Abstract:
Embodiments of the invention disclose a method for realizing WIMAX dynamic QoS and a WIMAX system. The method includes: a media gateway making awareness of the type of a service requested by a user terminal, and notifies a subscriber station to establish a corresponding connection with a base station; the subscriber station sends to the base station a request for establishing the connection and requesting the base station for bandwidth, and establishes a service channel from the media gateway to the subscriber station and then from the subscriber station to the base station. In the method for realizing dynamic QoS provided by the embodiments of the present invention, there is no need to reserve bandwidth; the Service-Aware is performed by Media Gateway (MG); bandwidth is allocated by requesting on demand; therefore the solution of the embodiments may improve the utilization of air interface bandwidth, decrease the complexity for realizing SS, reduce the cost, facilitate the interconnection between WIMAX devices, and improve the service processing efficiency.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to wireless access technologies, and more particularly to a method for realizing dynamic QoS in WIMAX system. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the past, the Internet generally provides only one level of service, that is, the “best-effort” service where all data packets are treated equally. However; in fact the Internet can not guarantee a uniform quality of service. When a serious congestion occurs, in some areas of the network, the quality of service is degraded seriously. Moreover, the “best-effort” Internet service is not good enough for today&#39;s users, whether they are children using Web as an extended school library, companies maintaining just-in-time inventory database, or the customs seeking more convenient ways to shop. The “best-effort” service cannot properly support the emerging Internet-based voice and video applications. Consequently, Internet service providers (ISPs) want to offer and charge for services that meet different requirements. To meet the users&#39; different requirements, it is put forwarded a Quality of Service (QoS) guarantee solution which allows a user service to have an expectable service level in packet loss rate, delay, jitter and bandwidth etc. The IP QOS guarantee is intended to achieve following purposes: avoiding and managing IP network congestion, decreasing IP packet lost rate, modulating IP network traffic, providing dedicated-bandwidth for particular users or services, and supporting real-time services over IP network. 
         [0003]    Compared with other Broadband Wireless Access (BWA) technologies in the prior art, the World Interoperability for Microwave Access (WiMAX) technology based on 802.16 standard resolves the problems both in physical-layer environment (outdoor radio transmission) and in QoS, enables WiMAX products to be used indoors and outdoors, supports voice and video services with high demand in data access and real-time. WiMAX is a Wireless Metropolitan Area Network technology satisfying the “last kilometer” access, which is capable of providing both fixed wireless broadband access and middle-speed or low-speed portable access. 
         [0004]    In a WIMAX system, data transmission is connection-oriented, that is, any uplink or downlink data are transported in a certain connection. A service flow bears a certain one-way data flow and has many related attributes and three statuses, wherein when being in Admitted or Active status, the service flow is also called a connection. 802.16x defines four service flow types, which are different from each other in bandwidth scheduling characteristic, bandwidth request mode and QoS parameter set. Any type of service data flow has a 32-bit service flow identifier (SFID), which is assigned by a base station (BS).The service types include: Unsolicited Grant Service (UGS), Real-time-polling Service (Rt-PS), Non real-time Polling Service (Nrt-PS) and Best Effort Service (BES). 
         [0005]    UGS service: for this type of service, the bandwidth is reserved; the BS periodically notifies a Subscriber Station (SS) of the available time-slot bandwidth, without the SS sending a bandwidth request, for its bandwidth is guaranteed. The UGS service is applicable to services with higher priorities, and mainly used in real-time services with fixed data packet length, such as T 1 /E 1 , VoIP and ATM private line. 
         [0006]    Rt-PS service: the BS assigns a regular bandwidth request slot to the SS for its sending a bandwidth request to the BS for bandwidth. The bandwidth is not reserved; however it is guaranteed and may be obtained by requesting on demand. The Pt-PS service is applicable to services with high real-time demand, and mainly used for supporting real-time video services. 
         [0007]    Nrt-PS service: the BS assigns a non-regular bandwidth request slot to the SS for its sending a bandwidth request to the BS for bandwidth; when the request slots are assigned, the intervals between them will be very short so as to guarantee the service has a chance to be sent in the condition of network congestion. The Nrt-PS service is applicable to services without high real-time demand, such as FTP. 
         [0008]    BE service: the service is delivered at best effort; the SS requests the BS for bandwidth by using a competitive request slot assigned by the BS, and sends the service only when getting the requested bandwidth, therefore the bandwidth is not guaranteed. The BE service is applicable to services with lower priorities, such as Web browsing, and receiving and sending E-mails. 
         [0009]    For Rt-PS service, the bandwidth may be requested periodically; and no bandwidth requested, no bandwidth resource occupied; for Rt-PS, whether to request for bandwidth is determined by Service-Aware, i.e., according to the service requirement. Service-Aware means that a device may parse a message; for example, since the characteristic of a VOIP message is a specific User Datagram Protocol (UDP) port number, to make awareness of the VOIP service, it is needed to parse the UDP port number of the VOIP message. 
         [0010]    As it is known, as voice service has high requirement on bandwidth and delay, and as the bandwidth and delay of UGS service or Rt-PS service are guaranteed, the type of the voice service may be defined as UGS service. UGS service is bandwidth-reserved, that is, SS and BS reserve the bandwidth for a UGS connection directly, and BS allocates air interface bandwidth to the SS directly with the bandwidth exclusive but not shared. If an Integrated Access Device (IAD) is capable of receiving 8 channels of voices and all the 8 channels of voices are UGS services, air interface bandwidth needs to be reserved for all those 8 channels of voice service flows no matter whether the voice channels are established, thus resulting in a low bandwidth utilization of air interface. 
       SUMMARY OF THE INVENTION 
       [0011]    Embodiments of the present invention provide a method for realizing WIMAX dynamic QoS based on Service-Aware terminal, in which there is no need to reserve bandwidth resource, and bandwidth may be requested dynamically on demand. 
         [0012]    According to an embodiment of the present invention, there is provided a method for realizing dynamic QoS in WIMAX system. The method includes: 
         [0013]    a media gateway making awareness of the type of a service which is requested by a calling user terminal, and notifying a subscriber station to establish a corresponding connection with a base station; and 
         [0014]    sending by the subscriber station a request of establishing the connection to the base station and requesting the base station for bandwidth, and establishing a service channel from the media gateway to the subscriber station as well as the base station. 
         [0015]    The method further includes: 
         [0016]    the calling user terminal sending the service request to the media gateway; and 
         [0017]    the media gateway responds the request of the calling user terminal, and reports the request of the calling user terminal to a Media Gateway Controller (MGC). 
         [0018]    After receiving the notification from the media gateway, the subscriber station sends a Dynamic Service Addition (DSA) to the base station (BS) to request for the connection, and the BS allocates the resource by a Connection Admission Control (CAC) or rejects the request. 
         [0019]    When the bandwidth is requested successfully, the media gateway controller notifies the media gateway to send a prompt signal to a called user terminal, and notifies the media gateway to send a prompt signal to the calling user terminal. 
         [0020]    After receiving the response from the called user, the media gateway controller notifies the calling user terminal and the called user terminal that they may begin the service communication with each other. 
         [0021]    The method also includes: 
         [0022]    when the bandwidth is not requested successfully, the media gateway sends a busy signal to the calling user terminal, and the media gateway controller notifies a related media gateway (MG 1 ) to release the resource. 
         [0023]    The media gateway controller sends a prompt signal to the called user terminal. 
         [0024]    When the bandwidth is requested successfully, the MGC requires the MG at the called side to send a ring tone to the called user terminal, and the MGC requires the MG at the calling side to send a ring back tone to the calling user terminal. 
         [0025]    When the bandwidth is not requested successfully, the MG notifies the MGC, and the MGC requires the MG at the calling side to send a busy tone signal to the calling user terminal and notifies the MG at the calling side to release the resource. 
         [0026]    The media gateway is any one of Integrated Access Device (IAD), Access Gateway (AG), Access Media Gateway (AMG), set-top box, trunk gateway, Universal Media Gateway (UMG) and IP visual telephone, and is adapted to access data and voice and process media data flow. 
         [0027]    The media gateway is embedded in the subscriber station. 
         [0028]    Compared with the prior technology, in the method of the present invention, only if a service requirement occurs indeed, a service flow is activated and occupies air interface bandwidth (an air interface refers to an interface between a base station and a subscriber station). In case that the service flow is not activated, no interface bandwidth needs to be occupied or reserved. The MG makes awareness of the service, and then notifies the SS to establish a connection with the BS and to obtain bandwidth. Accordingly, the SS need not make awareness of the service, thus decreasing the complexity for realizing SS, reducing the cost, facilitating the interconnection between WIMAX devices. The SS and the MG are integrated into one device, thus avoiding the requirement of employing a private protocol between the SS and the MG, guaranteeing the interconnection between the SS and the MG, and reducing processing time. 
         [0029]    By employing the method for realizing dynamic QoS provided by the embodiments of the present invention, there is no need to reserve bandwidth; the Service-Aware is performed by Media Gateway (MG); bandwidth is allocated by requesting on demand; thus improving the utilization of air interface bandwidth and improving the service processing efficiency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0030]      FIG. 1  is a schematic diagram illustrating the dynamic QoS system architecture according to a first embodiment of the present invention; 
           [0031]      FIG. 2  is a flow diagram illustrating a successful request for resource according to the first embodiment of the present invention; 
           [0032]      FIG. 3  is a flow diagram illustrating a failed request for resource according to the first embodiment of the present invention; 
           [0033]      FIG. 4  is a flow diagram illustrating another successful request for resource according to the first embodiment of the present invention; 
           [0034]      FIG. 5  is a flow diagram illustrating another failed request for resource according to the first embodiment of the present invention; 
           [0035]      FIG. 6  is a flow diagram illustrating yet another successful request for resource according to the first embodiment of the present invention; 
           [0036]      FIG. 7  is a flow diagram illustrating a failed request of the called subscriber station for resource according to the first embodiment of the present invention; 
           [0037]      FIG. 8  is a network architecture diagram according to a second embodiment of the present invention; 
           [0038]      FIG. 9  is a flow diagram illustrating a successful request for resource according to the second embodiment of the present invention; 
           [0039]      FIG. 10  is a flow diagram illustrating a failed request for resource according to the second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0040]    The principle, features and advantages of the present invention will become more apparent with reference to the following description of the preferred embodiments given in conjunction with the accompanying drawings. 
         [0041]    The services with high QoS requirement include: VOIP, VOD and video conference etc.; hereunder the implement of the embodiments of the present invention is described by taking VOIP service as an example. 
       Embodiment I 
       [0042]      FIG. 1  shows a system for realizing WIMAX dynamic QoS based on terminal-aware service, which includes a user terminal, a Media Gateway (MG), a subscriber station (SS), a base station (BS), a Broadband Access Server (BAS) and a Media Gateway Controller (MGC) connected to the broadband access server. 
         [0043]    In this embodiment, the MG may be any one of an Integrated Access Device (IAD), an Access Gateway (AG), an Access Media Gateway (AMG), a Set Top Box (STB), a Trunk Media Gateway (TMG), a Universal Media Gateway (UMG) and an IP video telephone, for accessing data and voice and processing the media data flow. 
         [0044]    The BAS is used for implementing management on the broadband access user terminal. 
         [0045]    The MGC is used for controlling the MG to carry out call processing. A soft-switch device, SOFTSWITCH, is also a kind of MGC. 
         [0046]    The procedures for dynamic QoS call in various cases are described hereunder respectively. 
         [0047]    In one case, the calling user terminal is a wireless subscriber, and the called user terminal is a wired subscriber, as shown is  FIG. 2 . 
         [0048]    Firstly, the calling user terminal sends an off-hook signal to a calling media gateway MG 1 . After making awareness of the service, the calling media gateway MG 1  reports to the MGC that the calling user terminal is off hook. Then, the MGC requests the calling media gateway MG 1  to send a dial tone to the calling user terminal, and the calling media gateway MG 1  sends the dial tone to the calling user terminal to notify the calling user terminal that it may start to dial. 
         [0049]    Aware service refers to that a device can parse a message to determine the type of the service flow carried in the message. For this purpose, firstly the service flow is classified (for example, according to IP address or MAC address), and then the protocol type is analyzed. For example, Voice Over IP (VOIP) calls adopts H.248 protocol, which are distinguished by UDP port number, therefore it is needed for the device to be capable of analyzing the UDP port number of each message. Then, the calling user terminal begins to dial, and sends dialing information to the calling media gateway MG 1 . After receiving the dialing information, the calling media gateway MG 1  reports the information to MGC, and notifies the SS to establish an RT-PS connection with the BS and to request the BS for bandwidth. After receiving the notification, the SS sends a Dynamic Service Addition (DSA) signal to the BS to request for a connection (the bandwidth may be allocated only after the connection is established). The BS performs a Connection Admission Control (CAC), and allocates the bandwidth resource or rejects the request. If the resource is obtained, the session between the MG and the MGC proceeds; otherwise the session terminates. 
         [0050]    If the resource request is successful, that is, the BS allocates the bandwidth to the SS, the SS notifies the calling media gateway MG 1  that the bandwidth is allocated. The MGC requests a called media gateway MG 2  to send a ring tone to the called user terminal to notify the called user terminal that a connection is requested by a user terminal; and requests the calling media gateway MG 1  to send a ring back tone to the calling user terminal. Then, the calling media gateway MG 1  sends a ring back tone to the calling user terminal, and the called media gateway MG 2  sends a ring tone to the called user terminal. At this point, if the called user terminal is off hook, the MGC will receive the off-hook information of the called user terminal, and then the calling user terminal and the called user terminal may begin to communicate with each other. 
         [0051]    If the resource request is failed, that is, the BS rejects to allocate bandwidth to the SS, the SS notifies the calling media gateway MG 1  that the request is rejected, as shown in  FIG. 3 . The calling media gateway MG 1  sends a busy tone to the calling user terminal, and reports the off-hook information to the MGC after the calling user terminal is off hook. At last the MGC requests the calling media gateway MG 1  to release the resource. 
         [0052]    In this embodiment, the MG is embodied as an TAD, and the MGC is embodied as a soft-switch device SOFTSWITCH. 
         [0053]    To be summarized, in the solution of the embodiments of the present invention, there is no need for the BS to reserve resources. Only after a call is initiated, the MG makes awareness of the service type and then notifies the SS to establish a connection with the BS to request the BS for bandwidth. If the request is successful, the service flow proceeds; otherwise the service flow terminates. That is, only if a service requirement occurs indeed, a service flow is activated and occupies air interface bandwidth. In the case that the service flow is not activated, no interface bandwidth is occupied. Therefore the utilization of air interface bandwidth is improved. Additionally, the MG makes awareness of the service type, and then notifies the SS to activate the service flow. The SS and the BS are both Layer  2  devices, which do not parse higher-layer protocols. Because the BS and the SS need not make awareness of services, the complexity and the cost for realizing the software are reduced, which also benefits the interconnection between WIMAX equipments of different vendors. 
         [0054]    In another case, the calling user terminal is a wired subscriber, and the called user terminal is a wireless subscriber, as shown in  FIG. 4 . The MG making awareness of the service is the called media gateway MG 2 . 
         [0055]    Firstly, the calling user terminal sends an off-hook signal to the calling media gateway MG 1 , and the calling media gateway MG 1  reports to the MGC that the calling user terminal is off hook. Then, the MGC requests the calling media gateway MG 1  to send a dial tone to the calling user terminal, and the calling media gateway MG 1  sends a dial tone to notify the calling user terminal that it may begin to dial. 
         [0056]    Then, the calling user terminal begins to send dialing information to the calling media gateway MG 1 . After receiving the dialing information, the calling media gateway MG 1  reports the dialing information of the calling user terminal to the MGC. And after receiving the dialing information of the calling user terminal, the MGC requests the calling media gateway MG 2  to send a ring tone to the called user terminal. The called media gateway MG 2  which makes awareness of the service immediately notifies the SS to establish an RT-PS connection with the BS and to request the BS for the bandwidth. After receiving the notification, the SS sends a DSA to request for establishing a connection. The BS performs a CAC, and allocates bandwidth resource or rejects the request. If the bandwidth resource is obtained, the session between the MG and the MGC proceeds; otherwise, the session terminates. 
         [0057]    If the resource request is successful, that is, the BS allocates the bandwidth to the SS, the SS notifies the calling media gateway MG 2  that the bandwidth is allocated. The called media gateway MG 2  sends a ring tone to the called user terminal, and the MGC requests the calling media gateway MG 1  to send a ring back tone to the calling user terminal. The calling media gateway MG 1  sends the ring back tone to the calling user terminal. At this point, if the called user terminal is off hook, the off-hook information of the called user terminal is received by the MGC, and then the calling user terminal and the called user terminal may begin to communicate with each other. 
         [0058]    As shown in  FIG. 5 , if the resource request is failed, that is, the BS rejects to allocate bandwidth to the SS, the SS notifies the called media gateway MG 2  that the request is rejected. The called media gateway MG 2  reports to the MGC that the called user terminal has not been off hook for a long time. The MGC requests the calling media gateway MG 1  to send a busy tone signal to the calling user terminal, and requests the called media gateway MG 2  to release the resource. The calling media gateway MG 1  sends the busy tone signal to the calling user terminal. 
         [0059]    In the present embodiment the MG is embodied as an IAD, and the MGC is embodied as a soft-switch device SOFTSWITCH. 
         [0060]    In yet another case, both the calling user terminal and the called user terminal are wireless subscribers, and both the calling media gateway MG 1  and the called media gateway MG 2  need to make awareness of services. In this case, only after both the calling subscriber station and the called subscriber station request for resource successfully, the communication can begin; if either is failed, a service channel can not be established. The flow in the case that the calling user station is failed to request for bandwidth is the same as the flow of the failed bandwidth request in the first case of the embodiment as shown in  FIG. 3 . Therefore, only the flow in the case that both the calling subscriber station and the called subscriber station request for resource successfully and the flow of failed request of the called subscriber station for resource are described hereunder. 
         [0061]    The flow in the case that both the calling subscriber station and the called subscriber station request for resource successfully is as follows: 
         [0062]    Firstly, the calling user terminal sends an off-hook signal to the calling media gateway MG 1 , and the calling media gateway MG 1  reports to the MGC that the calling user terminal is off hook. Then, the MGC requests the calling media gateway MG 1  to send a dial tone to the calling user terminal, and the calling media gateway MG 1  sends a dial tone to the calling user terminal to notify the calling user terminal that the calling user terminal may begin to dial. 
         [0063]    Then, the calling user terminal begins to send dialing information to the calling media gateway MG 1 . After receiving the dialing information, the calling media gateway MG 1  reports the dialing information of the calling user terminal to the MGC, and notifies the SS at the calling side to establish an RT-PS connection with the BS at the calling side and to request the BS for bandwidth. After receiving the notification, the SS at the calling side sends a DSA to the BS at the calling side to request for a connection. The BS at the calling side performs a CAC, and allocates the resource or rejects the request. 
         [0064]    As shown in  FIG. 6 , if the request is successful, that is, the BS at the calling side allocates the bandwidth to the SS at the calling side, the SS at the calling side notifies the calling media gateway MG 1  that the bandwidth has been allocated; and the MGC requests the called media gateway MG 2  to send a ring tone to the called user terminal, and requests the calling media gateway MG 1  to send a ring back tone to the calling user terminal. 
         [0065]    Then, the called side begins to request for bandwidth: upon receiving the request for sending a ring tone to the called user terminal, the called media gateway MG 2  immediately notifies the SS at the called side to establish an RT-PS connection with the BS at the called side and to request the BS at the called side for bandwidth. After receiving the notification, the SS at the called side sends a DSA to request the BS at the called side to establish a connection. The BS at the called side performs a CAC, and allocates the resource or rejects the request. 
         [0066]    If the request is successful, that is, the BS at the called side allocates the bandwidth to the SS at the called side, the SS at the called side notifies the called media gateway MG 2  that the bandwidth has been allocated. The called media gateway MG 2  sends a ring tone to the called user terminal, and then the calling media gateway MG 1  sends a ring back tone to the calling user terminal. At this point, if the called user terminal is off hook, the MGC will receive the off-hook information of the called user terminal, and then the calling user terminal and the called user terminal can begin to communicate with each other. 
         [0067]    The flow in the case that the called subscriber station fails is as follows: 
         [0068]    As shown in  FIG. 7 , after the calling subscriber station requests for bandwidth successfully, the MGC requests the called media gateway MG 2  to send a ring tone to the called user terminal, and requests the calling media gateway MG 1  to send a ring back tone to the calling user terminal. Then the called side begins to request for bandwidth: upon receiving the request for sending a ring tone to the called user terminal, the called media gateway MG 2  immediately notifies the SS at the called side to establish an RT-PS connection with the BS at the called side and to request the BS at the called side for bandwidth. After receiving the notification, the SS at the called side sends a DSA to the BS at the called side to request for a connection. The BS at the called side performs a CAC, and allocates the resource or rejects the request. 
         [0069]    If the request is failed, that is, the BS at the called side rejects to allocate bandwidth to the SS at the called side, the SS at the called side notifies the called media gateway MG 2  that the request is rejected. At this point, the called media gateway MG 2  doesn&#39;t make any process, and waits for the MGC to time out. If the MGC times out before receiving the user&#39;s off-hook signal reported by the media gateway, it terminates the procedure of this session. The MGC requests the calling media gateway MG 1  to send a busy tone signal to the calling user terminal, and requests the calling media gateway MG 1  and the called media gateway MG 2  to release the resource. The calling media gateway MG 1  sends a busy tone signal to the calling user terminal. 
         [0070]    In this case, the MGC is embodied as a soft-switch device SOFTSWITCH. The MG is embodied as an IAD. The calling user terminal and the called user terminal can use the same SS and BS, and also can use different SSs and BSs respectively. If different SSs and BSs are used, they may be differentiated as the SS at the calling side, the SS at the called side, the BS at the calling side and the BS at the called side; otherwise, the same SS and BS are used. 
       Embodiment II 
       [0071]    As shown in  FIG. 8 ,  FIG. 9  and  FIG. 10 , the second embodiment is different from Embodiment I in that: the MG is built in the SS, and the WIMAX SS itself is an MG, which has all the functions of the MG described in Embodiment I. 
         [0072]    Similar to Embodiment I, the second embodiment also has three cases. Because the second embodiment is different from Embodiment I only in that the MG is built in the SS, only the case as bellow is described: the calling user terminal is a wireless subscriber, and the called user terminal is a wired subscriber; the MG which is aware of services is built in the SS at the calling side. 
         [0073]    The procedure of a dynamic QoS call is described as follows. 
         [0074]    Firstly, the calling user terminal sends an off-hook signal to the SS, and the SS reports to the MGC that the calling user terminal is off hook. The MGC requests the SS to send a dial tone to the calling user terminal. The SS sends a dial tone to the calling user terminal to notify the calling user terminal that the calling user terminal may begin to dial. 
         [0075]    Then, the calling user terminal begins to send dialing information to the SS. After receiving the dialing information, the SS reports the dialing information of the calling user terminal to the MGC, and sends a DSA to request the BS to establish a connection. The BS performs a CAC, and allocates the resource or rejects the request. 
         [0076]    As shown in  FIG. 9 , if the request is successful, that is, the BS allocates bandwidth to the SS, the MGC requests the called media gateway MG 2  to send a ring tone to the called user terminal, and requests the SS to send a ring back tone to the calling user terminal. Then the called media gateway MG 2  sends a ring tone to the called user terminal, and the SS sends a ring back tone to the calling user terminal. Then if the called user terminal is off hook, the MGC receives the off-hook information of the called user terminal, and then the calling user terminal and the called user terminal can begin to communicate with each other. 
         [0077]    As shown in  FIG. 10 , the request is failed, that is, the BS rejects to allocate bandwidth to the SS. The SS sends a busy tone signal to the calling user terminal, and reports an on-hook information to the MGC after the calling user terminal is on hook. The MGC requests the SS to release the resource. 
         [0078]    In the second embodiment, the MGC is embodied as a soft-switch device SOFTSWITCH. The MG is embodied as an IAD built in the SS. 
         [0079]    In summary, the SS and the MG are integrated into one device in the second embodiment, thus avoiding employing a private protocol between the SS and the MG, guaranteeing the interconnection between the SS and the MG, and reducing processing time. For example, the IAD needs to notify the SS to request for resource, and the SS needs to notify the IAD that the resource has been allocated or the request for resource is rejected; therefore the time to establish the call is reduced.