Abstract:
A service method of a femtocell for simultaneously providing a plurality of femto services to a plurality of mobile stations, and a transmitter and receiver for the same. When a femto advanced base station supports a plurality of femtocell subscription types, and it simultaneously provides data services with different qualities to mobile stations having subscribed to different femtocells. The femtocell subscription type supported by the femto advanced base station is advertised to the mobile station through an identifier at a PHY level or an identifier at a MAC level. A CSG-closed femtocell provides a high-quality data service to limited subscribers, a CSG-open femtocell provides a relatively low quality data service to limited subscribers, and an OSG femtocell provides the lowest quality data service to all mobile stations irrespectively of subscription states.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of PCT application No. PCT/KR2010/001260, filed on Feb. 26, 2010, which claims priority to and the benefit of Korean Patent Application No. 10-2009-0017191 filed on Feb. 27, 2009 and Korean Patent Application No. 10-2010-0018001 filed on Feb. 26, 2010, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    a Field 
         [0003]    Embodiments of the present invention relate to a method for providing a service of a femtocell for simultaneously providing a plurality of femto services to a plurality of mobile stations, and a transmitter and receiver for the same. 
         [0004]    (b) Description of the Related Art 
         [0005]    A femtocell provides a wireless service to an area with the cell radius of less than 30 meters. A femto advanced base station represents a very small base station that is installed to support the femtocell within a macrocell, and it provides excellent signal quality compared to a macrocell base station in a concentrated area with houses or office buildings. 
         [0006]    The femto advanced base station serves an open subscriber group (OSG) such as public users, or serves a closed subscriber group (CSG) such as subscribers who are authenticated by owners of femtocell base stations or network service providers. 
         [0007]    The femto advanced base station determines to be operable as one of an OSG femto advanced base station and a CSG femto advanced base station, and broadcasts an operation method of the femto advanced base station to the mobile station of a serving cell. When the mobile station determines that the operation method of the femto advanced base station is the femtocell method to which the mobile station has registered, the mobile station registers to the femto advanced base station to receive a data service based on the femtocell method. 
         [0008]    However, since the current femtocell does not support simultaneous registration to different femto methods, the mobile station cannot be served with the femtocell service when the base station of the femtocell in which the mobile station is provided does not support the femtocell operation method to which the mobile station is registered. 
       SUMMARY 
       [0009]    Embodiments of the present invention provide a femto advanced base station for supporting a plurality of femto registration methods, and an operation process between a femto advanced base station and a mobile station. 
         [0010]    An embodiment of the present invention provides a method for a femtocell to provide a service in a method for a femto advanced base station to provide a data service, including: the femto advanced base station providing information on a plurality of femtocell subscription types to mobile stations in a serving cell; receiving a registration request from a first mobile station having designated a first subscription type from among the femtocell subscription types and a second mobile station having designated a second subscription type; and providing a data service with quality corresponding to the first subscription type to the first mobile station, and providing a data service with quality corresponding to the second subscription type to the second mobile station. 
         [0011]    Another embodiment of the present invention provides a receiver of a femtocell, including: a memory for storing an identifier of a femtocell subscription type to which the receiver is subscribed; and a controller including a comparison module for, when receiving information on a plurality of femtocell subscription types from a femto advanced base station, checking whether the femtocell subscription type information includes the identifier stored in the memory and a registration module for requesting registration from the femto advanced base station according to a femtocell subscription type that corresponds to the identifier stored in the memory. 
         [0012]    In the embodiments of the present invention, the femto advanced base station can support at least subscription types from among the CSG-closed femto method, the CSG-open femto method, and the OSG femto method. 
         [0013]    The femtocell subscription type information can be identified by a receiver through a PHY level and/or a MAC level, and particularly, femtocell subscription type information of the MAC level can be broadcast to the receivers in the femtocell or unicast by a request of a specific receiver. 
         [0014]    According to the embodiments of the present invention, a single femtocell provides a plurality of different femto services by providing different unicast qualities according to the respective femto services. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  shows a configuration of a communication network according to embodiments of the present invention. 
           [0016]      FIG. 2  shows a data flowchart among a macro base station, a femto advanced base station, and a mobile station for entering a femtocell network. 
           [0017]      FIG. 3  shows a data structure of a superframe including A-preambles. 
           [0018]      FIG. 4  shows a configuration of a femto advanced base station according to an embodiment of the present invention. 
           [0019]      FIG. 5  shows a configuration of a mobile station according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    In general, a communication system includes a transmitter and a receiver. The transmitter and the receiver can be called a transceiver for simultaneously performing a transmitting function and a receiving function. For ease of description, a first part for providing a femto data service will be defined to be a transmitter and a second part for entering a service area covered by the transmitter and receiving the femto data service will be called a receiver. 
         [0021]    The transmitter can be referred to as a base station (BS) or an advanced base station (ABS), and the receiver as a mobile station (MS) or an advanced mobile station (AMS). 
         [0022]    Throughout the specification, a femto service indicates a data service that is provided distinctively according to a subscription type to the femtocell. 
         [0023]    Embodiments of the present invention will be described with reference to accompanying drawings. 
         [0024]    &lt;A Network Topology of a Communication Network&gt; 
         [0025]      FIG. 1  shows a configuration of a communication network according to embodiments of the present invention. 
         [0026]    The communication network of  FIG. 1  provides a macrocell service and a femtocell service. A transmitter for the macrocell will be referred to as a macro base station  100  and another transmitter for the femtocell will be called a femto advanced base station  200 . 
         [0027]    The femto advanced base station  200  uses an air interface overlapped on the macro base station  100  to exchange a control message. The femto advanced base station  200  registers itself and the macro base station  100  to the network to directly receive radio link configuration information from the network. 
         [0028]    A mobile station  300  enters the network of the macro base station or that of the femto advanced base station depending on a subscription state to the femtocell service and a support state of the femtocell service. 
         [0029]    The femto advanced base station  200  supports at least one of the following subscription types, and can simultaneously support two or more. 
         [0030]    a) Closed subscriber group-closed femto advanced base station (CSG-closed femto ABS): provides high-speed data service to a limited subscriber group. 
         [0031]    b) Closed subscriber group-open femto ABS: provides low-speed data service to a limited subscriber group. 
         [0032]    c) Open subscriber group femto ABS: provides a data service regardless of service registration and provides the same with the lowest-quality data service. 
         [0033]    The femto advanced base station  200  broadcasts information on femto service subscription types provided by the femto advanced base station  200  to the mobile stations  300  in the serving cell, or unicasts it according to a request from the mobile station  300 . 
         [0034]    The mobile station  300  providing the femto service receives a femtocell information list (e.g., CSG white list) from the femto advanced base station  200 , and attempts to enter the network of the corresponding femto advanced base station  200  when it is found that the mobile station  300  has subscribed to the femto service. 
         [0035]    &lt;Network Entry&gt; 
         [0036]      FIG. 2  shows a data flowchart among a macro base station, a femto advanced base station, and a mobile station for entering a femtocell network. 
         [0037]    When the mobile station is turned on, it enters an initialization state. While in the initialization state, radio interface parameters are configured and time and frequency are synchronized. 
         [0038]    In the initialization state, the mobile station receives various control information from the macro base station through a preamble sequence. Particularly, a primary advanced (PA) preamble sequence and a secondary advanced (SA) preamble sequence are used to control the downlink. 
         [0039]      FIG. 3  shows a data structure of a superframe including A-preambles. Referring to  FIG. 3 , a first symbol of a frame is specified as an A-preamble symbol. The PA-preamble is positioned at the first symbol of the second frame in a superframe, and the SA-preamble is positioned at the first symbol of three other frames. 
         [0040]    The SA-preamble sequences are divided into a plurality of partitions that are dedicated to the base stations including the macrocell ABS, the macro hot zone ABS, and the femto ABS. For example, the femto advanced base station can be allocated to be dedicated to the 3rd sub-partition (SP3) of an S-SFH. The base stations except the macrocell base station are called non-macro base stations. 
         [0041]    At the PHY level, non-macro base station information can be broadcast in a hierarchical configuration formed with a secondary-superframe header (S-SFH) of the SA-preamble sequence and an advanced air interface_system configuration descriptor (AAI_SCD) message. Here, the S-SFH is a non-macro base station cell type and is partitioned for a public base station or a CSG femto advanced base station, and the AAI_SCD message is partitioned for the public base station and CSG femto advanced base station. The public base station can be classified as a hot zone, a relay, and an OSG, and the CSG femto advanced base station can be classified as a CSG-closed femto advanced base station and a CSG-open femto advanced base station. 
         [0042]    The mobile station identifies the femto advanced base station at the PHY level, and can also identify the femto advanced base station at a MAC level. 
         [0043]    That is, at the MAC level, non-macro base station information can be provided to the mobile station by use of a femtocell information list (e.g., CSG white list). The femtocell information list can be broadcast to the mobile stations in the cell, and it can also be provided according to a request of the mobile station. 
         [0044]    The femtocell information list displays types of the femto services provided by the femto advanced base station. The mobile station receives the femtocell information list from the femto advanced base station, and checks whether the femto service to which the mobile station is registered is included in the femtocell information list. If included, the mobile station enters the network of the corresponding femto advanced base station, and if not, it enters the network of the macrocell base station. 
         [0045]    &lt;The Configuration of the Femto Advanced Base Station (ABS)&gt; 
         [0046]      FIG. 4  shows a configuration of a femto advanced base station  200  according to an embodiment of the present invention. Referring to  FIG. 4 , the femto advanced base station  200  includes a channel encoder  210 , a mapper  220 , a modulator  230 , a receiving circuit  240 , a memory  250 , and a controller  260 . 
         [0047]    The channel encoder  210  encodes streams of information bits according to a predetermined coding scheme to generate coded data. 
         [0048]    The mapper  220  maps the coded data output by the channel encoder  110  on symbols that are represented with the positions following the constellation of the amplitude and the phase. The modulation scheme includes the m-quadrature phase shift keying (m-PSK) and the m-quadrature amplitude modulation (m-QAM). 
         [0049]    The modulator  230  modulates the mapped unicast symbols according to a predetermined multiple access modulation. The multiple access modulation scheme includes single-carrier modulation schemes such as the CDMA and the multi-carrier modulation schemes such as the OFDM. 
         [0050]    The receiving circuit  240  receives the unicast signals from the receiver through an antenna, generates them into digital signals, and transmits them to the controller  260 . 
         [0051]    The memory  250  stores system information for operating the femto advanced base station  200  and the femtocell information list. 
         [0052]    The controller  260  controls the femto advanced base station  200 , and particularly it includes a femtocell information transmitting module  261  and a service providing module  262 . 
         [0053]    The femtocell information transmitting module  261  broadcasts the femtocell information list to the mobile stations in the cell, or unicasts the femtocell information list to the corresponding mobile station through the receiving circuit  240  when the mobile station requests information. 
         [0054]    The service providing module  262  provides the data service with the quality corresponding to the femto service to which the mobile station  300  is subscribed to the mobile stations  300  in the serving cell. When the femto advanced base station  200  provides a plurality of femto subscription types and the mobile stations  300  in the serving cell are subscribed to different femto services, the service providing module  262  provides the data service with different quality to the mobile stations  300  according to the multiple access modulation so that the mobile stations  300  may correspond to the subscribed femto services. 
         [0055]    &lt;Configuration of the Mobile Station (AMS)&gt; 
         [0056]      FIG. 5  shows a configuration of a mobile station  300  according to an embodiment of the present invention. In  FIG. 5 , the mobile station  300  includes a channel decoder  310 , a demapper  320 , a demodulator  330 , a memory  340 , a transmitting circuit  350 , and a controller  360 . 
         [0057]    The demodulator  330 , the demapper  320 , and the channel decoder  310  of the mobile station  300  perform reverse functions of the above-described modulator  230 , mapper  220 , and channel encoder  210  of the femto advanced base station  200 . That is, the signal received through the antenna is demodulated by the demodulator  330 , and is demapped by the demapper  320  to be encoded data. The encoded data are decoded by the channel decoder  310 . The demodulator  330 , the demapper  320 , and the channel decoder  310  can be called a receiving circuit (not shown) overall. 
         [0058]    The memory  340  stores system information required for operating the mobile station  300  and an identifier of the femto service to which the mobile station is subscribed. 
         [0059]    The transmitting circuit  350  generates the various data provided by the controller  360  into analog data, and transmits the same to the femto advanced base station  200  or the macro base station  100  through the antenna. 
         [0060]    The controller  350  controls the mobile station  300 , and includes a comparison module  351  for checking whether the femtocell subscription type information includes the identifier stored in the memory when receiving information on a plurality of femtocell subscription types from the femto advanced base station  200 , and a registration module  352  for requesting registration from the femto advanced base station  200  according to the femtocell subscription type that corresponds to the identifier stored in the memory. When the femtocell subscription type information does not include the identifier stored in the memory, the registration module  352  can request registration from the macrocell base station  100  other than the femto advanced base station  200 . 
         [0061]    While this invention has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
         [0062]    The embodiments of the present invention are applicable to a service providing method of a femtocell for simultaneously providing a femto service to a plurality of mobile stations, and a transmitter and receiver for the same method. 
         [0063]    The above-described embodiments can be realized through a program for realizing functions corresponding to the configuration of the embodiments or a recording medium for recording the program in addition to through the above-described device and/or method, which is easily realized by a person skilled in the art.