitter 100 and the receiver 200, in terms of eliminating interference from reflected waves to the direct wave. Therefore, even when actually performing wireless communication, the attenuation L obtained by equation (3) is also applicable. ATT By using an attenuator with [specific characteristics], reflected waves can be sufficiently removed.
[0039] Furthermore, if the modulation schemes are not the same for all channels, the SNR in equation (6) req The values are not the same across all channels. In this case, there are multiple SNRs corresponding to the multiple modulation schemes used. req The highest value among them is the SNR in equation (6) req By adopting this approach, communication can be performed without problems across all channels.
[0040] The amount of attenuation L that should be set in the attenuator 103g-n of the transmitter 100 in the more general case, obtained from equations (3) and (4) ATT_TX (Units are dB) and the amount of attenuation L to be set in the attenuator 203g-n of the receiving device 200. ATT_RX (Units are dB) is given by equation (8). However, the isolation between input ports of the N:1 combiner 103a of the transmitter 100 is L iso_TX The isolation between the input ports of the N:1 distributor 203a of the receiving device 200 is set to L iso_RX That is what they say.
number
[0041] <Modification 1 of the first embodiment> Modification 1 of the first embodiment is the same as the first embodiment, except that at least one of the N transmitting circuit devices 103g-n is a variable attenuator capable of changing the attenuation amount (see Figure 14). Therefore, please refer to the description of the first embodiment for other technical matters. By such reference, the description of the first embodiment, excluding the differences, is explicitly incorporated herein. In the example shown in Figure 14, each of the N transmitting circuit devices 103g-n is a variable attenuator. The transmitting device 100 may include a controller 140 that controls the attenuation amount of the variable attenuator. The controller 140 of the transmitting device 100 controls the SNR, for example, by changing the communication environment. req If the value is changed, the changed SNR req Using the value of , the SNR that satisfies equation (7) achieved The control is performed to set the attenuation amount obtained from equation (3) or equation (8) to each variable attenuator.
[0042] <Modification 2 of the first embodiment> Modification 2 of the first embodiment is the same as the first embodiment, except that at least one of the N receiving circuit devices 203g-n is a variable attenuator whose attenuation can be changed (see Figure 15). Therefore, please refer to the description of the first embodiment for other technical matters. By such reference, the description of the first embodiment, excluding the differences, is explicitly incorporated herein. In the example shown in Figure 15, each of the N receiving circuit devices 203g-n is a variable attenuator. The receiving device 200 may include a controller 240 that controls the attenuation of the variable attenuator. The controller 240 of the receiving device 200 controls the SNR, for example, by changing the communication environment. req If the value is changed, the changed SNR req Using the value of , the SNR that satisfies equation (7) achieved The control is performed to set the attenuation amount obtained from equation (3) or equation (8) to each variable attenuator.
[0043] <Modification 3 of the first embodiment> Modification 3 of the first embodiment is the same as the first embodiment, except that at least one of the N transmitting circuit devices 103g-n is a variable attenuator capable of changing the attenuation amount, and at least one of the N receiving circuit devices 203g-n is a variable attenuator capable of changing the attenuation amount (see Figure 16). Therefore, please refer to the description of the first embodiment for other technical matters. By such reference, the description of the first embodiment, excluding the differences, is hereby explicitly incorporated. In the example shown in Figure 16, each of the N transmitting circuit devices 103g-n is a variable attenuator, and each of the N receiving circuit devices 203g-n is a variable attenuator. The transmitting device 100 may include a controller 140 that controls the attenuation amount of the variable attenuator. The controller 140 of the transmitting device 100 controls the largest SNR among the M types of modulation schemes (where M is an integer satisfying 1 ≤ M ≤ N) used by the N transmitters 101TX-n that generate the modulated signal. req Using the value of , the SNR that satisfies equation (7) achieved From equation (3) or equation (8), control is performed to set the obtained attenuation amount to one or more variable attenuators. The receiving device 200 may include a controller 240 that controls the attenuation amount of the variable attenuators. When performing wireless communication, the receiving device 200 also knows the modulation scheme of each channel in advance, so the controller 240 of the receiving device 200 sets the largest SNR among the M types of modulation schemes used by the transmitting device 100. req Using the value of , the SNR that satisfies equation (7) achieved The control is performed to set the attenuation amount obtained from equation (3) or equation (8) to one or more variable attenuators.
[0044] According to Modification 1, Modification 2, or Modification 3 of the first embodiment, the SNR can be changed by changing the modulation method in the channel including the variable attenuator. req Even if the signal changes, the attenuation amount of the variable attenuator can be appropriately adjusted, thus enabling stable and error-free communication. Furthermore, by appropriately adjusting the attenuation amount of the variable attenuator, the overall loss of the wireless communication system 1 can also be suppressed.
[0045] <Second Embodiment> The second embodiment is the same as the first embodiment, except that each of the N transmitting circuit devices 103g-n is a broadband amplifier having an operating bandwidth wider than the bandwidth of the channel bonding signal, and each of the N receiving circuit devices 203g-n is a broadband amplifier having an operating bandwidth wider than the bandwidth of the channel bonding signal (see Figure 17). Therefore, please refer to the description of the first embodiment for other technical matters. By such reference, the description of the first embodiment, excluding the differences, is explicitly incorporated herein. A broadband amplifier is, for example, a distributed amplifier (see Figure 18). For information on distributed amplifiers, please refer to the following references, for example. In the example shown in Figure 17, each of the N transmitting circuit devices 103g-n is a distributed amplifier, and each of the N receiving circuit devices 203g-n is a distributed amplifier. (Reference) T. Jyo et al., “A 241-GHz-Bandwidth Distributed Amplifier with 10-dBm P1dB in 0.25-μm InP DHBT Technology,” 2019 IEEE MTT-S International Microwave Symposium (IMS).
[0046] Generally, distributed amplifiers are known to have a flat gain over a very wide bandwidth, from near DC to the amplifier's cutoff frequency (around tens of GHz at the product level, and several hundred GHz at the research level). Furthermore, the input and output impedances of a distributed amplifier are purely resistive (generally 50Ω) up to the cutoff frequency. The frequency characteristics of the input and output impedances of a distributed amplifier are similar to those of an attenuator. Therefore, by employing a distributed amplifier capable of operating across the entire frequency band of a wideband channel bonding signal as all or part of the transmitting circuitry and / or all or part of the receiving circuitry, the reduction in SNR due to interference between reflected and direct waves can be suppressed. Moreover, according to the second embodiment, there is no signal attenuation by an attenuator—rather, the signal is amplified—so the second embodiment is very suitable for actual wireless communication where the signal level tends to be low due to large signal attenuation in the wireless section.
[0047] Furthermore, according to the second embodiment, a broadband amplifier such as a distributed amplifier has termination resistors (resistors shown as R1 and R2 in Figure 18) at both the input and output, and the reflected waves from the transmitting bandpass filter 103d-n or the receiving bandpass filter 203d-n are absorbed by the termination resistors and are not re-input to the N:1 combiner 103a or the N:1 distributor 203a, so there is no need to set an appropriate attenuation amount.
[0048] <Modified form of the second embodiment> Modifications of the second embodiment can be realized in the same way as the modifications of the first embodiment. For example, at least one of the N transmitting circuit devices 103g-n may be a variable-gain broadband amplifier whose gain can be changed (see Figure 19). In this case, the transmitting device 100 may include a controller 160 that controls the gain of the variable-gain broadband amplifier. Alternatively, for example, at least one of the N receiving circuit devices 203g-n may be a variable-gain broadband amplifier whose gain can be changed (see Figure 20). In this case, the receiving device 200 may include a controller 260 that controls the gain of the variable-gain broadband amplifier. Alternatively, for example, at least one of the N transmitting circuit devices 103g-n may be a variable-gain broadband amplifier whose gain can be changed, and at least one of the N receiving circuit devices 203g-n may be a variable-gain broadband amplifier whose gain can be changed (see Figure 21). In this case, the transmitting device 100 may include a controller 160 for controlling the gain of the variable-gain broadband amplifier, and the receiving device 200 may include a controller 260 for controlling the gain of the variable-gain broadband amplifier. By using a variable-gain amplifier, distortion of the amplifier itself or the frequency converter 203c-n of the receiving device 200 can be suppressed.
[0049] Controllers 160 and / or 260 control the gain of the variable-gain broadband amplifier by adjusting, for example, the gate voltage of the unit amplifier included in the distributed amplifier (a common-source FET amplifier in the example shown in Figure 18). Since the configuration of the distributed amplifier itself is not changed by the variable-gain mechanism, the gain can be changed while maintaining the distribution amplifier's key characteristic of operating across the entire broadband of the channel bonding signal. Furthermore, according to the configuration shown in Figure 18, reducing the gain (i.e., setting the gate voltage near the threshold and reducing the current flowing through the FET) reduces the power consumption of the distributed amplifier. Therefore, by using the distributed amplifier as a transmitting and / or receiving circuit, the power consumption of the transmitting device 100 and the receiving device 200 can be reduced by performing gate voltage control to minimize the gain as much as possible within the range where a sufficient SNR can be obtained for each channel.
[0050] <Third Embodiment> The third embodiment is a hybrid of the first and second embodiments. That is, each of the N transmitting circuit devices 103g-n is an attenuator (or a variable attenuator with a changeable attenuation amount) or amplifier (or a variable gain amplifier with a changeable gain) having an operating bandwidth wider than the bandwidth of the channel bonding signal, and each of the N receiving circuit devices 203g-n is an attenuator (or a variable attenuator with a changeable attenuation amount) or amplifier (or a variable gain amplifier with a changeable gain) having an operating bandwidth wider than the bandwidth of the channel bonding signal (see Figure 22). The wireless communication system 1 of the third embodiment may optionally include controllers 140, 160, 240, 260.
[0051] Generally, broadband distributed amplifiers consume a lot of power. Therefore, in order to reduce power consumption, instead of employing distributed amplifiers as transmitting circuitry 103g-n and / or receiving circuitry 203g-n in all channels, it is possible to employ distributed amplifiers as transmitting circuitry 103g-n and / or receiving circuitry 203g-n in some channels. For example, one configuration is to employ a distributed amplifier as the receiving circuit 203g-n only for channels of the receiving device 200 where the signal level is lower, and an attenuator (or variable attenuator) as the transmitting circuit 103g-n for the transmitting device 100 where ample transmission power can be secured (see Figure 22). Alternatively, one configuration is to employ a distributed amplifier as the transmitting circuit 103g-n and the receiving circuit 203g-n only for the high-frequency band channels (channel 2 in the example of Figure 23) where the power tends to be particularly low, and an attenuator (or variable attenuator) as the transmitting circuit 103g-n and the receiving circuit 203g-n for the remaining channels (see Figure 23).
[0052] <Addendum 1> The technical features disclosed in the various embodiments and their variations described above are not necessarily mutually exclusive. To the extent that they do not contradict each other from a technical standpoint, the technical features of one embodiment or its variation may be applied to the technical features of another embodiment or its variation.
[0053] The claims set forth in the claims of this application at the time of filing do not necessarily claim all inventions disclosed in this specification. In this regard, the applicant of this application should not be understood or interpreted as having waived the right to obtain a patent for inventions not claimed at the time of filing this application. To the extent permitted by the laws or treaties of the country or region that receives this application, the applicant of this application reserves the right to obtain a patent for inventions not claimed in this application, the right to file a divisional application for such inventions, the right to claim such inventions by amendment, and all other rights. However, this shall not apply if the applicant of this application expresses an explicit and definitive contrary intention.
[0054] An example of a summary of this disclosure from a different perspective is as follows:
[0055] The first invention is a wireless communication system for wireless communication using channel bonding, A wireless communication system includes a transmitter and a receiver. Let N be a predetermined integer satisfying 2 ≤ N, and let n represent each integer between 1 and N inclusive. The transmitting device includes N transmitters, N transmitting bandpass filters, N transmitting circuit devices, and a combiner. The nth transmitter among the N transmitters generates the nth transmitting signal, which is included in the N transmitting signals corresponding to each of the N channels. The nth transmitting bandpass filter among the N transmitting bandpass filters passes the nth transmitting signal through it. The nth transmitting circuit device among the N transmitting circuit devices acts on the nth transmitting signal from the nth transmitting bandpass filter. The combiner synthesizes a single channel bonding signal from the N transmitting signals that have been acted upon by the N transmitting circuit devices. The receiving device includes a distributor, N receiving circuit devices, N receiving bandpass filters, and N receivers, wherein the distributor separates the channel bonding signal into N received signals corresponding to each of the N channels, the nth receiving circuit device included in the N receiving circuit devices acts on the nth received signal included in the N received signals, the nth receiving bandpass filter included in the N receiving bandpass filters passes the nth received signal that has been acted upon by the nth receiving circuit device, and the nth receiver included in the N receivers receives the nth received signal from the nth receiving bandpass filter. Each of the N transmitting circuit devices is an attenuator or amplifier, and the operating bandwidth of each of the N transmitting circuit devices is wider than the bandwidth of the channel bonding signal. Each of the N receiving circuit devices is either an attenuator or an amplifier, and the operating bandwidth of each of the N receiving circuit devices is wider than the bandwidth of the channel bonding signal.
[0056] The second invention relates to the wireless communication system of the first invention, If at least one transmitting circuit device of N transmitting circuit devices is an attenuator, and at least one receiving circuit device of N receiving circuit devices is an attenuator, then the attenuation amount of at least one transmitting circuit device is L. ATT_TX (Unit: dB) and the attenuation of at least one receiving circuit device is set to L ATT_RX (Unit: dB) and channel isolation of the synthesizer is L iso_TX (Unit: dB) and the inter-channel isolation of the distributor is L iso_RX (Unit: dB) The required signal-to-noise ratio (SNR) is determined by the modulation scheme used in wireless communication. req (Unit: dB) L ATT_TX (Unit: dB)
number
[0057] The third invention relates to the wireless communication system of the first invention, If at least one of the N transmitting circuit devices is an attenuator, and / or if at least one of the N receiving circuit devices is an attenuator, then at least one of the attenuators is a variable attenuator whose attenuation amount can be changed.
[0058] The fourth invention is the wireless communication system of the second invention, At least one of the attenuators in the transmitting circuit device, which is an attenuator, and at least one of the attenuators in the receiving circuit device, is a variable attenuator whose amount of attenuation can be changed.
[0059] The fifth invention relates to the wireless communication system of the first invention, If at least one of the N transmitting circuit devices is an amplifier, and / or if at least one of the N receiving circuit devices is an amplifier, then at least one of the amplifiers is a variable amplifier whose gain can be changed.
[0060] The sixth invention relates to the wireless communication system of the first invention, Each of the N transmitting circuit devices is an attenuator. Each of the N receiving circuit devices is an amplifier.
[0061] The seventh invention relates to the wireless communication system of the sixth invention, At least one of the N transmitting circuit devices is a variable attenuator capable of changing the amount of attenuation. At least one of the N receiving circuit devices is a variable amplifier whose gain can be changed.
[0062] The eighth invention relates to the wireless communication system of the first invention, Let A be the set of integers between 1 and N (inclusive), and let φ be the empty set. Let P and Q be proper subsets of A such that P∩Q=φ and P∪Q=A, and let p ∈ P and q ∈ Q. Of the N transmitting circuit devices, the transmitting circuit device corresponding to the p-th channel out of the N channels is an attenuator. Of the N receiving circuit devices, the receiving circuit device corresponding to the p-th channel out of the N channels is an attenuator. Of the N transmitting circuit devices, the transmitting circuit device corresponding to the q-th channel out of the N channels is an amplifier. Of the N receiving circuit devices, the receiving circuit device corresponding to the q-th channel out of the N channels is an amplifier.
[0063] The ninth invention is a wireless communication system of the eighth invention, Let R be a subset of P, S be a subset of Q, let r ∈ R, and let s ∈ S. The transmitting and / or receiving circuitry corresponding to the r-th channel is a variable attenuator whose attenuation can be changed. The transmitting and / or receiving circuitry corresponding to the s-th channel is a variable amplifier whose gain can be changed.
[0064] <Addendum 2> While the present invention has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications can be made and elements can be replaced with equivalents without departing from the scope of the invention. Furthermore, many modifications can be made to adapt a particular system, device, or component thereof to the teachings of the invention without departing from the essential scope of the invention. Thus, the present invention is not limited to the specific embodiments disclosed for the purpose of carrying out the invention, but includes all embodiments that fall within the scope of the appended claims.
[0065] Furthermore, the use of terms such as “first,” “second,” etc. (ordinal numbers) does not indicate order or importance, if any; rather, terms such as “first,” “second,” etc. (ordinal numbers) are used to distinguish elements. The terms used herein are for the purpose of describing embodiments and are not intended in any way to limit the invention. The terms “including” and their variations, when used herein and / or in the appended claims, indicate the existence of the mentioned features, steps, operations, elements, and / or components, but do not exclude the existence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The terms “and / or” include, if any, any combination of one or more of the listed elements relating. Unless otherwise specified in the claims and specification, “connected,” “joined,” “joined,” “linked,” or their synonyms, and all their forms, do not necessarily negate the existence of one or more intermediate elements between two that are, for example, “connected” or “joined” or “linked” to one another. In the claims and description, the term “optional” should be understood to mean the same as the universal quantifier ∀, if any, unless otherwise specified.
[0066] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art to which the present invention pertains. Furthermore, terms such as those defined in commonly used dictionaries should be construed to have the meaning consistent with their meanings in the relevant art and in the context of this disclosure, and should not be construed ideally or excessively formally unless expressly defined.
[0067] It will be understood that many techniques and steps are disclosed in the description of this invention. Each of these has its own advantages, and each can be used in combination with one or more, or possibly all, of the other disclosed techniques. Therefore, to avoid complexity, this specification refrains from describing every possible combination of individual techniques or steps. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and claims.
[0068] In the following claims, all corresponding structures, materials, actions, and equivalents of functional elements combined with means or steps are intended to include structures, materials, or actions for performing a function in combination with other elements, if any.
[0069] While embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Various modifications and variations are permitted without departing from the spirit of the invention. The selected and described embodiments are for illustrating the principles of the present invention and its practical applications. The present invention can be used in various embodiments with various modifications or variations, and the various modifications or variations will be determined according to the expected use. All such modifications and variations are intended to fall within the scope of the present invention as defined by the appended claims and are intended to be given the same protection when interpreted in accordance with the fair, lawful and equitable breadth. [Explanation of Symbols]
[0070] 1. Wireless communication system 100 Transmitter 101TX-n Transmitter 103 Channel Synthesizer 103a Synthesizer 103b-n Local Oscillator 103c-n frequency converter 103d-n Transmitter-side bandpass filter 103e-n Isolator 103g-n Transmitter-side circuitry 105 Transmitting Antenna 140 controllers 160 controllers 200 Receiver 201RX-n receiver 203 Channel Separator 203a distributor 203b-n Local Oscillator 203c-n frequency converter 203d-n Receiver-side bandpass filter 203e-n Isolator 203g-n Receiver Circuitry Device 205 Receiving Antenna 240 controllers 260 controllers 900 Wireless Communication Systems
Claims
1. A wireless communication system for wireless communication using channel bonding, The above wireless communication system includes a transmitting device and a receiving device. Let N be a predetermined integer satisfying 2 ≤ N, and let n represent each integer between 1 and N, The above transmitting device includes N transmitters, N transmitting bandpass filters, N transmitting circuit devices, and a combiner. The nth transmitter among the N transmitters generates the nth transmitting signal, which is included in the N transmitting signals corresponding to each of the N channels. The nth transmitting bandpass filter among the N transmitting bandpass filters passes the nth transmitting signal through it. The nth transmitting circuit device among the N transmitting circuit devices acts on the nth transmitting signal from the nth transmitting bandpass filter. The combiner synthesizes a single channel bonding signal from the N transmitting signals that have been acted upon by the N transmitting circuit devices. The above receiving device includes a distributor, N receiving circuit devices, N receiving bandpass filters, and N receivers, wherein the distributor separates the channel bonding signal into N received signals corresponding to the N channels, the nth receiving circuit device included in the N receiving circuit devices acts on the nth received signal included in the N received signals, the nth receiving bandpass filter included in the N receiving bandpass filters allows the nth received signal, which has been acted upon by the nth receiving circuit device, to pass through, and the nth receiver included in the N receivers receives the nth received signal from the nth receiving bandpass filter. Each of the N transmitting circuit devices is an attenuator or an amplifier, and the operating bandwidth of each of the N transmitting circuit devices is wider than the bandwidth of the channel bonding signal. Each of the N receiving circuit devices is an attenuator or an amplifier, and the operating bandwidth of each of the N receiving circuit devices is wider than the bandwidth of the channel bonding signal. Wireless communication system.
2. In the wireless communication system according to claim 1, If at least one of the N transmitting circuit devices is the attenuator, and at least one of the N receiving circuit devices is the attenuator, then the attenuation amount of the at least one transmitting circuit device is L. ATT_TX (Unit: dB) The attenuation of at least one of the above receiving circuit devices is L ATT_RX (Unit: dB) and the channel isolation of the above synthesizer is L iso_TX (Unit: dB) and the inter-channel isolation of the above distributor is L iso_RX (Unit: dB) The required signal-to-noise ratio (SNR) is determined by the modulation scheme used in the above wireless communication. req (Unit: dB) as above L ATT_TX (Unit: dB) [Number 10] A wireless communication system characterized by satisfying the following conditions.
3. In the wireless communication system according to claim 1, If at least one of the N transmitting circuit devices is the attenuator, and / or if at least one of the N receiving circuit devices is the attenuator, then at least one of the attenuators is a variable attenuator capable of changing the amount of attenuation. A wireless communication system characterized by the following features.
4. In the wireless communication system according to claim 1, If at least one of the N transmitting circuit devices is the amplifier described above, and / or if at least one of the N receiving circuit devices is the amplifier described above, then at least one of the amplifiers is a variable amplifier capable of changing the gain. A wireless communication system characterized by the following features.