JP2012170096A - Wireless communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal, which consumes less power, having a compact-size circuit.SOLUTION: There is provided a wireless communication method in which a base station and a plurality of terminals communicate using, as a channel, slots divided by time band in a plurality of carriers divided by frequency band. The base station informs a terminal of monitoring information which designates as monitoring coverage a channel containing at least one of a carrier or a slot. The terminal receives the monitoring information and controls, based on whether a signal applies to the monitoring coverage included in the received monitoring information, whether to receive the signal applying to the monitoring coverage or whether to stop receiving the signal. Then the terminal transmits, to the base station, an estimate result of the status of a transmission path based on the signal in the monitoring coverage. The base station, based on the estimated result, allocates a channel containing at least one of a carrier or a slot to transmit a packet and transmits a packet to the terminal using the allocated channel.

Description

  The present invention relates to a mobile radio communication system including a radio communication base station and a radio communication terminal, and more particularly to a technique for performing packet scheduling.

  In cdma2000 1x-EV DO communication in the downlink direction (direction from the base station to the mobile station), the base station divides the time into 1/600 second units (slots), and one slot (channel) of a certain frequency. Then, communication is performed with only one terminal, and the communication terminal is switched for each channel to communicate with a plurality of terminals.

  The terminal receives the pilot signal of the base station, estimates the channel propagation path condition from the pilot signal, and transmits the propagation path condition estimation result (propagation path information) to the base station. The base station determines to which terminal the next channel is assigned and the packet is transmitted according to the received propagation path information. Such channel assignment is called packet scheduling. Packet scheduling will be described with reference to FIG.

  FIG. 30 is a channel schedule table of the prior art, where the vertical axis represents time and the horizontal axis represents frequency. The frequency band is divided into carriers (carrier waves) from F1 to F4, and the time band is divided into a slot from S1 to S8 in a predetermined time to constitute a channel divided into time and frequency.

  Terminal A determines carriers F1 to F4 to communicate with. Specifically, the terminal A monitors the first carrier serving as a reference stored in the SRAM of the terminal A, and determines whether the first carrier is full of other terminals from the broadcast information. When the first carrier is not full, terminal A sends its control information to the base station to register its location.

  On the other hand, when the first carrier is full, terminal A monitors a different second carrier. Similarly, when the second carrier is full, terminal A determines the carrier to communicate by monitoring the third carrier.

  Here, the terminal A determines to communicate with the carrier F1. Terminal A then estimates the propagation path condition for each of slot S1 to slot S8 of carrier F1, and transmits the propagation path information to the base station. As described above, the base station assigns channels according to the propagation path information from each terminal. The base station determines that the channel condition of the slot S3 of the terminal A is good and allocates (schedules) the channel of the slot S3 of the carrier F1 to the terminal A.

  Here, there may be a plurality of carriers with which terminal A communicates. For example, Patent Document 1 describes a technique in which terminal A communicates using a plurality of carriers. This will be described with reference to FIG.

  FIG. 31 is a channel schedule table in the prior art, where the vertical axis represents time and the horizontal axis represents frequency.

  The base station communicates with a plurality of terminals using carriers from F1 to F8. Here, the base station and terminal A perform low rate communication.

  First, the base station determines to communicate with terminal A by assigning three carriers. In the base station, a plurality of carriers F1, F4, and F8 may be allocated to the terminal A so that the frequency difference between the allocated carriers becomes a predetermined value or more. Thereafter, the base station transmits a packet to terminal A using carrier F1, carrier F4 and carrier F8.

  At this time, the terminal A transmits channel propagation path information for each of the slots S1 to S8 of the carriers F1, F4, and F8 to the base station. The base station performs scheduling according to channel propagation path information from each terminal. The base station determines that the channel conditions of the channel of slot S3 of carrier F1, the channel of slot S4 of carrier F4, and the channel of slot S7 of carrier F8 are good, and schedules to terminal A. Then, the base station transmits the packet through the channel scheduled for terminal A.

JP 2003-9240 A

  According to the above-described prior art, since a plurality of carriers in which the difference in the frequency of the allocated carriers is equal to or greater than a predetermined value are allocated, the terminal needs to observe a wide frequency band. Therefore, the terminal needs to have a plurality of RF parts or a wide-band RF part and divide each carrier in the baseband part. For this reason, the terminal has an increased circuit scale and power consumption.

  An object of the present invention is to reduce the power consumption by suppressing the circuit scale of a terminal.

  A typical example of the present invention is as follows. That is, a wireless communication method in which a base station and a plurality of terminals communicate using a slot divided in a time band for a plurality of carriers divided in a frequency band as a channel, the base station Monitoring information specifying a channel including at least one of a carrier and the slot as a monitoring range is notified, the terminal receives the monitoring information, and the terminal corresponds to the monitoring range included in the received monitoring information Based on whether or not the reception processing of the signal corresponding to the monitoring range is to be performed or to stop the reception processing, the terminal determines the estimation result of the propagation path condition based on the signal of the monitoring range Transmitting to the base station, and the base station allocates a channel including at least one of a carrier and a slot on which packet transmission is to be performed based on the estimation result. Against, the base station, by the assigned channel, and performs packet transmission to the terminal.

  According to the present invention, power consumption of a terminal can be reduced.

It is a system configuration figure of the radio communications system of an embodiment of the invention. It is a block diagram of the base station of 1st Embodiment. It is a block diagram of the terminal of a 1st embodiment. The spectrum in the process which takes out the signal of the specific carrier of 1st Embodiment is represented. It is a sequence diagram of the channel set allocation process when the terminal A of the first embodiment notifies the reception capability. It is a sequence diagram of the packet scheduling process performed by the channel set allocation process of 1st Embodiment. In the first embodiment, it is a channel schedule table in the case of assigning channel sets for frequencies. It is a timing chart of the channel of a 1st embodiment. It is a flowchart of the scheduling process of 1st Embodiment. It is a flowchart of the process of the base station after the scheduling process of 1st Embodiment. 5 is a flowchart of a propagation path state estimation process in the first embodiment. 6 is a flowchart of scheduling result reception processing in the first embodiment. 4 is a flowchart of packet reception processing in the first embodiment. FIG. 10 is a sequence diagram of channel set allocation when terminal A of the first embodiment notifies a change in reception capability. It is a sequence diagram of a channel set when the base station of the first embodiment takes the lead. In the first embodiment, it is a channel schedule table when assigning channel sets with respect to time. FIG. 10 is a channel timing chart when notifying a scheduling result when assigning channel sets with respect to time in the first embodiment. In 1st Embodiment, it is a flowchart of the propagation path condition estimation process in the case of assigning a channel set about time. FIG. 10 is a flowchart of scheduling result reception processing when assigning channel sets with respect to time in the first embodiment. FIG. 6 is a flowchart of packet reception processing when assigning channel sets with respect to time in the first embodiment. In the first embodiment, it is a channel schedule table in the case of assigning channel sets for frequency and time. It is a graph showing the propagation path condition of the carrier of 1st Embodiment. It is a sequence diagram which shows the packet scheduling process of 2nd Embodiment. It is a timing chart of a channel of a 2nd embodiment. In the second embodiment, it is a channel timing chart when a scheduling result is not notified when a channel set is allocated with respect to time. It is a block diagram of the base station 200 of 3rd Embodiment. It is a sequence diagram of the channel set of the third embodiment. It is a block diagram of the terminal of 4th Embodiment. The spectrum in the process which takes out the signal of the specific carrier of 4th Embodiment is represented. It is a schedule table of the channel of a prior art. 10 is a channel schedule table of Patent Document 1.

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

  FIG. 1 is a configuration diagram of a radio communication system according to a first embodiment of this invention.

  The wireless communication system of this embodiment includes a base station 200, a terminal A201 (A), a terminal B201 (B), a terminal C201 (C), a terminal D201 (D), and a terminal E201 (E). The terminal A 201 (A), the terminal B 201 (B), the terminal C 201 (C), the terminal D 201 (D), and the terminal E 201 (E) are in an area where communication with the base station 200 is possible.

  All the terminals 201 receive the pilot signal of the base station 200, estimate the downlink (base station → terminal) propagation path condition, and transmit the estimated propagation path condition result (propagation path information 203) to the base station 200. To do. The base station 200 performs scheduling according to the propagation path information 203 from the terminal 201. The base station 200 transmits a packet to the terminal 201 according to the scheduling (204).

  FIG. 2 is a block diagram of the base station 200 according to the first embodiment.

  The antenna 207 transmits or receives signals with the terminal 201. The circulator 208 sends the signal received by the antenna 207 to the reception unit 209 and sends the transmission signal generated by the transmission unit 215 to the antenna 207.

  The receiving unit 209 performs processing such as amplification and detection at a high frequency and an intermediate frequency, and converts a radio signal into a baseband signal. Thereafter, the baseband signal is demodulated, decoded and error-corrected. If the signal from the antenna is the reception capability information (MSAI) of the terminal, the information is sent to the channel condition control unit 210. If the signal is the propagation path status information (CSI), the information is sent. Is sent to the scheduler 213, and if it is user data, the data is sent through the network interface unit 211.

  The channel condition control unit 210 allocates a channel set based on the reception capability information of the terminal as described later, and accumulates information on the allocated channel set (CCI). Further, channel set information is sent to the scheduler 213 as necessary.

  The information storage unit 212 acquires and stores terminal user data and signals to be transmitted to the terminal from the network through the network interface unit 211. In addition, the information storage unit 212 creates and stores terminal management information (TD) using the past average transmission rate of the terminal and the like. Further, the information storage unit 212 sends the stored user data of the terminal and a signal to be transmitted to the terminal to the modulator 214.

  The scheduler 213 performs scheduling based on channel set information with reference to propagation path information and terminal management information. Then, scheduler 213 sends terminal encoding information (MI), signal transmission carrier information (F / S), etc., to information storage section 212 and modulator 214 in accordance with the scheduled packet transmission timing. .

  The control signal generator 216 generates information for controlling the transmission unit 215 and sends the information to the modulator 214.

  The modulator 214 encodes the signal to be transmitted to the terminal based on the information on the terminal encoding from the scheduler, the information on the carrier to be transmitted, and the like. Further, multiplexing with control information from the control signal generator 216 is performed. Then, the modulator 214 sends the multiplexed signal to the transmission unit 215. The transmission unit 215 converts this signal into an RF signal and transmits the signal to the terminal 201 from the antenna 207 through the circulator 208.

  FIG. 3 is a block diagram of the terminal according to the first embodiment, and shows a configuration when the communication system is the FDMA system.

  The antenna 233 transmits or receives signals with the base station 200. The circulator 217 inputs the signal received by the antenna 233 to the wireless reception unit 218 and inputs the transmission signal generated by the wireless transmission unit 228 to the antenna 233.

  The reception RF unit 230 includes a radio reception unit 218, a filter 219, an A / D converter 220, and a transmitter 231.

  The transmitter 231 generates a high frequency signal (local oscillation signal) having a specific frequency and inputs the high frequency signal to the wireless reception unit 218. The radio reception unit 218 converts the frequency of the signal from the base station 200 using the local oscillation signal.

  The filter 219 removes unnecessary frequency components other than the signal from the base station 200 whose frequency has been converted. Further, the filter 219 uses a different filter for each signal having a different data transmission rate (according to the signal bandwidth) (for example, when different filters are used for the call service and the broadband communication service), the width of the frequency to be extracted. May be able to switch between different filters 219. The A / D converter 220 converts the signal from the filter into a digital signal.

  The baseband processing unit 229 includes a filter bank 221, a demodulator 222, a selection unit 223, and a channel state measurement unit 224.

  The filter bank 221 extracts the signal of each carrier from the digitally converted signal using a filter suitable for each carrier. Further, the filter bank 221 sends the extracted signal for each carrier to the demodulator 222 and the channel state measurement unit 224.

  The demodulator 222 demodulates the transmitted signal for each carrier. The selection unit 223 extracts destination information from the demodulated signal, and sends a signal to the CPU 225 if the destination is its own terminal. On the other hand, if the destination is not its own terminal, the signal is discarded.

  On the other hand, the channel state measurement unit 224 estimates the state (S / I) of the propagation path from the pilot signal inserted in the signal of each carrier. However, the carrier for estimating the state of the propagation path may be only the carrier assigned by the channel set as will be described later. This is because packets are not transmitted on channels of other carriers.

  When the terminal 201 obtains the data transmission rate, the channel state measurement unit 224 obtains the data transmission rate with reference to a table in which the propagation path information and the data transmission rate are associated with each other.

  The CPU 225 controls the entire receiver 201 and controls reception or transmission of information with the base station 211. Further, the CPU 225 may be provided with a timer. The timer manages the operation / pause time of the receiver. The CPU 225 controls to cut off the power to the RF unit 230, the baseband processing unit 229, and the signal transmission unit 234 during the downtime. On the other hand, the CPU 225 controls to supply power to the RF unit 230, the baseband processing unit 229, and the signal transmission unit 234 immediately before switching to the operation time.

  The signal transmission unit 234 includes a modulation unit 226, a D / A converter 227, and a wireless transmission unit 228.

The modulation unit 226 modulates the information transmitted from the CPU 225 to the base station, the carrier information (CI) and user ID (UI) to be transmitted, and the channel condition (CSI) input from the channel state measurement unit 224. Create a signal. The D / A converter 227 converts the modulation signal created by the modulator 226 into an analog signal. Further, the wireless transmission unit 228 converts the analog-converted signal into a frequency of a carrier to be transmitted to the base station, and amplifies it to necessary power. The amplified signal is transmitted from the antenna 233 to the base station 200 through the circulator 217.

  FIG. 4 shows a spectrum in the process of extracting a signal of a specific carrier according to the first embodiment.

  The antenna 233 receives a signal having a spectrum as shown in FIG. The signal received by the antenna 233 is present on all carriers.

  From this signal, a carrier that the terminal needs is taken out by a filter 219 represented by a thick line in FIG. Specifically, as will be described later, the filter 219 extracts a signal so as to include all carriers of the assigned channel set. Therefore, the output of the filter 219 is a wideband signal including a plurality of carriers (for example, a band signal including three carriers in this embodiment).

  The signal extracted by the filter is shown in FIG. The filter bank 221 has a filter suitable for each carrier as indicated by a thick line in FIG. 4C, and extracts a signal for each carrier. One spectrum of the extracted signal for each carrier is shown in FIG.

  FIG. 5 is a sequence diagram of channel set allocation processing when terminal A of the first embodiment notifies reception capability.

  The reception capability is the capability of the terminal A 201 (A) to communicate with the base station 200, for example, the maximum communication rate of the terminal A 201 (A).

  In the following, a case where the terminal A 201 (A) is a low-rate terminal with a narrow band that can be used will be described as an example.

  First, the terminal A 201 (A) notifies the reception capability to the base station 200 using the control channel (309). For example, when the terminal A 201 (A) is turned on, or when the terminal A 201 (A) starts communication with the base station 200, the terminal A 201 (A) takes the initiative to allocate the channel set. Is done.

  The base station 200 receives the reception capability of the terminal A 201 (A) (310) and allocates a channel set so as to satisfy the reception capability. As will be described in detail later, the channel set is a plurality of channels composed of subbands composed of carriers that are continuous on the frequency axis and / or subframes composed of slots that are continuous on the time axis.

  The base station 200 notifies the terminal A 201 (A) of the allocated channel set using the control channel (312). Then, the base station 200 performs packet scheduling only for the assigned channel set in the subsequent communication with the terminal A201 (A) (300). The packet scheduling method will be described later, and there are a method of notifying the scheduling result to the terminal A 201 (A) and a method of not notification.

  When terminal A 201 (A) receives the notification of the channel set (313), it monitors only the assigned channel set and receives the packet from base station 200 in the subsequent communication.

  FIG. 6 is a sequence diagram of the packet scheduling process executed in step 300 of the channel set allocation process (FIG. 5), in which the scheduling result is notified.

  Base station 200 transmits a pilot signal at a certain timing within a communicable region.

  Terminal A 201 (A) receives the pilot signal from base station 200 and estimates the channel propagation path condition from the pilot signal (301). The propagation path state is estimated from, for example, RSSI (received electric field strength) or CIR (desired wave interference wave ratio).

  Terminal A 201 (A) transmits the estimated propagation path condition result (propagation path information) to base station 200 (302). The base station 200 receives channel propagation path information (303), and allocates (schedules) a channel for transmitting a packet based on the propagation path information (304). In this scheduling, the base station 200 calculates an evaluation function, which will be described later, and assigns a channel to a terminal having the highest evaluation function. Then, the base station 200 notifies the terminal A 201 (A) of the scheduling result (305).

  The terminal A201 (A) receives the scheduling result (306). Then, terminal A 201 (A) waits for reception on the channel through which base station 200 transmits a packet, based on the scheduling result.

  The base station 200 transmits the packet on the scheduled channel (307), and the terminal A201 (A) receives the packet (308).

  FIG. 7 is a channel schedule table in the case of assigning channel sets for frequencies in the first embodiment, where the vertical axis represents time and the horizontal axis represents frequency.

  Base station 200 communicates with a plurality of terminals 201 using carriers F1 to F8. Since terminal A 201 (A) and base station 200 perform low-rate communication, it is not necessary to communicate using all carriers.

  Therefore, the base station 200 allocates a channel set including three carriers F6 to F8 having continuous frequencies to the terminal A201 (A). Here, a plurality of carriers having continuous frequencies, such as carrier F6 to carrier F8, are collectively referred to as a subband. The channel set is allocated by determining the number of carriers to be communicated according to the data transmission rate between the terminal 201 and the base station 200.

  The base station 200 does not schedule the other carriers F1 to F5 to the terminal A201 (A), and transmits a packet using the assigned channel set. Therefore, terminal A 201 (A) monitors only subband 101 (carriers F6 to F8) of the assigned channel set.

  Specifically, the base station 200 schedules the channel of the slot S3 of the carrier F7, the channel of the slot S4 of the carrier F6, and the channel of the slot S7 of the carrier F8 to the terminal A201 (A) and transmits a packet. .

  FIG. 8 is a channel timing chart of the first embodiment. The hatched portion in the figure indicates the timing at which communication between the base station 200 and the terminal A 201 (A) is performed.

  The base station 200 transmits a pilot signal (Pilot) (500). Terminal A 201 (A) receives the pilot signal and estimates the propagation path condition from the received pilot signal. Terminal A 201 (A) then transmits channel information (CSI) to the base station 200 in the next slot that has received the pilot signal (501).

  The base station 200 receives the propagation path information and performs scheduling. The base station 200 transmits the scheduling result (RI) to the terminal A201 (A) in the next slot that has received the propagation path information (502). Here, the base station 200 transmits by increasing the spreading factor and decreasing the transmission power in order to reduce the overhead generated by transmitting the scheduling result, or transmitting by shortening the transmission time by intermittent transmission. .

  The base station 200 transmits data (Data) at the timing scheduled to the terminal A 201 (A) (503).

  FIG. 9 is a flowchart of the scheduling process according to the first embodiment, which is executed in the base station 200.

  The base station 200 selects one carrier from a plurality of carriers (401). Next, the base station 200 refers to the channel condition control unit 210 and identifies the terminal 201 assigned to the selected carrier (402). The channel condition control unit 210 assigns channel sets of all terminals 201 communicating with the base station 200 and stores the assigned channel sets.

  The base station 200 receives the propagation path information of the selected carrier for all the specified terminals, and calculates the evaluation function (403).

  For the calculation of the evaluation function, for example, proportional fairness is used, and the calculation is performed by Equation 1.

  Here, DRC is a data transmission rate based on propagation path information from the terminal 201. When the base station 200 receives the propagation path information from the terminal 201, the base station 200 refers to a table in which the propagation path information and the DRC are associated to obtain the DRC of the terminal 201. However, the base station 200 may receive the DRC obtained by the terminal 201 referring to a predetermined table.

  The base station 200 divides the DRC by the average data transmission rate (R) of the terminal 201 so far. This value is an evaluation function, and it can be determined whether the DRC is higher or lower than the average transmission rate so far. The base station 200 can perform scheduling while maintaining fairness for all the terminals 201 by using this evaluation function as a reference for allocation.

  The base station 200 compares the evaluation functions of all the terminals 201 identified in step 402, selects the terminal 201 having the highest evaluation function, and schedules the terminal 201 (404). With this operation, the base station 200 completes the scheduling of the selected carrier. The base station 200 determines whether all the carriers have been selected, and if not selected, schedules the carriers that have not been selected (405). If all carriers are selected, scheduling for this slot is complete.

  FIG. 10 is a flowchart of the process of the base station 200 after the scheduling process according to the first embodiment.

  The base station 200 selects one carrier from a plurality of carriers (406). Next, the base station 200 acquires information such as the ID and data transmission rate of the terminal 201 that transmits the packet by using the scheduling of the selected carrier (407).

  Further, the base station 200 uses the information storage unit 212 to acquire data to be transmitted to the terminal 201 and information on the selected carrier (408). Here, since the amount of data to be transmitted depends on the data transmission rate, the scheduler 213 instructs the modulator 214 on the data transmission rate (409). The instructed modulator 214 instructs the information storage unit 212 of the amount of information to be sent to the modulator 214 per unit time.

  The base station 200 determines whether or not all carriers have been selected. If not, the base station 200 prepares for packet transmission on the unselected carrier (405). If all the carriers are selected, preparation for transmission of the packet for this slot is completed.

  The base station 200 transmits data on the channel of the selected carrier to the scheduled terminal 201 from these pieces of information. At this time, the base station 200 modulates with an appropriate modulation scheme and transmits data to the terminal 201.

  FIG. 11 is a flowchart of the propagation path state estimation process in the first embodiment, which is executed in terminal A 201 (A).

This propagation path state estimation process is started and executed by an interrupt that occurs at the timing of each slot. First, the terminal A 201 (A) determines whether there is information to be received from the base station 200 (411). That is, it is determined whether or not it is connected to the base station. If there is no information to be received, terminal A 201 (A) ends the processing in this slot. On the other hand, when there is information to be received (when in a connected state), the terminal A 201 (A) is assigned using hardware configured to be able to observe the carrier of the assigned channel set. The pilot signal of the received carrier is received (412).
Terminal A 201 (A) then estimates the channel state of the allocated carrier from the received pilot signal (413). Here, the terminal A 201 (A) may obtain the data transmission rate from the estimated propagation path condition with reference to a table in which the propagation path condition and the DRC are associated with each other. Terminal A 201 (A) transmits the estimation result (propagation channel information) or the data transmission rate of the channel condition of the allocated carrier to base station 200.

  FIG. 12 is a flowchart of scheduling result reception processing according to the first embodiment, which is executed by terminal A 201 (A).

  After transmitting the propagation path information, the terminal A 201 (A) determines whether the scheduling result is transmitted from the base station 200 (414). When the scheduling result is not transmitted from the base station 200, the scheduling result receiving process is terminated. On the other hand, when the scheduling result is transmitted from the base station, the terminal A 201 (A) checks the scheduling of the carrier of the assigned channel set from the received scheduling result (415).

  The terminal A 201 (A) determines whether or not the base station 200 transmits a packet using the carrier assigned to the terminal A 201 (A) (416). If no packet is transmitted from the base station 200, the terminal A201 (A) ends this scheduling result reception process. On the other hand, when a packet is transmitted from the base station 200, the terminal A 201 (A) reserves reception of the packet in the corresponding slot and the corresponding carrier channel based on the scheduling result (417).

  FIG. 13 is a flowchart of packet reception processing in the first embodiment, and is executed by terminal A 201 (A).

  This reception process is started and executed by an interrupt that occurs at the timing of each slot. First, the terminal A confirms the scheduling reserved in step 417 and determines whether there is information to be received (418). If there is no information to be received, terminal A 201 (A) ends the packet reception process in this slot. On the other hand, if there is information to be received, the terminal A 201 (A) receives the packet on the scheduled channel (419).

  The packet scheduling executed when the terminal is turned on and the terminal starts operating has been described above. However, similar packet scheduling can be performed when the terminal 201 notifies the reception capability change (FIG. 14). Done.

  FIG. 14 is a sequence diagram of channel set assignment when the terminal A 201 (A) of the first embodiment notifies a change in reception capability.

  The change in the reception capability of the terminal A 201 (A) is a change in the data transmission rate of the terminal A 201 (A), for example, when the voice communication is changed to the broadband communication.

  Terminal A 201 (A) notifies the base station 200 of a change in reception capability using the control channel (314).

  The base station 200 receives the change in the reception capability of the terminal A (315), and assigns a channel set that satisfies the changed reception capability (311). The base station 200 notifies the channel set assigned to the terminal A 201 (A) using the control channel (312). Then, the base station 200 performs packet scheduling for only the assigned channel set (300).

  Terminal A 201 (A) receives the notification of the channel set (313). Terminal A 201 (A) then monitors only the assigned channel set and receives packets from base station 200 in subsequent communications.

  Receiving the channel set notification, terminal A 201 (A) changes the local oscillation frequency output from transmitter 231. In the case of the terminal A 201 (A) whose band is changed according to the received signal, the band limiting filter 219 is switched and the sampling clock supplied to the A / D converter 220 is also changed. Further, in the filter bank 221 of the terminal A201 (A), the number of filters used for observation is changed.

  Up to this point, the case where the terminal 201 led the channel set assignment has been described as the first embodiment, but the base station 200 can also lead the channel set assignment.

  FIG. 15 is a sequence diagram of channel sets when the base station 200 of the first embodiment takes the lead.

  The base station 200 measures the utilization factor for each channel and detects a channel deviation (316). The channel deviation is a deviation of the channel utilization rate. If the channel deviation is large, the channel utilization efficiency decreases.

  The base station 200 assigns a channel set of an arbitrary terminal 201 so as to reduce the channel deviation (311). For example, the base station 200 notifies the terminal A 201 (A) of the change of the channel set (312). Terminal A 201 (A) receives the notification of the channel set (313). Then, the base station 200 performs packet scheduling for only the assigned channel set (300).

  Terminal A 201 (A) receives the notification of the channel set (313). Terminal A 201 (A) then monitors only the assigned channel set and receives packets from base station 200 in subsequent communications.

  Up to this point, the embodiment has been described in which channel sets are assigned to frequencies. However, in the first embodiment, channel sets can be assigned to time.

  FIG. 16 is a channel schedule table when assigning channel sets with respect to time in the first embodiment, where the vertical axis represents time and the horizontal axis represents frequency.

  The base station 200 transmits a packet to all terminals 201 using the entire frame composed of slots S1 to S8. When the base station 200 and the terminal A 201 (A) perform low-rate communication, the base station 200 allocates a communication time (slot) to the terminal A 201 (A) in FIG. Power consumption can also be reduced.

  The base station 200 allocates a channel set including two slots S2 and S3 that are temporally continuous to the terminal A201 (A). Here, a group of a plurality of slots that are temporally continuous like S2 and S3 is referred to as a subframe 102.

  Base station 200 transmits a packet to terminal A 201 (A) in the slot of the assigned channel set. Specifically, in the first frame, base station 200 transmits a packet to terminal A 201 (A) using the channel in slot S2 of carrier F3 and the channel in slot S3 of carrier F1. In the next frame, base station 200 transmits a packet to terminal A201 (A) using the channel in slot S2 of carrier F6 and the channel in slot S3 of carrier F8.

  At this time, the terminal A 201 (A) can reduce power consumption by not operating unnecessary circuits in the unassigned slots (S 1 and S 4 to S 8).

  Note that the terminal A 201 (A) needs to perform overhead processing such as initial setting when starting operation, and if non-consecutive slots are allocated, the power required for the initial setting or the like for each allocated slot Consume. In order to reduce such power consumption, the base station 200 allocates continuous slots to the terminal A 201 (A). That is, terminal A 201 (A) requires initial setting in slot S 2, but does not require initial setting in slot S 3, and power consumption is reduced by assigning consecutive slots.

  FIG. 17 is a channel timing chart when notifying a scheduling result when assigning channel sets with respect to time in the first embodiment. A portion surrounded by a thick line is a slot in which the base station 200 and the terminal A 201 (A) are associated with each other. A hatched portion is a slot 514 in which the base station 200 transmits a packet to the terminal A 201 (A).

  Terminal A 201 (A) has received the packet only in the sub-frame 513 of the channel set because the channel set has been assigned with respect to time. Therefore, terminal A 201 (A) estimates the propagation path condition using pilot signal 510 that is a predetermined number of slots (six slots) ahead of subframe 513.

  Terminal A 201 (A) transmits the estimation result (propagation path information) of the propagation path condition to the base station 200 in the next slot that has received the pilot signal 510 (511). The base station 200 performs scheduling based on the propagation path information, and transmits the scheduling result to the terminal A 201 (A) (512). The base station 200 transmits data to the terminal A 201 (A) according to the scheduling (514).

  FIG. 18 is a flowchart of a propagation path state estimation process when assigning channel sets with respect to time in the first embodiment, and is executed by terminal A 201 (A) instead of the process of FIG. 11 described above.

  This propagation path state estimation process is started and executed by an interrupt that occurs at the timing of each slot. First, the terminal A 201 (A) determines whether it is the reception timing of the pilot signal (420). The timing for receiving the pilot signal (for example, 510 in FIG. 17) is a timing that is a predetermined time (6 slots) before the subframe (for example, 513 in FIG. 17) of the assigned channel set.

  If it is not time to receive the pilot signal, terminal A 201 (A) ends this propagation path state estimation process. On the other hand, if it is time to receive a pilot signal, it is further determined whether there is information to be received in this slot (421).

  As a result of the determination, if there is no information to be received, the terminal A 201 (A) ends this propagation path state estimation process. On the other hand, if there is information to be received, terminal A 201 (A) receives the pilot signal of the assigned carrier (422). The channel state of the allocated carrier is estimated from the received pilot signal (423).

  FIG. 19 is a flowchart of a scheduling result reception process when assigning channel sets with respect to time in the first embodiment, and is executed by terminal A 201 (A) instead of the process of FIG. 12 described above.

  After transmitting the propagation path information, the terminal A 201 (A) determines whether it is the timing to receive the scheduling result from the base station 200 (424). The reception timing of the scheduling result (for example, 512 in FIG. 17) is a timing after a predetermined time (one slot) from the slot (511 in FIG. 17) of the transmitted propagation path information.

  If it is not the reception timing of the scheduling result, the terminal A 201 (A) ends the scheduling result reception process. On the other hand, if it is the reception timing of the scheduling result, the scheduling result is received, and the scheduling of allocated carriers (all carriers when no channel set is allocated for the frequency) is examined (426).

  The terminal A201 (A) determines whether or not the base station 200 transmits a packet using the allocated carrier (427). If no packet is transmitted from the base station 200, the terminal A201 (A) ends this scheduling result reception process. On the other hand, when a packet is transmitted from the base station 200, the terminal A 201 (A) reserves reception of the packet in the corresponding slot and the corresponding carrier channel based on the scheduling result (428).

  FIG. 20 is a flowchart of packet reception processing when assigning channel sets with respect to time in the first embodiment, and is executed by terminal A 201 (A) instead of the processing of FIG. 13 described above.

  This reception process is started and executed by an interrupt that occurs at the timing of each slot. First, the terminal A 201 (A) determines whether or not it is a subframe (for example, 513 in FIG. 17) of a channel set to which a slot is assigned (429).

  If it is not a subframe, terminal A 201 (A) ends the packet reception process in this slot. On the other hand, if it is a sub-frame, the hardware for receiving the packet is turned on, and the packet is received on the assigned channel (430).

  In the first embodiment, channel sets can be assigned for both frequency and time.

  FIG. 21 is a channel schedule table when channel sets are allocated for frequency and time in the first embodiment, where the vertical axis represents time and the horizontal axis represents frequency.

  When the base station 200 and the terminal A 201 (A) perform low-rate communication, the base station 200 allocates the carriers F6 to F8 and the channel sets 103 of the times S2 and S3 to the terminal A201 (A).

  Thereafter, the base station 200 transmits a packet to the terminal A 201 (A) using the assigned channel set in the same manner as described above. Specifically, in the first frame, base station 200 transmits a packet to terminal A 201 (A) using the channel in slot S2 of carrier F6 and the channel in slot S3 of carrier F8. In the next frame, base station 200 transmits a packet to terminal A201 (A) using the channel in slot S2 of carrier F7 and the channel in slot S3 of carrier F6.

  As described above, in the first embodiment, since channel sets are allocated for frequency and / or time, terminal A 201 (A) receives only from slots that may receive packets. The terminal A201 (A) can reduce power consumption.

  Conventionally, even when the terminal A 201 (A) performs low-rate communication, there is a possibility that packets are communicated with all the carriers F1 to F8. Therefore, the terminal A 201 (A) has to perform propagation path condition estimation (301) and transmission of propagation path information (302) for all carriers.

  On the other hand, according to the first embodiment, propagation path state estimation 301 and propagation path information transmission 302 are performed only for the carriers F6 to F8 included in the assigned subband 101. If the number of carriers on which the propagation path state estimation (301) or the like is performed is small, it is possible to reduce the power consumption required for receiving the pilot signal, the propagation path state estimation (301), or the like.

  Furthermore, if the number of carriers for transmitting propagation path information (302) is small, the amount of propagation path information data to be transmitted to the base station is reduced, and the processing amount and power consumption for transmitting these data can be reduced.

  Also, the power consumption of the terminal A 201 (A) is smaller than when the frequency of the carrier scheduled for the terminal A is discontinuous (FIG. 31).

  That is, when the terminal A 201 (A) estimates the channel conditions of a plurality of carriers (301), the AD converter that can handle the sample clock that covers the frequencies of all the carriers that may receive the packet 220 is required. Here, the AD converter 220 increases power consumption as the width of the sample clock increases.

  Then, even if the number of assigned carriers is the same, if the frequency of the carrier scheduled for terminal A is discontinuous as in the prior art (FIG. 31), terminal A 201 (A) uses it. Since the carrier frequency is wide, the width of the sample clock is large, and the effect of reducing power consumption is small. On the other hand, in the present embodiment, terminal A 201 (A) is assigned a carrier having continuous frequencies, so that the width of the sample clock of AD converter 220 can be minimized. Therefore, terminal A 201 (A) in this embodiment has low power consumption.

  Further, in the first embodiment, since channel sets are allocated with respect to time, terminal A 201 (A) limits channels that may receive packets to a specific slot. What is necessary is just to perform propagation path condition estimation (301) and transmission of propagation path information (302). Therefore, the terminal A 201 (A) can reduce power consumption.

  FIG. 22 is a graph showing the propagation path condition of the carrier according to the first embodiment, where the horizontal axis represents time and the vertical axis represents the propagation path condition.

  In wireless communication, the larger the value of the propagation path condition S / (I + N), the higher the rate of carrier utilization, because the signal can be transmitted with a high rate coding rate or a large multi-level modulation. The propagation path condition S / (I + N) changes with time in accordance with the movement of the terminal 201 and the change in environment, and the change is independent at each terminal 201.

  FIG. 22A is a graph showing carrier propagation path conditions when three terminals A 201 (A), B 201 (B), and C 201 (C) communicate with the base station 200. The base station 200 selects the terminal 201 having the highest propagation path condition S / (I + N) reported from the three terminals 201 and causes the terminal 201 to use the carrier.

  FIG. 22 (b) is a graph showing the propagation path status of carriers when two terminals A201 (A) and B201 (B) communicate with the base station 200, and FIG. 22 (c) shows one terminal. It is a graph showing the propagation path condition of a carrier in case A201 (A) communicates with the base station 200. FIG.

  Comparing these figures, the propagation path condition S / (I + N) of the carrier increases as the number of terminals 201 increases, and a user diversity effect occurs, and the carrier utilization efficiency increases.

  In the first embodiment, the base station 200 increases the carrier utilization efficiency by assigning the same carrier to a plurality of terminals 201.

  Next, a second embodiment of the present invention will be described.

  FIG. 23 is a sequence diagram illustrating packet scheduling processing according to the second embodiment, which is executed in step 300 of channel set allocation processing (FIG. 5).

  The packet scheduling process of the second embodiment differs from the packet scheduling process of the first embodiment (FIG. 6) in that the base station 200 notifies the terminal A 201 (A) of the scheduling result (305) and The step (306) in which the terminal A 201 (A) receives the scheduling result is not executed. The other steps are the same as the packet scheduling for notifying the scheduling result. In addition, the same step attaches | subjects the same code | symbol and the description is abbreviate | omitted.

  However, unlike the case where terminal A 201 (A) notifies the result of scheduling, the packet addressed to terminal A 201 (A) is transmitted while waiting for reception on a channel that may always receive a packet. Monitor whether or not.

  That is, in the method of not reporting the scheduling result of the second embodiment, terminal A 201 (A) always waits for reception, and therefore consumes power compared to the method of notifying the scheduling result.

  However, for example, when the carrier frequency is 2 GHz and the moving speed is 60 km / h, the propagation path state fluctuates at about 1110 Hz. For this reason, scheduling needs to be performed every several ms, and it is technically difficult to notify the terminal 201 of the scheduling result in advance. Therefore, the third generation portable cdma2000 1xEV-DO and W-CDMA HSDPA employ packet scheduling that does not notify the scheduling result.

  FIG. 24 is a channel timing chart of the second embodiment. The hatched portion in the figure indicates the timing at which communication between the base station 200 and the terminal A 201 (A) is performed.

  The base station 200 transmits a pilot signal to the communication area (500). Terminal A 201 (A) receives the pilot signal and estimates the propagation path condition from the received pilot signal. Terminal A 201 (A) then transmits the estimation result (propagation path information) of the propagation path condition to the base station 200 in the next slot that has received the pilot signal (501).

  The base station 200 receives the propagation path information and performs scheduling. Then, when scheduling is performed for the terminal A 201 (A), the base station 200 transmits data to the terminal A 201 (A) in the next slot that has received the propagation path information (503).

  FIG. 25 is a channel timing chart in the case where the scheduling result is not notified when the channel set is allocated with respect to time in the second embodiment. A portion surrounded by a thick line is a slot in which the base station 200 and the terminal A 201 (A) are associated with each other. A hatched portion is a slot 514 in which the base station 200 transmits a packet to the terminal A 201 (A).

  Terminal A 201 (A) receives a packet only in subframe 513 because the channel set has been assigned for the time. Therefore, terminal A 201 (A) estimates the propagation path condition using pilot signal 510 that is a predetermined number of slots (two slots) ahead of subframe 513.

  Terminal A 201 (A) transmits the estimation result (propagation channel information) of the channel condition in the next slot that has received the pilot signal to base station 200 (511). Since the base station 200 does not need to notify the terminal A 201 (A) of the scheduling result, the base station 200 performs scheduling for the next slot 513 of the received propagation path information. Then, the base station 200 transmits the packet to the terminal A 201 (A) according to the scheduling (514).

  If the scheduling result is not notified, the terminal A 201 (A) conventionally cannot know when the packet is received, so it is necessary to wait for reception in all slots.

  As described above, according to the second embodiment, the base station 200 assigns a channel set of subframes (frames composed of temporally continuous slots) to the terminal 201 (A), whereby the terminal A201 ( A) need only receive the slots of the assigned channel set. Thus, the terminal A 201 (A) can save processing for reception and power consumption.

  Next, a third embodiment of the present invention will be described.

  FIG. 26 is a block diagram of the base station 200 according to the third embodiment.

  In the third embodiment, the base station 200 differs from the base station 200 of the first embodiment shown in FIG. 2 in that the reception capability information of the terminal is transmitted from the network to the channel condition control unit 210.

  When the signal from the network is the reception capability information of the terminal 201, the network interface unit 211 transmits the information to the channel condition control unit 210. Other configurations of the base station 200 in this modification are the same as those of the base station 200 of the first embodiment. Therefore, the same reference numerals are given to the same components, and description thereof is omitted.

  FIG. 27 is a sequence diagram of a channel set according to the third embodiment, and the base station 200 receives a notification of the reception capability of the terminal A 201 (A) from the base station control device.

  First, the terminal A 201 (A) transmits a control signal including ID, location registration, and the like (317). Base station 200 receives the control signal from terminal A 201 (A). Then, the received control signal is transferred to the base station controller (318).

  The base station control apparatus receives the control signal of the terminal A201 (A) (319). The base station control device searches the reception capability information stored in the storage means using the ID of the terminal added to the received control signal, and examines the reception capability of the terminal A 201 (A). Then, the base station controller notifies the base station 200 of the acquired reception capability (320).

  The base station 200 receives the reception capability of the terminal A 201 (A) (321), and allocates a channel set so as to satisfy the reception capability (322). The base station 200 notifies the terminal A 201 (A) of the allocated channel set using the control channel (323). The base station 200 performs scheduling only for the assigned channel set (300).

  Upon receiving the notification of the channel set (324), the terminal 201 monitors only the assigned channel set and receives a packet from the base station 200 in the subsequent communication.

  Next, a fourth embodiment of the present invention will be described.

  FIG. 28 is a block diagram of the terminal 201 of the fourth embodiment, and shows a case where the communication system is the OFDMA system.

  The terminal 201 in the case of the OFDMA system is different in that it includes an FFT unit 232 in place of the filter bank 221 of the FDMA system terminal 201 (FIG. 3) of the first embodiment described above. The FFT unit 232 separates the signal for each subcarrier by Fourier transform calculation.

  The rest of the configuration is the same as that of the FDMA terminal 201 of the first embodiment. The same components as those of the FDMA terminal 201 (FIG. 3) are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 29 shows a spectrum in the process of extracting a signal of a specific carrier according to the fourth embodiment, and shows a case where the communication system is the OFDMA system.

  The antenna 233 receives a signal having a spectrum as shown in FIG. In the OFDMA signal, signals for each subcarrier partially overlap each other.

  From this signal, a part required by the terminal 201 is extracted by a filter 219 represented by a thick line in FIG. Filter 219 extracts the signal to include the assigned channel set. Therefore, the output of the filter 219 is a wideband signal including a plurality of subcarriers (for example, a band signal including seven subcarriers in this embodiment).

  The signal extracted by the filter is shown in FIG. The FFT 232 separates the signal for each subcarrier. The spectrum of one of the separated subcarrier signals is shown in FIG. In the OFDMA scheme, one channel may be configured from one subcarrier, or one channel may be configured from a plurality of subcarriers.

  The following are typical examples of aspects of the present invention other than those described in the claims.

  (1) In a wireless communication method in which a base station and a plurality of terminals communicate with each other using a slot divided in a time band as a channel for a carrier divided in a frequency band, the base station transmits a plurality of continuous A radio communication method comprising: allocating a channel set composed of the carrier and / or a channel set composed of a plurality of consecutive slots, and allocating a channel included in the channel set to transmission of a packet to the terminal.

  (2) The radio communication according to (1), wherein the base station assigns the channel to transmission of a packet to the terminal by using a channel state estimation result received from the terminal. Method.

  (3) The radio communication method according to (1), wherein the base station notifies the terminal of the channel set.

  (4) The wireless communication method according to (3), wherein the terminal receives a notification of the channel set and determines a channel to be monitored by the channel set.

  (5) The radio communication method according to (1), wherein the base station receives the reception capability of the terminal and allocates the channel set so as to satisfy the reception capability.

  (6) The radio communication method according to (1), wherein the base station calculates a deviation of the channel and reassigns the channel set when the deviation is larger than a predetermined value.

  (7) The radio communication method according to (1), wherein the base station receives the reception capability of the terminal from a base station controller that stores the reception capability of the terminal.

  (8) An information storage unit that stores information to be transmitted to the terminal, a scheduler that determines the terminal that transmits information, a modulation unit that modulates information to be transmitted, and a transmission unit that transmits a modulated signal In a radio communication base station that communicates with a plurality of the terminals using channels divided in time bands for carriers divided in frequency bands, the reception capability of the terminals is acquired and the reception capability of the terminals is satisfied A wireless communication base station comprising a channel condition unit that allocates a channel set composed of a plurality of continuous carriers and / or a channel set composed of a plurality of continuous slots and stores the allocated channel sets.

  (9) The radio communication base station according to (8), further comprising a receiving unit that receives a signal from a terminal, wherein the receiving unit acquires the reception capability from a signal received from the terminal.

  (10) The radio communication base station according to (8), further comprising: a reception unit that receives a signal from a terminal, wherein the reception capability is acquired from a base station controller that stores the reception capability of the terminal.

  (11) The radio communication base station according to (8), wherein the scheduler assigns the channel included in the channel set to transmission of a packet to the terminal.

  (12) The radio communication base station according to (8), further comprising a control signal generation unit that generates a signal for notifying the terminal of the channel set.

  (13) A radio receiving unit including a filter that extracts a signal of a specific frequency from a signal received by an antenna, an A / D converter that digitally converts the signal, and a base that separates and demodulates the signal for each frequency A wireless communication terminal comprising a band unit and a control unit for controlling the overall operation of the wireless communication terminal, wherein the carrier divided by the frequency band uses a slot divided by the time band as a channel to communicate with the base station. The receiving unit receives, from the base station, a channel set consisting of a plurality of assigned continuous carriers and / or a channel set consisting of a plurality of continuous slots, and notifies the control unit of the received channel set, The control unit changes a frequency width or a center frequency extracted by the filter according to the channel set. Wireless communication terminals that butterflies.

  (14) A radio transmission unit that modulates information transmitted to a base station and transmits a signal is provided, the control unit creates a capability control signal that notifies reception capability, and the radio transmission unit The radio communication terminal according to (13), wherein the capability control signal is transmitted to a station.

  (15) The control unit according to (13), wherein the control unit controls the reception unit to operate in a channel included in the channel set and pauses the reception unit in a channel not included in the channel set. The wireless communication terminal described.

(16) A wireless reception unit including a filter that extracts a signal of a specific frequency from a signal received by the antenna, and an A / D converter that digitally converts the signal;
A baseband unit that separates and demodulates the signal for each frequency;
A control unit for controlling the overall operation of the wireless communication terminal;
In a wireless communication terminal that communicates with a base station using each channel obtained by dividing each frame of a time band into a plurality of slots for each of a plurality of carriers divided by a frequency band,
The radio reception unit receives a notification from the base station that assignment has been determined for a channel set in a subframe limited to some slots that are continuous on the time axis of the plurality of slots,
In response to the wireless reception unit receiving the notification, the control unit causes the reception unit to operate in the some slots corresponding to the channel set in each frame of the time band. A radio terminal apparatus, wherein the receiving unit is controlled to pause in another slot.

  The present invention can be applied to carrier scheduling in a mobile communication system, and is preferably applied to a system in which high-speed and low-speed terminals are mixed. Further, although the FDMA and OFDMA systems have been described in the above-described embodiments, the present invention can also be applied to other multiplexing systems.

200 Base station 201 (A) Terminal A
201 (B) Terminal B
201 (C) Terminal C
201 (D) Terminal D
201 (E) Terminal E
207 antenna 208 circulator 209 reception unit 210 channel condition unit 211 network interface unit 212 information storage unit 213 scheduler 214 modulator 215 transmission unit 216 control signal generation unit 217 circulator 218 radio reception unit 219 filter 220 A / D converter 221 filter bank 222 Demodulator 223 selection unit 224 propagation path estimation unit 225 CPU
226 Modulation unit 227 D / A converter 228 Wireless transmission unit 233 Antenna

Claims (3)

A wireless communication method in which a base station and a plurality of terminals communicate with each other using a slot divided in a time band as a channel for a plurality of carriers divided in a frequency band,
The base station notifies the terminal of monitoring information designating a channel including at least one of the carrier and the slot as a monitoring range;
The terminal receives the monitoring information;
The terminal controls whether to perform reception processing of a signal corresponding to the monitoring range or to stop the reception processing based on whether or not the monitoring range is included in the received monitoring information,
The terminal transmits an estimation result of a propagation path condition based on the signal in the monitoring range to the base station,
The base station allocates a channel including at least one of a carrier and a slot to perform packet transmission based on the estimation result,
The wireless communication method, wherein the base station performs packet transmission to the terminal using the allocated channel. The wireless communication method according to claim 1,
The radio communication method, wherein the terminal starts signal reception processing for a channel in the monitoring range and stops reception processing for a channel outside the monitoring range according to the one monitoring information. . A wireless communication method in which a base station and a plurality of terminals communicate using a plurality of carriers divided in a frequency band,
The base station notifies the terminal of monitoring information designating at least one of the carriers as a monitoring range,
The terminal receives the monitoring information;
The terminal controls whether to perform reception processing of a signal corresponding to the monitoring range or to stop the reception processing based on whether or not the monitoring range is included in the received monitoring information,
The terminal transmits an estimation result of a propagation path condition based on the signal in the monitoring range to the base station,
The base station allocates a carrier on which to perform packet transmission based on the estimation result,
The wireless communication method, wherein the base station performs packet transmission to the terminal using the allocated carrier.