Transmitters and receivers for communication systems, communication systems, and methods for transmitting information.

Abstract

An embodiment of the present invention provides a transmitter (100) for a communication system comprising a modulation device (110) configured to generate a transmit signal (120) and to modulate information onto a plurality of sub-bands (120a, ..., 120d), at least two of the sub-bands (120a, ..., 120d) having different bandwidths.

Description

Technical Field

[0001] Embodiments of the present invention relate to, for example, a communication system, a transmitter, and a receiver for transmitting information in a vehicle.

Background Art

[0002] Communication systems are used in many applications, for example, for communication between control devices, comfort devices, and entertainment devices in a vehicle. The in-vehicle electrical vehicle network and / or communication system is currently being developed in the direction of zonalization with respect to wiring. Several independent zones are connected to each other by a communication system. One factor contributing to the trend towards zonalization is the high complexity of customer-specific wire harnesses. At the same time, some conventional independent functions have often been concentrated on high-performance integrated platforms. As a result, between the resulting zones or zone integration modules and such integrated platforms, a high-performance backbone bus is required as part of a communication system that can carry a large amount of data and guarantee short latency, that is, support several use cases simultaneously. If the number of zones remains small, for example, less than five, in principle, switched Ethernet would be suitable for this. This would be true as long as the zonalization is based on the granularity of the power supply in the vehicle. For example, in the case of a larger zonalization in 10 - 25 zones, a switched system would be too complex and expensive. However, if the vehicle wire harness has to be manufactured completely automatically, zonalization in the direction of 20 - 25 zones is required.

[0003] European Patent Application Publication No. 1478148 describes a method for communication between radio stations in a wireless communication system using at least one frequency band divided into a number of subbands. There are various ways in which at least one frequency band is divided into subbands.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] Therefore, for example, to be adapted for use in a vehicle, an improved communication system is required. This requirement is met by the transmitter, receiver, communication system, and vehicle, which are separate components. [Means for solving the problem]

[0006] Embodiments of a transmitter for a communication system include a modulator configured to generate a transmission signal by modulating information over multiple subbands, at least two of which have different bandwidths. Modulation over subbands of different widths ensures that the required amount of information is transmitted in each band, and that the transceiver's electronics, specifically the analog-to-digital converter that digitizes the input signal, do not need to be oversized to accommodate the backup power supply typically required in conventional applications.

[0007] An embodiment of a receiver for a communication system includes a demodulator configured to demodulate an input signal across multiple subbands of different bandwidths and to reconstruct the information transmitted across one subband. The ability to demodulate an input signal across several subbands of different bandwidths allows for the use of an analog-to-digital converter within the receiver, which must be processed with less power consumption compared to conventional solutions, and this, for example, makes it more cost-effective.

[0008] An embodiment of a communication system for automobiles comprises a data bus, an embodiment of a first transmitter coupled to the data bus for transmitting information via the data bus, and an embodiment of a second transmitter coupled to the data bus for transmitting information via the data bus. The use of transmitters enables the reliable and efficient implementation of the communication system in a daisy-chain architecture.

[0009] Embodiments of a method for transmitting information that make this possible include modulating information on a first subband and modulating further information on a second subband, wherein the first and second subbands have different bandwidths. [Brief explanation of the drawing]

[0010] These embodiments will be described in more detail below with reference to the attached drawings. [Figure 1] This is a schematic diagram of the transmitter. [Figure 2] This is a schematic diagram of the receiver. [Figure 3] This is a schematic diagram of a transceiver. [Figure 4] This shows the dependency between the transmittable bitrate bandwidth and the signal-to-noise ratio. [Figure 5] This is a diagram of the structure of a communication system. [Figure 6] This is a schematic diagram of the communication system inside a vehicle. [Figure 7] This is a flowchart illustrating an embodiment of a method for receiving information. [Figure 8] This is a flowchart illustrating an embodiment of a method for transmitting information. [Modes for carrying out the invention]

[0011] Next, various embodiments will be described in more detail with reference to the accompanying drawings illustrating several embodiments. In the drawings, the thickness dimensions of lines, layers, and / or areas may be exaggerated for clarity.

[0012] Figure 1 shows a schematic diagram of an embodiment of a transmitter 100 for a communication system.

[0013] The transmitter is connected to a data bus 150 and includes a modulator 110 configured to generate a transmit signal and modulate information over several subbands 120a, 120b, 120c, and 120d, where at least two subbands have different bandwidths. Modulation can be performed using some modulation method and scheme. Each subband similarly has a number of subcarriers, e.g., 256, 512, or 1024. In this embodiment, four subbands 120a, 120b, 120c, and 120d are illustrated, but in additional embodiments, more or fewer subbands may be used. In another approach, in an orthogonal frequency division multiplexing (OFDM) scheme using several subbands, subbands of the same bandwidth are used and separated at the receiver side by an inverse Fourier transform before the transmitted information and / or bits are demodulated. Compared to conventional methods, modulation across subbands of different bandwidths ensures that the required amount of information can always be transmitted in each band, while simultaneously eliminating the need for the transceiver's electronics—specifically, the analog-to-digital converter for digitizing the input signal—to be oversized to accommodate the backup power supplies commonly required in conventional applications. This would be particularly important if the transmit power per subband were not dynamically adjusted. If this remains constant over time, the implementation becomes considerably less complex and less expensive. Furthermore, it eliminates the communication overhead that would otherwise be necessary for transferring received power from the receiver to the transmitter.

[0014] The advantages of subbands of different bandwidths become apparent when we consider the receiver schematically shown in Figure 2, and the entire system, i.e., a communication system having several transmitters and receivers daisy-chained together via a data bus, as schematically shown in Figure 5. Although the transmitters and receivers are initially illustrated separately in Figures 1 and 2 to clearly distinguish between transmission and reception, it should be noted that in many practical implementations, a single device, and / or one of the nodes 520a, ..., 520d shown in Figure 6, can perform both transmission and reception on the data bus 510, i.e., it includes a transceiver, as schematically shown in Figure 3.

[0015] According to some embodiments, while multiple transceivers are transmitting simultaneously on different subbands, only one of the transceivers among nodes 520a to 520d may transmit on the communication medium and / or data bus 510 at one subband or on multiple subbands at a time. According to further embodiments, different transceivers may also transmit simultaneously on the same subband using different subcarriers.

[0016] Figure 2 shows a schematic diagram of the receiver. To be compatible with the transmitter 100 of FIG. 1, the receiver 200 includes a demodulator 210 that demodulates the input signal 220 by a plurality of sub-bands 220a, …, 220d with different bandwidths and reconstructs the information transmitted in one sub-band. In a communication system, transmitters and receivers at different nodes are connected to each other via variable-length data buses. Further, there may be additional nodes in a daisy-chain configuration between two communication nodes. Additional nodes disposed between two communication nodes also cause additional insertion loss. Therefore, the receiver does not receive the power emitted by the transmitter, but the power is reduced depending on the length of the data bus between the transmitter during transmission and the receiver during reception and the number of nodes therebetween. The received power per sub-band 220a, …, 220d reduced in this way is schematically shown in FIG. 2 for the case of the received signal 220. FIG. 2 shows the frequency on the X-axis and the power normalized with respect to the frequency in dBm / Hz on the Y-axis. FIG. 2 shows the general attenuation behavior of the signal on the conductor. In particular, signals at higher frequencies are attenuated more than signals at lower frequencies. As a result, if the transmitted power is the same for all sub-bands, the sub-band having a higher center frequency has a lower signal power reaching the receiver than the sub-band having a lower center frequency.

[0017] FIG. 3 shows a transceiver 250 simply connected to the data bus 150 for the sake of completeness. The transceiver 250 has the capabilities of the transmitter 100 and the receiver 200 of FIGS. 1 and 2. As a result, the transceiver can transmit data to the data bus 150 and can read data from the data bus.

[0018] FIG. 4 shows a diagram of the dependency between the bit rate that can be transmitted over the bandwidth of a sub-band and the signal-to-noise ratio. The ADC that digitizes the input signal in the receiver must be sized such that it can digitize all of the received power in all applications and configurations of the communication system. The selected modulation format determines the minimum resolution of the ADC, together with the expected maximum power, the number of quantization levels, and the dynamic range of the ADC. The input signal to be digitized is a baseband signal. The more quantization levels the ADC has, the more semiconductor space it requires, the more expensive the ADC becomes, and potentially slower it becomes. The power components to be considered when designing an ADC in a receiver that digitizes an input signal over a wide bandwidth are schematically illustrated in FIG. 3.

[0019] In other embodiments, when using a carrier signal, if the medium of the data bus can carry higher frequencies, the input signal can also be a baseband signal downmixed from the carrier signal.

[0020] For the following considerations, the channel characteristics (especially channel attenuation) are essentially considered for the system design. Therefore, the noise components of the process noise 310, which essentially originate from the background noise that can be understood in terms of hardware design, cables and PCB design, and ambient noise within the vehicle, will not be discussed in detail. Therefore, for the system design, the components of the channel attenuation 320, and the bit rate and / or amount of information transmitted per sub-band 330 should be considered. The latter is explained by the Shannon-Hartley theorem shown in FIG. 3. This theorem describes the number of bits that can be transmitted as a function of the bandwidth B of the sub-band and the signal-to-noise ratio S / N. When the bandwidth B is set to 1 Hz, the result normalized with respect to frequency, i.e., the number of bits that can be transmitted per bandwidth, is illustrated. The maximum possible length of the data bus, and the maximum possible number of nodes, define the maximum channel attenuation and are included in the equation via the reduced signal power and signal-to-noise ratio.

[0021] For example, when transmitted at a bitrate of 10 bits / Hz, the equation results in a required signal-to-noise ratio of only 30 dB.

[0022] As with conventional systems, and in contrast to Figure 2, if all subbands are given the same bandwidth, the ADC would have to be oversized, or the bitrate would be wasted because channel attenuation depends on the distance between communication nodes, especially frequency. First, assuming that the normal behavior of channel attenuation increases with frequency, the signal-to-noise ratio (S / N) decreases with increasing frequency. If we want to transmit the same amount of information per subband, the ADC would have to be designed to digitize the input signal of the highest frequency subband with the required resolution. This means that the ADC would have to be oversized for the lower frequency subbands in order to handle higher received power without clipping. If this is not desired, the bitrate would be wasted.

[0023] For example, if we realistically assume a linear decrease in channel attenuation (e.g., 0.1 to 0.5 dB / m) between a frequency f1 of 100 kHz and a frequency f2 of 300 MHz, the structure of a communication system with a constant bitrate per subband and four subbands 220a, ..., 220d would result in the situation shown in Figure 4. Furthermore, the insertion loss per node can realistically be assumed to be 1.5 dB and constant with respect to frequency.

[0024] The worst possible signal-to-noise ratio (S / N) should be used to calculate the bandwidth of each subband 220a, ..., 220d. Due to monotonically increasing attenuation with frequency, there is a value marked X at the upper end of each subband 220a, ..., 220d. This results in the width of each subband for the required bitrate, or the bitrate per subband for a given bandwidth. For example, if the same bitrate is required per subband, this results in the effective range (subband width multiplied by attenuation at the critical point) of each subband 520a, ..., 520d being the same. If different transmit bandwidths and / or bitrates are required for each subband, for example, if the ADC used must have effective dimensions, then naturally, different bandwidths can be produced for those subbands.

[0025] Figure 6 shows a schematic diagram of a communication system in a vehicle 500 as one possible application of the concepts described in this specification. The communication system has a wired data bus 510 to which several nodes 520a, ..., 520d are coupled. The nodes 520a, ..., 520d are arranged in series with the data bus 510 in a daisy-chain configuration. Each of the nodes 520a, ..., 520d includes a transmitter or / or receiver, and in particular, the individual nodes interconnect different zones of a zoned architecture within the vehicle 500. Since the data bus 510 is a passive wired data bus 510, it is a good and stable transport medium compared to, for example, a cordless system. For example, the data bus according to embodiments of the present invention may use one or more pairs of unshielded twisted pair (UTP), coated UTP, or shielded twisted pair (STP). Similarly, one or more coaxial cables or optical fibers may be used. In a passive daisy-chain configuration, individual nodes 520a, ..., 520d do not actively amplify signals; that is, electronic devices are connected to the data bus internally, for example, via the shortest possible stub wires. In the passive version, two connections within a node are connected to each other, and / or the connections are closed through two possible connections for the node's external connection to the data bus.

[0026] For completeness, the essential steps of the above method, performed within the transmitter or receiver described above, will be briefly explained again below with reference to Figures 7 and 8.

[0027] First, the method for receiving information optionally includes receiving a transport signal from a data bus as an input signal for an ADC (step 610). The input signal is digitized by the ADC (step 620). Furthermore, the method includes demodulating at least two subbands of different bandwidths in the input signal in order to reconstruct the information transmitted in each subband (e.g., data bits) (step 630).

[0028] A method for transmitting information includes modulating the information on a first subband (step 710) and modulating the information (e.g., data bits) on a second subband (step 720), the first and second subbands having different bandwidths. The method further includes transmitting a transmit signal comprising the first and second subbands (step 730). The transmit signal may be, for example, the signal comprising the subbands themselves, or it may be a signal generated by mixing the signals of the subbands with a transport signal.

[0029] In summary, the aforementioned embodiments of the present invention enable OFDMA (Orthogonal Frequency Division Multiplexing with additional subband separation) as the physical layer of, for example, Ethernet, using broadband connectivity of all nodes via a passive daisy-chain. In particular, this allows analog-to-digital converters (ADCs) to be designed taking into account the required bitrate, channel attenuation (daisy-chain), and subband bandwidth (Hz or number of subcarriers).

[0030] While the embodiments of the present invention described above were essentially motivated by applications within automobiles, further embodiments may be used in any other application requiring robust and flexible data communication. Criteria other than mere attenuation of the channel itself may be used to design communication systems and determine subband bandwidths. For example, spectral transmit power can be limited by G.HN standards for several applications, such as data transmission over coaxial cables and telephone lines (ITU-T G.9660). Such spectral masks can be readily considered in the design of communication systems according to the above considerations. [Explanation of Symbols]

[0031] 100 Transmitters 110 Modulation device 120 Transmitted signal 120a, ..., 120d subband 150 data bus 200 receivers 210 Demodulator 220 Input Signals 220a, ..., 220d subband 250 transceivers 310 Process Noise 320 channel attenuation 330 Power required for information transmission 350 Dingment range 500 cars 510 Data Bus 520a, ..., 520d nodes 610 Receive 620 Digitize 630 Recovering 710 Modulate 720 Modulate 730 Send

Claims

1. A modulation device configured to generate a transmission signal and modulate information on multiple subbands, wherein at least two of the subbands have different bandwidths, and the amount of information modulated on each subband is the same. The bandwidth of the aforementioned subbands increases monotonically with the center frequency of the subbands. Modulation device, and A transmitter for a communication system, having an output for the transmission signal, configured to be coupled to a wired medium.

2. An input for an input signal, configured to be coupled to a wired medium, and A receiver for a communication system, comprising a demodulator configured to demodulate the input signal using multiple subbands of different bandwidths, and to reconstruct the information transmitted in one subband such that the amount of information in each subband is the same.

3. The receiver according to claim 2, further comprising an analog-to-digital converter configured to digitize the received signal and supply it to the demodulator as a digital input signal.

4. A communication system for automobiles, Data bus and A first node having the first transmitter according to claim 1, coupled to the data bus for transmitting information via the data bus, A communication system comprising: at least one second node having a second transmitter according to claim 1, coupled to a data bus for transmitting information via the data bus.

5. The communication system according to claim 4, wherein the first node and the second node are connected to the data bus in a daisy-chain configuration.

6. An automobile having the communication system described in claim 4 or 5.

7. A method of transmitting information, Modulating information on multiple subbands, where at least one of the subbands Both have different bandwidths, and the amount of information modulated on each subband is the same. The bandwidth of the aforementioned subbands increases monotonically with the center frequency of the subbands. Modulation and A method comprising transmitting a transmission signal having the aforementioned multiple subbands via a wired medium.

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