System and method for channel time reservation in distributed wireless personal area network

Abstract

Disclosed are a channel time reservation system and method, and a data slot reservation method for transmitting data in a medium access control for a mobile ad-hoc wireless personal area networks. A reservation conflict, which may occur during a data slot reservation process, can be detected and solved. For this purpose, the system exchanges various types of information. Thus, a slot reservation for communication between devices can be completed in a shorter period of time. Also, capacity of the network can be improved by spatial reuse of channel time.

1 . A method of reserving a channel time in a distributed wireless network including at least one device, the method comprising: 
 issuing a reservation request to a destination device with respect to at least one common free slot, wherein the common free slot is a data slot which is not used by a beacon group of a source device, and is a data slot having no data transmitter in a beacon group of the destination device; and    transmitting data after sending an acknowledgement in response to an acceptance response of the destination device to a reservation request for a slot, for which no reservation conflict is found during the source's reservation request.    
   
   
       2 . The method as claimed in  claim 1 , wherein the distributed wireless network is configured to be employed in ultra wide band ad-hoc wireless personal area networks.  
   
   
       3 . The method as claimed in  claim 1 , further comprising: 
 receiving a data slot reservation indicator, wherein at least one device within the distributed wireless network broadcasts a status of data slots, which is derived from its own beacon group; and    determining at least one common free slot according to the data slot reservation indicator.    
   
   
       4 . The method as claimed in  claim 3 , wherein the data slot reservation indicator is updated by at least one device each corresponding to the status of data slot, either when a desired period comes or when having received a data slot reservation indicator, which is broadcast by at least one device.  
   
   
       5 . The method as claimed in  claim 3 , wherein the data slot reservation indicator includes a status information on data slots of one superframe within a beacon group, to which the respective device broadcasting the data slot reservation indicator, and the data slot reservation indicator is broadcasted through a beacon of at least one device.  
   
   
       6 . The method as claimed in  claim 5 , wherein the status information indicates, from the view point of the device broadcasting the data slot reservation indicator, a state where each of the data slot is either vacant to be used or unavailable.  
   
   
       7 . The method as claimed in  claim 6 , wherein the unavailable state is either a state where at least one device broadcasting the data slot reservation indicator corresponds to either a transmitter or a receiver of a unicast or multicast communication mode, or a state where either the transmitter or the receiver of the communication mode exists in the beacon group.  
   
   
       8 . The method as claimed in  claim 7 , wherein the data slot reservation indicator indicates the status information in every data slot, using at least one bit.  
   
   
       9 . The method as claimed in  claim 1 , wherein, within the destination's beacon group, the free slot corresponds to either a slot vacant without communication or a slot where only a receiver of multicast communication mode exists, and, within the beacon group of the source device, the free slot corresponds to a slot vacant without communication.  
   
   
       10 . The method as claimed in  claim 1 , wherein, if the reservation request of the source device is for a unicast communication, the free slot is a vacant slot without communication within the beacon group of the destination device.  
   
   
       11 . The method as claimed in  claim 1 , wherein the response means a rejection of the reservation request of the source device, in case where a reservation other than the reservation request of the source device is carried out within the beacon group of he destination device with respect to at least one common free slot.  
   
   
       12 . The method as claimed in  claim 1 , wherein the acceptance response is sent in case of a higher priority decided in a desired manner, when the destination device has received from a neighbor device within the beacon group of the destination device a separate reservation request other than the reservation request of the source device, with respect to the common free slot.  
   
   
       13 . The method as claimed in  claim 12 , wherein the acceptance response is sent in case of a higher priority, which is determined based on an arbitrary number contained in the reservation requests, even if the priority of the different reservation request is the same as for same slot(s).  
   
   
       14 . The method as claimed in  claim 1 , further comprising canceling a reservation with the destination device, in spite of an acceptance response of the destination device, on reception of another reservation request having a higher priority from other device(s) within the beacon group of the source device with respect to the same common free slot(s), after the reservation request of the source device.  
   
   
       15 . The method as claimed in  claim 1 , wherein the destination device cancels the reservation request of the source in spite of the acknowledgement, when the destination device becomes aware, after the acceptance response, that another acceptance response having a higher priority for the same common free slot is sent from other device within the beacon group of the destination device.  
   
   
       16 . The method as claimed in  claim 15 , wherein the destination device becomes aware of another acceptance response having the higher priority, through a data slot reservation indicator which is broadcast on a status of data slot in each beacon group by at least one device of the distributed wireless network.  
   
   
       17 . A system for reserving a channel time in a distributed wireless network including at least one device, the system comprising: 
 a destination device configured to receive a reservation request and to send an acceptance response on reception of the reservation request for at least one common free slot for which no reservation has been made within a beacon group of the destination device during the reservation request; and    a source device configured to send the reservation request as a reservation request of the source device for at least one common free slot, and to receive the acceptance response, to send an acknowledgement for the acceptance response and transmit data, the common free slot being a data slot having no data transmitter in the beacon group of the destination device and is not used in a beacon group of the source.    
   
   
       18 . The system as claimed in  claim 17 , wherein the distributed wireless network is configured to be employed in ultra wide band ad-hoc wireless personal area networks.  
   
   
       19 . The system as claimed in  claim 17 , wherein the source device receives a data slot reservation indicator in which at least one device within the distributed wireless network, which includes information of respective beacon groups of the at least one device, and determines at least one free slot according to the data slot reservation indicator.  
   
   
       20 . The system as claimed in  claim 19 , wherein the data slot reservation indicator is updated by at least one device each corresponding to the status of a data slot, either when a desired period comes or on reception of a data slot reservation indicator, which is broadcasted by at least one device.  
   
   
       21 . The system as claimed in  claim 19 , wherein the data slot reservation indicator includes status information on data slots of one superframe within a beacon group, to which the respective device broadcasting the data slot reservation indicator belongs, and the data slot reservation indicator is broadcast through a beacon of at least one device.  
   
   
       22 . The system as claimed in  claim 21 , wherein the status information indicates, from the view point of the device broadcasting the data slot reservation indicator, a state where each of the data slot either is vacant and available to be used or is unavailable.  
   
   
       23 . The system as claimed in  claim 22 , wherein the unavailable state is either a state where at least one device broadcasting the data slot reservation indicator corresponds to either a transmitter or a receiver of a unicast or multicast communication mode, or a state where either the transmitter or the receiver of the communication mode exists in the beacon group.  
   
   
       24 . The system as claimed in  claim 22 , wherein the data slot reservation indicator indicates the status information in each data slot, using at least one bit.  
   
   
       25 . The system as claimed in  claim 17 , wherein, within the beacon group of the destination device, the free slot corresponds to either a slot vacant without communication or a slot where only a receiver of multicast communication mode exists, and, within the beacon group of the source device, the common free slot corresponds to a slot vacant without communication.  
   
   
       26 . The system as claimed in  claim 17 , wherein, if the reservation request of the source device is for a unicast communication, the common free slot is a slot vacant within the beacon group of the destination device without communication.  
   
   
       27 . The system as claimed in  claim 17 , wherein the destination device rejects the reservation request of the source device, in case where a reservation other than the reservation request of the source device is carried out within the beacon group of the destination device with respect to the common free slot.  
   
   
       28 . The system as claimed in  claim 17 , wherein the destination device sends an acceptance response to a reservation request having a higher priority decided in a certain desired manner, when the destination device has received from a neighbor device within the beacon group of the destination device a different reservation request other than the reservation request of the source device for the same common free slot.  
   
   
       29 . The system as claimed in  claim 28 , wherein the destination device sends an acceptance response to a single reservation request, based on an arbitrary number contained in reservation requests, even if multiple reservation requests having same priority as that of the reservation request of the source device.  
   
   
       30 . The system as claimed in  claim 17 , wherein the source device cancels a reservation with the destination device, in spite of an acceptance response of the destination device, on reception of a higher priority reservation for the same common free slot, after the reservation request of the source device.  
   
   
       31 . The system as claimed in  claim 17 , wherein the destination device cancels the reservation request of the source device in spite of the acknowledgement, when the destination device becomes aware, after the acceptance response, that another acceptance response having a higher priority for the same common free slot is sent from other device within the beacon group of the destination device.  
   
   
       32 . The system as claimed in  claim 31 , wherein the destination device becomes aware of another acceptance response having the higher priority, through a data slot reservation indicator which is broadcasted by at least one device of the distributed wireless network.  
   
   
       33 . A medium access control method in a distributed wireless network including at least one device, the method comprising: 
 receiving, at a source device, a data slot reservation indicator from a beacon group of the source device, and broadcasting a data slot reservation indicator to the beacon group of the source device; and    determining at least one common free slot based on the data slot reservation indicator, wherein the common free slot is not used within the beacon group of the source device and is a data slot having no data transmitter in a beacon group of a destination device.    
   
   
       34 . The medium access control method as claimed in  claim 33 , further comprising a step of broadcasting the data slot reservation indicator updated corresponding to the status of the data slot, either when the data slot reservation indicator is being broadcasted, received or at a certain desired interval.  
   
   
       35 . The medium access control method as claimed in  claim 33 , wherein the data slot reservation indicator includes status information on 256 slots of one superframe, and the data slot reservation indicator is broadcasted through a beacon of at least one device.  
   
   
       36 . The medium access control method as claimed in  claim 35 , wherein the status information indicates a state of the data slot as either vacant and can be used or unavailable, from the view point of the device, which is broadcasting the data slot reservation indicator.  
   
   
       37 . The medium access control method as claimed in  claim 36 , wherein the data slot reservation indicator includes the status information of the 256 slots, and the status information is constituted of at least one bit.