WO2010095898A2

WO2010095898A2 - Communication method for femto base station

Info

Publication number: WO2010095898A2
Application number: PCT/KR2010/001066
Authority: WO
Inventors: 이진; 김용호; 류기선; 정인욱
Original assignee: 엘지전자 주식회사
Priority date: 2009-02-20
Filing date: 2010-02-22
Publication date: 2010-08-26
Also published as: WO2010095898A3

Abstract

The present invention discloses a communication method for a femto base station in consideration of a legacy terminal, and an operating technique of terminals based on an improved system in the communication method. The femto base station communicates using a frame structure including only a preamble, FCH, and DL-MAP as legacy system information to enable the legacy terminal to detect the femto base station. Moreover, the femto base station converts modes to use a frame structure in which a legacy area and an improved system area are sequentially included in necessity to connect with the legacy terminal. Therefore, the legacy terminal detects the femto base station to perform handover/interference control. The improved system terminal which operates in L mode detects the femto base station to perform handover/interference control too.

Description

Communication Method of Femto Base Station Considering Legacy Terminal

In the following description, a mobile communication system including a macro base station, at least one femto base station, and at least one terminal, a communication method of a femto base station in consideration of a legacy terminal, and an additionally improved operation method of a terminal for a system.

A femto base station is a small version of a macro base station, which performs most of the functions of a macro base station, and is a type of base station that may be installed in an area covered by the macro base station or in a shaded area not covered by the macro base station. A femto base station has a network configuration that operates independently and can be installed much more than a relay base station in the city or indoors.

1 is a configuration diagram of a wireless communication system to which a femto base station is added.

As shown in FIG. 1, a wireless communication system to which a femto base station is added includes a femto base station 110, a macro base station, a femto network gateway (FNG) 130, and an access service network. service network (hereinafter referred to as "ASN") 140 and a connectivity service network (hereinafter referred to as "CSN") 150. Macro base station means a general base station of a conventional wireless communication system.

The femto base station 110 operates directly as a macro base station by directly connecting to a transmission control protocol / internet protocol (TCP / IP) network and has a coverage of about 0.1 to 30 m, and can be accommodated by one femto base station 110. It is assumed that there are about 10 to 20 terminals. The femto base station 110 may use the same frequency as the macro base station (in the case of intra FA), or may use another frequency (in the case of Inter FA).

The femto base station 110 may be connected to the macro base station through an R1 interface to receive a downlink channel of the macro base station, and the femto base station 110 may transmit a control signal to the macro base station.

The femto base station 110 may cover an indoor or shadowed area that the macro base station does not cover and may support high data transmission. The femto base station 110 may be installed in an overlay form in the macro cell, or may be installed in a non-overlay form in an area not covered by the macro base station.

Femto base station 110 is classified into two types. The first type is a closed subscriber group (CSG) femto base station, and the second type is an open subscriber group (OSG) femto base station. The CSG femto base station may group the terminals accessible to it to grant a CSG ID (identification), and may discriminate when the terminal that has been granted the CSG ID and the terminal that do not access the CSG femtocell base station. The OSG femtocell base station is a base station to which all terminals can access.

The FNG 130 is a gateway controlling the femto base station 110 and may be connected to the ASN 140 and the CSN 150 through the Rx interface and the Ry interface. The femto base station 110 may receive a service from the CSN 150 through the FNG 230, and the terminal connected to the femto base station 110 may provide functions such as authentication and IMS to the FNG 130 or the CSN 150. You can get the service from.

The CSN 150 provides a terminal with a connection of application services such as the Internet and VoIP, and provides authentication and billing functions. The ASN 140 can control the macro base station and manage the connection between the macro base station and the CSN 150. have.

On the other hand, the femto base station as described above is proposed to be introduced in the IEEE 802.16m (hereinafter referred to as 16m) system which is currently being standardized as an improvement model of the IEEE 802.16e (hereinafter referred to as 16e) system. The 16m system stipulates to selectively support legacy systems, that is, terminals according to the 16e system, for backward compatibility.

In the above system situation, when a legacy terminal (YMS) exists around a 16m femto base station, if a 16m femto base station uses the same frame structure as a macro base station supporting only a 16m system, a network entry may be performed with a 16m femto base station. It may cause serious interference to legacy legacy terminals.

Therefore, in the following description, when the femto base station communicates with the terminal / macro base station, considering the legacy terminal, the femto base station sets the femto base station to use the frame structure in which the legacy terminal can recognize the femto base station. Techniques for enabling over / interference adjustment will be described.

In addition, even when an improved system terminal performs communication using a legacy system resource region, a technique for efficiently performing a procedure such as handover by recognizing a femto base station will be described.

In an aspect of the present invention for solving the above problems, a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS) and a terminal for an improvement system (hereinafter referred to as AMS) in which a specific function is added to the legacy system. In the method for the femto base station to communicate with at least one of the macro base station, the YMS and the AMS in a mobile communication system comprising: a wireless having a first type frame structure without being connected to the YMS And communicating with at least one of the macro base station and the AMS using a frame, wherein the first type frame structure comprises: a first section corresponding to an initial predetermined symbol section of a specific radio frame; Only the preamble, the frame control header (FCH) and the DL-MAP are transmitted as system information, and the specific wireless program is transmitted. Im propose within the macro base station via the predetermined second time period subsequent to the symbol interval and the communication method of performing a femto base station is configured to transmit a signal for performing one or more of the communication with the AMS.

In this case, the first interval is located in the first predetermined symbol interval of the first subframe of the specific radio frame, and the femto base station punctures the symbol interval after the first predetermined symbol interval in the first subframe. The second period may be located from the second subframe of the specific radio frame.

In addition, the DL-MAP transmitted as the information for the legacy system includes a base station ID corresponding to the femto base station, and when the YMS receives a radio frame having the first type frame structure, the information as the legacy system information. A base station ID corresponding to the femto base station may be obtained through the transmitted DL-MAP.

In addition, the radio frame having the first type frame structure does not include the UL-MAP and the ranging region for the legacy system, when the YMS receives the radio frame having the first type frame structure, the femto base station May not try to enter the network.

In addition, the present embodiment includes the steps of receiving from the macro base station a message instructing to perform communication using a radio frame having a second type frame structure; And communicating with at least one of the macro base station and the AMS and the YMS using a radio frame having the second type frame structure, wherein the second type frame structure And a downlink region for the legacy system, a downlink region for the enhancement system, an uplink region for the legacy system, and an uplink region for the enhancement system in a specific radio frame. In this case, the femto base station may be a closed subscriber group (CSG) femto base station, and the YMS may be a member terminal of the CSG femto base station.

In addition, the present embodiment includes receiving an interference mitigation command from the macro base station; And in accordance with the interference coordination command, suspending the use of a particular resource region.

Meanwhile, in another aspect of the present invention, a mobile communication including a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS), and a terminal for an enhancement system (hereinafter referred to as AMS) in which a specific function is added to the legacy system. A method in which the AMS communicates with at least one of the macro base station and the femto base station in a system, the method comprising: operating in a first mode for communicating with the macro base station using the resource area for the legacy system; When the femto base station receives interference due to a signal transmitted using a radio frame having a first type frame structure, switching a mode to a second mode in which communication is performed using the resource region for the enhancement system; And performing a handover to the femto base station, wherein the first type frame structure includes a preamble and an FCH as information for the legacy system through a first section corresponding to an initial predetermined symbol section of a specific radio frame. (Frame Control Header) and DL-MAP only, and transmits a signal for communicating with at least one of the macro base station and the AMS through a second section following the predetermined symbol section in the specific radio frame. The AMS proposes a communication method of the AMS that acquires information on the femto base station by using the preamble transmitted as information for the legacy system, the FCH, and the DL-MAP.

The present embodiment includes reporting scan information about neighboring base stations to the macro base station using the information on the femto base station; And receiving a handover command from the macro base station. The method may further include performing a terminal-initiated handover to the femto base station by using the information on the femto base station.

Meanwhile, in another aspect of the present invention, a mobile communication including a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS), and a terminal for an enhancement system (hereinafter referred to as AMS) in which a specific function is added to the legacy system. A femto base station apparatus for communicating with at least one of the YMS and the AMS in a system, comprising: a processor including the legacy system MAC module and the enhancement system MAC module; And an RF unit, wherein the processor is configured to communicate with at least one of the macro base station and the AMS using a radio frame having a first type frame structure without being connected to the YMS through the RF unit. The first type frame structure is configured to transmit only a preamble, a frame control header (FCH), and a DL-MAP as information for the legacy system through a first period corresponding to an initial predetermined symbol period of a specific radio frame. And a femto base station apparatus configured to transmit a signal for communicating with at least one of the macro base station and the AMS through a second section following the predetermined symbol section in the specific radio frame.

In this case, the DL-MAP transmitted as the information for the legacy system includes a base station ID corresponding to the femto base station, and when the YMS receives a radio frame having the first type frame structure, the information as the legacy system information. A base station ID corresponding to the femto base station may be obtained through the transmitted DL-MAP.

Further, when receiving a message instructing to perform communication using a radio frame having a second type frame structure from the macro base station through the RF unit, the processor receives the second type frame structure through the RF unit. By using a radio frame having a may be controlled to communicate with at least one of the macro base station and the AMS, and also the YMS, wherein the second type frame structure, the downlink for the legacy system in a specific radio frame And a link region, a downlink region for the enhancement system, an uplink region for the legacy system, and an uplink region for the enhancement system. Here, the femto base station may be a closed subscriber group (CSG) femto base station, and the YMS may be a member terminal of the CSG femto base station.

In addition, when the RF unit receives an interference mitigation instruction from the macro base station, the processor may suspend the use of a specific resource region according to the interference mitigation instruction.

Meanwhile, in another aspect of the present invention, a mobile station includes a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS), and a terminal for an improved system (hereinafter referred to as AMS) to which a specific function is added to the legacy system. An AMS apparatus for communicating with at least one of the macro base station and the femto base station in a communication system, comprising: a processor including the legacy system MAC module and the enhancement system MAC module; And an RF unit, wherein the processor is configured to control the macro base station to operate in a first mode for performing communication using the macro base station and the legacy system resource area through the MAC module for the legacy system. When interference is caused by a signal transmitted using a radio frame having a type 1 frame structure, the mode is switched to a second mode in which communication is performed using the resource region for the enhancement system using the MAC module for the enhancement system. And performing a handover to the femto base station, wherein the first type frame structure includes a preamble and an FCH (information) for the legacy system through a first section corresponding to an initial predetermined symbol section of a specific radio frame. Frame Control Header) and DL-MAP only, and the predetermined symbol in the specific radio frame Is configured to transmit a signal for communicating with at least one of the macro base station and the AMS through a subsequent second interval, wherein the processor is transmitted as information for the legacy system and received by the RF unit; An AMS device for acquiring information about the femto base station using the FCH and the DL-MAP is proposed.

In this case, the processor may be configured to report scan information about neighboring base stations to the macro base station through the RF unit and to receive a handover command from the macro base station using the information on the femto base station.

In addition, the processor may control to perform a terminal-initiated handover to the femto base station by using the information on the femto base station.

According to the above-described technique, a terminal using a legacy terminal and / or a legacy system resource region may recognize a femto base station and perform a procedure such as handover / interference coordination to a femto base station, and the femto base station may also be a resource. Can be used efficiently.

2 illustrates a 16e frame structure.

3 illustrates a frame structure used by a legacy support macro base station.

4 and 5 illustrate a frame structure that can be used by the femto base station according to an embodiment of the present invention.

6 is a view for explaining a first embodiment of the present invention.

7 is a view for explaining a second embodiment of the present invention.

8 is a view for explaining a third embodiment of the present invention.

9 is a view for explaining a fourth embodiment of the present invention.

10 is a view for explaining a fifth embodiment of the present invention.

FIG. 11 is a diagram for briefly describing an apparatus configuration of a terminal, a femto base station, and a macro base station according to embodiments of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, “unit”, etc. described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. It can be implemented as.

Embodiments to be described below will be described with the assumption of a mobile communication system conforming to the IEEE 802.16m standard for convenience of description, but need not be limited thereto. The base station and the terminal according to the IEEE 802.16m system can be improved from a legacy system, for example, a mobile station (hereinafter referred to as YMS) and a base station (hereinafter referred to as YBS) according to the IEEE 802.16e system. Advanced BS (ABS), Advanced MS (AMS). In addition, hereinafter, for convenience of description, a legacy system will be described as an IEEE 802.16e system, and an improved system will be described as an IEEE 802.16m system. However, the present invention is not limited thereto. In a situation where two systems coexist, such as an additionally improved system, a legacy system, an improved system, may be defined to distinguish between the two systems.

Based on the above description, the following describes in detail the method for the femto base station to perform communication in consideration of the legacy terminal.

First, the legacy terminal recognizes the base station (macro base station), and looks at the 16e frame structure to specify the mechanism for performing the communication.

2 illustrates a 16e frame structure.

As shown in FIG. 2, the 16e frame starts with a preamble (OFDMA symbol k) for synchronization in the physical layer and cell ID discovery (OFDMA symbol k), and then used for the length of the DL-MAP message and the DL-MAP message. And a DL-MAP for allocating resources for a downlink data burst and a frame control header (FCH) including information on the repeated coding scheme (OFDMA symbol k + 1). Meanwhile, downlink bursts may be included in OFDMA symbols k + 3 to k + 15, and the first downlink burst may include UL-MAP. Meanwhile, the 16e frame may include a ranging subchannel and uplink bursts through a transmit / receive transition gap (TGT) for transmitting and receiving switching.

The legacy terminal synchronizes with the base station (macro base station) through the preamble of the frame structure of FIG. 2, obtains a cell ID, obtains information for receiving DL-MAP through FCH, and uses data using DL-MAP. Burst resource allocation information can be obtained.

Meanwhile, a frame structure that can be used by a macro base station supporting a legacy system in a situation where a legacy terminal and a 16m terminal coexist is as follows. Hereinafter, the 16m macro base station supporting the legacy system is referred to as legacy support base station (AMS) or mixed mode base station (AMS).

3 illustrates a frame structure used by a legacy support macro base station.

As shown in FIG. 3, the frame structure (5 ms) used by the legacy support macro base station may sequentially include a 16e downlink section, a 16m downlink section, a 16e uplink section, and a 16m uplink section in one radio frame. have. In addition, the 16e preamble may be transmitted to the start position of the 16e downlink period, and the 16m preamble may be transmitted to the start position of the 16m downlink period. The 16m preamble may be referred to as an advanced preamble or an A-Preamble to distinguish it from the preamble for the 16e system. Meanwhile, a switching point for switching transmission and reception may exist between the 16m downlink period and the 16e uplink period.

By using the frame structure as shown in FIG. 3, the legacy support macro base station can support not only AMS but also YMS.

Based on the above description, a method of efficiently communicating with a femto base station in consideration of a legacy terminal and a method of operating AMS at this time will be described. In order to explain these methods efficiently, the following terms will be defined and used.

16e zone: Refers to a resource zone that supports communication according to the 16e system in the frame structure shown in FIG. 3.

16m region: Refers to a resource region supporting communication according to the 16m system in the frame structure as shown in FIG.

L mode: Refers to a mode in which AMS or ABS operates in the 16e region.

M mode: Refers to a mode in which AMS or ABS operate in a 16m region.

M mode of the femto base station: The femto ABS operates in the 16m region and transmits the 16e preamble, the FCH, and the 16e general DL-MAP through the 16e region. This will be described later in detail with reference to FIGS. 4 and 5.

L, M mode of the femto base station: The femto ABS refers to operating in both the L mode and the M mode, like the legacy ABS.

The femto base station according to an embodiment of the present invention proposes to solve the problem of the legacy terminal not recognizing the femto base station by using the same frame structure used by the legacy support macro base station as shown in FIG. 3. That is, in the above definition, the femto base station proposes to operate in the L and M modes.

Specifically, if the femto ABS supports YMS and at least one or more YMSs are connected to the femto ABS, it is assumed that the femto ABS uses the same structure as the frame structure used by the legacy support macro ABS as shown in FIG. 3.

Meanwhile, femto ABS has various types as follows. First, the femto ABS can be divided into CSG femto ABS and OSG femto ABS as described above. In addition, even in the CSG femto ABS can be divided into two types according to the accessibility of the non-member terminal, that is, the terminal that is not given the CSG ID.

CSG Closed Femto ABS is a type that allows access only to member terminals. The terminal may store the CSG closed femto base station identifiers allowed for access thereof in a white list. In addition, the CSG open femto base station (CSG-Open Femto ABS) preferentially supports the service to the member terminals, and the type of allowing access to non-member terminals if there is sufficient resources. However, service levels for non-member terminals may be differentiated as compared to member terminals. The classification of the CSG open / closed femto base station can be known through partition information in an AAI_SCD (Advanced Air Interface System Configuration Descriptor) message.

According to the classification of the CSG femto ABS as described above, there may be a CSG femto that the legacy terminal cannot access. However, legacy terminals that do not have a white list, ie, a femto ABS list to which the AMS is allowed to access, may attempt to access a femto ABS that is not accessible, thereby causing unnecessary uplink signaling.

According to the present embodiment, the femto ABS using the frame structure as shown in FIG. 3 can operate in both the L mode and the M mode, such as the ABS operating in the mixed mode. In addition, since the 16e preamble, the FCH, and the DL-MAP are transmitted as in the mixed mode macro ABS, the legacy terminal can discover the femto ABS. Therefore, even though the legacy terminal is not allowed to access the femto ABS, the legacy terminal may request interference mitigation from the macro ABS as follows.

For example, when the macro base station and the femto base station are installed at the same frequency, non-member CSG terminals connected to the macro base station may feel interference from neighboring femto base stations. Accordingly, when the terminal can recognize the corresponding femto base station, scanning can be performed to report the scanning result to the macro base station. The macro base station may check the scanning result and select the femto base stations having a high degree of interference, and block or reserve resources of a predetermined area to the femto base stations so that the terminal does not feel interference. When the femto base station uses the frame structure as shown in FIG. 3 according to the present embodiment, the legacy terminal may also recognize the femto base station through the 16e preamble, FCH, DL-MAP, and request interference coordination from the macro base station. .

Meanwhile, another embodiment of the present invention proposes another frame structure that can be used by the femto base station in consideration of the legacy terminal.

First, FIG. 4 is an enlarged view of one radio frame of 5 ms in length, and FIG. 5 is a diagram continuously showing a radio frame of 5 ms in length. The frame structure according to the present embodiment proposes to transmit 16e preamble, FCH and DL-MAP in a predetermined OFDMA symbol period from the start position of every frame as shown in FIGS. 4 and 5. The 16e preamble transmitted as described above may allow the legacy terminal to discover the femto ABS. However, the base station ID (BS ID) cannot be directly detected by discovering the preamble from the legacy terminal point of view, and only the cell ID is found through the preamble. The 16e FCH includes a DL frame prefix and may inform the DL-MAP message length and the repetition code used for the DL-MAP message. The FCH may have a format as shown in Table 1 below.

Table 1

Syntax	Size (bits)	Notes
DL_Frame_Prefix_Format () {	-	-
Used subchannel bitmap	6	Bit # 0: subchannel group 0 bit # 1: sub channel group 1 bit # 2: sub channel group 2 bit # 3: sub channel group 3 bit # 4: sub channel group 4 bit # 5: sub channel group 5
Reserved	One	Set to 0
Repetition_Coding_Indications	2	0b00: No repetitive coding in DL-MAP 0b01: Repetitive coding 2 in DL-MAP 0b10: Repetitive coding 4 in DL-MAP 0b11: Repetitive coding 6 in DL-MAP
Coding_Indication
	3	0b000: CC encoding applied to DL-MAP 0b001: BTC encoding applied to DL-MAP 0b010: CTC encoding applied to DL-MAP 0b011: ZT CC encoding applied to DL-MAP 0b100: CC encoding with optional interleaving 0b101: LDPC encoding is applied to DL-MAP 0b110-0b111: Reserved
DL-MAP_Length	8	-
Reserved	4	Set to 0
}	-	-

As described above, the legacy terminal may not discover the BS ID through the 16e preamble, and the BS ID may be obtained through the DL-MAP message. In order for the legacy terminal to discover the full BS ID, the femto base station according to the present embodiment forms a 16e general DL-MAP message instead of the compact DL-MAP for transmitting a short BS ID. It is proposed to transmit a DL-MAP message. The 16e DL-MAP message format transmitted by the femto base station according to the present embodiment may be represented as shown in Table 2 below.

TABLE 2

Syntax	Size (bits)	Notes
DL-MAP_Message_Format () {	-	-
Management Message Type = 2	8	-
PHY Synchronization Field	variable	PHY Standard Reference
DCD Count	8	-
Base Station ID	48	-
Begin PHY-specific section {	-	See corresponding PHY section
if (WirelessMAN-OFDMA) {	-	-
No. OFDMA symbols	8	For TDD, the number of OFDMA symbols in the downlink subframe includes all AAS / permutation regions and preambles. See IEEE 802.16e section 8.4.4.2.2 for FDD
}	-	-
for (i = 1; i <= n; i ++) {	-	For each DL-MAP element 1 to n
DL-MAP_IE ()	variable	See corresponding PHY standard
}	-	-
}	-	-
if! (byte boundary) {	-	-
Pading nibble	4	Padding down to the byte boundary
}	-	-
}	-	-

When the legacy terminal recognizes the femto base station according to the present embodiment, when the legacy terminal reports the femto base station ID to the macro base station, the legacy terminal also transmits the entire BS ID. Reporting the detected femto BS through MOB_SCN-REP may be triggered based on a predetermined reporting condition.

4 and 5, all other subframes can be used in the 16m region except for symbols used by the femto base station to transmit 16e preamble, FCH and DL-MAP according to the present embodiment. have. Referring to FIG. 4, except for symbols used to transmit 16e signals (preamble, FCH, DL-MAP) in the first subframe, the remaining symbols are punctured and subframes 2 to 8 are all 16m regions. It is shown using. As described above, the use of subframe 1 for the 16e signal transmission and the puncturing of the rest part is performed by performing resource allocation in subframe units when allocating resources in the physical layer. However, if necessary, the remaining symbols may also be used as the 16m region except for the symbols used for the 16e signal transmission in the subframe 1. As shown in FIG. 4, the first subframe may consist of 5 or 6 OFDMA symbols. In addition, one or more symbols may be used for DL-MAP transmission.

The frame structure according to the present embodiment proposes that the legacy terminal is not connected and is configured such that the legacy terminal does not attempt an uplink connection. Accordingly, as compared with the embodiment shown in FIG. 3, as shown in FIG. 5, the 16e UL-MAP is not transmitted, and a ranging region is not allocated, so the legacy terminal (non-member MS) is corresponding. You cannot enter the network with Femto ABS. That is, in this embodiment, although femto ABS supports YMS, if there is no YMS currently connected to the femto ABS, it is proposed to use the frame structure as shown in FIGS. 4 and 5.

In the case of using the frame structures shown in FIGS. 4 and 5, an extended 16m zone can be obtained as compared to the frame structure shown in FIG. 3. By using the extended 16m area shown in FIGS. 4 and 5, the femto ABS can perform 16m communication more efficiently in a state in which the femto ABS is not connected to the YMS.

In summary, the frame structure shown in FIGS. 4 and 5 (hereinafter also referred to as 'first frame structure') has the following advantages and disadvantages compared to the frame structure shown in FIG. 3 (hereinafter also referred to as 'second frame structure'). Have

First, when the first frame structure is used, an extended M area may be obtained by using the L area more efficiently than the second frame structure. In addition, it has the advantage of preventing unnecessary connection signaling of the non-CSG member YMS. In general, since the femto base station is required to be implemented at a low cost of about $ 100, compared to setting the femto base station to support all legacy terminals in terms of cost / performance, the legacy terminal recognizes the femto base station as described above. It may be more efficient to only make it possible and to have the legacy terminal request interference coordination from the macro base station when interference is a problem.

However, in the case of the first frame structure, it is not appropriate to use when more than one YMS is connected. That is, the first frame structure is suitable for use when the YMS is not connected.

Therefore, hereinafter, a description will be given on various assumptions about a method for efficiently performing communication by a femto base station by using the advantages and disadvantages described above.

제 1 실시예First embodiment

6 is a view for explaining a first embodiment of the present invention.

As shown in FIG. 6, it is assumed that a legacy terminal (YMS) is a member of a legacy support femto BS, which is a CSG femto base station, and is currently connected to a macro ABS. In addition, it is assumed that the macro base station and the CSG femto base station are located in the same frequency band, causing interference to the YMS.

Step 1: If the femto ABS supports the legacy terminal but there is no legacy terminal currently connected to the corresponding femto base station, the femto base station uses the first frame structure described above as 16e information as 16e preamble, FCH, general Only DL-MAP will be transmitted.

Step 2: The legacy terminal may perform channel measurement through the 16e preamble transmitted by the femto base station and may discover the entire BS ID of the femto base station through the 16e general DL-MAP message read using the FCH information. Although the MAC module of the legacy terminal processor discovers the entire BS ID of the femto base station, it may not be able to distinguish whether or not the femto base station is accessible. This is because in the legacy terminal, the white list may be managed by an upper layer existing above the MAC layer.

Step 3: If the CINR level of the macro base station is below a predetermined threshold or the channel quality measured from the femto base station is greater than or equal to the predetermined threshold, the legacy terminal may transmit the channel measurement result to the macro base station through a scanning report. The above described scanning report triggering conditions are exemplary, and various triggering conditions may exist according to a system. If the macro base station determines that it can connect to the femto base station reported by the YMS to receive and determine the scanning report received from the YMS, the following process can be performed.

Step 4: The macro base station may transmit a mode change request (CHANGE_MODE-REQ) message to the femto base station via a backbone. This mode conversion request is a message for requesting the corresponding femto base station to switch from the mode using the first frame structure (M mode) to the mode using the second frame structure (L, M mode).

Step 5: The femto base station receiving the mode conversion request message from the macro base station may perform mode conversion from the mode using the first frame structure (M mode) to the mode using the second frame structure (L, M mode).

Step 6: The femto base station which has performed the mode conversion may transmit a mode change response (CHANGE_MODE-RSP) message to the macro base station as a response to the mode change request message (CHANGE_MODE-REQ) of the macro base station.

Step 7: The macro base station may transmit a handover command message to the legacy terminal to handover to the femto base station. FIG. 6 illustrates an example in which the macro base station delivers a fast ranging IE to a legacy terminal to avoid contention based ranging.

Step 8: Accordingly, the legacy terminal may request a handover by performing a ranging procedure with the legacy support femto base station.

제 2 실시예Second embodiment

7 is a view for explaining a second embodiment of the present invention.

In the present embodiment, it is assumed that the legacy terminal is a non-member terminal of the CSG femto base station and is currently connected to the macro base station. Also assume that the YMS is receiving interference from the femto base station.

Step 1: If the femto ABS supports the legacy terminal but no legacy terminal is currently connected to the corresponding femto base station, the femto base station uses the above-described first frame structure as a 16e signal as a preamble, FCH and general DL. Assume to send only MAP.

Step 3: If the CINR level of the macro base station is below a predetermined threshold or if the channel quality measured from the femto base station is greater than or equal to the predetermined threshold, the legacy terminal may transmit the channel measurement result to the macro base station through a scanning report. The above described scanning report triggering conditions are exemplary, and various triggering conditions may exist according to a system. Since it is assumed that the YMS is a non-CSG member in the present embodiment, the macro base station may determine that the YMS cannot access the corresponding femto base station, and may perform the following process.

Step 4: The macro base station may request a resource reservation to the corresponding femto base station through the backbone. In this case, the macro base station may use the MAC message or may use the reserved ranging code. In FIG. 7, the macro base station transmits an RSC_RSV-REQ message to the femto base station.

Step 5: The femto base station that has successfully received the resource reservation request message from the macro base station may perform resource reservation. Accordingly, the YMS can solve the interference problem caused by the femto base station.

Step 6: The femto base station performs a successful resource reservation and may transmit a response message (RSC_RSV-RSP) to the macro base station in response to the RSC_RSV-REQ message of the macro base station.

Step 7: In the present embodiment, additionally, the YMS periodically performs channel measurement, and the legacy terminal is satisfied when the triggering condition to send a channel measurement result scanning report is satisfied while the femto base station is no longer found and the femto base station is no longer found. It is proposed to transmit this scanning result to the macro base station. The macro base station that has received this may inform the femto base station to cancel the reservation of reserved resources.

In the present embodiment, a method of performing interference coordination with the femto base station through the macro base station is described in the present embodiment. However, according to the configuration of the YMS, the interference coordination may be requested by signaling the femto base station directly.

In addition, even if the femto base station is a femto base station supporting only 16m that can not operate in the L, M mode, the method of the embodiment described above with respect to FIG. That is, the femto base station supporting only 16m also uses the above-described first frame structure and accordingly, the legacy terminal can recognize the corresponding femto base station and request interference coordination from the macro base station.

In the third to fifth embodiments to be described below, it is assumed that the terminal is AMS rather than YMS. That is, it is assumed that the AMS is a terminal having both a 16e MAC module and a 16m MAC module in the processor, and the macro base station and the femto base station have the same environment. In addition, it is assumed that a specific upper layer module corresponding to a higher layer than the MAC layer in the processor of the AMS and the macro ABS can control switching between the 16e interface and the 16m interface.

제 3 실시예Third embodiment

8 is a view for explaining a third embodiment of the present invention.

In this embodiment, it is assumed that the AMS is operating in the macro ABS and the L mode as shown in FIG. 8. The AMS operates in the macro ABS and the L mode, which is an exceptional case and may be performed for cell load distribution.

Step 1: Meanwhile, it is assumed that the femto ABS transmits only the preamble, the FCH, and the general DL-MAP as 16e system information according to the first frame structure described above.

Step 2: Accordingly, the AMS may perform channel measurement from the 16e preamble transmitted by the femto base station, and acquire the BS ID of the femto base station through the FCH information and the general DL-MAP information.

Step 3: If the channel measurement result of the AMS is a CINR value from the macro base station is lower than the predetermined threshold, and the channel measurement result with the femto base station is higher than the predetermined threshold, the AMS sends MOB_SCN-REP to the macro base station, the channel measurement result May be reported to the macro base station. Accordingly, the macro base station may find that the AMS operating in the L mode may hand over to the femto ABS.

Step 4: The macro ABS may transmit a MAC message including a zone switch TLV (ALV) to the AMS to instruct the AMS to handover to the femto base station so that the AMS may change the interface.

Step 5: The AMS may perform a mode change from the L mode to the M mode by using the area switching TLV received in step 4.

Step 6: The 16m interface of the AMS may perform network entry to the femto base station using the 16m MAC message.

제 4 실시예Fourth embodiment

9 is a view for explaining a fourth embodiment of the present invention.

The fourth embodiment is similar to the third embodiment, but differs from the third embodiment in that the macro base station uses a 16m MAC message instead of a 16e MAC message.

In this embodiment, it is assumed that the AMS is operating in the macro ABS and the L mode as shown in FIG. 9. The AMS operates in the macro ABS and the L mode, which is an exceptional case and may be performed for cell load distribution.

Step 1: It is assumed that the femto ABS transmits only the preamble, the FCH, and the general DL-MAP as 16e system information according to the first frame structure described above.

Step 4: If the macro base station determines that the AMS can hand over to the femto base station, the macro base station itself may change the interface from L mode to M mode.

Step 5: In addition, the area switching TLV may be transmitted to the AMS through the 16e signal. Step 5 may be preferably performed before step 4 as shown in FIG. 9.

Step 6: The AMS may switch from L mode to M mode by performing mode switching according to the area switching TLV received from the macro base station.

Step 7: The M interface of the macro base station may command a handover to the AMS through a 16m message (eg, AAI_HO-CMD).

Step 8: The 16m interface of the AMS may perform network entry directly to the femto base station using the 16m MAC message.

제 5 실시예Fifth Embodiment

10 is a view for explaining a fifth embodiment of the present invention.

The fifth embodiment is similar to the third embodiment, but differs from the third embodiment in that handover is initiated by the terminal.

In the present embodiment, it is assumed that the AMS is operating in the macro ABS and the L mode as shown in FIG. 10. The AMS operates in the macro ABS and the L mode, which is an exceptional case and may be performed for cell load distribution.

Step 3: The AMS may request a handover to the femto base station found to the macro base station via the 16e signal. The MAC module of the AMS may not recognize the type of the base station as a femto, but may assume a macro base station and request a handover.

Step 4: The macro base station may send an area switching TLV together in a handover response (HO-RSP) message to allow the AMS to perform mode switching in order for the AMS to perform handover in M mode.

Step 5: After receiving the area switching TLV from the macro base station, the AMS may perform mode switching to convert to M mode.

Step 6: The 16m interface of the AMS may perform network entry directly to the femto base station using the 16m MAC message.

As can be seen in the above-described embodiments, each embodiment of the present invention can be used in various combinations. Accordingly, while the legacy terminal could not find the 16m femto base station, the interference generated from the femto base station installed in the same frequency domain as the macro base station could not be solved, but the interference adjustment or handover to the femto base station was performed using the present embodiments. Can be done.

In addition, by appropriately using the frame structures according to the embodiments of the present invention according to the situation, it is possible to prevent unnecessary femto base station access of the non-CSG member terminal, and to flexibly induce interference coordination / handover of the legacy terminal.

In addition, even when the AMS is operating in the L mode with the macro base station, the femto base station can be easily found to perform handover / interference coordination.

Hereinafter, an apparatus configuration for performing the communication method of the terminal, the femto base station, the macro base station as described above will be described.

The apparatus 50 shown in FIG. 11 may be a terminal (AMS or YMS), a femto base station, or a macro base station described in the above embodiments. The apparatus 50 includes a processor 51, a memory 52, a radio frequency unit (RF unit) 53, a display unit 54, and a user interface unit 55 as shown in FIG. 11. Layers of the air interface protocol are implemented in the processor 51. The processor 51 provides a control plan and a user plan. The function of each layer may be implemented in the processor 51. The processor 51 may include a contention resolution timer. Memory 52 is coupled to processor 51 to store operating systems, applications, and general files. If the device 50 is a terminal, the display unit 54 may display various information and use well-known elements such as a liquid crystal display (LCD) and an organic light emitting diode (OLED). The user interface unit 55 may be composed of a combination of well known user interfaces such as a keypad, a touch screen, and the like. The RF unit 53 may be connected to the processor 51 to transmit and receive a radio signal. The RF unit 53 may be divided into a transmission module and a reception module.

The layers of the air interface protocol between the terminal, the femto base station, and the macro base station are based on the lower three layers of the open system interconnection (OSI) model, which is well known in a communication system. And the third layer L3. The physical layer or the PHY layer belongs to the first layer and provides an information transmission service through a physical channel. A radio resource control (RRC) layer belongs to the third layer and provides control radio resources between the terminal, the femto base station, and the macro base station. The terminal and the network exchange RRC messages through the RRC layer.

When the apparatus 50 is a femto base station apparatus, the processor 51 of the apparatus 50 may control to use the above-described first type frame structure and the second type frame structure through the RF unit 53. In addition, the processor 51 may be divided into a physical layer module (not shown), a MAC module (not shown), and a higher layer module (not shown). In addition, when the device 50 is an AMS or legacy-supported femto base station device, the processor 51 may use a MAC module for legacy system / enhancement system, such as a 16e MAC module (not shown) and a 16m MAC module (not shown). It may include.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the hardware implementation, the control information transmission and reception method according to an embodiment of the present invention is one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable (PLDs) logic devices), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, according to an embodiment of the present invention, may be implemented in the form of a module, procedure, function, etc. to perform the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

The above-described invention is suitable for application to an IEEE 802.16 series wireless communication system. However, the same concept may be used and may be equally applied to various wireless communication systems.

Claims

In the mobile communication system including a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS) and a terminal for an enhancement system (hereinafter referred to as AMS) in which a specific function is added to the legacy system, the femto base station is used as the macro base station. In the method for communicating with at least one of the YMS and the AMS,

Communicating with one or more of the macro base station and the AMS using a radio frame having a first type frame structure in a state not connected to the YMS;

The first type frame structure,

It is configured to transmit only a preamble, a frame control header (FCH) and a DL-MAP as information for the legacy system through a first section corresponding to the first predetermined symbol section of a specific radio frame,

And transmit a signal for communicating with at least one of the macro base station and the AMS through a second period following the predetermined symbol period in the specific radio frame.
The method of claim 1,

The first interval is located in the first predetermined symbol interval of the first subframe of the specific radio frame, and the femto base station punctures the symbol interval after the first predetermined symbol interval in the first subframe. ,

And the second section is located from the second subframe of the specific radio frame.
The method of claim 1,

The DL-MAP transmitted as the information for the legacy system includes a base station ID corresponding to the femto base station,

And when the YMS receives the radio frame having the first type frame structure, obtains a base station ID corresponding to the femto base station through DL-MAP transmitted as information for the legacy system.
The method of claim 1,

The radio frame having the first type frame structure does not include the UL-MAP and the ranging region for the legacy system.

And when the YMS receives a radio frame having the first type frame structure, does not attempt to enter a network to the femto base station.
The method of claim 1,

Receiving a message from the macro base station instructing to perform communication using a radio frame having a second type frame structure; And

Using a radio frame having the second type frame structure, communicating with at least one of the macro base station and the AMS, and also communicating with the YMS,

The second type frame structure,

And perform the communication of the femto base station in a specific radio frame, the downlink region for the legacy system, the downlink region for the enhancement system, the uplink region for the legacy system, and the uplink region for the enhancement system. Way.
The method of claim 5,

The femto base station is a closed subscriber group (CSG) femto base station,

The YMS is a member terminal of the CSG femto base station, communication method of the femto base station.
The method of claim 1,

Receiving an interference mitigation command from the macro base station; And

And in accordance with the interference coordination command, suspending the use of a particular resource region.
In the mobile communication system including a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS) and a terminal for an enhancement system (hereinafter referred to as AMS) in which a specific function is added to the legacy system, In the method for communicating with at least one of the femto base station,

Operating in a first mode in which communication is performed using the macro base station and the resource area for the legacy system;

When the femto base station receives interference due to a signal transmitted using a radio frame having a first type frame structure, switching a mode to a second mode in which communication is performed using the resource region for the enhancement system; And

Performing a handover to the femto base station;

The first type frame structure,

It is configured to transmit only a preamble, a frame control header (FCH) and a DL-MAP as information for the legacy system through a first section corresponding to the first predetermined symbol section of a specific radio frame,

And transmits a signal for communicating with at least one of the macro base station and the AMS through a second section following the predetermined symbol section in the specific radio frame,

And the AMS obtains information on the femto base station by using the preamble transmitted as the information for the legacy system, the FCH, and the DL-MAP.
The method of claim 8,

Reporting scan information on neighboring base stations to the macro base station using the information on the femto base station; And

Receiving a handover command from the macro base station.
The method of claim 8,

And performing a terminal-initiated handover to the femto base station by using the information on the femto base station.
One of the YMS and the AMS in a mobile communication system including a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS) and a terminal for an enhancement system (hereinafter referred to as AMS) to which a specific function is added to the legacy system. In the femto base station apparatus which performs communication with the above,

A processor including the MAC module for the legacy system and the MAC module for the enhancement system; And

Including an RF unit,

The processor controls to communicate with at least one of the macro base station and the AMS using a radio frame having a first type frame structure, without being connected to the YMS through the RF unit.

The first type frame structure,

It is configured to transmit only a preamble, a frame control header (FCH) and a DL-MAP as information for the legacy system through a first section corresponding to the first predetermined symbol section of a specific radio frame,

And transmit a signal for communicating with at least one of the macro base station and the AMS through a second period following the predetermined symbol period in the specific radio frame.
The method of claim 11,

The DL-MAP transmitted as the information for the legacy system includes a base station ID corresponding to the femto base station,

And receiving the radio frame having the first type frame structure, acquiring a base station ID corresponding to the femto base station via DL-MAP transmitted as information for the legacy system.
The method of claim 11,

The radio frame having the first type frame structure does not include the UL-MAP and the ranging region for the legacy system.

And when the YMS receives a radio frame having the first type frame structure, does not attempt network entry to the femto base station.
The method of claim 11,

When receiving a message instructing to perform communication using a radio frame having a second type frame structure from the macro base station through the RF unit, the processor has the second type frame structure through the RF unit. Using a radio frame to control communication with at least one of the macro base station and the AMS and also with the YMS,

The second type frame structure,

And a downlink region for the legacy system, a downlink region for the enhancement system, an uplink region for the legacy system, and an uplink region for the enhancement system in a specific radio frame.
The method of claim 14,

The femto base station is a closed subscriber group (CSG) femto base station,

The YMS is a member terminal of the CSG femto base station, femto base station apparatus.
The method of claim 11,

And when the RF unit receives an interference mitigation instruction from the macro base station, the processor suspends use of a particular resource region in accordance with the interference mitigation instruction.
The macro base station and the femto base station in a mobile communication system including a macro base station, a femto base station, a terminal for a legacy system (hereinafter referred to as YMS) and a terminal for an improved system (hereinafter referred to as an AMS) in which a specific function is added to the legacy system. An AMS device that communicates with one or more of

A processor including the MAC module for the legacy system and the MAC module for the enhancement system; And

Including an RF unit,

The processor is controlled to operate in a first mode for performing communication using the macro base station and the legacy system resource region through the MAC module for legacy system, wherein the femto base station has a first type frame structure. When interference is caused by a signal transmitted using a frame, the mode is switched to a second mode in which communication is performed using the resource region for the enhancement system using the MAC module for the enhancement system, and the hand is transferred to the femto base station. Control over,

The first type frame structure,

It is configured to transmit only a preamble, a frame control header (FCH) and a DL-MAP as information for the legacy system through a first section corresponding to the first predetermined symbol section of a specific radio frame,

And transmits a signal for communicating with at least one of the macro base station and the AMS through a second section following the predetermined symbol section in the specific radio frame,

And the processor is transmitted as information for the legacy system to obtain information on the femto base station using the preamble, the FCH, and the DL-MAP received by the RF unit.
The method of claim 17,

And wherein the processor is configured to report scan information for neighboring base stations to the macro base station through the RF unit using the information on the femto base station, and to receive a handover command from the macro base station.
The method of claim 17,

And the processor controls to perform a terminal initiated handover to the femto base station using the information on the femto base station.