KR20100023720A - Method for transmitting and receiving synchronization channels - Google Patents

Abstract

PURPOSE: A method for transmitting and receiving synchronization channels is provided to include a frequency reuse factor to a synchronization channel, thereby conveniently discriminating location of a super frame header. CONSTITUTION: A primary synchronization channel is transmitted in a super frame header. The primary synchronization channel has a predetermined frequency reuse factor. In the rest frame, a secondary synchronization channel is transmitted. The secondary synchronization channel has a frequency reuse factor different to the frequency reuse factor of the primary synchronization channel. The super frame header does not belong to the rest frame. A sub frame header of the super frame includes a BCH(broadcasting channel).

Description

Method for transmitting and receiving synchronization channels

The present invention relates to a synchronization channel structure having two reuse factors in one superframe, and more particularly, to a method of transmitting synchronization symbols having different frequency reuse factors.

The sync channel is called differently depending on the system. For example, it is called SS (Synchronization Signal) in 3GPP LTE and Preamble in IEEE 802.16e. Accordingly, the synchronization channel is a general term for all channels / signals and the like in which the terminal performs time / frequency synchronization with the base station.

Hereinafter, based on the IEEE 802.16e standard, a new structure of IEEE 802.16m may be designed to have a frame structure of 5 ms based on the OFDM parameters of IEEE 802.16e shown in Table 1.

Transmission Bandwidth (MHz) 5 10 20 Over-sampling factor 28/25 Sampling Frequency (MHz) 5.6 11.2 22.4 FFT Size 512 1024 2048 Sub-carrier Spacing (kHz) 10.94 OFDM Symbol Time, Tu (us) 91.4 Cyclic Prefix (CP) Ts (us) OFDM Symbols per Frame Idle Time (us) Tg = 1/4 Tu 91.4 + 22.85 = 114.25 43 87.25 Tg = 1/8 Tu 91.4 + 11.42 = 102.82 48 64.64 Tg = 1/16 Tu 91.4 + 5.71 = 97.11 51 47.39 Tg = 1/32 Tu 91.4 + 2.86 = 94.26 53 4.22

The difference from the IEEE 802.16e frame structure in the structure of IEEE 802.16m is that there is a super-frame structure including a plurality of frames, and a small sub-frame in one frame ) Structure is included. Through the superframe structure, transmission efficiency of control information that does not need to be transmitted frequently can be transmitted in units of superframes, thereby improving transmission efficiency, and data allocation and scheduling are most frequently made in subframe units. Therefore, the delay characteristic of the data transmission considering the retransmission mechanism can be reduced. The size of the superframe considered for the IEEE 802.16m frame structure is four frames, and eight subframes constitute one frame. However, this is not an example and obviously includes other sizes of superframes and subframes.

1 shows a general frame structure of IEEE 802.16m.

In FIG. 1, the four frames described above are configured as one superframe, and eight subframes are configured as one frame. Each superframe includes control information called a super-frame header (SFH).

FIG. 2 illustrates a position in a superframe of a synchronization channel (SCH) of IEEE 802.16m.

Each sync channel consists of one OFDM symbol. In addition, an additional synchronization channel symbol for initial synchronization and cell information other than the present symbol or synchronization and cell information at the time of handover may be configured in a hierarchical synchronization channel structure in which every frame exists. However, in the above example, it is assumed that the simplest type of non-layered synchronization channel structure and transmission period are also transmitted in the most frequent 5ms unit.

The structure of the synchronization channel can be classified into two types according to the method of initial timing / frequency synchronization. The first method is to achieve initial timing / frequency synchronization using cross-correlation. In this case, the synchronization channel transmission should be carried on all subcarriers on the frequency axis. If only a subcarrier is sent on an even subcarrier or only on an even subcarrier, or if a sync channel signal is transmitted only on every n (n> = 2) th subcarriers, an ambiguous peak may occur. Occurs, and becomes a problem for initial timing / frequency synchronization formation. The second method is to achieve initial timing / frequency synchronization using auto-correlation. In order to use this method, the synchronization channel must be transmitted so that the repetition pattern of the signal appears on the time axis. The simplest way to create a repeating pattern on the time axis is to send a sync channel signal on every n (n> = 2) th subcarriers on the frequency axis.

Table 2 shows the advantages and disadvantages of the two types of channel structures.

Advantages Disadvantages Cross-correlation based algorithm In an environment with a fine frequency offset, sharp peaks can be obtained at the time of timing acquisition. This means that the coarse timing step can be omitted in the synchronization process. The complexity is greatly increased. In order to achieve the basic purpose, i.e. for cell search (for a synchronous channel), at least one additional channel is needed in any of the time / frequency / code / spatial domains to carry the cell ID information. Do. This is because, from a practical implementation point of view, it is difficult to apply multiple correlators to test hundreds of hypothesis tests during timing detection. In environments with large frequency offsets, the gain of sharp peaks may disappear due to a partial correlation that can produce stubby peaks. Auto-correlation based algorithm The complexity is very small. The synchronization channel may consist of only one OFDM symbol. In other words, no additional resources or channels are required. It can work well despite the frequency offset effect due to differential operation. In addition, fine timing is required after cell ID detection.

In conclusion, the auto-correlation-based synchronization channel structure is more preferable because it reduces the computational amount of the terminal upon reception and may not be affected by the frequency offset.

For this reason, the IEEE 802.16e preamble also has a synchronization channel structure for supporting an autocorrelation based synchronization algorithm, and a transmission signal is loaded on every third subcarrier on the frequency axis so that three repetition patterns are represented on the time axis. Has Even in the case of the IEEE 802.16m synchronization channel, a time axis repeating pattern should be created.

FIG. 3 illustrates a legacy-support mode in which synchronization channels of IEEE 802.16e and IEEE 802.16m are mixed and transmitted by TDM (Time Division Multiplexing).

In the case of FIG. 3, in order to avoid confusion with the IEEE 802.16e preamble signal, a synchronization channel of IEEE 802.16m is transmitted to have 3 repetitions and a disjoint repetition factor of each other. Should be.

On the other hand, the terminal may receive interference from the adjacent cell when receiving the synchronization channel, due to such interference may result in degradation of performance when obtaining the cell ID. In addition, the components due to interference may be combined with values to be measured for FFR (Fractional Frequency Reuse) or PC (Power Control), such as Received Signal Strength Indication (RSSI) value, thereby reducing the accuracy of the measured value. Therefore, as a solution to fundamentally solve this problem, the synchronization channel may be transmitted by giving a frequency reuse factor to the synchronization channel.

4A and 4B show examples of frequency reuse.

It is assumed that the reuse factor is F. There are no limitations on how the F cells are arranged using a predetermined portion of the frequency axis so as not to overlap each other. For example, there may be a localized allocation method in which frequency resources for a specific cell are stored in a specific part, or, on the contrary, distributed allocation in which frequency resources for a specific cell are uniformly spread and arranged in all frequency bands. There may be a way.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a synchronization channel transmission method and a reception method for easily distinguishing a location of a superframe header when a plurality of synchronization channels exist in a superframe.

In order to achieve the above technical problem, the synchronization channel transmission method according to an embodiment of the present invention transmits a first synchronization channel having a predetermined frequency reuse factor in a superframe header, and the remaining frames to which the superframe header does not belong. Transmitting a second synchronization channel having a frequency reuse factor different from that of the first synchronization channel.

Preferably, the second synchronization channel may be transmitted through at least a portion of a frequency band in which the first synchronization channel is transmitted.

Preferably, the first sync channel may have a different repeating structure from that of the second sync channel.

Preferably, the first sync channel may use a code having a code length different from that of the second sync channel. In this case, the first sync channel may use a code having a length corresponding to the reuse factor value of the second sync channel. More specifically, the first synchronization channel may use a code having a length corresponding to a value obtained by multiplying a ratio of the number of repetitions of the second synchronization channel to the number of repetitions of the first synchronization channel by a reuse factor value of the second synchronization channel. Can be.

Preferably, the second sync channel may use a code having the same code length as the code of the first sync channel. In this case, the first synchronization channel may use a plurality of different code sets.

Preferably, the first sync channel and the second sync channel can transmit codes mapped to a cell identifier to be supported.

Preferably, in the process of transmitting the first synchronization channel, the synchronization channel having a frequency reuse factor of 1 may be transmitted.

Preferably, in the process of transmitting the second synchronization channel, a synchronization channel having a frequency reuse factor of 3 or 4 may be transmitted.

In order to achieve the above technical problem, the method for receiving a synchronization channel according to an embodiment of the present invention receives a first synchronization channel having a predetermined frequency reuse factor in a superframe header, and in a remaining frame after the superframe header. Receiving a second synchronization channel having a frequency reuse factor different from the first synchronization channel.

Preferably, the method for receiving a synchronization channel according to an embodiment of the present invention may further include detecting and aggregating a cell identifier in the first and second sync channels, respectively.

According to an embodiment of the present invention, when there are a plurality of synchronization channels in a superframe, the location of the superframe header can be easily distinguished, and the effect of interference during RSSI measurement or other measurement can be reduced.

Hereinafter, with reference to the drawings will be described a preferred embodiment of the present invention. However, embodiments of the present invention illustrated below may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

5 illustrates a synchronization channel structure using different reuse factors according to an embodiment of the present invention.

The subframe header is located in the first frame within the superframe, and the subframe header is not located in the other three frames. In addition, the subframe header includes not only a synchronization channel but also a broadcasting channel (BCH) in which the terminal contains basic essential information for initial network entry.

Therefore, when the terminal grabs the synchronization channel and attempts to enter the initial network in the absence of information on the location of the superframe header, it should be able to distinguish the synchronization channel located in the superframe header and the synchronization channel located outside the superframe header. If the terminal does not distinguish this, the broadcast channel must be decoded at every sync channel detection, which is an unnecessary operation of the terminal, resulting in unnecessary power consumption. If the synchronization channel located in the superframe header and the synchronization channel which are not in different forms are configured, the UE can determine the location of the superframe header through this distinction.

On the other hand, if the UE is designed to obtain channel estimation information from the synchronization channel when decoding the broadcast channel in the subframe header, it is possible to reduce the burden on channel coding or overhead during the broadcast channel decoding. Therefore, the sync channel type 1 (type-1) is preferably transmitted to have a reuse factor 1 to enable MIMO channel estimation. However, in the case of a synchronization channel having a reuse factor 1, good performance cannot be guaranteed in a situation where interference from neighboring cells, such as a cell boundary, is received. Therefore, the sync channel type 2 (type-2) is preferably transmitted to have one or more reuse factors.

As shown in FIG. 5, the synchronization channel at F0 may be used to detect a frame boundary of a superframe. In addition, the synchronization channel in F0 may be designed to enable multi-antenna channel estimation.

6 illustrates an example of a frequency band used by a synchronization channel at each position in a superframe.

6 assumes that frequency reuse is configured in a region allocation form and that the reuse factor is four. The sync channel of F0 located in the superframe header has a reuse factor of 1 and is transmitted over the entire band from W1 to W4. The sync channel of F1 has a reuse factor of 4 and is transmitted in only one frequency band of W1 to W4. The sync channel of F2 and the sync channel of F3 likewise have a reuse factor of 4 and are transmitted in only one frequency band of W1 to W4. The bands used for the sync channel of F1, the sync channel of F2, and the sync channel of F3 may overlap each other. The above-described method can be applied to distributed allocation or to using other reuse factor values.

The mapping method of four sync channels to subcarriers in each band is based on a 2x repetition structure. Even if the UE has only one synchronization channel among the four, the time / frequency synchronization may perform an autocorrelation algorithm. On the other hand, there is no restriction on MIMO transmission in the present invention. 2x does not mean a case of maintaining two repetitions for each transmitting antenna. That is, 2x refers to a case in which two repetitions are maintained when all the signals transmitted from the transmitting antennas are added together.

In addition, the synchronization channel in the superframe header and the synchronization channel outside the superframe header may have different repetition structures. In this case, sync channels outside the superframe header may have the same repetition structure. For example, a synchronization channel in a superframe header may have a repetition structure twice, and a synchronization channel outside the superframe header may have a non-repeating structure. In the case of a synchronization channel outside of the superframe header, it is preferable not to repeat because the length of the code that can be used is shortened due to the reuse factor. Therefore, if the non-repetitive structure of the synchronization channel outside the superframe header is prevented from shortening the code length, deterioration of cell ID detection performance can be prevented.

Each sync channel carries the same cell ID. In general, when a terminal acquires a cell ID, cell ID detection through a single synchronization channel does not provide desired reliability. Therefore, after performing cross-correlation with the currently received sync channel for all possible cell IDs, storing them for each cell ID and calculating the cross-correlation value for each cell ID through the same process even when the next sync channel is received. It is preferable. By combining the cross-correlation values over these two stages, the cell ID can be detected more reliably. This process can be performed through multiple synchronization channels to aggregate the results.

In the proposed synchronization channel structure composed of two reuse factors, the number of subcarriers that can be used in the synchronization channel in the superframe header is larger than the number of subcarriers that can be used in the remaining three synchronization channels.

Therefore, in the case of assuming the same repetition structure in subcarrier mapping, the length of a code used for a sync channel located in a superframe header may be designed to be F times the length of a code used in three other sync channels.

Alternatively, the same cell ID may be transmitted, but a code having the same length as the remaining three sync channels may be transmitted by cutting the sync channel located in the superframe header by reuse factor.

FIG. 7 illustrates an example of transmitting a code having a length of F times the code length used for the remaining three sync channels to a sync channel located in a superframe header when assuming the same repetition structure in subcarrier mapping.

Nsub represents the number of subcarriers available in the entire band. The id value indicates a cell ID to be supported by the current cell. The sync channel in the superframe header transmits an Nsub / 2 length code mapped to an id value in the length code set C ', assuming a repetition structure. The other three sync channels carry Nsub / 8 length codes that map to id values in code set C.

When a code of a superframe header is transmitted using a long code, it may be designed by optimizing a peak-to-average power ratio (PAPR) of a transmission code corresponding to a C 'set. In this case, UEs in an environment with little interference around the base station can obtain a cell ID more accurately than when using three sync channels outside a superframe header having a short code length.

8 illustrates an example of transmitting a code having the same length as a code transmitted to the remaining three sync channels to a sync channel located in a superframe header.

As shown in FIG. 8, the code set used in the superframe header may be different from the transport code sets outside the superframe header. However, the code set used in the superframe header may be defined as code set C used outside the superframe header. C1, C2, C3, and C4, which are used for the synchronization channel located in the superframe header, may be defined in the same code set (C1 = C2 = C3 = C4 ≠ C) different from C, but C1, C2, C3, C4 It can be defined as a code set having a time / frequency cyclic shift relationship with each other.

As shown in FIG. 8, when all code sets are configured with code sets having the same length, there is an advantage in that power consumption of the terminal can be reduced unlike in the case of FIG. 7.

FIG. 9 illustrates an example of transmitting a length of a code used for a synchronization channel in a superframe header in an intermediate form of FIGS. 7 and 8.

In FIG. 9, the sync channel in the superframe header uses a code shorter than Nsub and longer than Nsub / 4, that is, a code of Nsub / 2 length. In addition, as shown in FIG. 9, the code set used in the superframe header may be different from the transport code sets outside the superframe header.

The foregoing description has been made on the premise of having a repetitive waveform in the time domain of the synchronization channel in the superframe header and the synchronization channel outside the superframe header. However, if not all sync channels transmit cell ID, then the sync channel in the superframe header or the sync channel outside the superframe header need not have a repetitive waveform. For example, when only cell ID detection is supported through a synchronization channel outside the superframe header and time / frequency synchronization is obtained through the synchronization channel in the superframe header, the synchronization channel outside the superframe header does not need to have a repetitive waveform. In this case, it is not necessary to use even or odd subcarriers or insert empty subcarriers in the frequency domain in a synchronization channel outside the superframe header. In this case, the sequence length relationship between the plurality of synchronization channels is different from that in FIG.

FIG. 10 illustrates a case where a frequency mapping relationship between synchronization channels in and out of a superframe header is different when a Nsub / 2 length code is transmitted to a synchronization channel in the superframe header.

For example, the synchronization channel in the superframe header may have a 2-repetited waveform, and the synchronization channel outside the superframe header may have a waveform that is not repeated in the time domain.

As shown in FIG. 10, in the case of a synchronization channel outside the superframe header (for example, W1 to W4) considering the frequency reuse factor 4, the synchronization channel in the superframe header has a code length twice as long as that of the synchronization channel outside the superframe header. Will have If the sync channel outside the superframe header considers the reuse factor F and the sync channel in the superframe header has a waveform that is repeated t times, the sync channel in the superframe header is F / t times that of the sync channel outside the superframe header. Will have a long code length. More specifically, when the synchronization channel outside the superframe header has a waveform repeated t_O times, the synchronization channel in the superframe header has a long code of t_O * F / t times. In this case, since cell ID detection is performed on a synchronization channel outside the superframe header, the card number of the code set C and the number of elements of C 'need not be the same.

In this case, when cell ID information is transmitted in a synchronization channel in a superframe header, one-to-one mapping between a code of C 'and a code of C is effective. However, when the code set C 'is larger than the code set C, information other than the cell ID (eg, control information) may be transmitted using the remaining code. In addition, the system may dynamically set what information is transmitted through a redundant code set.

In addition, there may be a case where the code of C 'does not transmit the cell ID. When the sync channel in the superframe header indicates some cell ID group, part of the transmittable information may be other control information. For example, some of the information that can be transmitted includes cyclic prefix length (CP), legacy support, femto / relay / sector / cell indicators, system bandwidth settings, and multi-carrier support operations. (multicarrier support operation) may be information for informing. Such a transmission method of additional information can be applied even when t_O and t are set to be the same.

In the following description, a synchronization channel includes a primary channel (P-SCH) and a secondary synchronization channel (S-SCH), and a symbol primary synchronization channel is transmitted in units of 20 ms, and the initial network of the terminal is transmitted through the secondary synchronization channel. Assume a case where entry is impossible. Hereinafter, when the UE should perform the initial timing / frequency synchronization task only through the primary synchronization channel, a primary synchronization channel design for efficient entry into the network will be described.

There are three ways of informing the terminal of arbitrary information through the primary synchronization channel at the time of initial network entry. That is, there is a method of transmitting information by distinguishing a code or a sequence, a method of transmitting information in an arrangement on a frequency axis, and a method of transmitting information in an arrangement on a time axis. Of the three methods, the time axis arrangement method is not applicable because there is no timing sequence at the initial network entry.

Hereinafter, a method of transmitting information by distinguishing a code or a sequence and a method of transmitting information by arrangement on a frequency axis will be described.

The former generates 2 ^ n different sequences mapped to n bits of information, and after performing an initial timing / frequency synchronization operation, obtains a correlation for each target code and selects the sequence having the highest peak.

In addition to generating different 2 ^ n sequences, a cyclic delay shift may be applied to a time or a frequency axis to allow a terminal to distinguish sequences. For example, if r circular delays can be given, only 2 ^ (n-r) sequences may be generated, and 2 ^ r information may use a cyclic delay shift.

Additional information transmitted in 2 ^ n different sequences is n bits of information. In this case, n may not be an integer. For example, when 3-sector information and additional m (integer) bit information are transmitted simultaneously as additional information, it is obvious that 3 * 2 ^ m different sequences can be allocated.

On the other hand, in the method of transmitting information through the arrangement in the latter frequency axis, there is no reference in the initial synchronization in the frequency axis as in the arrangement in the time axis. However, if the frequency offset value between the base station and the terminal does not deviate from one subcarrier and the transmission of the primary synchronization channel has N repetition structures, the terminal transmits the initial synchronization using the index of the subcarrier where the repetition structure is located. Can be used to distinguish information.

7 to 10 illustrate a configuration example of a synchronization channel using reuse factor 1 and reuse factor 4, an embodiment of the present invention is applied even when the synchronization channel code length does not have a functional relationship corresponding to the reuse factor. It is possible.

The following describes the information transmitted through the primary synchronization channel during initial synchronization.

First, sector ID information is one of information that must be transmitted through the primary synchronization channel. Assuming that cell planning is properly performed, the LOS direction is different from each other in the case of a sector having the same sector ID even in an adjacent cell. Thus, interference between two sectors can be eliminated. If a terminal receives a primary synchronization channel having the same sequence in two adjacent sectors or several sectors, delay spread of the receiving primary synchronization channel due to the formation of a single frequency network (SFN) ) May have a long effect, and there may be a problem in determining an accurate transmission timing of a sector to which the terminal is to enter. In this case, the interference problem of the primary synchronization channel can be solved by transmitting sector ID information on the primary synchronization channel.

Secondly, by transmitting 1-bit information through the primary synchronization channel, it is possible to distinguish between a fully configured carrier and a partially configured carrier. In this case, it is assumed that the primary sync channel is also transmitted to the partial carrier. The IEEE 802.16m system assumes a multi-carrier (MC) environment. In the MC environment, each terminal or base station may use a plurality of carriers as its frequency band instead of one carrier. In this case, the plurality of carriers may be adjacent to each other or may be separated from each other. In addition, each terminal or base station may transmit and receive a plurality of adjacent carriers by aggregating one carrier. In the MC environment, two carrier types are assumed. First, there may be a fully-configured carrier through which the terminal transmits all necessary control information for initial network entry. Second, the terminal cannot enter the initial network and transmit data. There may be a partially configured carrier for transmitting only simplified control information for the carrier. The MCI (Multi-carrier index) related to the MC and detailed information related thereto are transmitted through the broadcast channel, but the distinction between the full set carrier and the partial set carrier is performed in the primary synchronization channel in terms of reducing unnecessary operation of the terminal. desirable.

Third, 1-bit information may be transmitted through a primary sync channel to indicate whether a dedicated MBS carrier or a general carrier is used. When a specific carrier is allocated to a dedicated MBS in the MC situation, it is necessary to inform that its carrier is a dedicated MBS carrier through the primary synchronization channel. Assuming that the terminal directly enters the network by using the dedicated MBS carrier, the terminal briefly distinguishes between the network entry using the unicast carrier and the other type of network entry through the distinguishing information of the dedicated MBS carrier included in the primary synchronization channel. Can be done.

Fourthly, the bandwidth information of the secondary synchronization channel or system can be delivered. The primary synchronization channel must have a minimum bandwidth of the system (assuming 5 MHz in the case of 16m) because terminals with various capabilities must perform initial synchronization and initial network entry. However, the secondary synchronization channel may have a minimum bandwidth or occupy the entire bandwidth of the system bandwidth. In addition, in the MC environment, the position of the primary synchronization channel with respect to the entire system band may be various. For example, in the 10 MHz system band, the primary synchronization channel may be located in the middle, or may be located at either end of 5 MHz. In this MC environment, since the location and bandwidth of the secondary synchronization channel are not fixed, if the primary synchronization channel transmits information on the bandwidth of the secondary synchronization channel, efficient initial network entry can be performed.

Fifth, it is possible to obtain the CP length of the operating cell through the information contained in the primary synchronization channel itself.

The IEEE 802.16m system uses various CPs according to environmental and geographical influences. When acquiring the initial system information, the terminal does not know the used CP length of the cell attempting to acquire the information. Therefore, it is efficient to transmit CP information through the primary synchronization channel.

Sixth, whether the current carrier to perform the initial entry in the MC situation may indicate whether through the primary synchronization channel. The IEEE 802.16m system should be able to coexist with legacy IEEE 802.16e system by TDM or Frequency Division Multiplexing (FDM). Therefore, when acquiring initial system information through the primary synchronization channel, the target cell supports only legacy support mode (that is, a mode in which IEEE 802.16e and IEEE 802.16m coexist) and IEEE 802.16m through information contained in the synchronization channel itself. If the terminal can obtain the information that can distinguish whether the mode to be more efficient.

Seventh, it can inform the femto / relay information for a specific cell. The IEEE 802.16m system may be configured to have different characteristics from a macro cell, such as a femto cell or a relay cell. A femto cell with indoor or small cell size may be configured for increased data rate and coverage expansion, or a relay cell may be configured to support a shadow area caused by a geographic influence or an external environment. Therefore, when acquiring initial system information through the synchronization channel, it is more efficient if the terminal can acquire information on which cell is the target cell through a signal contained in the primary synchronization channel itself. In this process, the corresponding cell ID in the secondary synchronization channel may be recognized as a femto or relay cell ID based on the indication information on the femto or relay cell, or the femto or relay cell ID may be obtained through broadcast control information.

In this case, the base station may inherit the primary sync channel of the base station for information on the base station that manages the femto or relay and decode the broadcast channel. In addition, the base station may further transmit the indication information for the femto / relay. In the case of a UE accessing a femto / relay in an arbitrary cell, if the information of the corresponding base station can be acquired at the time of measuring or scanning a neighboring relay / femto cell, an effective access is possible at the time of handover or network entry.

Finally, the number of transmit antennas can be indicated by information contained in the primary sync channel itself. The IEEE 802.16m system considers multi-antenna transmission for synchronous channel transmission and control information and data transmission. Therefore, when acquiring initial system information through the primary synchronization channel, the terminal determines the number of antennas (for example, an antenna used for transmission of a broadcast channel or a secondary synchronization channel) through information included in the synchronization channel itself. It is more efficient if you can acquire it.

According to an embodiment of the present invention, by configuring a synchronization channel in the superframe header and a synchronization channel outside the superframe header and setting different frequency reuse factor values, it is easy to acquire the synchronization of the terminal, and the received signal strength and path loss ( It is possible to improve the accuracy of the pathloss measurement.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary and will be understood by those skilled in the art that various modifications and embodiments may be made therefrom. And, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

The present invention relates to a synchronization channel structure having two different reuse factors in one superframe, and can be applied to devices such as base stations and terminals in systems such as IEEE 802.16m and IEEE 802.16e.

1 shows a general frame structure of IEEE 802.16m.

2 shows the position in the superframe of the synchronization channel of IEEE 802.16m.

3 illustrates a legacy support mode in which a synchronization channel of IEEE 802.16e and IEEE 802.16m is mixed and transmitted by TDM.

4A and 4B show examples of frequency reuse.

5 illustrates a synchronization channel structure using different reuse factors according to an embodiment of the present invention.

6 illustrates an example of a frequency band used by a synchronization channel at each position in a superframe.

FIG. 7 illustrates an example of transmitting a code of length F times the code used for the remaining sync channels to the sync channel located in the superframe header.

8 illustrates an example of transmitting a code having the same length as a code transmitted to the remaining sync channels to a sync channel located in a superframe header.

FIG. 9 illustrates an example of transmitting a length of a code used for a synchronization channel in a superframe header in an intermediate form of FIGS. 7 and 8.

FIG. 10 illustrates a case where a frequency mapping relationship between synchronization channels in and out of a superframe header is different when a Nsub / 2 length code is transmitted to a synchronization channel in the superframe header.

Claims (13)

In the method for transmitting a synchronization channel in a superframe consisting of a plurality of frames, Transmitting a first synchronization channel having a predetermined frequency reuse factor in the superframe header; And Transmitting a second synchronization channel having a frequency reuse factor different from the first synchronization channel in the remaining frame to which the superframe header does not belong. A synchronization channel transmission method comprising a. The method of claim 1, The second sync channel, And transmitting at least a portion of a frequency band in which the first synchronization channel is transmitted. The method of claim 1, The first sync channel is, And a repetition structure different from the repetition structure of the second synchronization channel. The method of claim 1, The first sync channel is, And a code having a code length different from that of the second sync channel. The method of claim 4, wherein The first sync channel is, And using a code having a length corresponding to the reuse factor value of the second synchronization channel. The method of claim 5, wherein The first sync channel is, And a code having a length corresponding to a value obtained by multiplying a reuse factor value of the second synchronization channel by a ratio of the number of repetitions of the second synchronization channel to the number of repetitions of the first synchronization channel. . The method of claim 1, The second sync channel, And using a code having the same code length as that of the first sync channel. The method of claim 7, wherein The first sync channel is, And using a plurality of different code sets. The method of claim 1, The first sync channel and the second sync channel, Transmitting codes mapped to a cell identifier to be supported. The method of claim 1, The transmitting of the first sync channel may include: Transmitting a synchronization channel with a frequency reuse factor of one. The method of claim 1, Transmitting the second sync channel, Transmitting a sync channel with a frequency reuse factor of 3 or 4; In the method for receiving a synchronization channel in a superframe consisting of a plurality of frames, Receiving a first synchronization channel having a predetermined frequency reuse factor in the superframe header; And Receiving a second sync channel having a frequency reuse factor different from the first sync channel in the remaining frames after the superframe header A synchronization channel receiving method comprising a. The method of claim 12, And detecting and aggregating a cell identifier in the first sync channel and the second sync channel, respectively.

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