Abstract:
A method and system for emulating a user population for wireless local area network access point performance, optimization and configuration testing. The number of stations, data volume and related variables are programmed by a command and control computer, with a load emulator then offering a realistic station population and data traffic load to the wireless access point under test. Multiple load emulators may be deployed for the emulation and testing of very large networks.

Description:
CROSS REFERENCE TO A RELATED APPLICATION  
       [0001]    This application is entitled to, and claims the benefit of, provisional application No. 60/326,174 filed 25 Apr. 2002. 
     
    
     
       TECHNICAL FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to the field of data communications, and, more specifically, to the performance, optimization, and configuration testing of wireless local area network access points.  
         BACKGROUND OF THE INVENTION  
         [0003]    Many, including development engineers, network administrators, and network testing organizations, have occasion to test the performance of wireless local area networks. The accepted practice of testing wireless local area networks is to install numerous computers with wireless network capability, then associate, authenticate, and present requests for data to a wireless hardware device called an access point, sending and receiving data streams over a high frequency radio channel. This common practice is expensive, driven by the cost of the many computers, and is not easily configurable for the commonly needed variety of user population sizes and data traffic loads.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention, employing what is termed a load emulator, overcomes the considerable expense and inadequacies of the accepted practice of testing wireless local networks by emulating a programmable number of virtual stations, associating each virtual station with the access point, authenticating the user for security purposes, and transferring data designed to elicit performance parameters over a wireless link.  
           [0005]    The load emulator method and apparatus (or system) has many advantages over the accepted practice, providing variable and realistic network load conditions, allowing network builders to quickly determine the efficiency and capacity of an access point under test.  
           [0006]    Three components make up the load emulator test environment, 1) a computer to command test parameters and display results, 2) the load emulator, and 3) the wireless access point under test. With this configuration one can emulate from 1 to 255 virtual stations with realistic network addresses, network association procedures, user authentication processes, and transfer of data over the wireless network.  
           [0007]    From this test procedure, a variety of information is collected, analyzed and displayed. One can use this information to analyze the access point under test, make configuration adjustments to optimize overall performance, determine access point capacity, establish boundaries of the target user population size, conduct performance comparisons of network equipment manufacturers, and acquire other useful data and information.  
           [0008]    The objects, features, and advantages of the present invention will be apparent to the reader from the foregoing and the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a block diagram illustrating a typical test environment embodying the principles of the present invention and comprising a load, emulator as disclosed herein connected to a command and report computer and to a wireless access point under test;  
         [0010]    [0010]FIG. 2 is a block diagram illustrating the internal functional elements of the load emulator and the connections of the load emulator to the command and report computer and to the access point under test, and  
         [0011]    [0011]FIG. 3 is a flow diagram illustrating the operations of the load emulator functional elements along with load emulator command and report computer interaction. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]    Referring now the drawings, a representative wireless access point test environment embodying the principles of the present invention and utilizing a load emulator is depicted in FIG. 1 and identified by reference character  20 . In this system command and report computer  22  is connected by a serial wired connection  23  called a command line interface (CLI) to a load emulator  24  also encompassing those principles. The load emulator is connected over a wireless radio link  26  conforming to the 802.11 standard to an access point  24  under test. The access point is typically, but not necessarily, wired into a traditional enterprise data network  28 .  
         [0013]    The functional elements of the novel and representative load emulator  24  are depicted in FIG. 2. These are: a controller  30  for command/report computer  22 , a virtual station processor  32 , access point input/output controller  34 , and a log and statistics file  36 .  
         [0014]    System  20  is readied by initializing load emulator  24 . To initialize the load emulator, a body of virtual station parameters is entered into command and report computer  22  either manually, or from a table of parameters stored in that computer. This station profile block of information contains a media access control (MAC) address, Internet protocol (IP) address, a station name and password, and packetized data for the transmission to the access points being tested. The MAC and IP addresses are specified over a range which accommodates the desired number of virtual stations. Packet sizes are specified over an allowable range, and are unique for each virtual station, thus realistically emulating a typical station population.  
         [0015]    The virtual station processor  32  is responsible for execution of the test scripts  34 , performing initial access point authentication through the input/output controller  34 , the calculation of elapsed time, the recording of success or failure conditions, and the logging of the information into the log and statistics file  36 . With successful authentication based on a virtual station name and password, the virtual station processor  32  initiates an association procedure  44  through the input/output controller  34 . The input/output controller communicates directly with the access point  28  under test over 802.11 wireless link  26 . Virtual station association elapsed time is calculated, success or failure recorded and resulting information loaded into log and statistics file  36 . With successful authentication and association processes completed, virtual station processor  32  transfers a packet of realistic data to the input/output controller  34  for transmission over the wireless 802.11 link  26  to the access point  38  under test. Elapsed time and throughput of the data transfer is calculated with resulting data being stored in the log and statistics file  36 .  
         [0016]    This process is repeated in sequence for each virtual station until completion of the test run. At the conclusion of the test run controller  30  causes test data to be exported from log and statistics file  36  to command and report computer  22  for analysis of the recorded data and display of test results.  
         [0017]    [0017]FIG. 3 depicts internal operations of the load simulator  24 , beginning with station block initialization process  38  and station profile block definition process  40  by the external command and report computer  22 . In load emulator  24  the station profile block  41  is loaded with a MAC address, an IP address, and packetized data for transmission. A repeat loading process  42  tracks the number of virtual stations to be tested and determines when the last station has been emulated. Once all virtual station profile blocks have been loaded, active virtual station process  44  is enabled. A virtual station name and password are passed to input/output controller  34  and presented to the access point  28  under test for authentication of the particular virtual station. Elapsed time and success or failure of the virtual station authentication is stored in log and statistics file  36 . Upon successful authentication virtual station association is attempted by the initiate/end association process  46 . Elapsed time and success or failure of the virtual station association is stored in log and statistics file  36 .  
         [0018]    With successful authentication and association of the virtual station, a programmable sized packet of data is transferred to the input/output controller  34  for transmission over the 802.11 wireless link  26  to the access point  28  being tested (process  47 ). Elapsed time of the data transfer is calculated, error conditions reported and data throughput recorded in log and statistics file  36 .  
         [0019]    A second repeat process  48  sequentially processes all virtual stations, one after the other, by triggering activate virtual station process  43  until the last virtual station has been emulated. Upon completion of the test run, the repeat loading process  48  signals completion to log and statistics file  36 . The log and statistics file information is then transferred by export log file process  50  across CLI  23  to the command and report computer  22 , which analyzes the information (process  52 ), and displays the results (process  54 ).  
         [0020]    The invention may be embodied in many forms in addition to those disclosed herein without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.