JP2004242059A - Communication device and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, in performing simultaneous multiplex communication between a master station such as a codeless telephone and a plurality of master stations, the use of a frequency division multiplex spreads an occupancy band in accordance with the number of slave stations and the use of a time division multiplex lowers a transmission capacity. <P>SOLUTION: In this invention, the communication device has one or a plurality of master stations and a plurality of slave stations, and communicates by a signal in which a plurality of carriers cross at right angles to one another on a frequency axis and multiplied between the master stations and the slave stations and there are a plurality of hierarchies constituted of an arbitrary number of carriers. The device is equipped with a hierarchy allocating means for allocating necessary data for each slave station to one of the hierarchies and a demodulating means for demodulating the allocated hierarchies in the slave stations. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication device and a communication method such as a cordless telephone or a printer system using a signal in which a plurality of carriers represented by an OFDM signal and the like are orthogonally multiplexed on a frequency axis.
[0002]
[Prior art]
In a conventional communication device such as a cordless telephone that wirelessly transmits and receives between a master station and a slave station, one-to-one communication is performed. In general, even when a plurality of slave stations are provided, only simultaneous communication of the same information can be performed.
[0003]
On the other hand, when one-to-many simultaneous multiplex communication is performed between a master station and a plurality of slave stations, the master station and the slave stations are connected by frequency division multiplexing (hereinafter, referred to as “FDM”), and a plurality of channels are connected. It is necessary to transmit information to each slave station. Alternatively, it is necessary to connect by time division multiplexing (hereinafter, referred to as “TDM”) and to divide and transmit information to each slave station in time (for example, see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Publication No. Hei 7-501663
[0005]
[Problems to be solved by the invention]
However, with the recent development of networking and user-friendliness, there is an increasing need to communicate a large amount of data including an image, instead of the conventional communication using only voice. In particular, even with a cordless telephone, there is an increasing need to perform a large amount of data communication such as image and data communication from a master station to a slave station (so-called downlink line). In addition, there is an increasing demand for transmitting different pieces of information from one master station to a plurality of slave stations.
[0006]
In the case where such a large amount of data communication and one-to-many simultaneous multiplex communication are compatible, the performance of the conventional FDM or TDM is not sufficient.
[0007]
FIG. 13 is a block diagram showing a conventional technique using FDM in the conventional technique of the present invention. Reference numeral 80 denotes a master station, and reference numerals 82a to 82d denote slave stations, which are wirelessly communicated by an antenna 81 of the master station and antennas 83a to 83d of the slave stations. Here, in the case of simultaneous multiplex communication using FDM, communication is performed by dividing into channels corresponding to the number of slave stations on the frequency axis as indicated by reference numeral 84, and channels assigned to each band in the slave station are determined. Need to receive. For this reason, when performing communication using FDM, there is a problem in that the required bandwidth increases as the number of slave stations increases. Alternatively, when the band is limited, there is a problem that the number of slave stations that can perform simultaneous multiplex communication is limited.
[0008]
FIG. 14 is a block diagram showing a conventional technique using TDM in the conventional technique of the present invention. As shown in FIG. 85, channels are multiplexed for the number of slave stations existing in the same band on the time axis. Reference numeral 86 denotes a time division multiplexer, which divides each channel multiplexed on the time axis and distributes the divided channels to the slave stations 82a to 82d. For this reason, there is a problem that the switching waiting time increases as the number of slave stations increases, and it becomes difficult to perform a large amount of data communication. In FIG. 14, since there are four slave stations, the amount of data that can be transmitted is reduced to one fourth as compared with the case where no multiplexing is performed.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a communication apparatus and a communication method that enable simultaneous multiplex communication in communication between a master station and a plurality of slave stations without reducing the data transmission amount. And
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the invention of the present application has one or more master stations and a plurality of slave stations greater than the number of master stations, and a plurality of carriers between the master station and the slave stations have frequency axes. A communication device that communicates by signals having a plurality of layers composed of an arbitrary number of carriers, the signals being orthogonally multiplexed and multiplexed on each other. And a demodulation means for demodulating the hierarchy allocated in the slave station.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 has one or a plurality of master stations and a plurality of slave stations, and a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the master station and the slave stations. A communication device that communicates by a signal having a plurality of hierarchies constituted by an arbitrary number of carriers, wherein the hierarchal allocating means allocates necessary data for each slave station to one of the hierarchies, Demodulating means for demodulating the layer assigned in the communication device, wherein the function of performing simultaneous multiplex communication to a plurality of slave stations without reducing the amount of transmission in a certain band. Have.
[0012]
According to a second aspect of the present invention, in the slave station of the first aspect, the communication apparatus is characterized in that a band of an assigned layer is extracted by a filter and demodulated, and the function of demodulating the assigned layer is provided. Have.
[0013]
According to a third aspect of the present invention, in the slave station of the first aspect, hierarchy information relating to a hierarchy assigned to the station, hierarchy recognition means for recognizing the hierarchy assigned to the slave station using the hierarchy information, A hierarchical data extracting means for extracting data included in the hierarchy recognized by the recognizing means, the communication device having an operation of demodulating only the allocated hierarchy.
[0014]
According to a fourth aspect of the present invention, in the layer assigning means according to any one of the first to third aspects, the number of assigned layers is changed and assigned according to a change in the number of slave stations in which a communication state is established. A communication device having an effect of improving data transmission efficiency.
[0015]
According to a fifth aspect of the present invention, in the hierarchical allocating means according to any one of the first to third aspects, a transmission capacity information notifying means for notifying a data amount required by the slave station, and a transmission capacity information notifying means based on the notified required data amount. A communication device characterized in that the number of layers is proportionally allocated and assigned, and has an effect of improving data transmission efficiency.
[0016]
According to a sixth aspect of the present invention, in the hierarchical allocation means of the first to third aspects, a transmission capacity information notifying means for notifying a data amount required by the slave station and the importance of data transmission, A communication device characterized in that a hierarchy is assigned based on a data amount and importance of data transmission, and has an operation of improving data transmission efficiency.
[0017]
The invention according to claim 7 has one or a plurality of master stations, one or a plurality of relay stations, and a plurality of slave stations, and a plurality of carriers are arranged between the master station and the relay stations on a frequency axis. Is a signal that is mutually orthogonal and multiplexed, and is a communication device that communicates by a signal having a plurality of layers composed of an arbitrary number of carriers. Assigned to the relay station, demodulating means for demodulating all layers in the relay station, transmitting means for transmitting data demodulated in the relay station to the slave station, and data assigned in the slave station. And a reproducing means for reproducing hierarchical data. The communication device has a function of performing simultaneous multiplex communication with a plurality of slave stations without reducing a transmission amount in a certain band.
[0018]
The invention according to claim 8 includes one or a plurality of cordless telephone master units and a plurality of cordless telephone slave units, and a plurality of carriers mutually communicate on the frequency axis between the master unit and the slave units. A communication device that is a signal that is orthogonal and multiplexed and communicates with a signal having a plurality of layers composed of an arbitrary number of carriers, and that allocates data required for each child device to one of the layers. A communication device comprising an assignment unit and a demodulation unit for demodulating a layer assigned in a slave unit, and has an operation of performing simultaneous multiplex communication with a plurality of slave units in a fixed band.
[0019]
The invention according to claim 9 has one or a plurality of cordless telephone base units and a plurality of cordless telephone subunits, and a plurality of carriers between the parent unit and the subunits on the frequency axis. It is a signal that is mutually orthogonal and multiplexed, and is a communication device that communicates by a signal having a plurality of layers composed of an arbitrary number of carriers, and data required for each slave unit is transmitted to one of the layers. A communication device, comprising: a layer assignment unit to be assigned, and a demodulation unit that demodulates a layer assigned in a slave unit, wherein a plurality of slave units do not reduce a transmission amount in a certain band. To perform simultaneous multiplex communication.
[0020]
According to a tenth aspect of the present invention, there is provided a signal having one or a plurality of printer servers and a plurality of printers, wherein a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the printer server and the printers. A communication device that communicates by a signal having a plurality of hierarchies composed of an arbitrary number of carriers, wherein the hierarchies allocating means for allocating data required for each printer to one of the hierarchies, And a demodulating means for demodulating a hierarchy. The communication device has a function of performing simultaneous multiplex communication with a plurality of printers without reducing a transmission amount in a fixed band.
[0021]
The invention according to claim 11 has one or a plurality of private PBXs and a plurality of private telephones, and a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the private PBX and the private telephones. A communication device that communicates by a signal having a plurality of hierarchies composed of an arbitrary number of carriers, wherein the hierarchal allocating means for allocating data required for each private telephone to one of the hierarchies; A demodulating means for demodulating the assigned hierarchy, the demodulating means having an operation of performing simultaneous multiplex communication with a plurality of private telephones without reducing the transmission amount in a fixed band. .
[0022]
According to a twelfth aspect of the present invention, there is provided a signal having one or a plurality of LAN servers and a plurality of clients, wherein a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the LAN server and the clients. A communication device that communicates by a signal having a plurality of hierarchies composed of an arbitrary number of carriers, wherein hierarchal allocating means for allocating data necessary for each private telephone to one of the hierarchies; And a demodulating means for demodulating the hierarchical layer. The communication device has an operation of performing simultaneous multiplex communication to a plurality of clients without reducing a transmission amount in a fixed band.
[0023]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
(Embodiment 1)
FIG. 1 is a schematic diagram showing a cordless telephone according to an embodiment of the present invention.
[0025]
1 is a cordless telephone base unit corresponding to the master station, and 2a and 2b are cordless telephone slave units corresponding to the slave station. The master unit 1 and the slave units 2a and 2b communicate with each other through transmission paths 3a and 3b. For communication, mutually orthogonal and multiplexed signals described later are used.
[0026]
The cordless telephone shown in FIG. 1 is an example of communication between a master station and slave stations according to Embodiments 2 to 4 as well as Embodiment 1.
[0027]
FIG. 2 is a block diagram of the communication device according to Embodiment 1 of the present invention.
[0028]
Reference numeral 4 denotes a master station, which corresponds to a master station of a cordless telephone as shown in FIG. Reference numerals 5a to 5d denote slave stations that communicate with the master station, such as cordless telephone slaves, and FIG. 2 shows four slave stations for convenience of explanation.
[0029]
Reference numeral 6 denotes source data to be input to the master station, and data to be transmitted to each slave station is input collectively.
[0030]
The master station 4 has an antenna 7, and signals are transmitted to the slave stations 5a to 5d through the transmission paths 8a to 8d.
[0031]
On the other hand, slave stations 5a to 5d have antennas 10a to 10d, and receive signals transmitted from antenna 7 of the master station.
[0032]
Reference numeral 9 denotes a signal transmitted from the master station, which is a signal in which a plurality of carriers are multiplexed after being orthogonal to each other on the frequency axis. For example, it is an orthogonal frequency division multiplexing (hereinafter, referred to as “OFDM”) signal, and in the present embodiment, it will be described as an OFDM signal. An OFDM signal is a signal having a large number of carriers (multi-carriers) and a plurality of these carriers multiplexed orthogonally on the frequency axis. Therefore, it is possible to simultaneously transmit a plurality of carriers as signals in the same band. Since the OFDM signal has a long symbol length for each carrier, the OFDM signal has a strong feature against so-called multipath interference, and is a modulation and demodulation method that has been decided to be adopted in the terrestrial digital broadcasting standard (ISDB-T) scheduled to start in 2003. .
[0033]
Since the OFDM signal has a plurality of carriers on the frequency axis as described above, it is possible to have a plurality of hierarchical structures on the frequency axis.
[0034]
The OFDM signal 9 has four layers from layer 1 to layer 4. In the slave stations 5a to 5d, only the layers required by each slave station are demodulated, and finally, the necessary slaves for each slave station are demodulated. Sound and images are played. Reference numeral 11a denotes layer 1 data demodulated by the slave station 5a. Similarly, only the layer 2 is demodulated in the slave station 5b, only the layer 3 is demodulated in the slave station 5c, and only the layer 4 is demodulated in the slave station 5d. Thereby, individual data can be simultaneously communicated to a plurality of slave stations using only one OFDM signal occupying one band.
[0035]
Next, FIG. 3 is a block diagram of a slave station according to Embodiment 1 of the present invention.
[0036]
12 is a demodulation means. A tuner 16 selects a frequency band of the OFDM signal 9 transmitted from the master station. Reference numeral 17 denotes an analog-to-digital converter (hereinafter, referred to as an “ADC unit”), which converts an analog OFDM signal 9 into a digital signal in order to execute signal processing. Reference numeral 18 denotes a fast Fourier transform unit (hereinafter, referred to as "FFT unit"), which separates and extracts a plurality of carriers multiplexed on the frequency axis. The fast Fourier transform is a means for converting a signal from the time axis to the frequency axis, and is usually used to separate and extract a plurality of carriers mutually orthogonally multiplexed on the frequency axis.
[0037]
Note that the FFT unit 18 similarly separates and extracts the carriers multiplexed on the frequency axis even if a frequency discriminator is used.
[0038]
Reference numeral 19 denotes an equalizer, which performs equalization by interpolation using an equalizer and a pilot signal on a carrier affected by the state of the transmission path. As a result of the equalization, each carrier is demodulated in a state where the influence of the transmission path fluctuation is eliminated. Each carrier is subjected to multi-level modulation of 1,0 data on an orthogonal plane by QPSK, QAM, or the like, and is thus demodulated by the 20 demapping units into data represented by the original 1,0 binary.
[0039]
An error correction unit 21 corrects an error in the demodulated data by an inner code such as Viterbi decoding or an outer code such as Reed-Solomon paired with the convolutional code. For example, in a Reed-Solomon code, it is possible to detect an error that occurs randomly on a bit string and correct this error.
[0040]
Reference numeral 22 denotes a stream demodulation unit that classifies the error-corrected bit strings into types such as image, sound, and character data, and generates each bit stream. Further, if interleaving is performed, deinterleaving is also performed. Interleaving is a method that rearranges the original bit order according to a certain rule, or rearranges the carrier order multiplexed on the frequency axis according to a certain rule, so that errors occurring in a burst can be randomly generated. It can be converted to an error, and the robustness against a burst error is increased.
[0041]
Reference numeral 23 denotes a reproducing unit that reproduces a bit stream into an actual image or sound. Reference numeral 24 denotes a speaker that receives actual audio from the reproduced audio data, and reference numeral 25 denotes a display that displays an actual image from the reproduced image data.
[0042]
By integrating at least the ADC unit 17, the FFT unit 18, the equalization unit 19, the demapping unit 20, the error correction unit 21, and the stream demodulation unit 22 into an LSI, cost reduction and miniaturization can be achieved. Alternatively, the tuner 16 and the reproducing unit 23 can be integrated with the progress of the semiconductor technology, so that the cost and the size can be further reduced.
[0043]
A transmission unit 13 modulates a sound input from the microphone 26 into a transmittable signal. Reference numeral 14 denotes an overall control unit that performs overall control of a transmission unit and demodulation means. Reference numeral 15 denotes a multiplexer (MUX) that switches the signal direction of transmission and reception by the antennas 10a to 10d.
[0044]
Note that diversity reception using a plurality of antennas may be performed to improve reception performance.
[0045]
FIG. 4 is a schematic diagram showing that the OFDM signal and the OFDM signal according to Embodiment 1 of the present invention are hierarchized.
[0046]
27 is a waveform of the OFDM signal observed on the frequency axis. An OFDM signal in which many carriers are multiplexed is observed as a trapezoidal waveform as shown in the figure.
[0047]
Reference numeral 28 denotes one of the carriers, and as shown in FIG. 4, a number of carriers are multiplexed to form an OFDM signal occupying one band. For this reason, it is possible to multiplex a large number of information on the frequency axis, and it is possible to make a hierarchy using this. On the other hand, FDM and TDM described in the related art are “single carrier schemes” in which one carrier is assigned to one band on the frequency axis, and thus cannot be hierarchized on the frequency axis.
[0048]
If one layer is composed of an arbitrary number of carriers (for example, 100 carriers) and 1000 carriers are included in one band of the OFDM signal, it is possible to have ten layers. That is, it is possible to include ten channels in a signal occupying one band, and it is possible to simultaneously communicate ten types of data.
[0049]
Reference numeral 29 denotes a layered OFDM signal transmitted in one band. In FIG. 4, four layers from layer 1 to layer 4 are shown for convenience. Each layer contains a fixed number of carriers. The number of carriers included and the modulation method of each carrier (for example, QPSK has 2-bit data per carrier, and 64QAM has 5 bits of data). (Having bit data).
[0050]
In the drawing, the number of carriers in each layer is represented as the same number, but the number of carriers included in each layer may be different, and one carrier may form one layer. Further, the modulation scheme of each carrier included in the hierarchy by QPSK or the like may be different for each hierarchy.
[0051]
Alternatively, the number of slave stations and the number of hierarchies are described as the same number, but may be different.
[0052]
FIG. 5 is a block diagram of a master station according to Embodiment 1 of the present invention. The parent station includes a hierarchy assignment unit 30, an uplink processing unit 40, and the like.
[0053]
Reference numeral 31 denotes a hierarchy division unit, which divides the source data 6 based on information supplied from the hierarchy assignment information supply unit 32. In FIG. 5, layer 1 is assigned for slave station 5a (33a), layer 2 is assigned for slave station 5b (33b), layer 3 is assigned for slave station 5c, and layer 4 is slave station. Assigned for 5d.
[0054]
Next, error codes are assigned to the divided data for each layer in error correction code assigning units 34a to 34d. For example, it is a Reed-Solomon code, a cyclic code, or the like.
[0055]
Furthermore, each bit is mapped on a complex plane in the map units 35a to 35d using QPSK, multi-level QAM modulation, or the like. Reference numeral 36 denotes a layer synthesizing unit, which multiplexes data mapped for each layer again.
[0056]
Reference numeral 37 denotes an inverse fast Fourier transform unit (hereinafter, referred to as an "IFFT unit"), in which each carrier is orthogonally multiplexed. As a result, an OFDM signal is generated, the frequency is increased to the band required for transmission in the up-conversion unit 38, and transmitted to the slave station via the antenna 7.
[0057]
Note that at least the hierarchy allocating means 30 and the IFFT unit 37 are implemented as LSIs, so that downsizing and cost reduction can be achieved. Also, the uplink processing unit 40 and the like can be implemented as an LSI.
[0058]
FIG. 6 is a diagram showing the layer assignment means as viewed from the signal flow.
[0059]
The layer assignment will be described with reference to FIG. 6 based on the signal flow.
[0060]
Reference numeral 42 denotes a bit stream, which is information of so-called 1 and 0, and includes data allocated to the layer 1 to data allocated to the layer 4. 43a is data to be allocated to the tier 1, 43b is data to be allocated to the tier 2, 43c is data to be allocated to the tier 3, and 43d is data to be allocated to the tier 4. The bit stream 42 is divided in parallel by the layer dividing unit 31 for each layer. The bit signal is divided into four signals 44a to 44d, and is a bit signal represented by 1,0 at this time.
[0061]
The divided data 44a to 44d for each layer are converted into numerical values on the complex plane including the I axis and the Q axis by the map units 35a to 35d, and carriers are generated as indicated by 45a to 45d. That is, 45a is a carrier assigned to layer 1, 45b is a carrier assigned to layer 2, 45c is a carrier assigned to layer 3, and 45d is a carrier assigned to layer 4. is there.
[0062]
The carriers 45 a to 45 d for each layer are input to the IFFT unit 37, and the orthogonally orthogonal OFDM signals 46 are generated. As a result, the OFDM signal 46 becomes a signal having a hierarchical structure using carriers from layer 1 to layer 4 shown in 47a, 47b, 47c, and 47d, and layer assignment is realized.
[0063]
By increasing the number of hierarchies as the number of slave stations increases, simultaneous multiplex communication with a greater number of slave stations becomes possible.
[0064]
FIG. 7 is a block diagram of a demodulation means using a filter, and shows one of the systems for demodulating only a layer required in a child station.
[0065]
Elements that are assigned the same numbers as in FIG. 3 will not be described.
[0066]
Reference numeral 48 denotes a filter, which is configured by a band-pass filter that passes a signal of only a certain frequency band. As shown in FIG. 4, the OFDM signal is hierarchized on the frequency axis and corresponds to each slave station, so that only the corresponding layer needs to be received by the slave station. In the filter 48, for example, only the OFDM signal of the frequency band of the layer 1 corresponding to the slave station 5a is passed. In the case of the slave station 5b, only the OFDM signal of the frequency band of the corresponding layer 2 alone is passed.
[0067]
As a result, it is possible to extract and demodulate only a layer necessary for the slave station from one OFDM signal 9, and it is possible to perform simultaneous multiplex communication with a plurality of slave stations.
[0068]
Note that 48 may be realized by a combination of a low-pass filter and a high-pass filter instead of a band-pass filter.
[0069]
Next, FIG. 8 is a block diagram of a stream demodulation unit, and shows another method of demodulating only a necessary layer in a child station.
[0070]
For example, when interleaving is performed on the frequency axis to improve resistance to burst errors, there is a possibility that necessary data exists between layers when receiving an OFDM signal. In such a case, it is necessary to demodulate the data of the layer corresponding to each slave station after receiving all the layers.
[0071]
22 is a stream demodulation unit. Reference numeral 49 denotes a bit stream generation unit that converts the bit strings of all layers of the error-corrected OFDM signal into streams. Reference numeral 50 denotes a deinterleave unit, which returns the bit stream interleaved at the time of transmission to the original bit order.
[0072]
Reference numeral 52 denotes a layer information supply unit, which outputs information relating to the correspondence between child stations and layers. For example, it is the information that the hierarchy 1 corresponds to the slave station 5a and the hierarchy 2 corresponds to the slave station 5b. Alternatively, information on the bandwidth of the corresponding layer is also included as necessary.
[0073]
The hierarchy information is transmitted to the hierarchy recognizing means 51, and from the correspondence information between the child station and the hierarchy, the hierarchy finally required in the child station is recognized.
[0074]
According to the hierarchy recognized by the hierarchy recognizing means 51, only the bit stream of the necessary hierarchy is selected from the bit streams of all the hierarchized streams, and output from the hierarchical data extracting means 53. Finally, the bit stream for the layer required in the slave station is reproduced in the reproducing unit 23 according to the type of image or sound. This enables simultaneous multiplex communication to a plurality of slave stations in a limited band.
[0075]
FIG. 9 is a schematic diagram showing the effect compared with the conventional method.
[0076]
As described above, by communicating the master station and the slave stations with the layered OFDM signal, as shown in FIG. There is an advantage (54) that simultaneous communication to Furthermore, since there is no time division as compared with the case of TDM, the problem that the transmission amount per unit time is reduced is solved, and there is an advantage that simultaneous communication with a plurality of slave stations is possible (55). .
[0077]
The master station and the slave station may be a facsimile-equipped telephone and its slave unit in addition to the cordless telephone.
[0078]
Alternatively, the master station and the slave station may be a private PBX and a private telephone.
[0079]
Alternatively, the master station and the slave station may be a printer server and a printer. In this case, the speaker 24, the display 25, the microphone 26, and the transmission unit 13 are unnecessary, and a head device for printing or the like replaces them.
[0080]
Alternatively, the master station and the slave station may be a LAN server and a client terminal connected to the LAN server. In this case, the speaker 24, the display 25, and the microphone 26 correspond to a display device or an audio device of the client terminal.
[0081]
The communication between the master station and the slave stations is the same not only in wireless communication but also in wired communication.
[0082]
In addition, for transmission from the slave station to the master station, so-called uplink communication, communication is similarly performed using a band different from the band used for downlink communication from the master station to the slave station.
[0083]
Alternatively, unlike the downlink communication, the amount of data is often small for the uplink communication. Therefore, conventional multiplex communication using TDM or FDM may be used.
[0084]
The same effect can be obtained even when each means or each unit is processed by software instead of hardware.
[0085]
(Embodiment 2)
FIG. 10 is a block diagram of a communication device according to the second embodiment.
[0086]
In the second embodiment, a description will be given of communication in a case where a slave station in an actual communication state is a part of a plurality of slave stations.
[0087]
Reference numeral 62 indicates a case where three of the four slave stations are in a communication state. That is, three of the slave stations 5a to 5c are in a communication state, and the slave station 5d is in a non-communication state. In FIG. 10, the transmission line 8d drawn by a broken line is in a non-communication state.
[0088]
As shown in FIG. 56, when one OFDM signal is formed from four layers, when one layer is assigned to each of the four slave stations, one layer corresponds to the slave station 5d which is not in a communication state. Assigning this signal has poor transmission efficiency.
[0089]
57 to 59 are hierarchies assigned to the slave stations 5a to 5c.
[0090]
As shown at 57, the child station 5a is assigned two layers, that is, layer 1 and layer 2. The slave station 5b is assigned to one layer of layer 3, and the slave station 5c is assigned to one layer of layer 4. Since no communication has been established with the slave station 5d, no hierarchy is assigned. Actually, since the OFDM signal forms a signal in one band, the OFDM signal having the same waveform is transmitted to all of the slave stations 5a to 5d, and is required for the slave station 5a in the first and second layers. The data required for the slave station 5b is included in the hierarchy 3, the data required for the slave station 5c is included in the hierarchy 4, and the data for the slave station 5d is included in any hierarchy. Not included.
[0091]
Normally, in a communication process between the master station 4 and the slave stations 5a to 5d, a communication connection is established prior to actual communication. Therefore, the master station 4 can recognize which slave station is in a communication state and is in a non-communication state. That is, the master station performs the hierarchical assignment of the OFDM signal to the slave station according to this recognition.
[0092]
By the above processing, the data transmission to the slave station 5a is twice as much as usual, and the data efficiency is improved.
[0093]
On the other hand, reference numeral 63 denotes a case where the slave stations 5a and 5b are in a communication state, and the remaining slave stations 5c and 5d are in a non-communication state.
[0094]
Reference numeral 60 denotes a layer corresponding to the slave station 5a, and two layers of layer 1 and layer 2 are allocated. Reference numeral 61 denotes a layer corresponding to the slave station 5b, and two layers of layer 3 and layer 4 are allocated. No hierarchy is assigned to the child 5c and the child station 5d for which communication has not been established.
[0095]
As a result, the amount of data that can be transmitted to the slave stations 5a and 5b is double the normal amount, and the data efficiency is improved.
[0096]
Alternatively, it is also possible to allocate and transmit three levels of hierarchy 1, level 2 and level 3 to the slave station 5a, and to allocate and transmit one level of hierarchy 4 to the slave station 5b. Thus, even when the slave station 5a requires a large amount of data such as a moving image, and the slave station 5b requires a small amount of data such as a still image, efficient and appropriate data transmission can be performed.
[0097]
The same effect can be obtained even when each means or each unit is processed by software instead of hardware.
[0098]
(Embodiment 3)
FIG. 11 is a block diagram of a communication device according to the third embodiment.
[0099]
The third embodiment is a method of dynamically changing a layer to be allocated according to a change in a data amount required by a slave station among slave stations in a communication state, thereby further improving data transmission efficiency.
[0100]
Reference numeral 65 denotes a hierarchy included in the OFDM signal transmitted from the master station to the slave station. In the third embodiment, a hierarchical structure (6) having a number larger than the number (4) of slave stations is shown.
[0101]
Reference numeral 64 denotes a transmission capacity information transmission unit for notifying the transmission capacity required by the slave station 5a from the slave station 5a to the master station 4. Although not shown, the slave stations 5b to 5d also include a similar transmission capacity information transmission unit. The transmission capacity information transmission unit 64 is notified of information on the transmission capacity required by each slave station in the process of establishing a communication connection between the master station and the slave station.
[0102]
For example, in a certain communication connection, a large amount of data is required in the slave station 5a because a high-definition moving image is required, and a large amount of data is not required in the slave station 5c because only voice communication is performed. Is notified to the master station 4. As the notification method, there are a case where the data capacity required by the slave station is represented by an absolute value such as bps (bit per second) and a case where it is represented by the number of layers.
[0103]
In FIG. 11, the slave station 5a needs data for three layers, the slave station 5b needs data for two layers, and the slave station 5c needs data for one layer for the master station 4. Is notified.
[0104]
Reference numeral 66 denotes a layer assigned to the slave station 5a, and three layers from layer 1 to layer 3 are assigned. Reference numeral 67 denotes a layer assigned to the slave station 5b, and two layers of layer 4 and layer 5 are assigned. Reference numeral 68 denotes a layer assigned to the slave station 5c, and one layer of the layer 6 is assigned. That is, if the data amount per layer is the same, the slave station 5a transmits three times the data amount of the slave station 5c.
[0105]
If the number of sub-stations is equal to or greater than the number of sub-stations included in the master station shown in FIG. 65, it is possible to more precisely allocate and transmit the layers required by each sub-station.
[0106]
On the other hand, as shown in the right half of FIG. 11, when the communication connection is switched and the data amount required for each slave station changes from the previous communication connection, the hierarchical allocation transmitted from the master station to the slave station is changed. Changes.
[0107]
Reference numeral 66 denotes a hierarchy assigned to the slave station 5a, which has been changed to an allocation for two hierarchies, that is, hierarchy 1 and hierarchy 2. Similarly, the assignment to the slave station 5b is changed to the assignment of the three layers of the hierarchy 3, the hierarchy 4, and the hierarchy 5, and the slave station 5c is assigned to the one of the hierarchy 6 without change.
[0108]
As described above, the number of assigned layers dynamically changes in accordance with the switching of the required data capacity, so that the optimal data capacity transmission to each slave station can be performed.
[0109]
If the total required data capacity from each slave station exceeds the number of layers owned by the master station, the master station performs a proportional allocation or an allocation according to the importance. Realizes layer assignment.
[0110]
For example, the slave stations with which the communication connection is established are from the slave station 5a to the slave station 5c, the request of the slave station 5a is for six layers, the request of the slave station 5b is for four layers, and the request of the slave station 5c. If there are requests for 12 layers in total and there are requests for 12 layers, and the parent station has 6 layers, 3 layers for the child station 5a are allocated as proportional distribution. Two levels are assigned to the slave station 5b, and one hierarchy is assigned to the slave station 5a. This can prevent an unbalanced data transmission state from occurring between slave stations.
[0111]
Further, the slave station 5a and the slave station 5b are in a communication connection established state, each of which requests six layers, the slave station 5a has a high degree of importance in transmission over the current communication connection, and the slave station 5b has a current connection. When the importance in the communication connection is low, four layers are assigned to the slave station 5a and two layers are assigned to the slave station 5b according to the importance. The case where the importance is high is, for example, a case where the slave station 5a needs to reproduce a moving image with high real-time property, and the slave station 5b has a low real-time property and the frame rate of the moving image may be reduced. Alternatively, when the communication in the slave station 5a is given priority and the communication in the slave station 5b may be postponed, the importance of the slave station 5a is high, and all the layers are assigned only to the slave station 5a, and the slave station 5b Is also forcibly interrupting the communication connection.
[0112]
As described above, layer assignment according to importance is realized, and data transmission efficiency is further improved.
[0113]
The same effect can be obtained even when each means or each unit is processed by software instead of hardware.
[0114]
(Embodiment 4)
FIG. 12 is a block diagram of a communication device according to the fourth embodiment.
[0115]
Embodiment 4 is a system in which communication from a master station to a slave station is performed via a relay station.
[0116]
Depending on the environment in which the communication system is constructed, there is a case in which the state of the transmission path for direct communication from the master station to all slave stations is poor and a relay station is required. For example, there is a case where each slave station is hidden behind a shield and wireless communication with the master station is difficult. Alternatively, the environment is such that the distance between the master station and the slave station is large, the signal waveform distortion in the wired communication path is large, and the adverse effect on the reception performance is large.
[0117]
69 is a relay station.
[0118]
The OFDM signal 9 is transmitted between the relay station 69 and the master station 4. As described in Embodiment 1, the OFDM signal is a signal in which many carriers are orthogonally multiplexed, and has a plurality of hierarchical structures on the frequency axis.
[0119]
In the relay station 69, the OFDM signal 9 is received by the antenna 71.
[0120]
Numeral 72 denotes a demodulation means, which comprises the same components as those described in FIG. 3, and demodulates a bit stream from an OFDM signal.
[0121]
The bit stream demodulated by the relay station 69 is transmitted to each of the slave stations 5a to 5d. In the slave stations 5a to 5d, only the corresponding layer is selected from the bit streams received by the reproducing means 74a to 74d, and the necessary data such as sound and image is reproduced. In the slave station 5a, only the data of the hierarchy 1 is reproduced, and similarly, in the slave station 5b, the data of the hierarchy 2 is reproduced, in the slave station 5c, the data of the hierarchy 3 is reproduced, and in the slave station 5d, only the data of the hierarchy 4 is reproduced.
[0122]
If the relay station 69 has information on the correspondence between the slave stations and the layers in advance, when transmitting the bit stream from the relay station 69 to the slave stations, only the layers necessary for each slave station are provided. The same effect is achieved by transmitting a bit stream.
[0123]
Alternatively, when information relating to the correspondence between the slave station and the hierarchy is notified from the slave stations 5a to 5d to the relay station 69, each of the slave stations transmits the bit stream from the relay station to the slave station. A similar effect can be obtained by transmitting a bit stream of only the necessary layers.
[0124]
Note that a plurality of relay stations may be connected in multiple stages.
[0125]
Alternatively, a plurality of relay stations may be arranged in parallel to realize parallel communication with slave stations of each relay station group.
[0126]
As in the second embodiment, the data efficiency is improved by changing the number of layers to be allocated according to the number of slave stations for which a communication connection is established.
[0127]
Alternatively, as in the third embodiment, data efficiency is improved by dynamically changing the number of hierarchies allocated to slave stations according to the state of slave stations.
[0128]
In this embodiment, the method of demodulating an OFDM signal in a relay station and transmitting the demodulated bit stream to each slave station has been described. However, the relay station transmits the OFDM signal from the master station to the slave station again as it is. , And the OFDM signal may be demodulated in the slave station as in the first embodiment.
[0129]
The same effect can be obtained even when each means or each unit is processed by software instead of hardware.
[0130]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, compared with FDM by using the signal which a plurality of carriers mutually orthogonally multiplex on a frequency axis represented by the OFDM signal which has a hierarchical structure for communication between a master station and a slave station. Multiplex communication to a plurality of slave stations in a narrow band. Further, it is not necessary to perform time division as compared with TDM, and simultaneous multiplex communication with a plurality of slave stations can be performed without reducing the transmission capacity.
[0131]
In addition, the hierarchical structure of signals used for communication between the master station and the slave stations can be assigned to a hierarchy according to the number of slave stations in communication, or to a hierarchical allocation such as a proportional allocation according to the demand of the slave station, thereby improving data efficiency. Can be improved.
[0132]
Further, even when a relay station is provided between a master station and a slave station, simultaneous multiplex communication using a fixed band signal can be performed without reducing the transmission capacity.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a cordless telephone according to an embodiment of the present invention.
FIG. 2 is a block diagram of a communication device according to the first embodiment of the present invention.
FIG. 3 is a block diagram of a slave station according to Embodiment 1 of the present invention.
FIG. 4 is a schematic diagram showing that the OFDM signal is hierarchized according to the first embodiment of the present invention;
FIG. 5 is a block diagram of a master station according to the first embodiment of the present invention.
FIG. 6 is a diagram illustrating a layer allocation unit according to the first embodiment of the present invention as viewed from a signal flow;
FIG. 7 is a block diagram of a demodulation unit using a filter according to the first embodiment of the present invention.
FIG. 8 is a block diagram of a stream demodulation unit according to the first embodiment of the present invention.
FIG. 9 is a schematic diagram showing the effect of the first embodiment of the present invention as compared with the conventional system.
FIG. 10 is a block diagram of a communication device according to a second embodiment of the present invention.
FIG. 11 is a block diagram of a communication device according to a third embodiment of the present invention.
FIG. 12 is a block diagram of a communication device according to a fourth embodiment of the present invention.
FIG. 13 is a block diagram showing a conventional technique using FDM in the conventional technique of the present invention.
FIG. 14 is a block diagram showing a conventional technique using TDM in the conventional technique of the present invention.
[Explanation of symbols]
1 Cordless phone base unit
2a, 2b Cordless phone handset
3a, 3b, 8a, 8b, 8c, 8d, 70 transmission line
4,80 master station
5a, 5b, 5c, 5d, 82a, 82b, 82c, 82d Slave station
6 source data
7, 10a, 10b, 10c, 10d, 71, 81, 83a, 83b, 83c, 83d Antenna
9,56 OFDM signal
11a, 11b, 11c, 11d, 57, 58, 59, 60, 61, 66, 67, 68 Demodulated hierarchy
12, 72 demodulation means
13 Transmission section
14 Control unit
15, 39 Multiplexer
16 Tuner
17 Analog to Digital Converter ()
18 Fast Fourier Transform ()
19 Equalization Department
20 Demapping part
21 Error Correction Section
22 Stream demodulator
23 Playback unit
24 speakers
25 Display
26 microphone
27 OFDM signal waveform
28 career
29 OFDM signal hierarchy
30 Hierarchical assignment means
31 Hierarchical division
32 Layer allocation information supply unit
33a, 33b, 33c, 33d Assigned tiers
34a, 34b, 34c, 34d Error code giving unit
35a, 35b, 35c, 35d Map section
36 Hierarchical synthesis unit
37 Inverse Fourier Transform ()
38 Upconversion part
40 Uplink processing unit
41 Up Data
42 bit stream
43a, 43b, 43c, 43d, 44a, 44b, 44c, 44d Data for each layer
45a, 45b, 45c, 45d, 47a, 47b, 47c, 47d Carrier for each layer
46 OFDM signal
48 Filter
49 Bitstream generator
50 deinterleave section
51 Hierarchy recognition means
52 Hierarchical information supply unit
53 Hierarchical data extraction means
54 Advantages on the frequency axis
55 Benefits on the time axis
65 Hierarchical OFDM signal
69 relay station
73 Transmission means
74a, 74b, 74c, 74d playback means
84 Frequency division multiplexing
85 Time division multiplexing
86 time division multiplexer

Claims (15)

A signal having one or more master stations and a plurality of slave stations, wherein a plurality of carriers between the master station and the slave stations are multiplexed orthogonally to each other on a frequency axis, and A communication device that communicates by a signal having a plurality of layers composed of a number of the carriers,
Layer assignment means for assigning data required for each slave station to any of the layers,
Demodulation means for demodulating the layer assigned in the slave station;
A communication device comprising: 2. The communication apparatus according to claim 1, wherein the demodulation means extracts a band of a layer assigned to the slave station by a filter and demodulates the extracted band. The demodulation means, layer information on a layer assigned to the slave station,
Layer recognition means for recognizing a layer assigned to the slave station using the layer information,
Hierarchical data extraction means for extracting data included in the hierarchy recognized by the hierarchy recognition means,
The communication device according to claim 1, comprising: The tier assigning means,
The communication device according to any one of claims 1 to 3, wherein the allocation is performed by changing the allocation number of the hierarchy according to a change in the number of the slave stations in which a communication state is established. The tier assigning means,
Transmission capacity information notification means for notifying the data amount required by the slave station,
The communication device according to claim 1, wherein the number of the layers is proportionally allocated based on the notified required data amount. The tier assigning means,
Transmission capacity information notification means for notifying the data amount required by the slave station and the importance of data transmission,
4. The communication device according to claim 1, wherein the hierarchy is assigned based on the notified required data amount and importance of data transmission. One or more master stations, one or more relay stations, and a plurality of slave stations, and a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the master station and the relay station. A communication device that communicates by a signal having a plurality of layers composed of an arbitrary number of the carriers,
Layer assignment means for assigning data required for each slave station to any of the layers,
Demodulation means for demodulating all of the layers in the relay station;
Transmission means for transmitting data demodulated by the relay station to the slave station,
Reproducing means for reproducing data of a layer assigned from the transmitted data in the slave station;
A communication device comprising: One or a plurality of cordless telephone master units, and a plurality of cordless telephone slave units greater than the number of the master station, a plurality of carriers between the master unit and the slave unit mutually on the frequency axis. A communication device that is a signal that is orthogonal and multiplexed and communicates with a signal having a plurality of layers including an arbitrary number of the carriers,
Layer assignment means for assigning necessary data to each of the slave units to one of the layers,
Demodulation means for demodulating a layer assigned in the slave unit;
A communication device comprising: One or more facsimile-equipped cordless telephone master units, and a plurality of cordless telephone slave units, and a plurality of carriers are orthogonally multiplexed on the frequency axis between the master unit and the slave units. A communication device that communicates by a signal having a plurality of layers composed of an arbitrary number of the carriers,
Layer assignment means for assigning necessary data to each of the slave units to one of the layers,
Demodulation means for demodulating a layer assigned in the slave unit;
A communication device comprising: A signal having one or more printer servers and a plurality of printers, wherein a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the printer server and the printer, and an arbitrary number of A communication device that communicates by a signal having a plurality of layers including the carrier,
A layer assigning means for assigning data necessary for each printer to one of the layers,
Demodulation means for demodulating a layer assigned in the printer;
A communication device comprising: A signal having one or a plurality of private PBXs and a plurality of private telephones. A signal in which a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the private PBX and the private telephones. A communication device that communicates by a signal having a plurality of layers composed of the carriers of the above,
Layer assignment means for assigning data necessary for each private telephone to one of the layers,
Demodulation means for demodulating the layer assigned in the private telephone;
A communication device comprising: A signal having one or a plurality of LAN servers and a plurality of clients, wherein a plurality of carriers are mutually orthogonally multiplexed on the frequency axis between the LAN server and the clients. A communication device that communicates by a signal having a plurality of layers composed of carriers,
Layer assignment means for assigning data necessary for each private telephone to one of the layers,
Demodulation means for demodulating the layer assigned in the private telephone;
A communication device comprising: One or more master stations and a plurality of slave stations greater than the number of master stations, and a plurality of carriers are orthogonally multiplexed on the frequency axis between the master station and the slave stations. A signal, a communication method for communicating by a signal having a plurality of layers composed of an arbitrary number of the carriers,
Allocate necessary data to any of the layers for each slave station,
A communication method comprising demodulating a layer assigned in the slave station. 14. The communication method according to claim 13, wherein, in the demodulation of the hierarchy, a band of the hierarchy allocated to the slave station is extracted by a filter and demodulated. In the demodulation of the hierarchy, hierarchy information on the hierarchy assigned to the slave station,
Recognizing the hierarchy assigned to the slave station using the hierarchy information,
14. The communication method according to claim 13, wherein data included in the hierarchy recognized by the hierarchy recognition unit is extracted.

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