Suspending transmissions in a wireless network

Abstract

A method of increasing operational safety of a wireless communication network operating in a process control environment and having a plurality of network devices includes detecting a first triggering condition associated with an increased operational risk due to a wireless transmissions by at least one of the plurality of network devices, sending a suspend command to at least some of the plurality of network devices, suspending transmissions at the at least some of the plurality of network devices; and resuming transmissions at the at least some of the plurality of network devices upon occurrence of a second triggering condition.

1 . A method of temporarily suspending communications in a wireless communication network operating in a process control environment and having a plurality of network devices, comprising:
 detecting a first triggering condition that requires radio silence in a certain geographical area of the process control environment, the first triggering condition corresponding to a planned event in the process control environment; and   sending, via the wireless communication network, a suspend command to at least some of the plurality of network devices corresponding to the certain geographical area of the process control environment to cause wireless transmissions to be suspended at the at least some of the plurality of network devices.   
     
     
         2 . The method of  claim 1 , wherein detecting the first triggering condition corresponding to the planned event in the process control environment comprises detecting the first triggering condition corresponding to at least one of: an event having an elevated safety risk, a planned controlled explosion, a test, a measurement, or an operator request. 
     
     
         3 . The method of  claim 1 , wherein detecting the first triggering condition includes one of:
 receiving a suspension request from an external host operating outside the wireless communication network; or   receiving a suspension request from a handheld device operating in the wireless communication network as one of the plurality of network devices.   
     
     
         4 . The method of  claim 1 , wherein sending the suspend command to the at least some of the plurality of network devices includes broadcasting the suspend command to each of the plurality of network devices. 
     
     
         5 . The method of  claim 1 , further comprising sending, after a suspension period, a resume command to the at least some of the plurality of network devices to cause the at least some of the plurality of network devices to resume wireless transmissions. 
     
     
         6 . The method of  claim 5 , wherein sending the resume command to the at least some of the plurality of network devices comprises broadcasting the resume command to the at least some of the plurality of network devices. 
     
     
         7 . The method of  claim 1 , wherein sending the suspend command includes:
 specifying, in the suspend command, a suspend time at which a recipient network device must suspend wireless transmissions; and   specifying, in the suspend command, one of:   a resume time at which the recipient network device is allowed to resume wireless transmissions; and   a quiet time interval during which the recipient network device is not allowed to resume wireless transmissions.   
     
     
         8 . The method of  claim 7 ,
 further comprising maintaining an absolute slot number counter indicative of a number of communication timeslots of a predetermined duration scheduled since a formation of the wireless communication network, wherein each of the plurality of network devices communicates with at least one other of the plurality of network devices according to a communication schedule having a plurality of concurrent superframes, each superframe of the concurrent superframes defined as a repeating sequence of at least one of the communication timeslots; and   wherein specifying the suspend time includes specifying a first absolute slot number counter value, and specifying one of the resume time or the quiet time interval includes specifying a second absolute slot number counter value.   
     
     
         9 . The method of  claim 1 , further comprising pre-configuring each of the at least some of the plurality of network devices with a quiet time interval during which the each of the at least some of the plurality of network devices is not allowed to resume communications following a reception of the suspend command. 
     
     
         10 . The method of  claim 1 ,
 further comprising defining a communication schedule having a plurality of links, each link specifying a communication timeslot of a predetermined duration, at least one sender, and at least one receiver, wherein the at least one sender and the at least one receiver are included in the plurality of network devices and wherein each of plurality of network devices communicates according to the communication schedule; and   wherein sending the suspend command to the at least some of the plurality of network devices comprises sending the suspend command to the at least some of the plurality of network devices according to the communication schedule.   
     
     
         11 . The method of  claim 10 , wherein defining a communication schedule includes allocating timeslots to each of the plurality of network devices according to a respective rate at which the each of the at least some of the plurality of network devices transmits process control or measurement data. 
     
     
         12 . A method of temporarily suspending communications in a wireless communication network operating in a process control environment and having a plurality of network devices, comprising:
 receiving, at a particular network device included in the plurality of network devices, a suspend command corresponding to a planned event in the process control environment;   suspending, based on the reception of the suspend command, wireless transmissions by the particular network device; and   resuming wireless transmissions by the particular network device upon an occurrence of a triggering condition.   
     
     
         13 . The method of  claim 12 , wherein receiving the suspend command corresponding to the planned event comprises receiving the suspend command corresponding to at least one of: an event having an elevated safety risk, a planned controlled explosion, a test, a measurement, or an operator request. 
     
     
         14 . The method of  claim 12 , wherein resuming wireless transmissions upon the occurrence of the triggering condition comprises resuming wireless transmissions upon a reception of a resume command. 
     
     
         15 . The method of  claim 12 , wherein at least one of:
 receiving the suspend command comprises receiving a transmission suspend time;   receiving the suspend command comprises receiving a suspend command including a transmission resume time and wherein the triggering condition corresponds to the transmission resume time; or   receiving the suspend command comprises receiving a suspend command including a quiet time interval and wherein the triggering condition corresponds to an elapsing of the quiet time interval.   
     
     
         16 . The method of  claim 15 ,
 further comprising maintaining an absolute slot number counter indicative of a number of communication timeslots of a predetermined duration scheduled since a formation of the wireless communication network, wherein each of the plurality of network devices communicates with at least one other of the plurality of network devices according to a communication schedule having a plurality of concurrent superframes, each superframe of the concurrent superframes defined as a repeating sequence of at least one of the communication timeslots; and   wherein receiving the transmission suspend time comprises receiving a first absolute slot number counter value and receiving the transmission resume time comprises receiving a second absolute slot number counter value.   
     
     
         17 . The method of  claim 12 , wherein the particular network device is configured with a quiet time interval, and wherein resuming wireless transmissions upon the occurrence of the triggering condition comprises resuming wireless transmissions upon an elapsing of the quiet time interval. 
     
     
         18 . The method of  claim 12 , wherein receiving the suspend command comprises receiving the suspend command via the wireless communication network. 
     
     
         19 . The method of  claim 12 , wherein receiving the suspend command comprises receiving the suspend command according to a communication schedule having a plurality of links, each link specifying a communication timeslot of a predetermined duration, at least one sender, and at least one receiver; wherein the at least one sender and the at least one receiver are included in the plurality of network devices; and wherein each of plurality of network devices communicates according to the communication schedule. 
     
     
         20 . The method of  claim 12 , wherein receiving the suspend command according to the communication schedule includes receiving the suspend command via one or more timeslots allocated to the particular network device according to a rate at which the network device transmits process control or measurement data.