JP2002300628A - Processing method of handover and its transceiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that delay occurs in handover control for preventing handover from being started at appropriate handover timing since phase relationship information is notified and measured every time when the handover is activated, and a processing load in a mobile station is increased and control traffic is suppressed by a control signal for notifying to a base station since the phase relationship information is measured each time even if the handover is not smoothly activated and completed. SOLUTION: When the handover is carried out from a first base station that is currently communicating with the movable station for starting the communication with a second base station, the mobile station receives a slot for monitors from the second base station before the handover is started, and synchronization is established according to a known pilot symbol that is assigned to the slot for monitors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handover processing method for performing a handover in a cellular system based on an orthogonal frequency division multiplexing / time division multiple access (OFDM / TDMA) system, and a transmission / reception apparatus therefor.

[0002]

2. Description of the Related Art TDMA (Time Division Multiple Accel)
ess: Time-division multiple access) In cellular systems of the system, aiming at the improvement of communication speed and effective use of frequency,
OFDM (Orthog), a type of multi-carrier transmission system
The use of onal Frequency Division Multiplexing (orthogonal frequency division multiplexing) as a modulation scheme has been studied.

When considering the actual terrestrial propagation path of mobile communication, the biggest problem is multipath. In particular, when the information transmission speed is increased, the influence of this multipath causes frequency selective fading in which the frequency characteristics of the entire wide signal band become not flat, and the signal waveform is significantly distorted. For this reason, a multicarrier transmission system is used as one of the measures against multipath. The multi-carrier transmission system is a system in which a digital signal to be transmitted is divided into several series of signals having a low transmission rate and transmitted by a plurality of carriers. As a result, uniform fading can be considered within the band of one carrier.

[0004] OF which is a kind of multi-carrier modulation method
Regarding transmission and reception of a signal based on DM, FIG.
This will be described with reference to (b), (c) and (d).

FIG. 7 (a) shows ten frequency channels U
0, U1... U9. Each frequency channel U0, U1
.. U9 transmit signals using various numbers of subcarriers based on the information to be transmitted. For example, the channels U0 and U1 shown in FIG. 7A are assigned different numbers of subcarriers 1 determined according to the information transmitted by each. Thus, OFDM / TD
A transmitting device that transmits a signal based on the MA scheme allocates various numbers of subcarriers 1 to each channel. The number of carriers assigned to each channel is determined by the amount of information to be transmitted.

The channel U0 shown in FIG.
The signal is transmitted using the sub-carriers 80 and the channel U
1 transmits a signal using ten subcarriers 80.
Therefore, the transmission rate of channel U0 is at least twice the transmission rate of channel U1.

At the boundaries of channels U0, U1... U9,
A guard band 81, which is a subcarrier having a power of 0, is provided, and the guard band 81 functions as a spectrum mask for minimizing interference between adjacent frequency bands. When the influence of interference between adjacent frequency bands is small, there is no need to provide the guard band 81. On the other hand, when the influence of interference between frequency bands is very large, the guard band 81
May be provided in plurality. The sub-carrier 80 is generated by an OFDM process.

In FIG. 7C, W (f) indicates energy in the frequency axis, and B (Hz) indicates a distance between two adjacent subcarriers 80. By the OFDM processing, a multi-subcarrier-system
m), where the number of multiplexed sub-carriers is not affected by interference from other channels and can be set arbitrarily based on the allocated bandwidth.

As described above, since the transmission rate can be changed by changing the number of carriers allocated to the channel, various transmission rates can be obtained. In addition, the subcarriers between the channels can be easily separated by a filter, so that deterioration of the S / N characteristics can be prevented. By using OFDM processing for subcarrier multiplexing, there is no need to provide a guard band 81 between each channel, so that the frequency band utilization efficiency is very high. Further, the above-described processing can use a fast Fourier transform, which can increase the efficiency and speed of the processing.

As shown in FIG. 7D, the number of channels in each channel group can be changed. FIG. 7D shows six channels U0, U1,.
Is shown. OFDM / TDM
In the A method, the number of channels in one group can be changed within the frequency band based on information to be transmitted.

On the other hand, standard GSM (Global System fo
In a mobile communication system, the frequency channels are constant and the frequency bandwidth between adjacent channels is 200 kHz. The number of channels in the FDMA system is 124,
The TDMA method is used to realize a plurality of connections. In the TDMA system in the GSM system,
Eight GSM time slots are provided in one TDMA frame. As shown in FIG. 8, one GSM time frame is composed of eight GSM time slots,
It has a length of 4.615 ms. The length of one GSM time slot is 576.9 μs. The transmitted GSM time slots are not completely filled by the transmitted burst, and the interference between adjacent GSM time slots is suppressed even when the synchronization of the GSM system is not perfect. The guard period is 8.25 bits,
That is, it is 30.5 μs. The guard period is divided into two parts, one located at the beginning of the GSM time slot and the other located at the end of the GSM time slot.

FIG. 9 shows the order of time slots and low-frequency hopping between channels in the GSM system.
Only four channels, four transmission channels Tx, and two monitor channels Mn are shown. Each channel is composed of consecutive frames, and each frame has eight time slots.

A signal transmitted from the base station is received in a time slot 91 of the downlink frequency channel C0, and a transmission time slot 92 corresponding to the time slot 91 is transmitted three time slots later in the uplink frequency channel D0. .

During this cycle, the mobile station MS monitors the signals of the adjacent base stations in time slots 93. Monitoring does not necessarily have to be exactly aligned with the time slot. For example, although shown in the sixth time slot in the example shown in the figure, this is merely an example, and it may be provided at an appropriate place between the sixth and seventh time slots. Good.

In the subsequent frame, the time slot 94 for reception is replaced with the time slot 91 previously transmitted.
Transmitted using the same uplink frequency band as
It is transmitted over different frequency channels C1 based on slow frequency hopping. The time slot 94
Is transmitted via a frequency channel D1 different from the previous channel, and the frequency channel of the monitor is also changed from the previous E0 and received via the frequency channel E1.

The frequency characteristics of signal transmission and the characteristics of interference are improved by the slow frequency hopping and interleaving. A typical interleave depth in a GSM system is 3 corresponding to an 8 × 8 GSM time slot.
6.923 ms.

FIG. 10 shows a GSM constructed in a known manner.
FIG. 1 is a diagram showing main components of a cellular network of a system. The system comprises at least one center MS
C (Mobile Services Switching Center) 11
This center MSC11 is connected to a telephone network. The center MSC 11 includes base station controllers BSC (Base Station Controller) 8, 9 and 10
Each controller communicates with one or more base stations BTS (BaseTranscei
ver Station) 1, 2, 3, 4, 5 and 6. Furthermore, several mobile stations MS (Mobile Station) 7 move within the cell of each base station BTS. In this example, only one mobile station is shown to simplify the drawing.

The range in which radio communication with the BTS 1 is possible is called a cell 12, and the range in which radio communication with the BTS 2 is possible is called a cell 13. FIG. 10 shows a state where the mobile station MS7 moves from the cell 12 of the base station BTS1 of the handover source to the cell 13 of the base station BTS2 of the handover destination.

The mobile station MS7 initially communicates with the base station BTS1 through wireless communication. During communication, the base station BTS1 monitors the power of the mobile station MS7 and controls the base station BTS8 under the control of the base station controller BSC8.
When it is predicted that handover to No. 2 will occur, the result of this monitoring is reported to the center MSC 11. The mobile station MS7 receives the neighboring base station list, monitors the signals of the neighboring base stations at regular time intervals based on this list, and reports the result to the BTS1. When the handover boundary conditions are met, a message is sent to the base station controller BSC9. This message contains the parameters needed to recognize the mobile station MS, the mobile station MS and the base station BTS.
2 includes data on a new channel (time slot) to be used. When the mobile station 7 is in the range where the cell 12 and the cell 13 overlap, the handover to the base station BTS2 is started under the control of the MSC 11, and the handover is completed before the mobile station 7 enters the range of the cell 13. are doing.

On the other hand, CDMA (Code Division Multiple)
Access) system, the mobile station MS7 is the base station BTS1
In the case of moving from the cell 12 of the base station BTS2 to the cell 13 of another base station BTS2, soft handover is used. In soft handover, a plurality of base stations can receive a signal from one mobile station using the same code.
Similarly, multiple base stations can send the same signal to one mobile station using the same code. In this case, the mobile station receives a signal from the base station through multipath propagation.

[0021]

However, conventionally, since the measurement and notification of the phase relationship information are performed every time the handover is activated, a delay occurs in the handover control, and the handover cannot be started at an appropriate handover timing. There was a problem.

Further, even when the handover activation and termination fluctuate, the phase relation information is measured each time, so that the processing load on the mobile station is increased and a control signal for notifying the base station is provided. There is a problem that control traffic is compressed.

Further, a TDM synchronizing a plurality of base stations
When soft handover is applied in the A system, two or more base stations are configured to transmit to one mobile station at the same time using the same time slot and the same carrier frequency. If the mobile station simultaneously receives signals from the two base stations and the signals from the two stations have almost the same strength, a strong standing wave is generated, and in the standing wave, both signals strengthen each other. ,
Alternatively, the mobile stations may cancel each other, causing strong fading. This type of fading has a greater effect than fading caused by multipath propagation.

Such a problem is caused by providing an appropriate time delay between the base stations so that the signals from the two stations arrive at the mobile station at different times, so that the two signals do not cancel each other, for example, the Viterbi type It is solved by making it available in the receiver. However, adjusting the time delay is difficult, at least while the mobile station is moving. Adjusting the time delay increases transmission and reception of signals between the base station and the mobile station. Further, if the time delay between the two signals is too large, the receiver cannot handle both signals, so the time delay must be kept within a certain range. In addition, since a plurality of adjacent base stations use a specific frequency, there is a problem that the level of interference or interference in the entire network increases.

The present invention has been made in view of the above,
Orthogonal frequency division multiplexing / time division multiple access (OFDM / TD
TECHNICAL FIELD The present invention relates to a communication method, a base station, and a transmitting device and a receiving device of a mobile station which realize high-speed and highly stable handover in a cellular system based on the MA) system.

[0026]

In order to solve the above-mentioned problems, a communication method according to the present invention provides an OFDM system in which an arbitrary number of subcarriers are allocated to a frequency band corresponding to a predetermined number of GSM frequency channels. In a GSM communication system in which an integer multiple of a / TDMA time slot matches one or an integer number of GSM time slots and pilot symbols are allocated to subcarriers at predetermined intervals, the mobile station can perform communication at present. When performing handover from the first base station and starting communication with the second base station, before the handover is started, the mobile station transmits a monitoring slot from the second base station. And synchronization is established from a known pilot symbol assigned to the monitoring slot.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a communication method, a base station, and a transmitter and a receiver of a mobile station according to the present invention in a cellular system based on an orthogonal frequency division multiplexing / time division multiple access (OFDM / TDMA) system will be described. Embodiments will be described with reference to the drawings.

FIG. 10 shows a GSM constructed in a known manner.
FIG. 1 is a diagram showing main components of a cellular network of a system. The system comprises at least one center MS
C (Mobile Services Switching Center) 11
This center MSC11 is connected to a telephone network. The center MSC 11 includes base station controllers BSC (Base Station Controller) 8, 9 and 10
Each controller communicates with one or more base stations BTS (BaseTranscei
ver Station) 1, 2, 3, 4, 5 and 6. Furthermore, several mobile stations MS (Mobile Station) 7 move within the cell of each base station BTS. In this example, only one mobile station is shown to simplify the drawing.

The range in which radio communication with BTS1 is possible is called cell 12, and the range in which radio communication with BTS2 is possible is called cell 13. FIG. 10 shows a state where the mobile station MS7 moves from the cell 12 of the base station BTS1 of the handover source to the cell 13 of the base station BTS2 of the handover destination. Also,
FIG. 1 is a diagram showing a handover sequence according to the first embodiment of the present invention.

The communication method according to the first embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1 and FIG. 10, when the mobile station MS7 is communicating with the base station BTS1, the mobile station 7 always receives pilot channels transmitted from neighboring cells sequentially in preparation for handover. The reception level and phase information are measured from the pilot symbols of the received pilot channel, and the measured reception levels and phase shift information are stored in a memory as a reception level table and a phase information table corresponding to each peripheral cell.

At this time, the handover destination base station B
Each peripheral base station including the TS2 generates a pilot channel on a unique channel allocated differently, and always transmits the pilot symbol of the pilot channel including the frequency information of its own communication channel and the phase information of the time slot. are doing.

In such a state, the reception levels of the base stations BTS1 and BTS2 are determined,
When the level difference exceeds the reference level, handover is started in the mobile station MS7, the mobile station MS7 generates a handover request signal to the base station BTS1, and issues a handover start request to the base station BTS1. FIG. 2 shows the start and end of the handover.

Upon receiving the phase information request from the base station BTS1, the mobile station MS7 reads the phase information of the handover destination base station BTS2 from the phase information stored in the memory in advance, and transmits the phase information signal to the base station BTS1. To the base station BTS2 via

As described above, the measurement of the phase information of the mobile station 7 is not performed every time when the handover is started, but is performed before the start of the handover, and the resulting phase information is stored in the memory of the mobile station. By storing in advance, it is not necessary to newly measure the phase information at the time of starting the handover. Then, no matter when handover occurs, synchronization of the communication channel of the handover destination base station is to be quickly and efficiently established.

The base station BTS2, having received the radio channel designation request from the base station BTS1, allocates a communication channel of the mobile station MS7, and sends a radio channel designation signal to the mobile station MS7 via the base station BTS1. Further, the mobile station MS7 makes settings for synchronizing on the channel of the designated radio line, and notifies the base station BTS2 of the establishment of synchronization. When synchronization is confirmed from the base station BTS2,
End the handover.

FIG. 3 shows the flow of time slots between the channels of the mobile station MS7 and the base station BTS1 of the handover source and the base station BTS2 of the handover destination in one embodiment of the present invention. BTS
1, the reception channel Rx of the BTS2 and the mobile station MS7 indicate four channels, the transmission channel Tx indicates four channels, and the monitor channel Mn of the mobile station MS7 also indicates four channels. Each channel is composed of consecutive frames. The first one frame is before handover, the second one frame is during handover, and the third frame is after handover.

The signal of the time slot 40a transmitted from the base station BTS1 is received in the time slot 44a of the mobile station MS7, and the signal of the time slot 46a transmitted from the mobile station MS7 is received in the time slot 41a of the base station BTS1. Is done.

During this cycle, the mobile station MS7 monitors the signal of the adjacent base station in the time slot 48.

When the handover is started in the next frame following this, the signal in the time slot 40b transmitted from the base station BTS1 is received in the time slot of the mobile station MS7 44b and transmitted from the mobile station MS7. The signal in the time slot 46b is received in the time slot 41b of the base station BTS1. Here, the mobile station MS7 does not monitor the peripheral base station and transmits the signal of the time slot 42b transmitted from the base station BTS2 to the mobile station MS7.
Or the time slot 47b transmitted from the mobile station MS7 is received in the time slot 43b of the base station BTS2.
When the handover is completed in the next frame, the signal in the time slot 42c transmitted from the base station BTS2 is received in the time slot 45c of the mobile station MS7, and the signal in the time slot 47c transmitted from the mobile station MS7 is transmitted to the base station. It is received in time slot 43c of BTS2.

FIG. 4 is a block diagram of the transmitting apparatus according to the present embodiment. The signal to be transmitted is input terminal 5
0 is supplied to the channel encoder 51. The encoded signal is supplied to an interleaver 52,
For example, 8 × 8 OFDM / TDMA frame or 16 × 8
It is interleaved at a predetermined depth such as an OFDM / TDMA frame. The interleaved signal is supplied to the switch 53b. Pilot symbol generator 53
c generates a pilot symbol, and this pilot symbol is inserted into the data sequence of the signal supplied from the interleaver 52 in the switch 53b. Further, the signal is supplied to a modulator 53a, which performs an OFDM process on the signal to generate a predetermined number of subcarriers. The switch 53b inserts a pilot symbol known for each GSM frequency channel into a plurality of sub-carriers for modulating and transmitting a signal to be transmitted, and performs a modulation process.

The sub-carrier generated as described above is
The data is converted into a time domain by a discrete / fast discrete Fourier transformer or a discrete / fast fast Fourier transformer 54 and supplied to a guard interval generator 55. The guard interval generator 55 adds a guard time to a burst in the time domain and forms a time burst. OFDM / T
The DMA time slot is further supplied to a D / A converter 56. The D / A converter 56 converts the OFDM / TDMA time slot from a digital signal to an analog signal, and converts the converted signal to an RF up-converter 57. Supply. The RF up-converter 57 up-converts the converted signal. The up-converted signal is transmitted via antenna 58.

FIG. 5 is a diagram for explaining the assignment of one pilot symbol. In FIG. 5, reference numeral 60 denotes four GSs.
One OFDM / TDMA time slot composed of M time slots, and 61 is one GSM time slot constituting the OFDM / TDMA time slot 60. Reference numeral 62 denotes a configuration of an OFDM time slot in one GSM time slot 61;
Pilot symbols 63 are arranged.

In the example shown at 60 in FIG. 5, OFDM / TDM
The A channel is composed of four GSM frequency channels, and as described above, the transmission frequency band in the OFDM / TDMA system may be different from the GSM transmission frequency band, in which case the sub-carriers are in the frequency band of the GSM frequency channel. Assigned accordingly. Note that in this example, the OFDM / TDMA channel is GS
Assigned to M frequency channels. Since the bandwidth of the GSM frequency channel is 200 kHz,
The bandwidth of the DM / TDMA channel is 800 kHz.

In the example shown at 62 in FIG. 5, the total number of subcarriers allocated to one GSM frequency channel is 49
And four OFDM / TDMA time slots are 1
Mapped to one GSM time slot. The length of this GSM time slot is 576.9 μs.

FIG. 5 shows in detail the sub-carriers allocated to the GSM frequency channel having a bandwidth of 200 kHz. In the example of 62 in FIG. 5, 49 subcarriers are allocated to one GSM frequency channel,
4 OFDM / TDM in 1 GSM time slot
This is done by mapping the A time slot. As shown in FIG. 5, the pilot symbols 63 are basically allocated to every sixth and twelfth carrier, and are modulated together with the carrier and subjected to interlace processing.

FIG. 6 is a block diagram of a receiving apparatus to which the present invention is applied. Antenna 58 receives the transmission signal and supplies this signal to RF downconverter 70. The RF downconverter 70 downconverts this signal and supplies the downconverted signal to the A / D converter 72. The A / D converter 72 converts this signal from the analog format to the digital format, and supplies the converted signal to the guard interval remover 73 and the symbol synchronization circuit 71. The symbol synchronization circuit 71 establishes synchronization by detecting a known pilot signal, and synchronizes the propagation characteristic estimation circuit 76b.

On the other hand, the signal from which the guard interval has been removed by the guard interval remover 73 is supplied to the discrete / fast Fourier transformer 75, which converts the supplied signal into the frequency domain. The discrete / fast Fourier transformer 75 is synchronized with a predetermined time and frequency by a time synchronizer 74a and a frequency synchronizer 74b.

The frequency domain signal output from the discrete / fast Fourier transformer 75 is a signal obtained by modulating a subcarrier with a data signal, a signaling signal, a pilot symbol and the like, and this signal is demodulated by the demodulation means 76a. Of the signals obtained as a result of this demodulation, pilot symbols are supplied to a propagation characteristic estimating circuit 76b, whereby the propagation characteristic estimating circuit 76b
And the pilot symbol generator 53c. That is, in the transmission system to which the present invention is applied, the receiving device and the transmitting device operate based on the known pilot symbols and the pilot symbol modulation rate of the subcarrier of each GSM channel. For example, in a wireless communication system, when a transmitting device is used in a mobile station and a receiving device is used in a base station, the mobile station and the base station each have information about pilot symbols in advance, and It has information on whether the pilot signal is included in the subcarrier.

The propagation characteristic estimating circuit 76b of the receiving apparatus compares the received pilot symbol with a known pilot symbol recorded in a memory, for example.
For example, a channel transfer function such as channel attenuation is estimated, and a channel transfer function that complements time and frequency is generated. The equalizer 76c can perform equalization processing on the transmitted data sequence using the channel transfer function obtained as described above, and can appropriately and accurately equalize the transmitted data. . The signal subjected to the equalization processing is supplied to a deinterleaver 77, and the signal deinterleaved by the deinterleaver 77 is supplied to a channel decoder 78. Channel decoder 78
Performs a channel decoding process on the signal and outputs the signal from an output terminal 79.

Here, the channel transfer function estimated by the receiving device is, for example, channel attenuation, and the equalizer 76c determines the received signal based on the estimation of the channel attenuation by the propagation characteristic estimating circuit 76b and the estimation result. Is equalized.

[0052]

As described above, the present invention provides an OFDM / TD
In a mobile communication system of the GSM system for transmitting and receiving signals based on the MA system, a process execution method for temporarily switching communication from a base station currently performing communication to a next base station by handover in accordance with movement of a mobile station. Then, an arbitrary number of subcarriers are allocated to frequency bands corresponding to a predetermined number of GSM frequency channels, and OFDM /
GSM in which an integer multiple of the time slot of the TDMA scheme matches one or an integer number of time slots of the GSM scheme, and pilot symbols are allocated to subcarriers at predetermined intervals.
In the communication system of the system, when the mobile station performs a handover from the first base station that is currently communicating and starts communication with the second base station, the mobile station moves before the handover is started. The station receives a monitoring slot from the second base station and establishes synchronization from a known pilot symbol assigned to the monitoring slot, thereby realizing a fast and highly stable handover.

[Brief description of the drawings]

FIG. 1 is a diagram showing a handover sequence in a communication method according to an embodiment of the present invention.

FIG. 2 is a diagram showing the start and end of handover

FIG. 3 is a diagram showing the order of time slots between channels according to the present embodiment.

FIG. 4 is a block diagram of a transmission device according to the present embodiment.

FIG. 5 is a diagram for explaining pilot symbol assignment according to the present embodiment.

FIG. 6 is a block diagram of a receiving device according to the present embodiment.

7A is a diagram illustrating a frequency channel in the known OFDM. FIG. 7B is a diagram illustrating a carrier in the channel in the known OFDM. FIG. 7C is a diagram illustrating a subcarrier in the known OFDM. Diagram showing channels

FIG. 8 is a diagram illustrating a time frame and a time slot in GSM.

FIG. 9 is a diagram showing the order of time slots between channels in GSM.

FIG. 10 is a diagram showing a configuration of a known mobile station network and a situation where a mobile station moves from a cell of one base station to a cell of another base station.

[Explanation of symbols]

 1 Base station of handover source 2 Base station of handover destination 7 Mobile station 8 Controller of base station 1 9 Controller of base station 2 11 Center 12 Cell of base station 1 13 Cell of base station 2

Continued on the front page F term (reference) 5K067 AA02 AA25 BB04 CC02 CC04 DD02 DD25 EE02 EE10 EE24 EE61 EE71 JJ03 JJ12 JJ13 JJ39 JJ52 JJ54 JJ65

Claims (8)

[Claims] 1. In a mobile communication system of a global communication system for transmitting and receiving signals based on an orthogonal frequency division multiplexing / time division multiple access system, a base station which is currently communicating with a mobile station following the movement of the mobile station. A method for executing processing for temporarily switching communication to a station by handover, wherein an arbitrary number of subcarriers are allocated to a predetermined number of frequency bands corresponding to frequency channels of a mobile communication global system, and orthogonal frequency division multiplexing / time In a mobile communication global communication system in which an integer multiple of the division multiple access system time slot matches one or an integer number of mobile communication global system time slots and pilot symbols are allocated to subcarriers at predetermined intervals, The station performs a handover from the first base station with which it is currently communicating and communicates with the second base station. Before starting the handover, the mobile station receives a monitoring slot from the second base station before the handover is started, and synchronizes with a known pilot symbol assigned to the monitoring slot. The established handover handling method. 2. The communication method according to claim 1, wherein one time division multiple access is performed while the mobile station is performing a handover from the first base station to the second base station. The handover processing method according to claim 1, wherein the signal is received from both the first base station and the second base station using different channels in a frame of a scheme. 3. The method according to claim 1, wherein the frequency channels assigned to the mobile station are a plurality of continuous groups. 4. The method according to claim 1, wherein the time slots allocated to the mobile station are a plurality of continuous groups. 5. The method of claim 1, wherein the pilot symbols are assigned at regular intervals. 6. The method according to claim 1, wherein the assignment of the pilot symbols is a scatter pilot.
2. The method for processing a handover according to item 1. 7. The transmitting apparatus according to claim 1, wherein the monitoring slot is transmitted before the start of the handover. 8. The receiving apparatus according to claim 1, wherein synchronization is performed from pilot symbols assigned to the monitoring slots.