Abstract:
This invention discloses a method in a wireless communication network, the method comprises generating a first piece of feedback information by a first hub serving a user terminal, transmitting a second piece of feedback information to the first hub by a second hub, combining the first and second pieces of feedback information by the first hub to form a third piece of feedback information, and transmitting the third piece of feedback information to the user terminal.

Description:
CROSS REFERENCE  
       [0001]     The present application claims the benefit of U.S. Provisional Application Ser. No. 60/736,474, which was filed on Nov. 12, 2005. 
     
    
     BACKGROUND  
       [0002]     The present invention relates generally to mobile communication networks, and, more particularly, to feedback information to user-terminals.  
         [0003]     Present day communication networks with a grid of hubs (base-stations) serving multiple user-terminals (mobile stations or any other access-terminals), e.g. cellular networks, are often required to provide some measure of reception quality at the serving hub back to a user accessing the network. This feedback is typically used by the user terminal for periodically updating its transmission parameters in such a way that the overall communication network performance may be optimized. A particular selection of the transmission parameters at a user-terminal can also affect the link performances with the nearby hubs within the reception range of user&#39;s transmissions, in addition to the performance of the link with its serving hub. In the interest of overall optimization of the network performance, the selection of transmission parameters at the user terminal at any given time should be based on not only the reception quality at the serving hub, but also on the effects of its transmissions with the neighboring hubs within the reception range.  
         [0004]     In a traditional communication network, all of the hubs within the reception range of the transmissions from a user-terminal are required to provide an estimation of the reception quality as perceived by them individually, directly to the user-terminal. This means that the user-terminal receives a feedback on the reception quality of its transmissions not only from the hub it is being served, but also from many other hubs in its vicinity. This requires the user-terminal to possess the ability to receive and process those multiple streams of the feedback information, in addition to the ability to receive and process the data and feedback received from the serving hub it is connected to. This capability is usually provided in the user-terminal by implementing more processing elements for the feedback from multiple hubs than needed to maintain the connection with the serving hub.  
         [0005]     Implementation of extra elements requires additional hardware and software resources in the user-terminal. Besides, the receiver design of the user terminal will be more complicated because of the number of processing elements for the feedback information may vary as networks and locations may be different.  
         [0006]     For instance, in High Rate Packet Data (HRPD) networks, which have a synchronous forward link and an asynchronous reverse link, the reverse-link power control is often influenced by multiple sectors or base-stations. In a typical scenario, a single base-station (or sector) serves the forward link to minimize the interference, while multiple base-stations (or sectors) serve the reverse link to gain from diversity. In such a system, the user-terminal receives the power-control bits from multiple base-stations (or sectors), while receiving the forward link data from a single base-station (or sector). This imposes an additional requirement in the user-terminal receiver design to handle the data and the power control bits separately, especially with a different number of processing elements.  
         [0007]     As such, what is desired is a system and method to reduce the number of data streams received by a user terminal.  
       SUMMARY  
       [0008]     This invention discloses a method and system in a wireless communication network. According to a first aspect of the invention, a method comprises generating a first piece of feedback information by a first hub serving a user terminal, transmitting a second piece of feedback information to the first hub by a second hub, combining the first and second pieces of feedback information by the first hub to form a third piece of feedback information, and transmitting the third piece of feedback information to the user terminal.  
         [0009]     According to a second aspect of the invention, a wireless communication network comprises a first hub serving a user terminal and is configured to generate a piece of first feedback information corresponding to the user terminal, and a second hub within the reception range of the user terminal configured to transmit a second piece of feedback information also corresponding to the user terminal to the first hub, wherein the first hub is configured to combine the first and second pieces of feedback information to form a third piece of feedback information and to transmit the third piece of feedback information to the user terminal.  
         [0010]     The construction and method of operation of the invention, however, together with additional objectives and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The drawings accompanying and forming part of this specification are included to depict certain aspects of the invention. A clearer conception of the invention, and of the components and operation of systems provided with the invention, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings, wherein like reference numbers (if they occur in more than one view) designate the same elements. The invention may be better understood by reference to one or more of these drawings in combination with the description presented herein. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale.  
         [0012]      FIG. 1  shows a conventional wireless communication network having multiple hubs with separate information feedback.  
         [0013]      FIG. 2  shows a wireless communication network having multiple hubs with collective information feedback according to one embodiment of the present invention.  
         [0014]      FIG. 3  is a flow chart illustrating steps of collectively feeding back information to a user terminal according to the embodiment of the present invention. 
     
    
     DESCRIPTION  
       [0015]     The present invention may be implemented to provide a mechanism for multiple hubs to feedback information to a user terminal in a communication network.  
         [0016]      FIG. 1  shows a conventional wireless communication network  100  with separate information feedback  105 [ 0 : 4 ] from multiple hubs  110 [ 0 : 4 ].  FIG. 1  shows five exemplary hubs  110 [ 0 : 4 ], that offer communication services to cells  115 [ 0 : 4 ], respectively. A user terminal  120  is placed in the cell  115 [ 3 ], so that the hub  110 [ 3 ] serves the user terminal  120 , while the hubs  110 [ 0 : 2 ] and  110 [ 4 ] are within the reception range of the user terminal  120 . Each hub  110 [x], where x = 0 : 4 , feeds back its reception quality information  105 [x] to the user terminal  120 , individually. Such multiple streams of feedback information  105 [ 0 : 4 ] require the user terminal  120  to have more processing elements to process them, therefore increases the number of hardware and software, as well as complicate the design of the user terminal  120 .  
         [0017]      FIG. 2  shows a wireless communication network  200  having multiple hubs with a collective information feedback.  FIG. 2  shows five exemplary hubs  210 [ 0 : 4 ], that offer communication services to cells  215 [ 0 : 4 ], respectively. A user terminal  220  is placed in the cell  215 [ 3 ], so that the hub  210 [ 3 ] serves the user terminal  220 , while the hubs  210 [ 0 : 2 ] and  210 [ 4 ] are within the reception range of the user terminal  120 . Instead of feeding back reception quality information to the user terminal  220  individually by each hub, the network  200  designate a hub  210 [ 1 ] as a center hub, and have all other none serving hubs yet within the reception range,  210 [ 0 ],  210 [ 2 ] and  210 [ 4 ], to send their reception quality information,  205 [ 0 ],  205 [ 2 ] and  205 [ 4 ], respectively, to the center hub  210 [ 1 ]. The center hub  210 [ 1 ] then collects all the feedback information and sends a combined reception quality feedback stream  205 [ 1 ] to the serving hub[ 3 ]. The serving hub  210 [ 3 ] merges this combined reception quality information  205 [ 1 ] with its own reception quality feedback information to form a single feedback stream  205 [ 3 ], and then sends it to the user terminal  220 , it is serving. The aforementioned center hub may simply be the serving hub, or a dedicated hub exclusively for feeding the user terminal with feedback information.  
         [0018]     The principle advantages of this invention include efficient resource utilization by eliminating the need for multiple hubs to transmit the reception quality feedback directly to the user-terminal. By receiving a single feedback stream, the user terminal has no need for extra reception and processing elements. Thus, the implementation of diversity combining (if any) in the user-terminal is simplified due to the fact that the number of processing elements is fixed for the data and the feedback streams.  
         [0019]     Although this embodiment describes only feeding back reception quality information, one having skill in the art would also appreciate that the present disclosure applies to different information feedbacks. As an example, the present invention may be applied in a High Rate Packet Data (HRPD) network, which has a synchronous forward link and an asynchronous reverse link. According to one embodiment of the present invention, all of the base-stations of the HRPD network receives the reverse link from a user terminal, and sends their respective power-control bit decisions to a central location, either the serving base-station, or the base-station controller (BSC). The central location then sends the combined power-control bits decision to the serving base-station. The serving base-station sends the overall combined power-control bit decision on the forward link along with the forward link data. Thus, the user terminal can process the forward-link data and the power-control bits with the same number of processing elements in its receiver.  
         [0020]      FIG. 3  is a flow chart illustrating steps of collectively feeding back information to a user terminal according to the embodiment of the present invention. A user terminal is placed in a wireless communication network with a grid of hubs. A particular hub serving the user terminal will generate feedback information, and all other hubs within the reception range of the user terminal also generate feedback information. The feedback information may be reception quality information. According to the embodiment of the present invention, step  310  is to generate feedback information by each hub within the reception range of the user terminal. Step  320  is to transmit all the feedback information to a center hub. Step  330  is to combine all the feedback information to form a piece of combined feedback information by the center hub. Step  340  is to transmit the combined feedback information to the serving hub. Step  350  is to combine the combined feedback information with the feedback information generated by the serving hub to form a single stream of feedback information. Step  360  is to transmit the single feedback information to the user terminal, wherein the user terminal receives only one feedback data stream and hence does not need to have extra processing elements.  
         [0021]     The above illustration provides many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims.  
         [0022]     Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.