Abstract:
Systems and methods of allocating radio resources are provided. The systems and methods involve assigning each of a plurality of mobile stations to one of a plurality of categories, wherein each of the plurality of categories is associated with a different resource allocation scheme. An amount of available radio resources is allocated to each of the plurality of categories. An amount radio resources assigned to each category is allocated to mobile stations assigned to the category based on the resource allocation scheme associated with the category.

Description:
BACKGROUND OF THE INVENTION 
     In wireless communication systems radio frequency resources are allocated for communication between base stations and mobile stations. Due to a number of factors, such as governmental allocation of frequencies, interference and the like, there are a limited number of radio frequency resources to allocate for wireless communications. Thus, allocation of radio frequency resources requires careful consideration of a large number of factors, and any particular allocation technique will have drawbacks with regard to other allocation techniques. 
       FIG. 1  illustrates a WiMAX wireless communication system implementing one resource allocation technique. This system includes a base station  105  and two mobile stations  110  and  115 . In the exemplary WiMAX system, resources (e.g., sub-channels, time slots and modulation and coding schemes (MCSs)) are allocated on the basis of signal quality measurements (e.g., carrier-to-interference noise ratio (CINR)), where more resources are allocated to mobile stations that have better signal quality conditions than mobile stations with worse conditions. This typically results in mobile stations that are located closer to base station  105  being allocated more resources than mobile stations located further away from the base station. In this technique the base station includes a scheduler to allocate the resources, and this allocation technique is referred to as proportional fair scheduling. 
     SUMMARY OF THE INVENTION 
     Exemplary systems and methods of allocating radio resources are provided. The systems and methods involve assigning each of a plurality of mobile stations to one of a plurality of categories, wherein each of the plurality of categories is associated with a different resource allocation scheme. An amount of available radio resources is allocated to each of the plurality of categories. An amount radio resources assigned to each category is allocated to mobile stations assigned to the category based on the resource allocation scheme associated with the category. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  is a block diagram of a conventional wireless communication system; 
         FIG. 2  is a block diagram of an exemplary scheduler in accordance with the present invention; and 
         FIG. 3  is a flow diagram of an exemplary method in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 2  is a block diagram of an exemplary scheduler in accordance with the present invention. Scheduler  200  includes processor  210  coupled to memory  230 , wireless communication interface  235  and network communication interface  240 . Processor  210  includes logic  212 - 226 , which will be described in more detail below in connection with  FIG. 3 . Processor  210  can be any type of processor, such as a microprocessor, field programmable gate array (FPGA) and/or an application specific integrated circuit (ASIC). When processor  205  is a microprocessor then logic  212 - 226  can be processor-executable code loaded from memory  250 . 
     Scheduler  200  can be a component of a base station or can be a separate network component. When scheduler  200  is a separate network component, wireless communication interface  235  can be omitted. Wireless communication interface  235  is employed for communicating with mobile stations over an air interface. Network communication interface  240  is employed for communication with infrastructure components of the network. When scheduler  200  is not a component of a base station, network communication interface can be used to provide the resource allocation to one or more base stations. Furthermore, when scheduler  200  is a component of a base station, processor  210  can be part of a base station processor and/or memory  230  can be part of the base station memory. 
     As will be described in more detail below, scheduler  200  allocates radio resources to one or more mobile stations. The resources allocated by the present invention can include uplink and/or downlink resources. The resources can include transmission power, modulation and coding scheme (MCS), number of codes or tones, time slots and/or the like. 
       FIG. 3  is a flow diagram of an exemplary method in accordance with the present invention. Initially, logic  212  creates categories that will be used to categorize the mobile stations (step  305 ). Logic  214  then assigns a scheduling algorithm to each of the categories (step  310 ). Although  FIG. 3  illustrates these two steps as not being repeated, if desired these steps can be performed on a periodic basis. 
     Each of the categories can be assigned to a particular signal quality measurement range, such as a range of carrier to interference-plus-noise ratio (CINR) values. Category 1 can be for mobile stations with a CINR above 22 dB, category 2 can be for mobile stations with a CINR between 12 and 21 dB, and category 3 can be for mobile stations with a CINR below 13 dB. In this example, category 1 can be assigned a throughput driven scheduling algorithm that allocates resources to users in the best radio frequency (RF) conditions, which results in the best sector throughput. Category 2 can be assigned a proportional fairness scheduling algorithm that considers both fairness and throughput. Category 3 can be assigned a round-robin scheduling algorithm that promotes fairness among all mobile stations at the expense of a lower overall sector throughput. Although this example includes specific ranges of signal quality values and types of scheduling algorithms, the present invention is equally applicable to other ranges and other types of, and assignments of, scheduling algorithms. Furthermore, the present invention can employ more or less than three categories and scheduling algorithms. 
     Logic  216  then collects information from mobile stations (step  315 ). This information can include signal quality measurements (such as CINR, received signal strength indications (RSSI) and/or the like), speed, location (e.g., geographical coordinates and/or elevation) and/or amount of traffic requested by the mobile station. Logic  218  then determines whether a predetermined event has occurred (step  320 ). The predetermined event can be the passage of a predetermined amount of time, e.g., the time corresponding to one uplink and downlink transmission period, such as a frame. When the predetermined event has not occurred (“No” path out of decision step  320 ), then logic  216  continues to collect information from the mobile stations. 
     When the predetermined event has occurred (“Yes” path out of decision step  320 ), then logic  220  identifies mobile stations subject to reallocation based on the speed and/or location information (step  325 ). For example, a mobile station that moves very slowly, is stationary or located within a building, may not necessarily require reallocation of resources with the same frequency as other mobile stations, e.g., on a frame-by-frame basis. Accordingly, these mobile stations could have their resources reallocated, for example, every four frames. Although not illustrated, if no mobile stations are subject to reallocation, then method would return to step  315  to receive information from the mobile stations. 
     Logic  222  then categorizes the identified mobile stations based on signal quality measurements (step  330 ), and logic  224  determines a percentage of the total available resources for allocation to each category (step  335 ). The percentage of resources is based on an amount of traffic requested for transmission to/or from mobile stations within each category compared to the total amount of available resources. Although not illustrated, if amount of traffic requested by all of the mobile stations cannot be satisfied by the amount of available resources, the scheduler can then allocate the available resources on the basis of the percentage of requested traffic to the total available resources, based on Quality of Service (QoS) requirements of each category, and/or the like. Logic  226  then allocates resources to each category based on a percentage of resources assigned to the category and resources to each mobile station within the category based on the assigned scheduling algorithm for that category (step  340 ). The method then returns to step  315  to receive information from mobile stations. 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.