WO2004030397A1 - 無線装置、チャネル割当方法、およびチャネル割当プログラム - Google Patents
無線装置、チャネル割当方法、およびチャネル割当プログラム Download PDFInfo
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- WO2004030397A1 WO2004030397A1 PCT/JP2003/011180 JP0311180W WO2004030397A1 WO 2004030397 A1 WO2004030397 A1 WO 2004030397A1 JP 0311180 W JP0311180 W JP 0311180W WO 2004030397 A1 WO2004030397 A1 WO 2004030397A1
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- wireless device
- parameter
- channel
- modulation
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
- H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
- H04L1/0016—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy involving special memory structures, e.g. look-up tables
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
- H04L1/0019—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy in which mode-switching is based on a statistical approach
- H04L1/0021—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy in which mode-switching is based on a statistical approach in which the algorithm uses adaptive thresholds
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/02—Access restriction performed under specific conditions
- H04W48/06—Access restriction performed under specific conditions based on traffic conditions
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/02—Terminal devices
- H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
Definitions
- the present invention relates to a radio apparatus, a channel allocation method, and a channel allocation program, and more specifically, to a radio apparatus capable of coping with a plurality of modulation schemes having different modulation multi-level numbers (hereinafter, multi-level numbers), and a radio apparatus therefor.
- the present invention relates to a channel allocation method and a program in a case where the modulation method is switched during communication in such a wireless device.
- a predetermined modulation method for example, a well-known ⁇ / 4 shift QPSK
- a mobile terminal device hereinafter referred to as a terminal or PS (Personal Station)
- a wireless base device hereinafter referred to as a base station or CS (Cell Station)
- CS Cell Station
- FIG. 8A is a diagram showing the arrangement of the symposium / reception points by the ⁇ 4 shift Q P S ⁇ modulation method on the IQ coordinate plane.
- the symbol of the received signal is placed on one of four signal points located concentrically on the IQ coordinate plane. Since the points correspond, two-bit data indicating one of the four signal points can be transmitted at a time.
- a radio connection is established between a terminal and a base station via a control channel CCH (Control Channel), and then desired data communication such as voice is performed via a communication channel TCH (Traffic Channel).
- CCH Control Channel
- TCH Traffic Channel
- a 16 Q AM (Quadrature Amplitude Modulation) modulation scheme is known, and has already been put to practical use in certain types of data communication.
- FIG. 8B is a diagram showing the arrangement of the symbol points by the 16 Q AM modulation method on the IQ coordinate plane.
- the 16-QAM system as is well known, four signals are arranged in a grid pattern in each quadrant on the IQ coordinate plane, for a total of 16 signals in the entire coordinate plane.
- the symbol of the received signal corresponds to one of the points. Therefore, 4-bit data indicating any of the 16 signal points can be transmitted at a time.
- a wireless connection request is transmitted from the terminal to the base station, and the base station transmits a desired signal as a parameter representing the state of the communication environment of the transmission path.
- a well-known RSSI (Received Signal Strength Indication) value based on the received signal power level is measured as a D (Desired) wave level, and the measured D wave level is stable under ⁇ ⁇ shift QPSK modulation. It is determined whether or not a threshold value for realizing communication with communication quality is exceeded, and it is determined whether or not to allocate a wireless channel according to the result.
- the D-wave level corresponds to S of the signal-to-noise ratio (S / N ratio). If the received noise amount N of the base station is known in advance, the D-wave level is S / N It can be seen as equivalent to the ratio.
- this threshold value is a D-wave that satisfies an error rate BER (Bit Error Rate) that can achieve stable communication quality when performing communication using a ⁇ / 4 shift QPSK modulation scheme. Set to level. If the actually measured D-wave level does not reach this threshold, the communication quality will degrade, causing a reception error, disconnection of wireless connection, etc., and normal and stable communication will be performed. Can not.
- BER Bit Error Rate
- the wireless channel is allocated to the terminal requesting the connection (that is, the connection is permitted), and the threshold is not reached. In this case, the wireless channel is not allocated (that is, the connection is refused).
- FIG. 9 is a diagram for explaining a communication procedure between the terminal (PS) and the base station (CS) with time when the modulation scheme is switched (adaptive modulation) as described above.
- connection request may be made from either the terminal or the base station.
- the request has been transmitted from the terminal.
- signals related to a wireless connection request are exchanged between the terminal and the base station through the link channel establishment phase.
- the D-wave level from the terminal is measured at the base station side, and the measured D-wave level exceeds the threshold for wireless channel allocation in the ⁇ / 4 shift QPS ⁇ modulation method described above. It is determined whether or not it is, and if it exceeds, the subsequent processing for establishing a wireless connection is executed.
- the service channel establishment phase is exchanged thereafter, and when synchronization is established between the terminal and the base station, message control (call control, etc.) is performed between the terminal and the base station.
- message control call control, etc.
- the communication quality may deteriorate for the reasons described below, and data communication may not be performed as shown by the broken line in FIG.
- the ⁇ 4 shift QPSK modulation scheme is significantly different from the 16 QAM modulation scheme. Therefore, just because the D-wave level of the signal from the terminal at the base station satisfies the channel allocation threshold value in the ⁇ / 4 shift QPS ⁇ modulation scheme, it is stable under the 16 Q AM modulation scheme. Communication quality cannot always be achieved.
- FIG. 10 is a graph illustrating the relationship between the communication environment of the transmission path and the error rate in the received signal in that case for each of the ⁇ / 4 shift QPS S modulation scheme and the 16 Q AM modulation scheme. Note that FIG. 10 illustrates an example in which the characteristics of the error rate corresponding to the modulation scheme can be visually recognized, and specific numerical values themselves are not necessarily accurate.
- the horizontal axis of FIG. 10 indicates the signal-to-noise ratio (3/1 ratio: equivalent to the 0-wave level) on the transmission path, and the vertical axis indicates the error rate of the received signal. BER is shown.
- the signal waveform received on the receiving side is returned to the digital information that the transmitting side tried to send by demodulation processing, but the digital information is a binary value of “0” or “1”. Since it is information, there is basically no noise mixed here. However, as described with reference to FIGS. 8A and 8B, when large noise is mixed in the transmission path, the noise causes the digital information of “0” or “1” to be transmitted. Can be misrepresented. As described above, the cause of transmission errors is noise and interference waves. For example, the S / N ratio (or DZU ratio) of noise mixed with the modulated wave (desired transmission signal wave) mixed on the transmission line and a large amount of information Error rate, which indicates the percentage of errors that occur when
- this error rate is closely related to the S / N ratio (DZU ratio) on the transmission line, and can be derived by calculation using well-known statistical logic. It is also known that different modulation schemes have different error rates even if the S / N ratio (D / U ratio) of the transmission path is the same.
- the relationship between the SZN ratio and the error rate BER in the ⁇ 4 shift QPSK modulation scheme is shown by a broken-line graph, and the SZN in the 16QAM modulation scheme is shown.
- the SZN ratio for stable communication in the ⁇ / 4 shift QPSK modulation scheme (About 6 dB in the above examples of Figure 8 ⁇ and Figure 8B), and even if a radio channel is assigned in the link channel establishment phase, the S / N ratio at that time will be 16QAM modulation.
- the modulation method is changed from ⁇ / 4 shift QPSK modulation to 16 QAM as it is. switching to mode, the error rate bE R deteriorated (in the above example mentioned in FIG. 10 increases the error rate is 10 4 or more), the cause of the radio communication quality is deteriorated, the communication error one or wireless connection disconnection It becomes.
- an object of the present invention is to provide a radio apparatus which can cope with a plurality of modulation schemes having different multi-level numbers and which does not degrade the communication quality even when the modulation scheme is switched during communication, and such a radio apparatus To provide a channel allocation method and a program in the above.
- a radio apparatus capable of supporting two types of modulation schemes having different multi-level numbers includes a modulation scheme switching unit, a storage unit, a parameter measurement unit, a parameter comparison unit, a channel And an assignment determining unit.
- the modulation scheme switching unit is configured to transmit the signal to the other wireless apparatus when the other wireless apparatus wirelessly connected to the wireless apparatus can support two types of modulation schemes while communicating with the other wireless apparatus.
- the modulation method is switched between the modulation method of 1 and the second modulation method having a large number of levels.
- the storage means stores a first threshold value of a parameter representing a communication environment of a transmission path, at which the wireless device can communicate with another wireless device by at least a second modulation method of the two types of modulation methods.
- the parameter measuring means measures the parameter based on a signal received from another wireless device.
- the parameter comparing means when receiving a connection request from another wireless device to the wireless device, compares the first threshold value of the stored parameters corresponding to the second modulation scheme with the measured parameter. Compare.
- the channel assignment determining means determines the assignment of the wireless channel to another wireless device. To give permission.
- the storage means stores in advance a second threshold value of a parameter representing a communication environment of a transmission path, which allows the wireless device to communicate with another wireless device according to the first modulation scheme. . If another wireless device that supports the first modulation method but does not support the second modulation method requests a connection to the wireless device, the parameter The parameter comparing means compares the second threshold value of the stored parameter corresponding to the first modulation scheme with the parameter measured by the parameter measuring means, and the channel assignment determining means measures the parameter by the parameter comparing means. If it is determined that the set parameter is equal to or greater than the second threshold value of the stored parameter, another wireless device that supports the first modulation scheme but does not support the second modulation scheme Allows the assignment of wireless channels to.
- the channel assignment determining means determines whether or not there is an empty slot and an empty channel in the wireless device, and if there is no empty slot or empty channel, regardless of the comparison result of the parameter comparing means, Reject wireless channel assignment.
- the wireless device further includes a unit that, when the channel assignment determining unit rejects the assignment of the wireless channel, notifies another wireless device that is requesting a connection to the wireless device to that effect.
- the parameter is a parameter based on a signal level received from another wireless device requesting connection to the wireless device.
- a channel assignment method in a wireless device capable of coping with two types of modulation schemes having different multi-level numbers, wherein the wireless device is connected to another wireless device wirelessly connected to the wireless device. If the wireless device can communicate with other wireless devices, it can perform modulation between the first modulation method with a smaller number of values and the second modulation method with a larger number of values if the wireless device can communicate with other wireless devices.
- the channel allocation method includes, when a connection request is received from another wireless device to the wireless device, the first threshold value of the stored parameters corresponding to the second modulation scheme and the measured parameter. Comparing, and, if it is determined that the measured parameter is greater than or equal to the first threshold value of the stored parameter, allowing the wireless channel to be allocated to another wireless device.
- the storage means stores in advance a second threshold value of a parameter representing a communication environment of a transmission path, by which the wireless device can communicate with another wireless device by the first modulation scheme. ing.
- the channel assignment method corresponds to the first modulation scheme when another wireless apparatus that supports the first modulation scheme but does not support the second modulation scheme issues a connection request to the wireless apparatus. Comparing the second parameter of the stored parameter with the measured parameter; and determining that the measured parameter is greater than or equal to the second threshold of the stored parameter. Permitting allocation of a wireless channel to another wireless device that supports the first modulation scheme but does not support the second modulation scheme.
- the channel assignment method includes determining whether there is an empty slot and an empty channel in the wireless device, and if there is no empty slot and an empty channel, assigning the wireless channel regardless of the result of the parameter comparison step. Further comprising the step of rejecting.
- the channel assignment method further includes, when rejecting the assignment of the wireless channel, notifying another wireless device requesting a connection to the wireless device to that effect.
- the parameter is a parameter based on a signal level received from another wireless device requesting connection to the wireless device.
- a channel assignment program in a wireless device capable of coping with two types of modulation schemes having different multi-valued numbers, wherein the wireless device is connected to another wireless device wirelessly connected to the wireless device.
- the radio equipment may communicate between the first modulation scheme with a small number of levels and the second modulation scheme with a large number of levels while communicating with another wireless device.
- a modulation scheme switching means for switching a modulation scheme by using a parameter indicating a communication environment of a transmission path, in which the wireless device can communicate with another wireless device by at least the second modulation scheme among the two modulation schemes.
- Storage means for storing the first threshold value in advance, and parameter measurement means for measuring parameters based on signals received from other wireless devices.
- the channel assignment program when receiving a connection request from another wireless device to the wireless device, sets the first threshold value of the stored parameter corresponding to the second modulation method and the measured threshold value.
- the storage means stores in advance a second threshold value of a parameter representing a communication environment of a transmission path, which allows the wireless device to communicate with another wireless device according to the first modulation scheme.
- the channel assignment program when the computer requests a connection to the wireless device from another wireless device that supports the first modulation method but does not support the second modulation method, performs the first modulation. Comparing the measured parameter with a second threshold of the stored parameter corresponding to the method; and the measured parameter is greater than or equal to the second threshold of the stored parameter. Is determined, the step of permitting the assignment of a wireless channel to another wireless device that supports the first modulation scheme but does not support the second modulation scheme is further performed.
- the channel assignment program determines whether or not there is an empty slot and an empty channel in the wireless device. If there is no empty slot and an empty channel, regardless of the result of the parameter comparison step, Cause the computer to further perform the step of refusing the assignment.
- the channel assignment program when rejecting the assignment of the wireless channel, causes the computer to further execute a step of notifying another wireless device requesting connection to the wireless device.
- the parameter is a parameter based on a signal level received from another wireless device requesting connection to the wireless device.
- a wireless device compatible with adaptive modulation similarly receives a connection request from another wireless device compatible with adaptive modulation
- a parameter representing the communication environment of the transmission path is measured, and the parameter is measured. Allows the assignment of wireless channels to other wireless devices when the value is greater than or equal to the threshold value of a parameter that allows communication with the modulation method with the larger number of values, so that communication can be performed during connection. Even when switching from a modulation scheme with a small number of values to a modulation scheme with a large number of values, it is possible to prevent deterioration in communication quality.
- FIG. 1 is a diagram for explaining a communication hand between a terminal and a base station according to the present invention over time.
- FIG. 2 is a functional block diagram showing a configuration of a base station as a wireless device according to the embodiment of the present invention.
- FIG. 3 is a functional block diagram showing a configuration of a terminal as a wireless device according to the embodiment of the present invention.
- FIG. 4 is a flowchart illustrating a channel assignment method according to the first embodiment of the present invention.
- FIG. 5 is a flowchart illustrating a channel assignment method according to Embodiment 2 of the present invention.
- FIG. 6 is a flowchart illustrating a channel assignment method according to Embodiment 3 of the present invention.
- FIG. 7 is a diagram for explaining details of a communication procedure between a terminal and a base station according to Embodiment 3 of the present invention over time.
- FIGS. 8A and 8B are diagrams showing symbol point arrangements of ⁇ / 4 shift QPSK and 16QAM on the IQ coordinate plane.
- FIG. 9 is a diagram for explaining a communication procedure between a terminal and a base station by conventional adaptive modulation over time.
- FIG. 10 is a diagram showing the relationship between the S / N ratio of the transmission path of ⁇ -no 4 shift QPSK and 16 QAM and ⁇ ⁇ R. BEST MODE FOR CARRYING OUT THE INVENTION
- the present invention is applicable to a base station that constitutes a mobile communication system such as a PHS as long as it is a radio apparatus that supports adaptive modulation, that is, a radio apparatus that can communicate with a plurality of types of modulation schemes having different multi-level numbers. Bureau, edge Applicable to any of the last.
- a base station that constitutes a mobile communication system
- a radio apparatus that supports adaptive modulation
- Bureau edge Applicable to any of the last.
- a case where the present invention is applied to a PHS base station as a mobile communication system will be described as an example.
- ⁇ / 4 shift QPSK is used as a modulation method with a small number of values and 16 QAM is used as a modulation method with a large number of values as a modulation method of adaptive modulation.
- the present invention is not limited to these modulation schemes, and can be applied to a wireless device that can support a plurality of modulation schemes having different multilevel numbers.
- An embodiment of the present invention is to determine which modulation method to use for communication initially when another wireless device capable of adaptive modulation (hereinafter, a terminal) requests connection to a wireless device capable of adaptive modulation (hereinafter, a base station).
- a terminal another wireless device capable of adaptive modulation
- a base station a wireless device capable of adaptive modulation
- the modulation scheme with the larger number of levels that is commonly used between the two, and the RSSI value as a parameter of the communication environment of the transmission path, that is, the D-wave level (can be regarded as equivalent to the S / N ratio) ) Is compared with the D-wave level measured at that time, and if it is determined that the measured D-wave level is equal to or higher than the threshold, the base station permits the assignment of the wireless channel. (That is, allow connection).
- communication can be performed without deteriorating communication quality when the communication environment of the transmission path is switched to a modulation method with many levels (for example, 16 QAM).
- a modulation method with many levels for example, 16 QAM.
- the connection is rejected and modulation after the connection is established. It is intended to prevent the degradation of communication quality that can occur at the time of system switching.
- FIG. 1 is a diagram for explaining a communication procedure between a terminal and a base station according to the present invention over time.
- connection request may be made from either the terminal or the base station. In this example, it is assumed that the request has been transmitted from the terminal.
- signals related to wireless connection requests are exchanged between the terminal and the base station through the link channel establishment phase. That is, the D-wave level from the terminal is measured on the base station side, and the measured D-wave level is a 16-QAM modulation method with many levels as described above. It is determined whether or not the threshold value for wireless channel allocation in the equation is exceeded, and if it exceeds the threshold value, subsequent processing for establishing a wireless connection is executed.
- the service channel establishment phase is exchanged.
- message control (such as call control) is executed between the terminal and the base station. The above is the stage of establishing a wireless connection performed by communication using the ⁇ / 4 shift QPSK modulation method.
- the modulation method is switched from the ⁇ 4 shift QPSK modulation method to the 16 QAM modulation method in order to further increase the communication speed.
- the channel assignment (connection permission) is performed after the communication environment of the transmission path is determined in advance that connection is possible with 16 QAM at the time of connection. Even if the modulation method is switched from ⁇ 4 shift QPSK with a small number of values to 16 QAM with a large number of values during communication, data communication is maintained while maintaining good communication quality as shown by the solid line in Fig. 1. Can be performed.
- FIG. 2 is a functional block diagram showing the configuration of a base station as a wireless device according to an embodiment of the present invention.
- a radio frequency signal from another radio apparatus (terminal) received by antenna 1 is received by RF processing section 2 and provided to signal processing section 3.
- RF processing section 2 receives a radio frequency signal from another radio apparatus (terminal) received by antenna 1 and provides signals processing section 3.
- signal processing unit 3 under the control of the radio control unit 4, a process of switching between a plurality of modulation schemes having different multilevel numbers is executed.
- the signal received and processed by the RF processing unit 2 is demodulated by the signal processing unit 3 in accordance with the selected modulation method ( ⁇ - shift QPSK or 16-QAM).
- the demodulated received signal is supplied to the main control unit 5 and decoded into a data signal.
- the decoded data signal is provided to a public line (not shown) via the line control unit 6.
- a data signal to be transmitted is transmitted from a public line (not shown) through the line control unit 6. And is given to the main controller 5.
- the data signal encoded by the main control unit 5 is modulated by the signal processing unit 3 in accordance with the selected modulation method ( ⁇ / 4 shift QP SK or 16QAM).
- the modulated transmission signal is subjected to transmission processing in RF processing section 2 and transmitted from antenna 1.
- the operations of the radio control unit 4 and the line control unit 6 are controlled by the main control unit 5.
- FIG. 3 is a functional block diagram showing a configuration of a terminal as another wireless device according to the embodiment of the present invention.
- the signal received from the base station by the antenna 11 is provided to the receiving unit 13 via the switch circuit 12, and is subjected to a receiving process. That is, the received signal down-converted by the oscillation frequency supplied from the synthesizer 14 is supplied to the control unit 16.
- Control section 16 demodulates the received signal in accordance with the selected modulation scheme ( ⁇ / 4 shift QP SK or 16 QA ⁇ ).
- the demodulated received signal is converted to a voice signal by the receiver 19 and transmitted to the user, or displayed on the display 17 as image information to the user.
- the transmission signal is input to the control unit 16 via the input unit 18 or the transmission unit 20, and the control unit 16 modulates the transmission signal according to the selected modulation method ( ⁇ 4 shift QPSK or 16Q AM).
- the selected modulation method ⁇ 4 shift QPSK or 16Q AM.
- the transmission unit 15 performs transmission processing on the transmission signal. That is, the transmission signal up-complied by the oscillation frequency supplied from the synthesizer 14 is provided to the antenna 11 via the switch circuit 12, and transmitted from the antenna 11.
- the operation of the synthesizer 14 is controlled by the control unit 16.
- the operation of the entire terminal in FIG. 3 is controlled by a user's instruction via the IZF unit 21.
- FIGS. 4 to 6 show a channel assignment method according to Embodiments 1 to 3 of the present invention. It is a flowchart explaining each.
- the channel assignment method described below is assumed to be executed by the base station shown in FIG. 2 upon receiving a connection request from the terminal shown in FIG.
- the configuration of the functional block diagram of the base station shown in FIG. 2 is actually executed by software by a digital signal processor (DSP) (not shown) in accordance with the flow charts shown in FIGS. It is.
- DSP digital signal processor
- This DSP reads out a program including the steps of the flow charts shown in FIGS. 4 to 6 from a memory (not shown) and executes the program.
- This program can be downloaded from a center (not shown) via the line controller 6 and the public line in FIG.
- Embodiment 1 of FIG. 4 determines channel assignment based on the D-wave level (or S / N ratio).
- step S1 the base station receives a wireless connection request from a terminal by ⁇ / 4 shift QPSK communication.
- the base station constantly measures the received signal power, and in step S2, measures the RSS.I value based on the carrier sense level, that is, the D-wave level from the result. Then, in step S3, the D-wave level at which communication can be performed by 16 QAM is compared with a threshold previously calculated and stored in a memory (not shown) of the base station. As shown in the channel assignment threshold table ⁇ in Fig. 4, it is assumed that the D-wave level needs to be about 22 dBuV in order to secure the BER required for 16 Q AM communication. Therefore, such a D-wave level is stored in a memory (threshold value table A) as a threshold value.
- step S3 the D wave level measured in step S2 is compared with the stored threshold value of the D wave level, and the measured D wave level is compared with the threshold value (2 2 dBu). If V) or more, the required BER can be secured even if communication is performed by 16QAM, so channel allocation is permitted, and the process proceeds to the channel allocation procedure of step S5 and subsequent steps. On the other hand, if the measured D-wave level is smaller than the threshold value (22 dBuV) in step S3, the required BER cannot be secured when communicating with 16QAM, so the process proceeds to step S4 to determine rejection of channel assignment. Then, in step S14, the terminal is notified of the fact, and in step S15, the terminal shifts to a standby state.
- step S3 If it is determined in step S3 that channel allocation is possible, the process first proceeds to step S5, and a search is performed to determine whether or not there is an empty slot in the base station. If there is no empty slot in step S6, rejection of channel assignment due to no slot is determined in step S7, and the process proceeds to steps S14 and S15 described above.
- step S6 if an empty slot is found in step S6, the process proceeds to step S8, and a search is performed to determine whether there is an empty channel. Further, in step S9, if there is a vacant channel, the U-wave level of the channel is measured and compared with the channel allocation standard of the PHS standard (STD-28), so that the vacant channel can be allocated. Determine whether or not force is applied.
- step S10 If there is no available channel that can be allocated in step S10, it is determined in step S11 that channel allocation is rejected due to no channel, and the process proceeds to steps S14 and S15 described above.
- step S10 if a vacant channel that can be allocated is found in step S10, the process proceeds to step S12, and information on the slot / channel to be allocated is notified to the terminal.
- step S13 a link of a communication channel is established using the slot and the wireless channel, and transmission of a synchronization burst is performed between the terminal and the base station. Thereafter, the ⁇ ⁇ 4 shift QP SK is actually switched to 16 QAM, and data communication is performed on the communication channel TC #.
- the terminal of the communication partner of the base station capable of adaptive modulation can perform adaptive modulation similarly. For example, if the base station has ⁇ / 4 shifted QP SK and 16
- the base station must determine whether or not to perform channel assignment for a terminal that communicates only with ⁇ 4 shifted QP SK. Therefore, the base station supporting adaptive modulation adds to the first threshold of the D-wave level when communicating at 16 QAM, and the second threshold of the D-wave level when communicating at pit 4 shift QP SK.
- the measured D-wave level must be compared with its second threshold to determine the channel assignment. is there. For example, as shown in the channel assignment threshold table A in Fig. 4, the required D-wave level of 18 dBu V for ⁇ / 4 shift QP SK is Desirably stored.
- a plurality of modulation schemes ( ⁇ / 4 shift QP SK and 16 QAM ) May be configured to have a communication threshold.
- the threshold table ⁇ in Fig. 4 when the reception noise level of the base station is known (for example, ⁇ 2 dBuV), it is converted not to the D-wave level but to the SZN ratio as the determination criterion. It is also possible to use. This is equivalent to the threshold value of the channel allocation threshold value table C of the S / N ratio shown in the threshold value table C of FIG. Further, the S / N ratio may be measured in place of the U wave measurement in step S9 to determine whether or not to allocate an empty channel.
- Embodiment 2 of FIG. 5 determines channel allocation based on the DOJ ratio.
- steps S21 to S35 are the same as steps S1 to S15 in FIG. 4, and therefore description thereof will not be repeated here.
- the assignment determination method of the second embodiment in FIG. 5 is different from the assignment determination method of the first embodiment in FIG. 4 in addition to the method in the first embodiment in FIG. The point is that channel allocation is determined based on the / U ratio.
- step S30 the DZU ratio is determined from the D-wave level measured in step S23 and the U-wave level measured in step S29. Then, in step S36, the DZU ratio communicable by 16QAM is calculated in advance and compared with a threshold value stored in a memory (not shown) of the base station.
- a D / U ratio of about 20 dB is required to secure the required BER when communicating at 16 QAM. Therefore, such a DZU ratio is stored in a memory (threshold table D) as a threshold.
- step S36 the calculated D / U ratio is compared with the stored threshold value of the D / U ratio, and when the calculated D / U ratio is equal to or greater than the threshold value (20 dB), If so, the required BER can be secured even if communication is performed by 16 QAM. Therefore, channel assignment is permitted, and the process proceeds to step S32.
- step S36 if the calculated D / U ratio is smaller than the threshold value (20 dB) in step S36, the required BER cannot be secured when communicating with 16 QAM. Decide assignment refusal. Then, in step S34, this is notified to the terminal, and in step S35, the terminal shifts to the standby state.
- the terminal requesting connection may not support ⁇ / 4 shift Q.PSK.
- the base station has to determine whether or not to assign a channel to a terminal that communicates only with the four-shift QP SK. Therefore, the base station supporting adaptive modulation has the second threshold of the D / U ratio when communicating with ⁇ 4 shifted QP SK in addition to the first threshold for the D / U ratio when communicating with 16 QAM. If the threshold value is held and a terminal that communicates only with ⁇ 4 shift QPSK requests a connection, it is necessary to compare the calculated DZU ratio with the second threshold value and determine the channel assignment.
- the base station sets a plurality of modulation schemes ( ⁇ / 4 series) having different multi-level numbers as adaptive modulation targets as thresholds of the DZU ratio. It may be configured to have a communication threshold for each of QPSK and 16 Q AM).
- the DZU ratio threshold value determination is also performed, so that more accurate channel allocation determination can be performed. it can. ⁇ 3 ⁇ 4
- the channel allocation is determined based on the DZU ratio.
- steps S41 to S51 are the same as steps S21 to S31 in FIG. 5, and therefore description thereof will not be repeated here.
- the difference between the assignment determination method of Embodiment 3 in FIG. 6 and the assignment determination method of Embodiment 2 in FIG. 5 is that the method of Embodiment 3 in FIG.
- the point is that the DZU ratio is calculated using the D-wave level (step S53) measured at the time of receiving the synchronous burst instead of the level (step S42).
- step S53 the D-wave level of the synchronous burst signal received in the assigned slot is measured, and the D / U ratio is calculated in step S54. Performs a comparison with the value.
- the comparison between the DZU ratio and the threshold table D has been described in detail in the second embodiment of FIG. 5, and will not be repeated here.
- step S54 if it is determined in step S55 that the assignment is rejected, the connection with the terminal is disconnected in step S56, and the apparatus enters a waiting state (step S58).
- step S54 determines whether allocation is possible. If the result of determination in step S54 is that allocation is possible, a slot search is performed in step S59, and the modulation scheme is changed in step S60.
- Embodiment 3 in addition to the D-wave level threshold determination at the time of connection, the D / U ratio threshold determination based on the D-wave level during synchronization burst reception is also performed. Therefore, more accurate channel assignment determination can be performed.
- the terminal when rejecting channel assignment, the terminal is only notified to that effect. For example, if channel assignment in 16 QAM is rejected, 16 Q Communicate with other modulation schemes with fewer values than AM It may be configured to control terminals and base stations as described above.
- the terminal that has received the channel allocation rejection notification from the base station displays this fact on the display unit (for example, the display unit 17 in FIG. 3) and notifies the user.
- FIG. 7 is a diagram for explaining the details of a communication procedure between terminal PS and base station CS according to Embodiment 3 of the present invention shown in FIG. 6 over time. More specifically, it is a diagram showing a calling sequence started from the terminal side.
- an on-hook wireless connection request is executed on the PS side. That is, first, on the control channel, a link channel establishment request is made from the PS to the CS.
- the D-wave level is measured, and the measured D-wave level becomes 16
- the threshold of the D-wave level corresponding to QAM is determined to be equal to or higher than the threshold (first channel assignment determination). If it is determined that the value is equal to or larger than the threshold, it is determined that the channel assignment is permitted, the U wave is measured, and the link channel assignment is transmitted to the PS.
- the exchange of the link channel assignment procedure is performed by the ⁇ 4 shift QP SK with a small number of values in the control channel CCH.
- the modulation scheme remains ⁇ / 4 shift QP SK at this stage.
- the D-wave level is measured again at the time of receiving the synchronization burst from the terminal, and the DZlJ ratio is calculated from the D-wave level and the above-described measured U-wave level. Then, it is determined whether the D / U ratio is equal to or greater than the threshold value of the 16QAM compatible (second channel allocation determination). If it is determined that the value is equal to or greater than the threshold value, it is determined that the channel assignment is permitted, a synchronization burst is transmitted, and known control signals such as SABM and UA are exchanged. Well-known procedures such as setting, definition information, function request / response, and authentication are performed.
- the modulation scheme shall be switched from ⁇ 4 shifted QPSK to 16 QAM, which has a larger number of values.
- the DZU ratio satisfies the threshold corresponding to 16QAA, communication quality is not degraded by this switching of the modulation scheme.
- Subsequent communication on the communication channel will be performed by 16 QAM. That is, known control signals such as DISC and UA are exchanged, and after passing through well-known procedures such as calling, RBT, and response, data communication is started.
- a parameter representing a communication environment of a transmission path is measured. If the measured value of the parameter is equal to or greater than the threshold value of the parameter that allows communication with the modulation method with the larger number of values, the configuration is such that the assignment of the wireless channel to other wireless devices is permitted. Therefore, even if the modulation method is switched from a modulation method with a small number of values to a modulation method with a large number of values during communication after connection of another wireless device (after channel assignment), the communication environment of the transmission path may vary. Thus, it is possible to prevent communication quality from deteriorating. Industrial applicability
- the present invention communication quality is prevented from being degraded when the modulation scheme is switched, so that the present invention is effective in a wireless device that supports adaptive modulation.
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- Engineering & Computer Science (AREA)
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- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Artificial Intelligence (AREA)
- Physics & Mathematics (AREA)
- Probability & Statistics with Applications (AREA)
- Mobile Radio Communication Systems (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
Description
Claims
Priority Applications (3)
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AU2003261881A AU2003261881A1 (en) | 2002-09-24 | 2003-09-01 | Radio device, channel allocation method, and channel allocation program |
EP03798386A EP1551197A1 (en) | 2002-09-24 | 2003-09-01 | Radio device, channel allocation method, and channel allocation program |
US10/528,340 US7613460B2 (en) | 2002-09-24 | 2003-09-01 | Radio device, channel allocation method, and channel, allocation program |
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JP2002277026A JP4251841B2 (ja) | 2002-09-24 | 2002-09-24 | 無線装置、チャネル割当方法、およびチャネル割当プログラム |
JP2002-277026 | 2002-09-24 |
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PCT/JP2003/011180 WO2004030397A1 (ja) | 2002-09-24 | 2003-09-01 | 無線装置、チャネル割当方法、およびチャネル割当プログラム |
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US (1) | US7613460B2 (ja) |
EP (1) | EP1551197A1 (ja) |
JP (1) | JP4251841B2 (ja) |
CN (1) | CN1682565A (ja) |
AU (1) | AU2003261881A1 (ja) |
TW (1) | TWI258926B (ja) |
WO (1) | WO2004030397A1 (ja) |
Cited By (1)
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CN1312959C (zh) * | 2004-08-19 | 2007-04-25 | Ut斯达康通讯有限公司 | Phs基站控制信道分配的方法 |
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US7706326B2 (en) * | 2004-09-10 | 2010-04-27 | Interdigital Technology Corporation | Wireless communication methods and components that implement handoff in wireless local area networks |
JP2006253754A (ja) * | 2005-03-08 | 2006-09-21 | Nec Corp | 無線通信システム及び初期通信速度設定方法 |
US7489944B2 (en) * | 2005-06-01 | 2009-02-10 | Alcatel-Lucent Usa Inc. | Method of allocating power over channels of a communication system |
JP2007150800A (ja) | 2005-11-29 | 2007-06-14 | Kyocera Corp | 無線基地局装置及び無線基地局装置の制御方法 |
JP4761232B2 (ja) * | 2006-06-23 | 2011-08-31 | 日本電気株式会社 | 無線通信装置及びその変調方式切り替え方法 |
US20080037661A1 (en) * | 2006-08-08 | 2008-02-14 | Adaptix, Inc. | Mobile communication system having multiple modulation zones |
JP4355333B2 (ja) * | 2006-09-13 | 2009-10-28 | 京セラ株式会社 | 移動体通信システム、移動局装置、基地局装置、およびチャネル割当方法 |
KR101478356B1 (ko) * | 2006-11-01 | 2014-12-31 | 삼성전자주식회사 | 패킷 데이터 통신 시스템에서 패킷 데이터를 위한 제어정보 송수신 방법 및 장치 |
KR20080041096A (ko) * | 2007-03-13 | 2008-05-09 | 엘지전자 주식회사 | 무선 통신 시스템에서 피드백 정보를 이용한 링크 적응방법 |
DE602007012565D1 (de) * | 2007-12-14 | 2011-03-31 | Sony Corp | Strahlensteueralgorithmus für NLOS-Drahtlossysteme mit vordefinierten Parametern |
CN101237437B (zh) * | 2008-01-24 | 2010-09-29 | 华为技术有限公司 | 实现不同阶数调制的方法与装置 |
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2003
- 2003-09-01 WO PCT/JP2003/011180 patent/WO2004030397A1/ja active Application Filing
- 2003-09-01 CN CNA038224291A patent/CN1682565A/zh active Pending
- 2003-09-01 EP EP03798386A patent/EP1551197A1/en not_active Withdrawn
- 2003-09-01 US US10/528,340 patent/US7613460B2/en not_active Expired - Fee Related
- 2003-09-01 AU AU2003261881A patent/AU2003261881A1/en not_active Abandoned
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JP2002084329A (ja) * | 2000-06-23 | 2002-03-22 | Matsushita Electric Ind Co Ltd | 適応変調通信システム |
JP2002064424A (ja) * | 2000-08-21 | 2002-02-28 | Matsushita Electric Ind Co Ltd | 通信端末装置、基地局装置および無線通信方法 |
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CN1312959C (zh) * | 2004-08-19 | 2007-04-25 | Ut斯达康通讯有限公司 | Phs基站控制信道分配的方法 |
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JP4251841B2 (ja) | 2009-04-08 |
US7613460B2 (en) | 2009-11-03 |
TWI258926B (en) | 2006-07-21 |
JP2004120051A (ja) | 2004-04-15 |
CN1682565A (zh) | 2005-10-12 |
TW200405671A (en) | 2004-04-01 |
AU2003261881A1 (en) | 2004-04-19 |
US20060052122A1 (en) | 2006-03-09 |
EP1551197A1 (en) | 2005-07-06 |
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