Simulating time-varying conditions in a wireless network

Abstract

Time-varying conditions in a wireless network are simulated using an architecture that includes an enclosure for shielding a wireless device under test (“DUT”) from electromagnetic interference, including other wireless devices; and at least one of: (1) a communications traffic generating device operable to generate communications traffic having selected characteristics; and (2) at least one dynamically adjustable attenuator in communication with the wireless device and the traffic generator. Embodiments of the architecture include wireless test equipment for testing operating range, roaming and capacity. The attenuator is used to adjustably attenuate signals between the device and the traffic generator over time during a test, whereby motion of the device is simulated. By connecting multiple access points, each associated with a dynamically adjustable attenuator, it is possible to force the DUT to roam between access points. The communications traffic generating device can be used to vary traffic over time during a test in order to test capacity, prioritization and admission control. For example, the communications traffic generator may include phone and data client emulators which simulate different traffic types that can be independently varied over time during a test.

1 . Apparatus for testing a wireless device under test (“DUT”) comprising: 
 an enclosure for shielding the DUT from electromagnetic interference;    a communications traffic generating device in communication with the DUT, the traffic generating device operable to generate communications traffic; and    a dynamically adjustable attenuator in communication with the DUT and the traffic generating device, the attenuator being operable to adjustably attenuate signals between the DUT and the traffic generating device over time during a test,    whereby motion of the DUT relative to the traffic generating device is simulated.    
   
   
       2 . The apparatus of  claim 1  further including a monitoring device operable to monitor communications between the DUT and the traffic generating device, whereby operating range can be tested.  
   
   
       3 . The apparatus of  claim 2  wherein the monitoring device measures at least one of: quality of service, packet loss, delay and jitter.  
   
   
       4 . The apparatus of  claim 3  wherein the monitoring device provides data indicative of at least one of: 
 quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       5 . The apparatus of  claim 1  wherein the communications traffic generating device emulates at least one client device.  
   
   
       6 . The apparatus of  claim 1  wherein the communications traffic generating device is a real wireless device in a separate shielded enclosure.  
   
   
       7 . The apparatus of  claim 1  further including at least one access point connected between the DUT and traffic generating device.  
   
   
       8 . The apparatus of  claim 1  wherein the dynamically adjustable attenuator is further operable to adjustably attenuate signals at variable rates over time, whereby changes in rate of motion of the DUT are simulated.  
   
   
       9 . The apparatus of  claim 1  wherein the dynamically adjustable attenuator is further operable to adjustably increase and decrease signal strength over time, whereby changes in direction of motion of the DUT are simulated.  
   
   
       10 . The apparatus of  claim 9  further including at least two communications paths which can be operated upon independently by the dynamically adjustable attenuator, whereby changes in direction of motion of the DUT can be simulated.  
   
   
       11 . The apparatus of  claim 1  further including a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and a monitor connected to the tap.  
   
   
       12 . A method for testing a wireless device under test (“DUT”) comprising the steps of: 
 shielding the DUT from electromagnetic interference;    generating communications traffic with a communications traffic generating device that is in communication with the DUT; and    dynamically attenuating signals communicated to and from the DUT over time during a test, thereby simulating motion of the DUT relative to the communications traffic generating device.    
   
   
       13 . The method of  claim 12  further including a monitoring device, and including the further step of monitoring communications between the DUT and the traffic generating device with the monitoring device, whereby operating range can be tested.  
   
   
       14 . The method of  claim 13  including the further step of measuring at least one of: quality of service, packet loss, delay and jitter.  
   
   
       15 . The method of  claim 14  including the further step of providing data indicative of at least one of: 
 quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       16 . The method of  claim 12  wherein the communications traffic generating device emulates at least one client device.  
   
   
       17 . The method of  claim 12  wherein the communications traffic generating device is a real wireless device in a separate shielded enclosure.  
   
   
       18 . The method of  claim 12  further including at least one access point connected between the DUT and traffic generating device.  
   
   
       18 . The method of  claim 12  including the further step of adjustably attenuating signals at variable rates over time, whereby changes in rate of motion of the DUT are simulated.  
   
   
       19 . The method of  claim 12  including the further step of adjustably increasing and decreasing signal strength over time, whereby changes in direction of motion of the DUT are simulated.  
   
   
       20 . The method of  claim 19  including the further step of establishing at least two communications paths which can be operated upon independently by the dynamically adjustable attenuator, whereby changes in direction of motion of the DUT can be simulated in two dimensions.  
   
   
       21 . The method of  claim 12  further including a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and including the further step of monitoring signals at the tap.  
   
   
       22 . Apparatus for testing roaming of a wireless device between access points comprising: 
 an enclosure for shielding the wireless device from electromagnetic interference;    a communications traffic generating device in communication with the wireless device, the traffic generating device operable to generate communications traffic;    a plurality of access points, each in a communications path between the wireless device and the communications traffic generating device; and    at least one dynamically adjustable attenuator operable to individually and adjustably attenuate signals between the wireless device and the traffic generating device via each communication path over time during a test,    whereby roaming of the wireless device between access points can be tested by varying path loss between the wireless device and access points.    
   
   
       23 . The apparatus of  claim 22  further including, for each access point, a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and a monitor connected to the tap.  
   
   
       24 . The apparatus of  claim 22  further including a device operable to measure at least one of: roaming time, quality of service, packet loss, delay and jitter.  
   
   
       25 . The apparatus of  claim 24  wherein the device provides data indicative of at least one of: 
 roaming time, quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       26 . The apparatus of  claim 22  wherein the dynamically adjustable attenuator is further operable to adjustably attenuate signals at variable rates over time, whereby changes in rate of motion of the wireless device are simulated.  
   
   
       27 . The apparatus of  claim 22  wherein the dynamically adjustable attenuator is further operable to adjustably increase and decrease signal strength over time, whereby changes in direction of motion of the wireless device are simulated.  
   
   
       28 . The apparatus of  claim 22  further including a device in communication with the dynamically adjustable attenuator, the device being operable to control operation of the attenuator in a predetermined manner.  
   
   
       29 . A method for testing roaming of a wireless device between access points comprising the steps of: 
 shielding the wireless device from electromagnetic interference;    generating communications traffic with a communications traffic generating device in communication with the wireless device;    providing a plurality of communications paths between the wireless device and the communications traffic generating device, each path associated with an access point; and    individually, dynamically, adjustably attenuating signals between the wireless device and the traffic generating device via each communication path over time during a test with at least one attenuator,    whereby roaming of the wireless device between access points can be tested by varying path loss between the wireless device and access points.    
   
   
       30 . The method of  claim 29  further including, for each access point, a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and including the further step of monitoring signals at the tap.  
   
   
       31 . The method of  claim 29  further including the step of measuring at least one of: roaming time, quality of service, packet loss, delay and jitter.  
   
   
       32 . The method of  claim 29  further including the step of providing data indicative of at least one of: 
 roaming time, quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       33 . The method of  claim 29  including the further step of adjustably attenuating signals at variable rates over time, whereby changes in rate of motion of the wireless device are simulated.  
   
   
       34 . The method of  claim 29  including the further step of adjustably increasing and decreasing signal strength over time, whereby changes in direction of motion of the wireless device are simulated.  
   
   
       35 . The method of  claim 29  further including a device in communication with the dynamically adjustable attenuator, the device being operable to control operation of the attenuator in a predetermined manner.  
   
   
       36 . Apparatus for testing capacity of a wireless device under test (“DUT”) comprising: 
 an enclosure for shielding the DUT from electromagnetic interference; and    a communications traffic generating device in communication with the DUT, the communications traffic generating device being operable to generate traffic in amounts which are variable over time during a test;    whereby capacity of the DUT can be tested by varying communications traffic.    
   
   
       37 . The apparatus of  claim 36  wherein the traffic generating device includes a phone emulator which generates packets carrying voice traffic and a data client emulator which generates packets not carrying voice traffic, and being operable to generate communications traffic representative of a selected, variable number of voice traffic devices and data client devices.  
   
   
       38 . The apparatus of  claim 36  wherein the traffic generating device is operable to generate traffic of at least first and second types, where the first traffic type has a higher priority than the second traffic type, whereby prioritization support may be tested.  
   
   
       39 . The apparatus of  claim 38  wherein the higher priority traffic is increased during the test.  
   
   
       40 . The apparatus of  claim 38  wherein the lower priority traffic is increased during the test.  
   
   
       41 . The apparatus of  claim 36  further including a second real device in a separate shielded enclosure in communication with the DUT.  
   
   
       42 . The apparatus of  claim 37  wherein the communications traffic generator is operable to increase the number of simulated phones during a test.  
   
   
       43 . The apparatus of  claim 37  wherein the communications traffic generator is operable to increase the number of simulated data clients during a test.  
   
   
       44 . The apparatus of  claim 36  further including a measurement device operable to measure at least one of: roaming time, quality of service, packet loss, delay and jitter.  
   
   
       45 . The apparatus of  claim 36  wherein the monitoring device provides data indicative of at least one of: 
 roaming time, quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       46 . The apparatus of  claim 36  further including at least one dynamically adjustable attenuator operable to individually and adjustably attenuate signals between the DUT and the communications traffic generating device over time during a test.  
   
   
       47 . The apparatus of  claim 46  wherein the dynamically adjustable attenuator is further operable to adjustably attenuate signals at variable rates over time, whereby changes in rate of motion of the DUT are simulated.  
   
   
       48 . The apparatus of  claim 46  wherein the dynamically adjustable attenuator is further operable to adjustably increase and decrease signal strength over time, whereby changes in direction of motion of the DUT are simulated.  
   
   
       49 . The apparatus of  claim 36  further including a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and a monitor connected to the tap.  
   
   
       50 . A method for testing capacity of a wireless device under test (“DUT”) comprising the steps of: 
 shielding the DUT from electromagnetic interference; and    generating communications traffic representative of a traffic load which varies during a test;    whereby capacity can be tested by varying communications traffic.    
   
   
       51 . The method of  claim 50  wherein the traffic generating device includes a phone emulator, and including the further step of generating packets carrying voice traffic, and wherein the traffic generating device includes a data client emulator, and including the further step of generating packets not carrying voice traffic, the traffic generating device being operable to generate communications traffic representative of a selected, variable number of voice traffic devices and data client devices.  
   
   
       52 . The method of  claim 50  including the further step of generating, by the traffic generating device, traffic of at least first and second types, where the first traffic type has a higher priority than the second traffic type, whereby prioritization support may be tested.  
   
   
       53 . The method of  claim 52  including the further step of increasing the higher priority traffic during the test.  
   
   
       54 . The method of  claim 52  including the further step of increasing the lower priority traffic during the test.  
   
   
       55 . The method of  claim 50  further including a second real device in a separate shielded enclosure in communication with the DUT.  
   
   
       56 . The method of  claim 51  including the further step of increasing the number of simulated phones during a test.  
   
   
       57 . The method of  claim 51  including the further step of increasing the number of simulated data clients during a test.  
   
   
       58 . The method of  claim 50  further including a measurement device, and including the further step of employing the measurement device for measuring at least one of: roaming time, quality of service, packet loss, delay and jitter.  
   
   
       59 . The method of  claim 50  including the further step of providing data indicative of at least one of: 
 roaming time, quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       60 . The method of  claim 50  further including at least one dynamically adjustable attenuator, and including the further step of individually and adjustably attenuating signals between the DUT and the communications traffic generating device over time during a test.  
   
   
       61 . The method of  claim 60  including the further step of dynamically adjustably attenuating signals at variable rates over time, whereby changes in rate of motion of the DUT are simulated.  
   
   
       62 . The method of  claim 60  including the further step of dynamically adjustably increasing and decreasing signal strength over time, whereby changes in direction of motion of the DUT are simulated.  
   
   
       63 . The method of  claim 50  further including a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and including the further step of monitoring signals at the tap.  
   
   
       64 . Apparatus for testing roaming of a wireless device associated with changing traffic conditions comprising: 
 an enclosure for shielding the device from electromagnetic interference;    a communications traffic generating device in communication with the wireless device, the communications traffic generating device being operable to generate traffic in amounts which are variable over time during a test; and    a plurality of access points, each in a communications path between the wireless device and the communications traffic generating device;    whereby roaming of the wireless device between access points can be tested by varying traffic.    
   
   
       65 . The apparatus of  claim 64  further including at least one dynamically adjustable attenuator operable to individually and adjustably attenuate signals between the wireless device and the traffic generating device via each communication path over time during a test.  
   
   
       66 . The apparatus of  claim 64  wherein the traffic generating device includes a phone emulator which generates packets carrying voice traffic and a data client emulator which generates packets not carrying voice traffic, and being operable to generate communications traffic representative of a selected, variable number of voice traffic devices and data client devices.  
   
   
       67 . The apparatus of  claim 64  wherein the traffic generating device is operable to generate traffic of at least first and second types, where the first traffic type has a higher priority than the second traffic type, whereby prioritization support may be tested.  
   
   
       68 . The apparatus of  claim 67  wherein the higher priority traffic is increased during the test.  
   
   
       69 . The apparatus of  claim 67  wherein the lower priority traffic is increased during the test.  
   
   
       70 . The apparatus of  claim 64  further including a second real device in a separate shielded enclosure in communication with the wireless device.  
   
   
       71 . The apparatus of  claim 66  wherein the communications traffic generator is operable to increase the number of simulated phones during a test.  
   
   
       72 . The apparatus of  claim 66  wherein the communications traffic generator is operable to increase the number of simulated data clients during a test.  
   
   
       73 . The apparatus of  claim 64  further including a measurement device operable to measure at least one of: roaming time, quality of service, packet loss, delay and jitter.  
   
   
       74 . The apparatus of  claim 73  wherein a device provides data indicative of at least one of: 
 roaming time, quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       75 . The apparatus of  claim 64  further including at least one dynamically adjustable attenuator operable to individually and adjustably attenuate signals between the wireless device and the communications traffic generating device over time during a test.  
   
   
       76 . The apparatus of  claim 75  wherein the dynamically adjustable attenuator is further operable to adjustably attenuate signals at variable rates over time, whereby changes in rate of motion of the DUT are simulated.  
   
   
       77 . The apparatus of  claim 75  wherein the dynamically adjustable attenuator is further operable to adjustably increase and decrease signal strength over time, whereby changes in direction of motion of the DUT are simulated.  
   
   
       78 . The apparatus of  claim 64  further including a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and a monitor connected to the tap.  
   
   
       79 . A method for testing roaming of a wireless device associated with changing traffic conditions comprising the steps of: 
 shielding the wireless device from electromagnetic interference;    generating, with a communications traffic generating device in communication with the wireless device, traffic in amounts which are variable over time during a test; and    monitoring communications between the wireless device and a plurality of access points, each in a communications path between the wireless device and the communications traffic generating device;    whereby roaming of the wireless device between access points can be tested by varying traffic.    
   
   
       80 . The method of  claim 79  further including at least one dynamically adjustable attenuator operable to individually and adjustably attenuate signals between the wireless device and the traffic generating device via each communication path over time during a test.  
   
   
       81 . The method of  claim 79  wherein the traffic generating device includes a phone emulator which generates packets carrying voice traffic and a data client emulator which generates packets not carrying voice traffic, and being operable to generate communications traffic representative of a selected, variable number of voice traffic devices and data client devices.  
   
   
       82 . The method of  claim 79  including the further step of generating traffic of at least first and second types, where the first traffic type has a higher priority than the second traffic type, whereby prioritization support may be tested.  
   
   
       83 . The method of  claim 82  including the further step of increasing the higher priority traffic is increased during the test.  
   
   
       84 . The method of  claim 82  including the further step of increasing the lower priority traffic during the test.  
   
   
       85 . The method of  claim 79  further including a second real device in a separate shielded enclosure in communication with the wireless device.  
   
   
       86 . The method of  claim 81  further including the step of increasing the number of simulated phones during a test.  
   
   
       87 . The method of  claim 81  further including the step of increasing the number of simulated data clients during a test.  
   
   
       88 . The method of  claim 79  including the further step of measuring at least one of: roaming time, quality of service, packet loss, delay and jitter.  
   
   
       89 . The method of  claim 88  including the further step of providing data indicative of at least one of: 
 roaming time, quality of service, packet loss, delay and jitter, as a function of at least one of:    call load, background load, distance, path loss, roam, and rate of simulated motion.    
   
   
       90 . The method of  claim 79  further including at least one dynamically adjustable attenuator, and including the further step of individually and adjustably attenuating signals between the wireless device and the communications traffic generating device over time during a test.  
   
   
       91 . The method of  claim 90  including the further step of adjustably attenuating signals at variable rates over time, whereby changes in rate of motion of the wireless device are simulated.  
   
   
       92 . The method of  claim 90  including the further step of adjustably increasing and decreasing signal strength over time, whereby changes in direction of motion of the DUT are simulated.  
   
   
       93 . The method of  claim 79  further including a pair of dynamically adjustable attenuators connected in series with a tap connected therebetween, and including the further step of monitoring at the tap.