A method for improving spectrum sensing and efficiency in cognitive wireless systems

Abstract

Systems and methods for adaptive method exploits self-interference suppression (SIS) and full-duplex (FD) capabilities in cognitive radio and dynamic spectrum access (DSA) systems to enable simultaneous transmission-and-sensing (TS) or transmission-and-reception (TR) over the same frequency channel in a single operation. The adaptive methods enable secondary users or units (SUs) to switch between different modes of operation, taking into account the primary units (PUs) state, the SUs' traffic, and standards' rules. These adaptive methods significantly enhance the SU throughput and reduce the probability of colliding with PU transmissions.

1 . A computer-implemented method of spectrum access for wireless communications by a secondary unit (SU) in a wireless network environment comprising one or more SUs and one or more primary units, the method comprising:
 sensing, with a first SU operating in a first mode, a channel of the network for transmissions by the one or more primary units while simultaneously transmitting data over the channel of the network by suppressing self-interference on the first SU caused by transmitting data; and   receiving, with the first SU operating in a second mode, data over the channel of the network from a second SU while simultaneously transmitting data over the channel of the network by suppressing self-interference on the SU caused by transmitting data.   
     
     
         2 . The computer-implemented method of  claim 1 , further comprising switching between the first mode and the second mode based on a probability determination obtained while operating in the first mode or second mode, the probability determination determining a likelihood that the channel is idle. 
     
     
         3 . The computer-implemented method of  claim 1 , wherein the SU operates in a third mode comprising sensing only using a sensing-only algorithm configured to facilitate detection of an idle channel of the wireless network. 
     
     
         4 . The computer-implemented method of  claim 1 , further comprising sensing the channel of the network for transmissions by the one or more primary units according to a predetermined periodic sensing interval. 
     
     
         5 . The computer-implemented method of  claim 3 , wherein the the SU operates in a fourth mode comprising switching from the channel to a different channel on the wireless network. 
     
     
         6 . The computer-implemented method of  claim 1 , wherein while operating in the second mode, determining if the first or second SUs have more data to transmit and, if both the first and second SUs are determined to have more data to transmit, causing both the first and second SUs to continue operating in the second mode. 
     
     
         7 . The computer-implemented method of  claim 1 , wherein while operating in the first mode, determining if the first or second SUs have more data to transmit and, if only one of the first and second SUs is determined to have more data to transmit, causing the SU having more data to transmit to operate in the first mode while causing the other SU to operate in a receive only mode. 
     
     
         8 . The computer-implemented method of  claim 7 , wherein if at a first time only the first SU has data to transmit, the first SU assumes a role of a master device that is operable in the first and second modes and the second SU assumes a role of a slave device operable in the second mode and inoperable in the first mode. 
     
     
         9 . The computer-implemented method of  claim 8 , wherein if at a second time only the second SU has data to transmit, causing the first and second SU to switch roles so that the first SU is a slave node and the second SU is a master node. 
     
     
         10 . The computer-implemented method of  claim 9 , wherein the slave node is also operable in the receive only mode. 
     
     
         11 . The computer-implemented method of  claim 6 , wherein determining if the second SUs have more data to transmit further comprises examining a specified data field in a transmission received from the second SU. 
     
     
         12 . A computer-implemented method of spectrum access for wireless communications by an SU in a wireless network environment comprising one or more SUs and one or more primary units, the method comprising:
 determining by a first SU a probability that a channel of the wireless network is idle;   based on the determined probability, making a first decision to operate the first SU in one of four modes comprising (i) a transmit-receive (TR) mode, wherein the first SU transmits and receives data simultaneously over the wireless network, (ii) a transmit-sense (TS) mode, wherein the first SU transmits data over the wireless network while simultaneously sensing for transmissions by a primary unit over the wireless network, (iii) a sense only (SO) mode, wherein the first SU only senses for transmissions by a primary unit over the wireless network, and (iv) a channel-switching (CS) mode, wherein the first SU switches channels of the wireless network; and   if the first decision for the first SU is to operate the first SU in the TR mode and the first decision for a second SU is to operate the second SU in the TR mode, causing each of the first and second SUs to operate in the TR mode so long as each unit has more packets to transmit, and if only one of the first SU and the second SU has more packets to transmit, causing the one SU to operate in the TS mode while causing the other SU to operate in a receive (R) mode in which the other secondary unit only receives data over the wireless network.   
     
     
         13 . The computer-implemented method of  claim 12 , wherein if the first decision is to operate the first SU in the SO mode or the CS mode, making a final decision to operate the first SU in the SO mode or the CS mode, respectively. 
     
     
         14 . The computer-implemented method of  claim 12 , wherein if the first decision for one of the first SU and the second SU is to operate in the TS mode and the first decision for the other of the first and second SUs is to operate in the R mode, causing the one SU to operate in the TS mode while causing the other SU to operate in the R mode so long as the one SU has more packets to transmit, and if only the other SU has more packets to transmit, causing the one SU to operate in the R mode while causing the other SU to operate in the TS mode. 
     
     
         15 . The computer-implemented method of  claim 12 , wherein if a final decision is to operate the first and second SUs in the TR mode, updating the first decision based at least in part on whether or not a transmission by the first SU to the second SU was successfully received and whether or not a transmission received by the first SU from the second SU was successfully decoded. 
     
     
         16 . The computer-implemented method of  claim 12 , wherein if a final decision for one of the first SU and a second SU is to operate in the TS mode and the first decision for the other of the first SU and the second SU is to operate in the R mode, updating the first decision based at least in part on a probability that the channel is idle and whether or not a transmission from the one of the first and second SUs was successfully received by the other of the first and second SUs. 
     
     
         17 . A non-transitory computer readable medium comprising computer executable instructions that, when executed by a processor of a SU in a wireless network environment, cause the SU to perform the method set forth in  claim 1 . 
     
     
         18 . A wireless communication device, comprising:
 a wireless transmitter and receiver;   a spectrum sensing engine for sensing wireless channels in a wireless network for transmissions by one or more primary units;   a processor;   a memory operatively coupled to the processor, the memory storing instructions that, when executed by the processor, cause the wireless communication device to:   operate in a first mode comprising sensing, with the spectrum sensing engine, a channel of the network for transmissions by the one or more primary units while simultaneously transmitting data over the channel of the network by suppressing self-interference on the wireless communication device caused by transmitting data by the SU; and   operate in a second mode comprising receiving data over the channel of the network from an SU while simultaneously transmitting data over the channel of the network by suppressing self-interference on the SU caused by transmitting data by the SU.   
     
     
         19 . The wireless communication device of  claim 18 , wherein the instructions, when executed by the processor, further cause the wireless communication device to switch between the first mode and the second mode based on a probability determination obtained while operating in the first mode, the probability determination determining a likelihood that the channel is idle. 
     
     
         20 . The wireless communication device of  claim 18 , wherein the instructions, when executed by the processor, further cause the wireless communication device to determine, while operating in the first mode, if the wireless communication device or the SU has more data to transmit and, if only the SU is determined to have more data to transmit, cause the SU to operate in the first mode while causing the wireless communication device to operate in a receive only mode.