JP7611518B2 - Base station, control station, timing shift amount measuring device, and communication method - Google Patents

Description

This disclosure relates to a base station, a control station, a timing shift amount measuring device, and a communication method.

Self-operated LTE systems, where companies and other organizations introduce LTE (Long Term Evolution) for their own networks, are attracting attention. Self-operated LTE systems are also called private LTE systems. Such self-operated LTE systems are also expected to be an alternative to existing self-operated PHS (Personal Handy-phone System) systems. This PHS system is based on the TDD (Time Division Duplex) system.

A system based on the TD-LTE (Time Division-LTE) standard, sXGP (shared extended Global Platform) was institutionalized in Japan in 2017 as a license-free private LTE system. Unlike the PHS system, which is primarily used for voice calls, the sXGP system allows data communication in addition to voice calls, so it can be used with ordinary smartphones. The frequency band used by the sXGP system is the same 1.9 GHz band as "Band 39," which is internationally defined for LTE, and overlaps with part of the frequency band used by the PHS system.

When an existing private PHS system is large-scale, it is difficult to replace the entire in-house telephone network from a private PHS system to a private sXGP system at once, so the scope of replacement is limited and the PHS system is replaced with the sXGP system in sequence. In order to ensure business continuity until the system switchover is complete, it is necessary to share the PHS network and the sXGP network for a certain period of time. However, because the sXGP system uses a frequency band that overlaps with the PHS system, mutual interference makes it difficult to share and operate the sXGP system and the PHS system in the same area.

In prior art document 1, interference is reduced by utilizing the guard period (GP) in a special subframe in the TD-LTE frame format to align the timing of the downlink (DL) and uplink (UL) of TD-LTE and PHS.

Furthermore, in prior art document 1, interference is reduced by halting data transmission in the downlink subframe of the TD-LTE system that corresponds to the downlink slot in which the control channel required for the operation of the PHS system (hereinafter referred to as the "PHS control channel") is transmitted.

JP 2018-19233 A

The PHS control channel is transmitted in a specific time slot on two channels, and the two channels interfere with a part of the frequency band of the TD-LTE (sXGP) system. Therefore, if the transmission of a specific subframe of the TD-LTE system is stopped in all frequency bands as in Patent Document 1, the transmission in the frequency band (in other words, resource block) of the sXGP system that does not interfere with the PHS control channel will also be stopped, resulting in poor resource utilization efficiency.

Non-limiting examples of the present disclosure contribute to providing technology that reduces mutual interference while improving resource utilization efficiency.

A base station in the present disclosure is a base station of a second communication system using a second communication method that uses a second frequency band that is common to a part of a first frequency band used in a first communication method used in a first communication system, and includes an estimation unit that estimates timing of a slot of a downlink control channel transmitted from a base station of the first communication system at a predetermined channel frequency and a predetermined period, a scheduling unit that performs scheduling to allocate data to a resource block that does not overlap with the predetermined channel frequency in resources of the second communication method that correspond on the time axis to the estimated timing of the slot of the downlink control channel, and a transmitting/receiving unit that performs transmission and reception based on the scheduling.
Equipped with:

These comprehensive or specific aspects may be realized as a system, device, method, integrated circuit, computer program, or recording medium, or as any combination of a system, device, method, integrated circuit, computer program, and recording medium.

According to the present invention, when two systems that share part of the frequency band, such as an sXGP system and a PHS system, coexist, it is possible to suppress mutual interference while improving resource utilization efficiency.

Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and/or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them need be provided to obtain one or more identical features.

FIG. 1 is a diagram showing the relationship between the frequency band used by the PHS system and the frequency band used by the sXGP system. FIG. 1 is a diagram showing the transmission power of PHS control channels transmitted by a plurality of PHS base stations according to the first embodiment of the present disclosure. FIG. 1 is a diagram for explaining a method of combining the received power of a PHS control channel in a TD-LTE base station according to a first embodiment of the present disclosure. FIG. 1 is a diagram showing data allocation in a TD-LTE base station according to a first embodiment of the present disclosure. FIG. 1 is a diagram showing a flow of operations of a TD-LTE base station according to a first embodiment of the present disclosure. FIG. 1 is a diagram showing a configuration of a TD-LTE base station according to a first embodiment of the present disclosure. FIG. 13 is a diagram showing a method for detecting slot timing of a PHS control channel in a TD-LTE base station according to a second embodiment of the present disclosure. FIG. 13 is a diagram showing a method for detecting frame timing of a PHS in a control server according to a second embodiment of the present disclosure. FIG. 11 is a sequence diagram showing operations between a TD-LTE base station and a control server according to a second embodiment of the present disclosure. FIG. 1 is a diagram showing a configuration of a TD-LTE base station according to a second embodiment of the present disclosure. FIG. 13 is a configuration diagram of a control server according to a second embodiment of the present disclosure. FIG. 13 is a diagram showing a method for notifying a transmission timing shift amount by a base station equipped with a PHS control channel receiver according to a third embodiment of the present disclosure. FIG. 11 is a sequence diagram showing operations between a base station according to a third embodiment of the present disclosure, a base station equipped with a PHS control channel receiver, and a control server. FIG. 1 is a block diagram of a base station equipped with a PHS control channel receiver according to a third embodiment of the present disclosure. FIG. 13 is a configuration diagram of a control server when using a base station equipped with a PHS control channel receiver according to a third embodiment of the present disclosure. FIG. 13 is a diagram showing a method for notifying an amount of transmission timing shift by a timing shift amount measuring device of TD-LTE according to embodiment 4 of the present disclosure. FIG. 13 is a sequence diagram showing operations between a timing shift amount measuring device, a base station, and a control server according to a fourth embodiment of the present disclosure. 1 is a block diagram of a base station according to a fourth embodiment of the present disclosure. FIG. 13 is a configuration diagram of a timing shift amount measuring device according to a fourth embodiment of the present disclosure. FIG. 13 is a diagram showing an example of residual interference from a TD-LTE system to a PHS system according to a fifth embodiment of the present disclosure. FIG. 13 is a diagram showing residual interference to a PHS terminal directly under a TD-LTE base station according to a fifth embodiment of the present disclosure. FIG. 13 is a diagram showing an effect of reducing interference by reducing the transmission power of a TD-LTE base station according to a fifth embodiment of the present disclosure. FIG. 13 is a diagram showing the received power after combining the control channels of the PHS measured at the TD-LTE base station according to the fifth embodiment of the present disclosure. FIG. 13 is a configuration diagram of a base station according to a fifth embodiment of the present disclosure. 13 is a flow diagram of an operation of a base station according to a fifth embodiment of the present disclosure.

Below, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easier for those skilled in the art to understand.

The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

Figure 1 is a diagram showing the relationship between the frequency bands used by the PHS system and the sXGP system. As shown in Figure 1, the frequency band 101 of the PHS system ranges from 1893.5 MHz (102) to 1906.1 MHz (103). The PHS control channel is transmitted using the 12th channel (CH12) and the 18th channel (CH18). Specifically, the PHS control channel uses CH12 with a frequency of 1898.45 MHz (A) and CH18 with a frequency of 1900.25 MHz (B). On the other hand, the 5 MHz system of the sXGP system uses a frequency band 104 with a center frequency of 1899.1 MHz and a bandwidth of 5.0 MHz. In this way, the frequencies of CH12 and CH18 used in the PHS control channel overlap with the frequency band of the sXGP system. This causes mutual interference at the timing and frequency at which the PHS control channels are transmitted.

In wireless communication using the TD-LTE system (sXGP system), an LTE radio frame (RF: Radio Frame) having a predetermined period (Tf = 10 ms), which is one unit on the time axis, is composed of 10 divided 1 ms subframes (SF: Subframes). One subframe (SF) is composed of two divided time slots (TS: Time Slots). That is, one LTE radio frame is composed of 10 subframes (in other words, 20 time slots). In LTE, a portion surrounded by 12 subcarriers on the frequency axis (subcarrier interval is 15 kHz in Release 8) and one slot on the time axis is called a resource block (RB: Resource Block), and allocation (scheduling) to users is performed in units of nRBs (n is an integer that differs depending on the band) that are continuous in time.

The PHS radio frame (RF) of a given period (Tf = 5 ms), which is one unit on the time axis in PHS-based wireless communication, is composed of eight 0.625 ms time slots (TS).

(Embodiment 1)
The first embodiment of the present disclosure will be described with reference to FIGS.

Figures 2A and 2B are diagrams showing a method for estimating the transmission timing of a PHS control channel on a downlink according to embodiment 1 of the present disclosure. More specifically, Figure 2A is a diagram showing the transmission power of PHS control channels transmitted by multiple PHS base stations according to embodiment 1 of the present disclosure. Figure 2A shows, as an example, three TD-LTE base stations 201, 203, and 205 and three PHS base stations 202, 204, and 206.

Note that "TD-LTE base station" may be interchangeably replaced with other terms such as "base station" or "sXGP base station."

As shown in the graph in box 211 of FIG. 2A, PHS base station 202 transmits the PHS control channel in one specific slot every period T (e.g., superframe = 125 ms). Similarly, PHS base station 204 transmits the PHS control channel every period T, as shown in the graph in box 212 of FIG. 2A. Also, PHS base station 206 transmits the PHS control channel every period T, as shown in the graph in box 213 of FIG. 2A. Note that the vertical axis of each graph in FIG. 2A is the transmission power of the PHS control channel of each PHS base station 202, 204, 206, and the horizontal axis is time. Also, the transmission power shown in FIG. 2A represents the transmission power of the PHS control channel in one of the two PHS transmission channels (i.e., CH12 and CH18).

Figure 2B is a diagram for explaining a method of combining the received power of the PHS control channel in a TD-LTE base station according to embodiment 1 of the present disclosure. Figure 2B shows a method of combining the received power of the PHS control channel in TD-LTE base station 205, one of the three TD-LTE base stations 201, 203, and 205 shown in Figure 2A.

To know the transmission timing of the PHS control channel of the PHS base station, the TD-LTE base station 205 divides the two specified frequencies of the PHS control channel (hereinafter also referred to as "PHS control channel frequencies") into fixed periods as shown in box 250 in Figure 2B, synthesizes the received power according to the start timing, and estimates the transmission timing of the signal whose combined signal power is equal to or greater than a threshold as the slot timing (transmission period) of the PHS downlink control channel.

Specifically, the TD-LTE base station 205 measures the received power of the PHS control channel every period T, as shown in the upper diagram in box 250. In the example of this diagram, the received power of the PHS control channel is measured in each of four periods T (261, 262, 263, 264).

By setting this fixed period to an integer multiple of the transmission period of the PHS control channel (in the example of FIG. 2B, twice (2T)), it becomes easy to exclude non-periodic noise. Specifically, in the upper diagram of FIG. 2B, when the received power is synthesized every two periods (2T) (2T (271), 2T (272)), a graph is created in which the vertical axis is the synthesized received power (273) and the horizontal axis is time (283), as shown in the lower diagram of FIG. 2B. In this diagram, the received power portion less than a predetermined threshold (284) is assumed to be noise, so it does not need to be included in the estimation of this slot timing. In the example of FIG. 2B, the received power portion indicated by 282 is excluded from the estimation of the slot timing as noise. In addition, the non-periodic received power portion (281) in the synthesized received power (273) is also assumed to be noise, so it is excluded from the estimation of the slot timing. Then, the TD-LTE base station 205 estimates the reception timing of the portion of the received power that is equal to or greater than a predetermined threshold and has periodicity as the slot timing of the PHS control channel.

Note that TD-LTE base stations 201 and 203 also estimate the slot timing of the downlink PHS control channel, just like TD-LTE base station 205.

As mentioned above, the PHS control channel on the downlink is transmitted at a predetermined cycle, but unlike the PHS control channel on the downlink, the PHS control channel on the uplink is not transmitted at a predetermined cycle. Also, because the PHS terminal is farther from the TD-LTE base station than the PHS base station, the received power of the PHS control channel is small. For these reasons, even if the received power of the PHS control channels on the uplink is combined, the combined received power is less than a predetermined threshold, and the slot timing cannot be estimated.

It is also possible to estimate slot timing by performing a threshold judgment on a single received power without combining the received power of the uplink control channels as described above, but this would result in lower accuracy in estimating the slot timing.

In this embodiment, since the control channel of the PHS uplink line is transmitted a predetermined number of slots after the slot timing of the downlink control channel at the same two predetermined frequencies as the downlink line, the slot timing of the uplink control channel is estimated based on the estimated slot timing of the downlink control channel.

Figure 3 is a diagram showing data allocation in a TD-LTE base station according to embodiment 1 of the present disclosure. As shown in Figure 3, the TD-LTE base station performs scheduling that does not allocate data for the downlink or uplink to the estimated slot timing of the PHS control channel for the downlink and uplink, and to frequency resources (in other words, CH12 and CH18) that overlap with the specified frequency of the PHS control channel.

Specifically, in a graph shown in FIG. 3, in which the combined power 301 in the PHS control channel (CH18) is plotted on the vertical axis and time on the horizontal axis, the received power of some PHS control channels exceeds threshold 302. The TD-LTE base station does not assign downlink data to resources (resource blocks) corresponding to the frequency of the PHS control channel in slots in which the combined received power 301 of the PHS control channel exceeds threshold 302. In FIG. 3, resources 311 in CH18 to which downlink data is not assigned based on the estimation for CH18 are shown, and it can be seen that they are synchronized with the combined power in the PHS control channel that exceeds threshold 302. Note that a similar estimation may be performed for CH12, and scheduling may be performed in which downlink data is not assigned, as shown by resource 311 in CH12 in FIG. 3.

For the uplink, the TD-LTE base station does not allocate uplink data to resources (subframes) corresponding to slots a predetermined number after resources to which downlink data has not been allocated. Figure 3 shows resource 312 to which uplink data is not allocated. As shown in Figure 3, it can be seen that the transmission slot of the PHS control channel on the uplink is delayed a predetermined number of slots from the transmission slot of the PHS control channel on the downlink.

In this manner, in this embodiment, the TD-LTE base station avoids allocating downlink and uplink data for both PHS control channels, CH18 and CH12, at the slot timing of the PHS control channel. In addition, for channels other than CH18 and CH12, the TD-LTE base station allocates downlink and uplink data even at the slot timing of the PHS control channel.

In order to improve the resource utilization efficiency of the TD-LTE base station, the slot timing of the PHS control channel may be scheduled to avoid allocation to only frequency resources that overlap with the frequency of one of the two PHS control channels (i.e., CH12 or CH18).

Figure 4 is a diagram showing the flow of operation of a TD-LTE base station according to embodiment 1 of the present disclosure. First, the TD-LTE base station measures the received power at the PHS control channel frequency (ST401).

Next, the TD-LTE base station combines the multiple measured received powers (ST402).

Next, the TD-LTE base station estimates the transmission timing of the PHS control channel on the downlink based on the combined received power (ST403).

Next, the TD-LTE base station estimates the transmission timing of the PHS control channel on the uplink based on the estimated transmission timing of the PHS control channel on the downlink (ST404).

Next, the TD-LTE base station schedules the TD-LTE uplink and downlink based on the estimated transmission timing of the PHS control channel (ST405).

Figure 5 is a configuration diagram of a TD-LTE base station according to the first embodiment of the present disclosure. The TD-LTE base station 201 includes an antenna 501, a transceiver unit 502, a received power measurement unit 503, a received power synthesis unit 504, a PHS control channel timing estimation unit 505, a scheduling unit 506, and a data processing unit 507.

The transceiver unit 502 transmits and receives signals at the PHS control channel frequency via the antenna 501. The received power measurement unit 503 measures the received power of the signal received by the transceiver unit 502.

The received power synthesis unit 504 synthesizes the received power of signals at multiple PHS control channel frequencies received from the received power measurement unit 503.

The PHS control channel timing estimation unit 505 estimates the timing of the PHS control channel based on the magnitude relationship between the combined received power received from the received power combination unit 504 and a threshold value.

The scheduling unit 506 performs TD-LTE transmission scheduling based on the estimated PHS control channel timing received from the PHS control channel timing estimation unit 505 and the data received from the data processing unit 507.

As described above, according to the first embodiment, in the resources corresponding to the slot timing of the PHS control channel, by performing scheduling such that data is not assigned to resources that overlap with the PHS control channel, and data is assigned to resources that do not overlap with the PHS control channel, it is possible to suppress mutual interference while improving utilization efficiency. Also, by using the received power of the PHS control channel signal, it is possible to estimate the transmission timing of the PHS control channel without using a receiver for the PHS control channel. It is also possible to avoid interference not only with the PHS control channel on the downlink but also with the PHS control channel on the uplink.

(Embodiment 2)
A second embodiment according to the present disclosure will be described with reference to FIGS.

Figure 6 is a diagram showing a method for detecting the slot timing of the PHS control channel in a TD-LTE base station according to embodiment 2 of the present disclosure. The configuration of embodiment 1 described above makes it possible to schedule the TD-LTE data channel using the slot timing of the PHS control channel, avoiding the allocation of data on the downlink and uplink. However, in order to actually transmit and receive data between a TD-LTE base station and a terminal, it is more preferable to synchronize the timing between the PHS base station and the TD-LTE base station. To do this, it is necessary to estimate the frame timing of the PHS.

As shown in FIG. 6, the TD-LTE base station synchronizes between base stations using location information such as GPS (Global Positioning System). Next, the received PHS control channel is divided into sections of 10 ms of TD-LTE radio frames (sections separated by vertical dashed lines of the combined received power 601 shown in FIG. 6). The TD-LTE base station then further combines radio frames including PHS control channels having combined received power exceeding threshold 602 (dotted line) as obtained in the first embodiment to generate combined received power 604, and creates a combined radio frame 605 with a period of 10 ms.

Figure 7 is a diagram showing a method for detecting PHS frame timing in a control server according to embodiment 2 of the present disclosure. Figure 7 shows one control server 701, four TD-LTE base stations 721, 723, 725, and 727, and four PHS base stations 722, 724, 726, and 728. The control server 701 is also called a control station.

As shown in FIG. 7, each TD-LTE base station 721, 723, 725, 727 notifies the control server 701 connected by a LAN or the like of power information (711, 712, 713, 714) indicating the received power synthesized on a radio frame basis. Next, the control server 701 further synthesizes the received power synthesized on a radio frame basis at each TD-LTE base station to detect the time for all four slots for the PHS downlink (702) and estimates that the first downlink slot is the PHS frame start 703. This allows the control server 701 to detect how much the PHS frame timing is shifted from the TD-LTE radio frame timing. Next, the control server 701 notifies each TD-LTE base station 721, 723, 725, 727 of the amount of shift in the transmission timing on the TD-LTE side. This enables timing synchronization between PHS base stations 722, 724, 726, and 728 and TD-LTE base stations 721, 723, 725, and 727.

FIG. 8 is a sequence diagram showing the operation between the TD-LTE base station 721 and the control server 701 shown in FIG.

As shown in FIG. 8, the TD-LTE base station 721 measures the received power of a signal at the PHS control channel frequency (ST801). Next, the measured received power is combined based on the TD-LTE radio frame timing (ST802).

Next, each TD-LTE base station 721 transmits power information indicating the combined received power to the control server 701 (ST803).

Next, the control server 701 combines the power information received from each TD-LTE base station based on the TD-LTE radio frame timing (ST804).

Next, the control server 701 estimates the PHS frame timing based on the combined power information (ST805). Next, the control server 701 calculates the amount of timing shift for TD-LTE based on the estimated PHS frame timing (ST806) and transmits the amount of timing shift to each TD-LTE base station 721 (ST807).

Next, each TD-LTE base station 721 shifts the transmission timing based on the timing shift amount received from the control server 701 (ST808).

Figure 9 is a diagram showing the configuration of a TD-LTE base station according to embodiment 2 of the present disclosure.

The TD-LTE base station 721 includes an antenna 901, a transceiver unit 902, a received power measurement unit 903, a received signal synthesis unit 904, a network unit 905, and a frame timing control unit 906.

The transmitting/receiving unit 902 transmits and receives signals at the PHS control channel frequency via the antenna 901. The received power measuring unit 903 measures the power of radio waves (wireless signals) received by the transmitting/receiving unit 902. The received signal combining unit 904 combines the received power based on the TD-LTE radio frame timing to generate power information. The network unit 905 transmits the power information generated by the received signal combining unit 904 to the control server 701. The frame timing control unit 906 shifts the transmission timing of the base station 721 based on the amount of timing shift received from the control server 701 via the network unit 905.

Figure 10 is a configuration diagram of a control server according to the second embodiment of the present disclosure. The control server 701 includes a network unit 1001, a PHS frame timing detection unit 1002, and a timing shift amount calculation unit 1003.

The network unit 1001 receives power information from each TD-LTE base station via the network. The PHS frame timing detection unit 1002 receives power information from the network unit 1001, synthesizes multiple pieces of power information based on the TD-LTE radio frame timing, and detects the PHS frame timing. The timing shift amount calculation unit 1003 calculates the amount of TD-LTE timing shift based on the detected PHS frame timing, and transmits the amount of timing shift to each TD-LTE base station via the network unit 1001.

As described above, according to the second embodiment, it is possible to detect PHS frame timing and achieve inter-base station synchronization between a PHS base station and a TD-LTE base station without using a PHS control channel receiver.

The TD-LTE base station described in the first embodiment may include some or all of the configuration of the TD-LTE base station described in the second embodiment using FIG. 9, etc.

(Embodiment 3)
A third embodiment of the present disclosure will be described with reference to FIGS.

Figure 11 shows a method for notifying the amount of transmission timing shift by a base station equipped with a PHS control channel receiver according to embodiment 3 of the present disclosure.

In FIG. 11, a control server 1102 is connected via a network to multiple PHS base stations 1104, 1106, 1108, and 1110, and multiple TD-LTE base stations 1103, 1105, 1107, and 1109. The TD-LTE base station 1105 is a base station equipped with a PHS control channel receiver.

The base station 1105 equipped with a PHS control channel receiver receives the PHS control channel, detects the timing of the PHS frame, calculates the amount of shift in the transmission timing of the TD-LTE base station, and transmits the calculated amount of timing shift to the control server 1102. The control server 1102 transmits the amount of timing shift received from the base station 1105 equipped with a PHS control channel receiver to each of the TD-LTE base stations 1103, 1105, 1107, and 1109.

In this embodiment, as shown in FIG. 11, only one TD-LTE base station may have a PHS control channel receiver, and the other TD-LTE base stations may not have a PHS control channel receiver. The PHS control channel receiver-equipped base station 1105 may calculate the amount of shift in the TD-LTE transmission timing, and notify each base station 1103, 1105, 1107, and 1109 of the amount of timing shift via the control server 1102.

Figure 12 is a sequence diagram showing the operations between a base station, a base station equipped with a PHS control channel receiver, and a control server according to embodiment 3 of the present disclosure.

First, the base station 1105 equipped with a PHS control channel receiver receives a PHS frame on the frequency used by the PHS control channel and detects the PHS frame timing from the received PHS frame (ST1201). Next, the base station 1105 equipped with a PHS control channel receiver calculates the amount of timing shift for TD-LTE based on the detected PHS frame timing (ST1202). Next, the base station 1105 equipped with a PHS control channel receiver transmits the calculated amount of timing shift for TD-LTE to the control server 1102 (ST1203).

The control server 1102 transmits the timing shift amount received from the base station 1105 equipped with a PHS control channel receiver to the base station 1105 equipped with a PHS control channel receiver (ST1204), and similarly transmits the timing shift amount to other TD-LTE base stations 1103 (ST1205). Note that the control server does not have to transmit the timing shift amount to the base station 1105 equipped with a PHS control channel receiver.

Base station 1105 equipped with a PHS control channel receiver shifts the transmission timing of base station 1105 equipped with a PHS control channel receiver based on the amount of timing shift received from control server 1102 (ST1206). Note that base station 1105 equipped with a PHS control channel receiver may also shift the transmission timing of base station 1105 equipped with a PHS control channel receiver based on the amount of timing shift calculated by itself.

Base station 1103 shifts its transmission timing based on the amount of timing shift received from control server 1102 (ST1207).

The base station 1105 equipped with a PHS control channel receiver may notify the base station 1103 of the timing shift amount directly without going through the control server 1102. In this case, the base station 1103 may shift the transmission timing based on the timing shift amount notified without going through the control server 1102.

Figure 13 is a configuration diagram of a base station equipped with a PHS control channel receiver according to embodiment 3 of the present disclosure. The base station equipped with a PHS control channel receiver 1105 includes an antenna 1301, a transmission/reception unit 1302, a PHS frame timing detection unit 1303, a timing shift amount calculation unit 1304, a network unit 1305, and a frame timing control unit 1306.

The transmitting/receiving unit 1302 receives PHS and TD-LTE signals via the antenna 1301. The PHS frame timing detection unit 1303 receives PHS frames at the frequency of the PHS control channel received by the transmitting/receiving unit 1302, and detects the PHS frame timing based on the received PHS frame. The timing shift amount calculation unit 1304 calculates the amount of timing shift for TD-LTE based on the PHS frame timing detected by the PHS frame timing detection unit 1303. The network unit 1305 is connected to a network, and transmits the amount of timing shift calculated by the timing shift amount calculation unit 1304 to the control server 1102 or the TD-LTE base station via the network. The frame timing control unit 1306 receives the amount of timing shift via the network unit 1305, and controls the frame timing (i.e., transmission timing) of TD-LTE.

Figure 14 is a configuration diagram of a control server when using a base station equipped with a PHS control channel receiver according to embodiment 3 of the present disclosure. The control server 1102 includes a network unit 1401 and a timing shift amount determination unit 1402.

The network unit 1401 is connected to a network and transmits and receives data via the network. The timing shift amount determination unit 1402 determines the amount of timing shift for TD-LTE based on the amount of timing shift received via the network unit 1401, and transmits the amount of timing shift via the network unit 1401 to the base station 1103 and the base station 1105 equipped with a PHS control channel receiver. Here, the timing shift amount determination unit 1402 may simply notify the other base station 1103 of the amount of timing shift received from the base station 1105 equipped with a PHS control channel receiver as is, or may uniquely determine the amount of timing shift when different amounts of timing shift are notified from multiple base stations.

As explained above, according to the third embodiment, it is necessary to install a PHS control channel receiver in only one base station, and only the base station equipped with the PHS control channel receiver detects the PHS frame timing, and based on the result, inter-base station synchronization between the PHS base station and the TD-LTE base station can be achieved.

The TD-LTE base station described in the first embodiment may include some or all of the configuration of the base station equipped with the PHS control channel receiver described in the third embodiment using FIG. 13, etc.

(Embodiment 4)
A fourth embodiment of the present disclosure will be described with reference to FIGS.

Figure 15 is a diagram showing a method for notifying the amount of transmission timing shift by a timing shift amount measuring device for TD-LTE according to embodiment 4 of the present disclosure.

In FIG. 15, the control server 1502 is connected to a timing shift amount measuring device 1501, multiple PHS base stations 1504, 1506, 1508, 1510, and multiple TD-LTE base stations 1503, 1505, 1507, 1509. The timing shift amount measuring device 1501 detects the timing of the PHS frame at the PHS control channel frequency, calculates the amount of shift in the transmission timing of the TD-LTE base stations 1503, 1505, 1507, 1509, and transmits the calculated amount of timing shift to the control server 1502. The control server 1502 determines the amount of timing shift based on the amount of timing shift received from the timing shift amount measuring device 1501, and transmits the determined amount of timing shift to each of the TD-LTE base stations 1503, 1505, 1507, 1509.

As a method for calculating the amount of shift in the transmission timing of a TD-LTE base station, as shown in FIG. 15, a timing shift amount measuring device 1501, which is a device having a function for detecting the frame timing of a PHS connected via a LAN or the like, may calculate the amount of shift in the transmission timing of a TD-LTE base station and notify each TD-LTE base station 1503, 1505, 1507, and 1509 of the amount of timing shift via a control server 1502.

Figure 16 is a sequence diagram showing the operation between a timing shift amount measuring device, a base station, and a control server according to the fourth embodiment of the present disclosure. Figure 16 explains the operation of the fourth embodiment whose configuration is explained in Figure 15.

The timing shift amount measuring device 1501 receives a PHS frame at the PHS control channel frequency and detects the timing of the PHS frame (ST1601). Next, the timing shift amount measuring device 1501 calculates the amount of timing shift for TD-LTE based on the detected PHS frame timing (ST1602). Next, the timing shift amount measuring device 1501 transmits the calculated amount of timing shift to the control server 1502 (ST1603).

The control server 1502 transmits the amount of timing shift received from the timing shift amount measuring device 1501 to the base station 1503 (ST1604).

Base station 1503 shifts the transmission timing of base station 1503 based on the amount of timing shift received from control server 1502 (ST1605).

Figure 17 is a configuration diagram of a base station according to embodiment 4 of the present disclosure. Figure 17 illustrates the configuration of the TD-LTE base station 1503 according to embodiment 4 described in Figure 15. The base station 1503 includes an antenna 1701, a transceiver unit 1702, a frame timing control unit 1703, and a network unit 1704.

The transmitting/receiving unit 1702 transmits and receives signals via the antenna 1701. The frame timing control unit 1703 controls the transmission timing of the base station 1503 based on the amount of timing shift received via the transmitting/receiving unit 1702. The network unit 1704 communicates with other devices via a network.

Fig. 18 is a configuration diagram of a timing shift amount measuring device according to embodiment 4 of the present disclosure. Fig. 18 illustrates the configuration of the timing shift amount measuring device of embodiment 4 whose configuration has been explained in Fig. 15. The timing shift amount measuring device 1501 includes an antenna 1801, a transmitting/receiving unit 1802, a PHS frame timing detection unit 1803, a timing shift amount calculation unit 1804,
A network unit 1805 is provided.

The transmitting/receiving unit 1802 receives PHS frames at the PHS control channel frequency via the antenna 1801. The PHS frame timing detection unit 1803 detects the PHS frame timing based on the PHS frame received from the transmitting/receiving unit 1802. The timing shift amount calculation unit 1804 calculates the amount of timing shift for TD-LTE based on the detected PHS frame timing. The network unit 1805 transmits the calculated amount of timing shift to the control server 1502 via the network.

As explained above, according to the fourth embodiment, each base station does not need a PHS control channel receiver. By connecting a timing shift amount measuring device equipped with a PHS control channel receiver to a control server, the timing shift amount measuring device detects the PHS frame timing and calculates the timing shift amount based on the result. Then, the timing shift amount measuring device notifies the TD-LTE base station of the calculated timing shift amount via the control server, thereby realizing inter-base station synchronization between the PHS base station and the TD-LTE base station.

The TD-LTE base station described in the first embodiment may include some or all of the configuration of the TD-LTE base station described in the fourth embodiment using FIG. 17, etc.

(Embodiment 5)
A fifth embodiment of the present disclosure will be described with reference to FIGS.

Figure 19 is a diagram showing an example of residual interference from a TD-LTE system to a PHS system in embodiment 5 of the present disclosure.

In the TD-LTE frame format in the 3GPP standard, data channels that transmit and receive data for the downlink or uplink can be temporarily stopped from transmitting and receiving as described above. On the other hand, according to the 3GPP standard, the transmission of the broadcast channel that transmits system information, the synchronization channel for synchronization, the downlink control channel, and the reference signal cannot be stopped. Therefore, when a TD-LTE base station complies with the 3GPP standard, such TD-LTE control channels cannot be stopped even if the scheduling of the downlink and uplink data channels is avoided at the slot timing of the PHS control channel using the method of embodiment 1. For this reason, the transmission power of channels other than user data that cannot be stopped according to the standard, such as these TD-LTE control channels, causes interference with the PHS control channel, and further measures are required.

Referring to FIG. 19, a PHS frame 1901 includes four transmit frames Tx1, Tx2, Tx3, and Tx4 and four receive frames Rx1, Rx2, Rx3, and Rx4, and the PHS frame length 1906 is 5 ms.

When transmitting a TD-LTE frame 1904, it is possible to stop transmission of the downlink data channel 1908, which is a TD-LTE subframe consisting of a control channel 1907 and a data channel 1908. However, in compliance with the 3GPP standard, it is not possible to stop transmission of the TD-LTE control channel 1907. Therefore, residual interference 1905 may occur between the TD-LTE transmission power 1903 of the TD-LTE control channel 1907 and the PHS transmission power 1902 of Tx1 of the PHS frame 1901.

20 is a diagram showing residual interference to a PHS terminal located immediately below a TD-LTE base station according to the fourth embodiment of the present disclosure.
When the S base station 2001 is installed on the ceiling 2003 or the like away from the TD-LTE (sXGP) base station 2002, the power of the residual interference signal 2004 from the TD-LTE base station 2002 of the PHS terminal 2006 located immediately below the TD-LTE (sXGP) base station 2002 is relatively large compared to the power of the desired signal 2005 from the PHS base station. By installing the TD-LTE base station 2002 close to the PHS base station 2001, the ratio of the residual interference power to the desired signal power can be reduced. However, if the TD-LTE base station 2002 cannot be installed close to the PHS base station 2001 due to restrictions on the installation location, the power of the residual interference signal 2004 becomes large.

Figure 21 is a diagram showing the effect of reducing the transmission power of the control channel of the TD-LTE base station according to the fifth embodiment of the present disclosure and the interference reduction caused thereby. When it is possible to reduce the interference between the PHS and the TD-LTE by reducing the transmission power of the TD-LTE base station, such as when the transmission timing of the PHS downlink control channel and the TD-LTE control channel overlap, the transmission power of the TD-LTE base station is reduced as shown in Figure 21. This makes it possible to reduce the residual interference described in Figure 20. The vertical axis of the upper diagram of Figure 21 represents the PHS transmission power 2101, and the horizontal axis represents time. The vertical axis of the lower diagram of Figure 21 represents the TD-LTE transmission power 2102, and the horizontal axis represents time. For example, the residual interference can be reduced by reducing the TD-LTE transmission power 2102 in Figure 21 by the power reduction 2103 from the TD-LTE transmission power 1903 described in Figure 19. In other words, the effect of interference reduction 2104 can be achieved.

FIG. 22 is a diagram showing the received power after the combination of the PHS control channel measured at the TD-LTE base station according to the fifth embodiment of the present disclosure, similarly to the first embodiment. As shown in FIG. 22, the smaller the received power P phs _rx [dBm] is with respect to the maximum power P _{phs _rx [} dBm] 2202 of the combined received power 2201 of the PHS control channel measured at the TD-LTE base station, the more distant the TD-LTE base station is from the PHS base station. If the transmission power of the TD-LTE base station that can coexist when the TD-LTE base station is installed with the base station distance from the PHS base station = 0 (m) is P _{lt_tx_max} [dBm], the transmission power of the TD-LTE base station is reduced from P _{lt_tx_max} [dBm] according to the maximum received power P _{phs _rx} [dBm] of the PHS control channel measured at the TD-LTE base station.

Specifically, the path loss difference L = (L _phs -L _lte ) calculated from the path loss L _phs from the PHS base station at a point directly below the TD-LTE base station and the path loss L _lte from the TD-LTE base station is uniquely estimated from the received power P _{phs_rx} , and the transmission power is reduced by L from P _{lte_tx_max} .

Figure 23 is a flow diagram of the operation of a base station according to embodiment 5 of the present disclosure. TD-LTE base station 2002 measures the received power of a signal at the PHS control channel frequency (ST2301). Next, TD-LTE base station 2002 estimates the path loss difference from the received power (ST2302). Next, TD-LTE base station 2002 calculates the transmission power of the TD-LTE base station based on the estimated path loss difference (ST2303). Based on the calculated transmission power, the transmission power of channels that cannot be stopped according to the standard, such as a broadcast channel through which system information of the TD-LTE base station is transmitted, a synchronization channel for synchronization, and a downlink control channel, is controlled.

Figure 24 is a configuration diagram of a base station according to embodiment 5 of the present disclosure. The base station 2002 includes an antenna 2401, a transceiver unit 2402, a received power measurement unit 2403, a path loss difference estimation unit 2404, and a transmission power control unit 2405.

The transmitting/receiving unit 2402 transmits and receives PHS and TD-LTE signals via the antenna 2401. The received power measuring unit 2403 estimates the received power of the PHS control channel received by the transmitting/receiving unit 2402. The path loss difference estimating unit 2404 estimates a path loss difference based on the estimated received power received from the received power measuring unit 2403. The transmission power control unit 2405 calculates the transmission power of the base station 2002 based on the estimated path loss difference.

As described above, according to the fifth embodiment, it is possible to reduce residual interference from channels that cannot be stopped according to the standard, such as the broadcast channel through which system information of the TD-LTE base station is transmitted, the synchronization channel for synchronization, and the downlink control channel.

The TD-LTE base station described in the first to fourth embodiments may include some or all of the configuration of the base station described in the fifth embodiment using FIG. 24, etc.

Summary of this disclosure
The base station in the present disclosure is a base station of a second communication system that uses a second communication method that uses a second frequency band that is common to a part of a first frequency band used in a first communication method employed in a first communication system, and includes an estimation unit that estimates the timing of a slot of a downlink control channel transmitted from a base station of the first communication system at a predetermined channel frequency and a predetermined period, a scheduling unit that performs scheduling to allocate data to resource blocks that do not overlap with the predetermined channel frequency in resources of the second communication method that correspond on the time axis to the estimated slot timing of the downlink control channel, and a transceiver unit that performs transmission and reception based on the scheduling.

The estimation unit of the base station of the present disclosure estimates a slot a predetermined number after the slot of the downlink control channel as the timing of the slot of the uplink control channel transmitted from the terminal of the first communication system at the predetermined channel frequency and the predetermined period, and the scheduling unit schedules data to be assigned to resource blocks that do not overlap with the predetermined channel frequency in resources that correspond on the time axis to the timing of the slot of the uplink control channel.

The base station of the present disclosure further includes a reception power measurement unit that measures the reception power of a signal transmitted from a base station of the first communication system at the specified channel frequency, and a reception power synthesis unit that synthesizes the reception powers divided at regular intervals by aligning the start timing of each of the reception powers, and the estimation unit estimates the transmission section of the downlink control channel based on the magnitude relationship between the synthesized reception power and a threshold value.

The fixed period of the base station disclosed herein is an integer multiple of the predetermined period.

The base station of the present disclosure further includes a path loss difference estimation unit that estimates a path loss difference based on the difference between the maximum received power and the received power of a signal transmitted from the base station of the first communication system, and a transmission power control unit that controls the transmission power based on the path loss difference.

The base station of the present disclosure performs transmission power control based on the path loss difference for at least one of a broadcast channel through which system information in the second communication method is transmitted, a synchronization channel for synchronization, a downlink control channel, and a reference signal.

The base station of the present disclosure further includes a network unit that transmits, to a control station connected to the base station, power information indicating received power measured at a predetermined channel frequency at which a downlink control channel is transmitted from a base station of the first communication system, and a frame timing control unit that receives a timing shift amount of the second communication method from the control station, the received timing shift amount of the second communication method being calculated by the control station by synthesizing the received power information based on frame timing of the second communication method, detecting frame timing of the first communication method based on the synthesized power information, and calculating the received timing shift amount based on the detected frame timing of the first communication method, and shifting a transmission timing in accordance with the received timing shift amount.

The first communication method of the base station disclosed herein is a PHS (Personal Handy-phone System) method, and the second communication method is a sXGP (shared extended Global Platform) method.

The control station of the present disclosure is a control station that connects to a plurality of base stations of a second communication system that uses a second communication method that uses a second frequency band that is common to a portion of the first frequency band used in a first communication method used in a first communication system, and includes a network unit that receives, from each of the plurality of base stations, power information indicating the received power measured at a predetermined channel frequency at which a downlink control channel is transmitted from a base station of the first communication system, a frame timing detection unit that combines the plurality of power information based on the frame timing of the second communication method and detects the frame timing of the first communication method based on the combined power information, and a timing shift amount calculation unit that calculates a timing shift amount of the second communication method based on the frame timing of the first communication method and transmits the timing shift amount to each of the plurality of base stations via the network unit.

The base station of the present disclosure is a base station of a second communication system using a second communication method that uses a second frequency band that is common to a part of the first frequency band used in the first communication method used in the first communication system, and includes a frame timing detection unit that receives frames of the first communication method at a predetermined channel frequency at which a downlink control channel is transmitted from a base station of the first communication system and detects frame timing of the first communication method, a timing shift amount calculation unit that calculates a timing shift amount of the second communication method based on the frame timing of the first communication method, a network unit that transmits the timing shift amount to another base station of the second communication system via a network, and a frame timing control unit that shifts the transmission timing according to the timing shift amount.

The timing shift amount measuring device disclosed herein is a timing shift amount measuring device connected to a control station that is connected to multiple base stations of a second communication system using a second communication method that uses a second frequency band that is common to a part of the first frequency band used in a first communication method used in a first communication system, and includes a frame timing detection unit that receives frames of the first communication method at a predetermined channel frequency at which a downlink control channel is transmitted from a base station of the first communication system and detects the frame timing of the first communication method, a timing shift amount calculation unit that calculates the timing shift amount of the second communication method based on the frame timing of the first communication method, and a network unit that transmits the timing shift amount to the control station or the multiple base stations via a network.

The communication method disclosed herein is a communication method for a base station of a second communication system using a second communication method that uses a second frequency band that is common to a portion of a first frequency band used in a first communication method used in a first communication system, and estimates the timing of a slot of a downlink control channel transmitted from a base station of the first communication system at a predetermined channel frequency and a predetermined period, performs scheduling to assign data to resource blocks that do not overlap with the predetermined channel frequency in resources of the second communication method that correspond on the time axis to the timing of the slot of the estimated downlink control channel, and performs transmission and reception based on the scheduling.

The present disclosure can be realized in software, hardware, or software in conjunction with hardware.

Each functional block used in the description of the above embodiments may be realized, in part or in whole, as an LSI, which is an integrated circuit, and each process described in the above embodiments may be controlled, in part or in whole, by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the level of integration, the LSI may be called an IC, system LSI, super LSI, or ultra LSI.

The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. In addition, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells inside the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derived technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

This disclosure is applicable to, for example, base stations, control stations, timing shift amount measuring devices, and communication methods.

201 TD-LTE base station 202 PHS base station 203 TD-LTE base station 204 PHS base station 205 TD-LTE base station 206 PHS base station 501 Antenna 502 Transmitter/receiver 503 Received power measurement unit 504 Received power synthesis unit 505 PHS control channel timing estimation unit 506 Scheduling unit 507 Data processing unit 701 Control server 721 TD-LTE base station 722 PHS base station 723 TD-LTE base station 724 PHS base station 725 TD-LTE base station 726 PHS base station 727 TD-LTE base station 728 PHS base station 901 Antenna 902 Transmitter/receiver 903 Received power measurement unit 904 Received signal synthesis unit 905 Network unit 906 Frame timing control unit 1001 Network unit 1002 PHS frame timing detection unit 1003 Timing shift amount calculation unit 1102 Control server 1103 TD-LTE base station 1104 PHS base station 1105 Base station equipped with PHS control channel receiver 1106 PHS base station 1107 TD-LTE base station 1108 PHS base station 1109 TD-LTE base station 1110 PHS base station 1301 Antenna 1302 Transmitter/receiver unit 1303 PHS frame timing detection unit 1304 Timing shift amount calculation unit 1305 Network unit 1306 Frame timing control unit 1401 Network unit 1402 Timing shift amount determination unit 1501 Timing shift amount measurement device 1502 Control server 1503 TD-LTE base station 1504 PHS base station 1505 TD-LTE base station 1506 PHS base station 1507 TD-LTE base station 1508 PHS base station 1509 TD-LTE base station 1510 PHS base station 1701 Antenna 1702 Transmitter/receiver 1703 Frame timing control section 1704 Network section 1801 Antenna 1802 Transmitter/receiver 1803 PHS frame timing detection section 1804 Timing shift amount calculation section 1805 Network section 2001 PHS base station 2002 TD-LTE base station 2006 PHS terminal 2401 Antenna 2402 Transmitter/receiver 2403 Received power measurement section 2404 Path loss difference estimation section 2405 Transmission power control section

Claims (2)

A control station connected to a plurality of base stations of a second communication system using a second communication method that uses a second frequency band common to a part of a first frequency band used in a first communication method used in a first communication system,
a network unit that receives, from each of the plurality of base stations, power information indicating a combined reception power on a radio frame basis at a predetermined channel frequency at which a downlink control channel is transmitted from a base station of the first communication system;
a frame timing detection unit that combines the plurality of pieces of power information based on frame timing of the second communication method and detects frame timing of the first communication method based on the combined power information;
a timing shift amount calculation unit that calculates a timing shift amount for a TD-LTE frame of the second communication method based on frame timing of the first communication method and transmits the timing shift amount to each of the plurality of base stations via the network unit;
A control station comprising: A control method for a control station to connect to a plurality of base stations of a second communication system using a second communication method that uses a second frequency band common to a part of a first frequency band used in a first communication method used in a first communication system, comprising:
receiving, from each of the plurality of base stations, power information indicating a combined reception power on a radio frame basis at a predetermined channel frequency at which a downlink control channel is transmitted from a base station of the first communication system;
synthesizing the plurality of pieces of power information based on frame timing of the second communication method, and detecting frame timing of the first communication method based on the synthesized power information;
calculating a timing shift amount for the TD-LTE frame of the second communication method based on the frame timing of the first communication method, and transmitting the timing shift amount to each of the plurality of base stations;
method.

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