WO2013027637A2 - Système de communication - Google Patents

Système de communication Download PDF

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Publication number
WO2013027637A2
WO2013027637A2 PCT/JP2012/070713 JP2012070713W WO2013027637A2 WO 2013027637 A2 WO2013027637 A2 WO 2013027637A2 JP 2012070713 W JP2012070713 W JP 2012070713W WO 2013027637 A2 WO2013027637 A2 WO 2013027637A2
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WO
WIPO (PCT)
Prior art keywords
primary user
master node
node
mobile
user transmission
Prior art date
Application number
PCT/JP2012/070713
Other languages
English (en)
Other versions
WO2013027637A3 (fr
Inventor
Philippe DELAHAYE
Pierre Marchand
Original Assignee
Nec Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nec Corporation filed Critical Nec Corporation
Priority to JP2014507783A priority Critical patent/JP5835468B2/ja
Publication of WO2013027637A2 publication Critical patent/WO2013027637A2/fr
Publication of WO2013027637A3 publication Critical patent/WO2013027637A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/14—Spectrum sharing arrangements between different networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
    • H04W16/06—Hybrid resource partitioning, e.g. channel borrowing
    • H04W16/08—Load shedding arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference

Definitions

  • the present invention relates to a communications system and to parts and methods thereof.
  • the invention has particular, although not exclusive relevance to cognitive radio systems and devices thereof.
  • a Cognitive Radio Device has been defined as a terminal which is aware of its electro-magnetic environment and able to adapt its transmission accordingly.
  • a Cognitive Radio Device may sense a specific frequency band in order to estimate its occupancy and take a decision whether it transmits or not.
  • the primary signals to be detected are subject to different environment changes (shadowing, fading, path loss) and therefore sometimes primary licensed users are very difficult to detect by a single cognitive radio device.
  • the primary transmitter is considered to be "hidden” (i.e., hidden primary transmitter) from the sensing device, and therefore the use of a single sensing device is unlikely to provide a reliable decision.
  • a problem with using such a cooperative approach is that sensor nodes must be specifically instructed when and in which frequency bands to sense and when to report back to the master node.
  • the master node relies on upper layers of the communications stack to control the operation of the sensor nodes and this leads to relatively long delays between the sensor node signalling the presence of the primary and the master node taking action to stop secondary users transmissions; which in turn can contribute to undesired interference for the primary licensed users during the time it takes to receive and process such signalling at the master node.
  • the invention aims to provide an alternative cooperative system for detecting and reporting transmission characteristics of primary users and hence to control transmission opportunities for secondary users.
  • the present invention provides a master node for use with a plurality of mobile nodes, the master node comprising: receiving means for receiving from at least one of the mobile nodes primary user transmission information indicative of a signal strength of a primary user transmission received at the at least one mobile node; obtaining means for obtaining position information for each of the at least one mobile node; estimating means for estimating an area of possible transmission overlap between the master node and the primary user using the received primary user transmission information and the obtained position information; comparing means for comparing the location of each mobile node with the estimated area of possible transmission overlap; and control means for controlling the operation of the mobile nodes in dependence upon a result of the comparison in order to avoid interference to the primary user by the master node and the mobile nodes.
  • the receiving means receives the information in a Medium Access Control, MAC, control element.
  • MAC Medium Access Control
  • the obtaining means obtains the position information for each of the at least one mobile node from the mobile node.
  • the obtaining means obtains the position information for each of the at least one mobile node from a positioning system or from communications with other master nodes.
  • control means controls the operation of the mobile nodes using at least one of: preventing use of the band of the primary user transmission, performing a handover to a different band than the band of the primary user transmission, limiting a transmission power of the mobile node in the band of the primary user transmission, and allowing the mobile node to continue transmission in the band of the primary user transmission.
  • control means controls a transmission power and/or a transmission direction of the master node in the band of the primary user transmission in order to avoid interference to the primary user.
  • control means is operable to send the primary user transmission information within a MAC control element to at least one of the plurality of mobile nodes for causing the at least one mobile node to stop its transmission within the band of the primary user transmission.
  • the present invention also provides a sensor node for use with a master node, the sensor node and master node being arranged to communicate with each other within a licensed operating band of a primary user device, the sensor node comprising: sensing means for sensing a transmission of the primary user device; measuring means for determining a measure of a signal strength of the sensed primary user transmission; and reporting means for reporting the determined signal strength measure to the master node; wherein the reporting means is operable to report the determined signal strength measure within a Medium Access Control, MAC, layer frame for processing by a MAC entity within the master node.
  • MAC Medium Access Control
  • the reporting means reports the determined signal strength measure within a MAC control element.
  • the reporting means may also report an indication of the position information for the sensor node.
  • the sensor node stops its transmission in the band of the primary user transmission. This may be done after receiving an acknowledgement from the master node.
  • the present invention also provides a master node for use with a plurality of mobile nodes, the master node comprising: receiving means for receiving from at least one of the mobile nodes primary user transmission information indicative of a signal strength of a primary user transmission received at the at least one mobile node; and control means for controlling the operation of the mobile nodes in dependence upon the received primary user transmission information to avoid interference to the primary user by the master node and the mobile nodes; wherein the receiving means operates at a Medium Access Control, MAC, layer of the master node and is arranged to extract the primary user transmission information from a MAC layer frame.
  • MAC Medium Access Control
  • the receiving means receives the primary user transmission information within a MAC control element.
  • the master node may further comprise sending means for sending an acknowledgement to the at least one mobile node for causing the mobile node to stop its transmission within the band of the primary user transmission.
  • the master node may further comprise sending means for sending the primary user transmission information within a MAC control element to at least one of the plurality of mobile nodes for causing the at least one mobile node to stop its transmission within the band of the primary user transmission.
  • the present invention also provides a sensor node for use with a master node, the sensor node and master node being operable to communicate with each other within a licensed operating band of a primary user device, the sensor node comprising: communications control means for receiving uplink resource allocation data indicating uplink resources that the sensor node can use for transmitting data to the master node; sensing means for sensing a transmission of the primary user device; reporting means for reporting a determined signal strength measure to the master node using uplink resources allocated by the master node; wherein if the sensing means senses the primary user transmission at a time when the sensor node has not been allocated uplink resources, the communications control means is arranged to request uplink resource allocation from the master node.
  • the reporting means reports primary user transmission information, indicative of the sensed primary user transmission, in a message sent by the sensor node as part of a Random Access Procedure.
  • the message may be an uplink request message of the
  • Random Access Procedure may comprise a reserved preamble that notifies the master node of detection of the primary user transmission within the licensed operating band.
  • the reporting means reports the primary user transmission information within a MAC control element.
  • the reporting means may report said determined signal strength measure, after uplink resources have been granted to the sensor node, in a further message sent by the sensor node as part of the Random Access Procedure.
  • the present invention also provides a master node for use with a plurality of mobile nodes, the master node comprising: receiving means for receiving from at least one of the mobile nodes primary user transmission information indicative of a signal strength of a primary user transmission received at the at least one mobile node; and control means for controlling the operation of the mobile nodes in dependence upon the received primary user transmission information to avoid interference to the primary user by the master node and the mobile nodes; wherein the receiving means is operable to receive the primary user transmission information within a message sent by the at least one mobile node as part of a Random Access Procedure.
  • the master node receives a notification of a sensed primary user transmission, in an uplink request message sent by the mobile node as part of a Random Access Procedure.
  • the uplink request message may comprise a reserved preamble that notifies the master node of detection of the primary user transmission within the licensed operating band.
  • control means is operable, in response to receiving the uplink request message comprising the reserved preamble, to control operation of the master node and the plurality of mobile nodes to avoid interference to the primary user by the master node and the mobile nodes.
  • the receiving means receives the primary user transmission information within a MAC control element.
  • the primary user transmission information may be received, after uplink resources have been granted to the mobile node, in a further message sent by the mobile node as part of the Random Access Procedure.
  • the present invention also provides a sensor node for use with a master node, the sensor node and master node being operable to communicate with each other within a licensed operating band of a primary user device, the sensor node comprising: means for storing a reserved preamble; means for sensing a transmission of the primary user device; and means for notifying the master node of the sensed primary user transmission, wherein the means for notifying is arranged to notify the master node by sending the stored reserved preamble in an initial message of a Random Access procedure.
  • the reserved preamble may be pre-programmed in the sensor node but is preferably received as a part of system information broadcast by the master node.
  • the sensor node further comprises means for determining a signal strength measurement of the primary user transmission and means for sending the signal strength measurement to the master node.
  • the sensor node can send the determined signal strength to the master node using uplink resources allocated to the sensor node by the master node.
  • the sensor node further comprises means for randomly generating a preamble for use in a Random Access procedure.
  • the sensor node may compare the randomly generated preamble with the stored reserved preamble, and when the randomly generated preamble matches the stored reserved preamble, the sensor node randomly generates another preamble for use in the Random Access procedure.
  • the present invention also provides a master node for use with a plurality of mobile nodes, the master node and mobile nodes being operable to communicate with each other within a licensed operating band of a primary user device, the master node comprising: means for receiving from at least one mobile node, an initial message of a Random Access procedure; means for processing the received initial message to determine whether or not the mobile node that transmitted the initial message has sensed a primary user transmission; and means for controlling operation of the mobile nodes to avoid interference to the primary user if the determining means determines that the mobile node that transmitted the initial message has sensed a primary user transmission.
  • the master node further comprises means for storing a reserved preamble used to indicate the sensing of a primary user transmission and wherein the processing means is arranged to determine if the preamble in the received initial message matches the stored reserved preamble and to determine that the mobile node that transmitted the initial message has sensed a primary user transmission if the received preamble matches the reserved preamble.
  • the master node further comprises means for sending the stored reserved preamble to the plurality of mobile nodes. This may be broadcast as a part of system information.
  • control means is arranged, in response to the determining means determining that the mobile node that transmitted the initial message has sensed a primary user transmission, to cease transmissions to other mobile terminals in the licensed operating band.
  • the master node further comprises means for sending an uplink resource allocation message to the mobile node that has sensed the primary user transmission. This allocation may be used by the sensor node to send signal measurements back to the master node.
  • the master node is operable to receive, from the mobile node, a signal strength measurement of the sensed primary user transmission and wherein the controlling means is arranged to re-determine control actions for each mobile node in light of the received signal strength measurement.
  • the present invention also provides a communications system comprising a plurality of mobile nodes and the master node according to any one of the above embodiments.
  • the present invention also provides a method performed by a master node that communicates with a plurality of mobile nodes within a licensed operating band of a primary user device, the method comprising: receiving from at least one of the mobile nodes primary user transmission information indicative of a signal strength of a primary user transmission received at the at least one mobile node; obtaining position information for each of the at least one mobile node; estimating an area of possible transmission overlap between the master node and the primary user using the received primary user transmission information and the obtained position information; comparing the location of each mobile node with the estimated area of possible transmission overlap; and controlling the operation of the mobile nodes in dependence upon a result of the comparison in order to avoid interference to the primary user by the master node and the mobile nodes.
  • the information is received in a Medium Access Control, MAC, control element.
  • MAC Medium Access Control
  • the present invention also provides a method performed by a master node that communicates with a plurality of mobile nodes within a licensed operating band of a primary user device, the method comprising: receiving from at least one of the mobile nodes primary user transmission information indicative of a signal strength of a primary user transmission received at the at least one mobile node; and controlling the operation of the mobile nodes in dependence upon the received primary user transmission information to avoid interference to the primary user by the master node and the mobile nodes; wherein the receiving step is carried out at a Medium Access Control, MAC, layer of the master node and comprises extracting the primary user transmission information from a MAC layer frame.
  • MAC Medium Access Control
  • the present invention also provides a method performed by a mobile node that communicates with a master node within a licensed operating band of a primary user device, the method comprising: sensing a transmission of the primary user device; determining a measure of a signal strength of the sensed primary user transmission; and reporting the determined signal strength measure to the master node; wherein the reporting step comprises reporting the determined signal strength measure within a Medium Access Control, MAC, layer frame for processing by a MAC entity within the master node.
  • MAC Medium Access Control
  • the present invention also provides a method performed by a mobile node that communicates with a master node within a licensed operating band of a primary user device, the method comprising: receiving uplink resource allocation data indicating uplink resources that the sensor node can use for transmissions data to the master node; sensing a transmission of the primary user device; reporting a determined signal strength measure to the master node using uplink resources allocated by the master node; wherein if at the sensing step the sensor node has not been allocated uplink resources, the reporting step further comprises requesting uplink resource allocation from the master node.
  • the method further comprises reporting the sensed primary user transmission, in a message sent by the sensor node as part of a Random Access Procedure.
  • the message may be an uplink request message of the Random Access Procedure and may comprise a reserved preamble that notifies the master node of detection of the primary user transmission within the licensed operating band.
  • the reporting step is part of a Random Access Procedure.
  • the determined signal strength measure is reported within a MAC control element.
  • the determined signal strength measure may be reported, after uplink resources have been granted to the sensor node, in a further message sent by the sensor node as part of the Random Access Procedure.
  • the present invention also provides a method performed by a master node that communicates with a plurality of mobile nodes within a licensed operating band of a primary user device, the method comprising: receiving from at least one of the mobile nodes primary user transmission information indicative of a signal strength of a primary user transmission received at the at least one mobile node; and controlling the operation of the mobile nodes in dependence upon the received primary user transmission information to avoid interference to the primary user by the master node and the mobile nodes; wherein the receiving step comprises receiving the primary user transmission information within a message sent by the at least one node as part of a Random Access Procedure.
  • the method further comprises receiving a notification of a sensed primary user transmission, in an uplink request message sent by the sensor node as part of a Random Access Procedure.
  • the uplink request message may comprise a reserved preamble that notifies the master node of detection of the primary user transmission within the licensed operating band.
  • controlling the operation comprises, in response to receiving the uplink request message, controlling operation of the plurality of mobile nodes to avoid interference to the primary user by the master node and the mobile nodes.
  • said primary user transmission information is received within a MAC control element.
  • the present invention also provides a method performed by a master node that communicates with a plurality of mobile nodes within a licensed operating band of a primary user device, the method comprising: receiving from at least one mobile node, an initial message of a Random Access procedure; processing the received initial message to determine whether of not the mobile node that transmitted the initial message has sensed a primary user transmission; and controlling operation of the mobile nodes to avoid interference to the primary user if it has been determined that the mobile node that transmitted the initial message has sensed a primary user transmission.
  • the method further comprises storing, at the master node, a reserved preamble used to indicate the sensing of a primary user transmission and determining if the preamble in the received initial message matches the stored reserved preamble and determining that the mobile node that transmitted the initial message has sensed a primary user transmission if the received preamble matches the reserved preamble.
  • the method further comprises sending the stored reserved preamble to the plurality of mobile nodes as a part of system information.
  • controlling the operation further comprises controlling the master node, in response to determining that the mobile node that transmitted the initial message has sensed a primary user transmission, to cease transmissions to other mobile terminals in the licensed operating band.
  • the uplink resource allocation may be provided to the mobile node that sent the initial message.
  • the method may also comprise receiving, from the mobile node, a signal strength measurement of the sensed primary user transmission and re-determining control actions for each mobile node in light of the received signal strength measurement.
  • the present invention also provides a method performed by a sensor node that communicates with a master node within a licensed operating band of a primary user device, the method comprising: storing a reserved preamble; sensing a transmission of the primary user device; and notifying the master node of the sensed primary user transmission, wherein the means for notifying is arranged to notify the master node by sending the stored reserved preamble in an initial message of a Random Access procedure.
  • the reserved preamble may be pre-programmed in the sensor node but is preferably received as a part of system information broadcast by the master node.
  • the method further comprises receiving an uplink resource allocation from the master node.
  • the method further comprises determining a signal strength measurement of the primary user transmission and sending the signal strength measurement to the master node.
  • the determined signal strength may be sent to the master node using the uplink resource allocation received from the master node.
  • the method further comprises randomly generating a preamble for use in a Random Access procedure.
  • the randomly generated preamble may be compared with the stored reserved preamble, and when the randomly generated preamble matches the stored reserved preamble, another preamble may be generated for use in the Random Access procedure.
  • the invention provides, for all methods disclosed, corresponding computer programs or computer program products for execution on corresponding equipment, the equipment itself (user equipment, master node, mobile nodes or components thereof) and methods of updating the equipment.
  • Fig. 1 illustrates coverage areas of a master node and a primary transmitter and an overlapping region in which interference may occur.
  • Fig. 2 is a block diagram illustrating the main components of a sensor mobile terminal shown in Fig. 1.
  • Fig. 3 is a block diagram illustrating the main components of the master node shown in
  • Fig. 4 is a flow chart illustrating the cooperative sensing technique used in the first embodiment.
  • Fig. 5 is a flow chart illustrating the steps that the master node can use to determine actions for mobile terminals to take in order to reduce interference.
  • Fig. 6A is an overview of the protocol stack used by the mobile terminal and the master node implementing the invention.
  • Fig. 6B is an overview of the lower layers of the protocol stack used by the mobile terminal and the master node implementing the invention.
  • Fig. 7A is an overview illustrating a protocol data unit implementing the invention.
  • Fig. 7B is an overview illustrating a protocol data unit implementing the invention.
  • Fig. 7B is an overview illustrating the service data unit of the protocol data unit of Fig.
  • Fig. 7C is an overview of a control element used with the protocol data unit of Fig. 7 A.
  • Fig. 8 is a signalling diagram illustrating the communication taking place between the sensor mobile terminal and the master node according to an embodiment of the invention.
  • Fig. 1 schematically illustrates a cognitive wireless communication network 1 that has a master node 3 and a plurality of mobile terminals 5 (marked as 5a-5e) within an area 13 controlled by the master node 3.
  • the master node 3 and the mobile terminals 5 are secondary users of a frequency band (B) that is licensed to one or more primary users.
  • the primary users will typically include a wideband primary transmitter 4 that transmits over the whole or any part of its licensed frequency band (B) and primary user equipment 7 (marked as 7a-7c) that transmit or receive signals over different channels within the licensed band (B).
  • the licensed band (B) may correspond to a television channel (DVB-T operating on 6MHz or 8MHz channels) and the wideband primary transmitter 4 will transmit over a number of channels whilst the primary user equipment 7 receive the transmitted signal in the whole or any part of the licensed band.
  • Some primary user equipment 7, such as PMSE (Programme Making Special Event) devices) may also transmit within sub-bands (e.g. 200 KHz or 400KHz sub-bands) of the larger 6MHz or 8MHz television channel.
  • Transmissions of the mobile terminals 5 are controlled by the master node 3.
  • the secondary users are able to communicate within all or a part of the frequency band (B) whilst the primary users are not transmitting in all or that part of the band (B); or as long as the interference caused by the transmissions of the secondary users is acceptable to the primary users.
  • the master node 3 will be fixed in location and the mobile terminals 5 can move.
  • the master node 3 is a cellular telephone base station that operates in accordance with the Long Term Evolution (LTE) standards and the mobile terminals 5 are LTE user equipment, such as cellular telephones and the like.
  • LTE Long Term Evolution
  • Some or all of the mobile terminals 5 are arranged to act as sensor nodes (hereinafter referred to as sensor mobile terminals 5) that are able to sense for primary user transmissions within the licensed frequency band (B). Once a sensor mobile terminal senses a primary user transmission, it informs the master node 3 which then decides if it is allowable for any of the secondary users to transmit in any part of the licensed band (B).
  • various data and control information is transmitted between the master node 3 and the mobile terminals 5 in multiple frequency bands, including the frequency band (B) licensed to the primary user.
  • the master node 3 keeps track of the location of the mobile terminals 5 either continuously, periodically or from time to time to ensure that communication between the master node 3 and the mobile terminals 5 can be maintained.
  • transmission of data and control information is handed over to another master node (not shown) that is able to maintain transmission of data and control information with the mobile terminals 5. Handover might also be initiated for mobile terminals 5 that are still within the area 13 controlled by the master node 3 for various reasons that are well known to the person skilled in the art.
  • the master node 3 Whilst the master node 3 is typically installed at a fixed location, and hence it is able to make measurements at a single location, the sensor mobile terminals 5 can provide
  • Sensor mobile terminals 5 may be closer to the primary transmitter 4, 7 than the master node 3 and thus may make a more accurate detection and measurement of the primary user transmission.
  • a sensor mobile terminal 5 reports the detection and signal measurements in a signalling message that it sends to the master node 3.
  • the master node 3 uses the measurements from the different sensor mobile terminals 5 and information about the locations of those sensor mobile terminals 5 to establish areas of possible interference between the primary user and the secondary user of the licensed band (B).
  • areas of possible interference include the area of overlap 17 between the coverage area (cell) 13 controlled by the master node 3 and the coverage area 14 of the primary transmitter 4.
  • a sub-area 19 of possible interference might also be present where the transmission area 15a of mobile terminal 5a overlaps with the coverage area 14 of the primary transmitter 4.
  • the size of the area 17 is predominantly determined by the transmission characteristics of the master node 3 and the primary transmitter 4; and the size of sub-area 19 is mainly dependent on the location and transmission characteristics of mobile terminal 5a and primary transmitter 4.
  • the primary transmitter 4 is not transmitting in the licensed frequency band (B) - so there is no area of overlap 17 and the master node 3 can control all of the mobile terminals 5 operating within its cell 13 to operate within the licensed frequency band (B).
  • the sensor mobile terminals 5b and 5c will detect this transmission and will sense the strength of the primary user signal. They will then transmit a report to the master node 3 informing the master node that they have detected the primary user transmission and the strength of that transmission.
  • the master node 3 instructs sensor mobile terminals 5b and 5c to stop transmitting on the frequency band (B) and allocates a new frequency band for subsequent transmissions with sensor mobile terminals 5b and 5c.
  • the master node 3 also uses the reported signal strengths and the locations of the sensor mobile terminals 5b and 5c, to work out the approximate location of the primary transmitter 4 and from this to work out the coverage area 14 and hence the overlap area 17. From this information, the master node 3 can determine how much it needs to reduce its own transmission power in the licensed frequency band (B) in order to avoid its transmissions interfering with primary users located within the coverage area 14.
  • Fig. 1 shows the reduced size of the cell 13' that can be provided by the master node 3 in the frequency band (B) whilst avoiding interference with the primary user 4.
  • Changing the size of the cell 13 will have consequences for other mobile terminals 5 being served by the master node 3. For example, mobile terminal 5e will be outside the cell 13 and so can't continue using the licensed frequency band (B). If the master node 3 operates another cell on a different operating frequency, then the mobile terminal 5e can be handed over to that other cell. Otherwise mobile terminal 5e will have to be handed over to a neighbouring master node 3.
  • B licensed frequency band
  • the master node 3 can use the location information of the different sensor mobile terminals to determine which mobile terminals 5 fall into this category and then either instruct them to reduce their transmission power or hand them over to another cell operating on a different frequency.
  • Other mobile terminals 5 that are still located inside the reduced cell 13' and which are located far enough away from the coverage area 14 of the primary user 4 may continue to use the licensed frequency band (B), although in this preferred embodiment, the master node 3 will track the location of such mobile terminal 5d and as it moves towards the coverage area 14, the master node 3 may instruct the mobile terminal 5d to reduce its transmission power or handover the mobile terminal 5d to another cell operating on a different frequency.
  • B licensed frequency band
  • the master node 3 should identify the mobile terminals 5 that will be affected by the apparition of the primary transmitter 4 and perform the required control action in respect of each of them before it reduces its own transmission power in the licensed band (B).
  • the required control action will be to stop transmitting in the licensed frequency band (B), for others the required control action will be to reduce their transmission power in the licensed frequency band (B), for others the required control action will be to hand them over to another cell operating on a different frequency.
  • sensor mobile terminals 5 detecting the apparition of the primary transmitter on frequency band (B) measure the transmission power of the primary, and send an indication to the master node 3. Then they stop communications within the operating frequency band (B) after making sure that the indication has been correctly received by the master node 3. Receipt of the indication might be confirmed by the master node 3 by sending an
  • acknowledgement message commonly used in the Hybrid Automatic Retransmission Request (HARQ) mechanism of the air interface in LTE networks.
  • Fig. 2 is a block diagram illustrating the main components of a sensor mobile terminal 5, shown in Fig. 1.
  • the mobile terminal 5 includes transceiver circuitry 223 which is operable to transmit signals to and to receive signals from other nodes (e.g. the master node 3) via one or more antennas 225.
  • a controller 227 controls the operation of the transceiver circuitry 223 in accordance with software stored in memory 237.
  • the mobile terminal 5 also includes a user interface 229 that is controlled by the controller 227 and which allows a user to interact with the communication device.
  • the software stored in memory 237 includes, among other things, an operating system 239, a communication module 241, a positioning module 243, a sensor module 245, a measuring module 246, a reporting module 247 and a transmission frequency control module 249.
  • the operating system 239 controls the operation of the mobile terminal 5.
  • the communication module 241 controls communications between the mobile terminal 5 and external devices via the transceiver circuitry 223 and the antenna 225.
  • the positioning module 243 operates to determine location information for the sensor mobile terminal 5. It may be a GPS or similar satellite or terrestrial location determining module.
  • the positioning module 243 sends regular position updates to the master node 3 either on demand or at predetermined time intervals.
  • the sensor module 245 operates to sense for transmissions made by primary users.
  • the sensor module 245 will normally be able to sense for primary user transmissions within the entire licensed band (B) (and perhaps in other frequency bands as well). Whenever the sensor module 245 detects a primary user transmission, the measuring module 246 measures the power of the primary user's transmission, i.e.
  • the transmission frequency control module 249 operates to receive the information transmitted from the master node 3 identifying if there are any bands within the licensed band (B) in which they can transmit opportunistic signals without interfering with a primary user; and to control the transmission frequency used by the transceiver circuitry 223 for such opportunistic transmissions accordingly.
  • Fig. 3 is a block diagram illustrating the main components of the master node 3, shown in Fig. 1.
  • the master node 3 includes transceiver circuitry 323 which is operable to transmit signals to and to receive signals from other nodes via one or more antennas 325.
  • a controller 327 controls the operation of the transceiver circuitry 323 in accordance with software stored in memory 337. The controller 327 is also able to communicate with other
  • the software stored in memory 337 includes, among other things, an operating system 339, a communication module 341, a positioning module 342, a mapping module 343, a band assignment module 345, a results analysis and decision module 347 and a secondary user control module 349.
  • the operating system 339 is operable to control operation of the master node 3.
  • the communication module 341 provides the functionality to allow the master node 3 to
  • the positioning module 342 allows the master node 3 to determine the location of the different mobile terminals 5, including the sensor mobile terminals 5 - either from measurements received from the mobile terminals 5 or by triangulation from signals transmitted to or received from the mobile terminals 5 by a plurality of network nodes (such as the master node 3).
  • the band assignment module 345 operates to assign available frequency bands to mobile terminals 5 within the cell 13 controlled by the master node 3.
  • the results analysis and decision module 347 operates to receive the sensed results back from the different sensor mobile terminals 5 and to analyse the results and to make a decision as to whether or not each mobile terminal 5 or the master node 3 itself is likely to cause interference to a primary user currently operating in any part of the licensed frequency band (B).
  • the secondary user control module 349 operates to inform the secondary users when to start and stop using their respective assigned frequency band, or if they need to hand over to another frequency band, or to change their transmission power to avoid interfering with the primary users.
  • the master node 4 and the mobile terminals 5 have been described, for ease of understanding, as having a number of discrete modules (such as the communication modules, the positioning modules, the sensor module, the reporting module etc). Whilst these modules may be provided in this way for certain applications, for example where an existing system has been modified to implement the invention, in other applications, for example in systems designed with the inventive features in mind from the outset, these modules may be built into the overall operating system or code and so these modules may not be discernible as discrete entities.
  • Fig. 4 is flow chart illustrating the overall operation of the master node 3.
  • the communication module 241 of the master node 3 receives from one or more sensor mobile terminal 5 information indicative of a signal strength of a primary user transmission received at those sensor mobile terminals 5.
  • step s43 the positioning module 342 obtains position information for the mobile terminals 5.
  • step s45 the mapping module 343 estimates an area 17 of possible transmission overlap between the master node 3 and the primary user 4 using the received primary user transmission information and the obtained position information for the mobile terminals 5 that detected the primary user 4.
  • step s47 the results analysis and decision module 347 of the master node 3 compares the location of each mobile node 5 currently being served by the master node 3 with the estimated area 17 of possible transmission overlap.
  • step s49 the secondary user control module 349 of the master node 3 controls the operation of the mobile nodes 5 in dependence upon a result of the comparison, in order to avoid interference to the primary user 4 by the master node 3 and the mobile nodes 5.
  • Fig. 5 illustrates the steps carried out by the results analysis and decision module 347 in step s47, for each of the served mobile terminals 5 within the area 13 controlled by the master node 3.
  • step s50 the results analysis and decision module 347 checks whether a current mobile terminal 5 under consideration is currently operating in the licensed frequency band (B). If the mobile terminal 5 is not currently operating in this band (B), then in step s51 , the decision module 347 decides whether or not this terminal is a suitable candidate to start using frequency band B (without causing interference). If the result of this analysis is positive, then the results analysis and decision module 347 will allow the current terminal 5 to start transmitting in the licensed frequency band (B), in the step s52. If the result of the analysis in step s51 is negative, then the module 347 concludes, in step s57, that no change in the operation of the current mobile terminal 5 is necessary. After step s52 or step s57, the results analysis and decision module 347 ends consideration of the current mobile terminal 5 and starts considering the next mobile terminal 5.
  • step s50 the results analysis and decision module 347 determines that the current terminal 5 is operating in frequency band (B), then it proceeds to steps s53 where it checks whether or not the mobile terminal 5 is located within the estimated area of interference 17. If the mobile terminal 5 is not located within area 17, then the results analysis and decision module 347 will check, in step s54, whether or not the mobile terminal's transmission area 15a overlaps with coverage area 14 of the primary transmitter 4. If there is no overlap, then the results analysis and decision module 347 will conclude, in step s57, that no change in the operation of the current mobile terminal 5 is necessary and the results analysis and decision module 347 will start considering the next mobile terminal 5.
  • step s54 the results analysis and decision module 347 determines that there is an overlap
  • the processing proceeds to step s56, where a decision is made to limit the transmission power of the mobile terminal 5 in order to avoid interference.
  • the amount by which the mobile terminal limits its transmission power depends on how close it is to the area of primary transmission.
  • the results analysis and decision module 347 then proceeds to step s58.
  • step s53 for mobile terminals 5 located within the area 17 of interference, the results analysis and decision module 347 will move to step s55, wherein a decision is made to disallow transmission in the licensed frequency band (B) for the current mobile terminal 5, and then the processing proceeds to step s58.
  • step s58 the results analysis and decision module 347 determines whether handover is necessary (or indeed possible) for a mobile terminal 5 that is allowed to transmit at a limited power only, and for a mobile terminal 5 that is not allowed to transmit at all on the licensed frequency band (B). If handover is not deemed necessary (or not possible), the results analysis and decision module 347 ends its processing of the current mobile terminal 5, otherwise a handover decision is made first, in step s59.
  • the above steps are performed for at least those mobile terminals 5 that may cause interference to the primary users, although in this embodiment the steps are performed for all mobile terminals served by the master node 3.
  • the decision made for each mobile terminal 5 is then communicated to them as discussed above with reference to the master node 3 and the secondary user control module 349 of Fig. 3.
  • the Open System Interconnection (OSI) reference model describes the flow of data from one computer to another computer in a network, using a 7-layered protocol stack. As illustrated in Fig. 6A, these logical layers are the Physical Layer (Layer 1), the Data Link Layer (Layer 2), the Network Layer (Layer 3), the Transport Layer (Layer 4), the Session Layer (Layer 5), the Presentation Layer (Layer 6), and the Application Layer (Layer 7), from the lowest to the highest layer, respectively.
  • OSI Open System Interconnection
  • Each logical layer has specific functions and handles a unique data format.
  • data flows from an upper layer to a lower layer it is converted to the lower layer data format and a lower layer header is added to it. This process is called encapsulation.
  • encapsulation Conversely, when data flows from a lower layer to an upper layer, it is converted to the upper layer data format and the lower layer header is discarded.
  • the Physical Layer (Layer 1) specifies physical and electrical characteristics of the network, and handles the transmission of information over the network medium (i.e. cable or radio link).
  • the Data Link Layer (Layer 2) is the lowest layer in the OSI model that is concerned with addressing, i.e. labelling information with a particular destination location.
  • the Data Link Layer is responsible for the final encapsulation of higher-level messages into frames that are sent over the network at the Physical Layer.
  • the Network Layer (Layer 3) performs routing and addressing and it is responsible for sending a data packet to its destination within an acceptable time period.
  • the Transport Layer (Layer 4) is responsible for end-to-end transport between end users. This layer performs buffering, ordering, flow control, and error checking to make sure that data is received in the correct sequence and without error.
  • Session Layer (Layer 5), Presentation Layer (Layer 6), and Application Layer (Layer 7) are often referred to as upper layers. These layers handle user connection and data formatting. In most network technologies, the differences between these three layers are blurred and their functions are often handled by one protocol.
  • the Data Link Layer (Layer 2) will now be described in more detail.
  • Data Link Layer protocols enhance the service to upper layers by increased reliability, security, and integrity.
  • the Data Link Layer is responsible for medium access and scheduling.
  • the Data Link Layer (Layer 2) is divided into further layers, such as the Medium Access Control (MAC) Layer, the Packet Data Convergence Protocol (PDCP) Layer, and the Radio Link Control (RLC) Layer.
  • the MAC Layer is the lowest part, close to the Physical Layer (Layer 1), and is responsible for controlling access to the physical medium.
  • the PDCP Layer is responsible mainly for IP header
  • the RLC layer comprises mainly Automatic Retransmission Request (ARQ) functionality and supports data segmentation and concatenation.
  • ARQ Automatic Retransmission Request
  • the Radio Resource Control (RRC) protocol is the main controlling function in the master node 3, being responsible for establishing the radio bearers and
  • the RRC Layer (Layer 3) performs a number of services and functions, such as broadcasting system information; paging; establishment, maintenance and release of an RRC connection between the mobile terminals 5 and the master node 3; security functions including key management; establishment, configuration, maintenance and release of radio bearers;
  • a message when a message is sent between two peers, it propagates through the protocol stack towards the lower layers, for transmission via the lowest layer, and on the receiving side, the message propagates all the way up to the peer layer in the receiving terminal.
  • the route of messages is illustrated by the arrows in Fig. 6A.
  • a Layer 3 message is created on the RRC Layer and then it is processed by the PDCP layer, the RLC layer, the MAC layer, and the Physical Layer that handles the actual transmission between the mobile terminal 5 and the master node 3 (or vice versa), and after transmission to the receiving device, the message is processed again, first by the MAC layer, then the RLC layer, the PDCP layer, before it is finally delivered to the RRC layer where it is actioned.
  • the logical structure of the layered protocol stack guarantees that each function is performed on the layer where it is most applicable, in interference situations, the layered architecture can introduce unnecessary delays in handling information on the apparition of a primary transmitter 4.
  • the sensor nodes are configured to transmit their control data indicating that they have sensed a primary user transmission at the MAC layer, rather than a higher layer that might typically be used.
  • the sensor mobile terminal 5 when a sensor mobile terminal 5 detects the transmission of the primary transmitter 4, the sensor mobile terminal 5 measures the received power of the primary user signal and informs the master node 3 of the detected transmission and the strength of the primary user signal as received by the sensor node. In this embodiment, the measured power of transmission is reported to the master node 3 in a MAC layer signalling message that will be processed and actioned by the MAC layer of the master node 3.
  • Fig. 7A illustrates the MAC protocol data unit 71 (PDU) used in this embodiment.
  • a MAC PDU 71 is also commonly known as a frame, and is the unit of information that can be delivered between peers on the Data Link Layer (Layer 2).
  • the main parts of a MAC PDU 71 are the header 72, which comprises frame control fields 73, a sequence number field 74, and address fields 75 (some of these elements might be referred to as sub-headers).
  • the header elements define the transmission related characteristics of the MAC PDU 71, such as sender/addressee, control parameters, order of frame in a sequence of units, quality of service, whether the contents are being retransmitted etc..
  • the MAC service data unit 76 contains the data intended for upper layers (e.g. RLC, PDCP, and RRC layers) to process.
  • upper layers e.g. RLC, PDCP, and RRC layers
  • error detection code 79 is usually a cyclic redundancy check (CRC) field.
  • the MAC layer SDU 76 might comprises a PDU 171 of a higher layer.
  • a higher layer PDU 171 does not fit within the MAC SDU 76, it will be split across several consecutive MAC SDUs 76; the technique is known as segmentation. Once all of the segments of a split higher layer PDU 171 have been received by the higher layer, it will be processed at the higher layer, or it will be passed on to a higher layer still. Thus the contents of the higher layer PDU 171 are processed relatively slowly compared to the header 72 of the MAC PDU 71.
  • the higher layer PDU 171 also contains frame control fields 173, a sequence number field 173, address fields 175, and an SDU 176 for another layer, and also an error detection code 179.
  • the term used to describe the part of MAC PDU 71 after the header 72 is the 'payload' 78. Not all of the payload 78 is always intended for a higher layer.
  • the frame control fields 73 might indicate the presence of one or more MAC control elements 77 in the payload 78 that are intended for the MAC layer itself, thus such control element 77 will not be sent to the higher layer. Not all MAC PDUs 71 contain a control element 77 and different MAC PDUs 71 may contain different control elements 77 as they generally don't relate to the MAC SDU 76 carrying higher layer data.
  • a control element 77 is always inserted as the first part of the MAC SDU 76, thus before any part of the higher layer PDU 171 is inserted. This priority guarantees that a control element 77 is processed before any higher layer data is delivered, thus any information contained therein will be processed by the master node 3 much faster than regular higher layer signalling messages, such as Radio Resource Control (RRC) messages.
  • RRC Radio Resource Control
  • the sensor mobile terminals 5 include the received power value in a control element 77 of the MAC signalling message (MAC PDU 71) sent from the sensor mobile terminal 5 to the master node 3.
  • MAC PDU 71 MAC signalling message
  • Such a control element 77 may be added to any MAC frame 71 and thus can be sent without delay.
  • the master node 3 After defining the area 17 of possible interference, the master node 3 sends, to each mobile terminal 5 causing interference, a MAC signalling message which includes the received power value in a suitable control element 77 of the MAC PDU 71. This way, the master node 3 can notify all mobile terminals 5 which need to stop transmission in the licensed band (B).
  • a new specific control element 77 is required in the uplink (notification from the sensor mobile terminals 5 to the master node 3), and another one in the downlink (notification from the master node 3 to mobile terminals 5).
  • Fig. 7C One possible format for these two new MAC control elements is shown in Fig. 7C.
  • the MAC control element 77 has a fixed size and comprises a single octet as follows.
  • the first two bits, bl and b2 are reserved bits, set to "0", or in this case, marked "R”.
  • the remaining bits, b3 to b8, contain a binary value corresponding to the primary received power, which is the signal level or power of the detected primary user transmission as measured at the sensor mobile terminal 5.
  • LCID Logical Channel ID
  • the recipient Whenever the appropriate LCID values are used in a MAC PDU 71 transmitted between the sensor mobile terminal 5 and the master node 3, the recipient will know that a MAC control element 77 is present and it will be processed at the data link layer (MAC layer). For example, the value of the primary transmission power from the control element 77 will be extracted from the MAC control element 77 by the MAC layer and used as an input for the result analysis and decision module 347 of the master node 3.
  • MAC layer data link layer
  • the mobile terminals 5, including sensor mobile terminals 5 have to have been allocated uplink resources for the node to be able to transmit uplink data (including the above MAC signalling messages). Therefore, the allocation of these uplink resources can affect the ability of the mobile terminal 5 to send the measurement report.
  • uplink data including the above MAC signalling messages.
  • a mobile terminal 5 has been allocated sufficient uplink resources to meet its current data transmission needs
  • a mobile terminal 5 has been allocated some uplink resources, but these do not meet its current data transmission needs,
  • a mobile terminal 5 has not been allocated any uplink resources, either because it does not have any data to send on the uplink, or for other reasons, such as a temporary overload situation in the LTE system.
  • Sensor mobile terminals 5 that have some uplink resource allocation will be able to inform the master node 3 immediately that they detect the apparition of the primary user 4 using the allocated resources.
  • sensor mobile terminals 5 that are not actively transmitting data to the master node 3 may not have any uplink resources granted (i.e. the third situation above), and thus they might not be able to send information immediately on the received power of a detected primary user transmission.
  • such sensor mobile terminals 5 may be configured to send this information on a common channel or a signalling channel. If such channels cannot be used, the sensor mobile terminals 5 may initiate setting up a new data connection towards the master node 3 for sending the information on the received power of the primary user transmission. In LTE systems, this is called a random access procedure, whereby a new connection may be set up between the master node 3 and the mobile terminal 5, and it is illustrated in Fig. 8.
  • the procedure for starting communication in the uplink direction is implemented according to the following.
  • step s81 the sensor mobile terminal 5 requests uplink resources, which are controlled by the master node 3.
  • this comprises the Random Access Preamble message, which is generated on the MAC layer and sent by the mobile terminal 5 to the master node 3 on the random access channel.
  • the master node 3 informs the sensor mobile terminal 5 about the successful allocation of uplink resources, so that the sensor mobile terminal 5 can begin its transmission on the allocated channel.
  • this comprises the Random Access Response message, which is generated on the MAC layer by the master node 3 and contains the Cell Radio Network Temporary Identifier (C-RNTI) that uniquely identifies the mobile terminal 5.
  • C-RNTI Cell Radio Network Temporary Identifier
  • the master node 3 informs the mobile terminal 5 about the correct timing-advance value to be used for subsequent transmissions and grants the first resources for an uplink transmission.
  • the sensor mobile terminal 5 is now able to inform the master node 3 about the apparition of the primary transmitter 4, in step s85, the mobile terminal 5 sends the uplink data using the allocated resources in which it includes the measured signal power of the detected primary user transmission in a MAC control element 77 and in the manner discussed above.
  • this comprises the RRC Connection Request message, which is generated by the RRC layer, and carries the mobile terminal 5 identity (to identify the sender of the message) and the establishment cause (to identify reason for uplink resource request).
  • the measurement results are inserted as a MAC control element 77 in this message and are actioned by the master node 3 on the MAC layer (Layer 2) before or instead of passing the message up to the RRC layer (Layer 3).
  • the master node 3 acknowledges receipt of the measurement results in step s87 and is then able to control the operation of the mobile terminals 5 within its cell 13 in the manner described above.
  • the duration of reporting and processing the measurements is reduced, as the MAC control elements 77 provide an almost instantaneous and simple means to inform the master node 3 about the apparition of the primary user 4.
  • the master node 3 receives measurement reports from a number of sensor mobile terminals 5 that are positioned at locations closer to the primary user 4 than the master node 3.
  • the calculation of an area 17 of possible interference contributes to better utilization of the resources available in the licensed frequency band (B), as only those mobile terminals 5 that will be affected by the apparition of the primary user 4 need to be moved to a different frequency band in order to avoid interference.
  • all of the sensor mobile terminals used to sense for primary user transmissions were secondary users - i.e. they transmitted in the licensed band (B) as well as sensing in the licensed band (B).
  • one or more of the sensor mobile terminals may not be secondary users. Instead, they may simply sense within the licensed band (B) and report their sensing results accordingly.
  • the term primary transmitter might also refer to a base station of a wireless
  • the received power of the primary user transmission might not represent an accurate measurement, for example, the sensor mobile terminals might estimate or derive a comparative level of the transmit power, e.g. by applying various quantization techniques.
  • the master node will typically be formed by an LTE base station.
  • Multiple base stations are provided in an LTE system and they may each operate as masters controlling sensor mobile terminals (typically user devices such as cellular telephones) within its cell(s).
  • the base stations may operate autonomously in a de-centralised manner taking decisions about their respective localities without communicating with a higher network entity.
  • the base stations may also co-operate with each other exchanging information over their "X2" interface and taking decisions based on information received from neighbouring base stations.
  • any other part of a MAC protocol (or other low-layer protocol) message may be used, such as a header, a sub-header, a control element, or payload.
  • the sensor mobile terminals will stop using the primary licensed band immediately, i.e. before receiving such an
  • sensor mobile terminals that are operable to use multiple frequency bands might be configured to notify the master node in a band other than the primary licensed band. These modifications will further reduce the interference caused by the secondary users.
  • the sensor mobile terminal is configured to send the control element with the primary user signal measurement in the third message (after uplink resources have been granted).
  • the sensor mobile terminal may include the control element in the first message of the uplink request procedure; while in another embodiment, the sensor mobile terminal might employ a signalling message that is part of another procedure to send the control element.
  • control element is sent by the sensor mobile terminal in the third message of the random access procedure to notify the master node of detected primary user transmissions within the licensed frequency band (B) and the control element is also used to provide signal measurements of the primary user transmissions to the master node.
  • the notification of the detected primary user is provided.
  • the sensor mobile terminal in the first message of the random access procedure (i.e. the initial message of the random access procedure used to request uplink resources) and the signal measurements of the primary user transmissions may be provided in a subsequent message of the random access procedure, such as the third message (i.e. once the sensor mobile terminal has been allocated and granted uplink resources by the master node).
  • the first message of the random access procedure i.e. the initial message of the random access procedure used to request uplink resources
  • the signal measurements of the primary user transmissions may be provided in a subsequent message of the random access procedure, such as the third message (i.e. once the sensor mobile terminal has been allocated and granted uplink resources by the master node).
  • a "no grant" terminal either a mobile terminal that is in a connected mode, whereby the mobile terminal is connected with the master node without having been allocated any uplink resources or a mobile terminal that is in an idle mode, having no current ongoing services with the master node
  • the master node may select a subset of the mobile terminals to behave as sensor mobile terminals, the sensor mobile terminals being capable of notifying the master node of detected primary user transmissions within the licensed frequency band (B).
  • B licensed frequency band
  • RACH Random Access Channel
  • each mobile terminal selects a random access transmission opportunity and also randomly selects (or generates) a preamble for inclusion in an uplink request message to be sent to the master node.
  • the master node will reply with a message that allocates uplink resources to the mobile terminal.
  • two or more mobile terminals happen to randomly choose the same preamble and transmit on the same RACH at the same time, then a collision may occur and, due to the collision, the master node may not receive the transmitted messages.
  • the master node is therefore unaware of the uplink request messages. If the resource allocation message is not received by the mobile terminal within a specified time period, the mobile terminal will assume that the master node has not received the uplink request message and will therefore re-transmit the message at a higher transmission power in the next available random access opportunity.
  • the master node assigns a unique preamble to each mobile terminal.
  • the random access transmission opportunity can either be selected by each mobile terminal or assigned by the master node.
  • the mobile terminals do not contend for use of the RACH - they can share use at the same time.
  • the contention for the RACH may also be eliminated by enabling the master node to assign different random access transmission opportunities to the different mobile terminals.
  • the master node assigns a single reserved preamble that all of the sensor nodes should use to notify the master node of the detection of the primary user transmission.
  • the reserved preamble may be included in system information broadcast by the master node to the mobile terminals.
  • a new specific field "Primary_detection_specific_incumbent” can be defined within the system information in order to define the specific preamble (the reserved preamble) to use in the case of primary user transmission notification.
  • This can be defined the "RACH-ConfigCommon” information element of the "RadioResourceConfigCommon” element present with the SystemlnformationBlocks (SIBs) of the system information.
  • the RACH-ConfigCommon information element comprising the
  • Primary detection specific incumbent element may take the following format:
  • n4 n8, nl2, nl6 ,n20, n24, n28,
  • Timer for contention resolution in TS 36.321 Value in subframes. Value sf8 corresponds to 8 subframes, sf 16 corresponds to 16 subframes and so on.
  • TS 36.321 used for contention based random access. Value is an integer.
  • Threshold for preamble selection in TS 36.321 Value in bits.
  • Value b56 corresponds to
  • Threshold for preamble selection in TS 36.321 Value in dB. Value minusinfinity
  • dBO corresponds to 0 dB
  • dB5 corresponds to 5 dB
  • Number of non-dedicated random access preambles in TS 36.321 is an integer.
  • n4 corresponds to 4
  • n8 corresponds to 8 and so on.
  • Initial preamble power in TS 36.321 Value in dBm.
  • Value dBm-120 corresponds to -120 dBm
  • dBm-118 corresponds to -1 18 dBm and so on.
  • the size of the random access preambles group A is equal to
  • n3 corresponds to 3
  • n4 corresponds to 4 and so on.
  • sf3 corresponds to 3 subframes and so on.
  • Size of the random access preambles group A in TS 36.321 is an integer.
  • n4 corresponds to 4
  • n8 corresponds to 8 and so on.
  • the RACH-Config-Dedicated information element is used by the master node to specify dedicated random access parameters for each mobile terminal and may comprise the following format:
  • ra-Preamblelndex defines the reserved preamble that the mobile terminalshall use.
  • This table is already defined in the TS36.321 because LTE mobile devices use dedicated preambles during the hand-over procedure.
  • the mobile device receives the RRCConnectionReconfiguration message from the source eNB (base station) with the parameters needed for the handover (i.e. new C-RNTI, target eNB security algorithm identifiers, and optionally dedicated RACH preamble, target eNB SIBs, etc.) and is commanded by the source eNB to perform the handover and accesses the target cell via RACH following a contention-free procedure using a dedicated RACH preamble.
  • This dedicated preamble is defined by the above RACH-Config-Dedicated table. So, in this embodiment, the master node will re-use these RACH configuration parameters to broadcast the reserved preamble to be used to notify the master node of the apparition of the primary user.
  • ra-PRACH-Masklndex is a index which allows the master node to restrict when the mobile terminal can transmit a random preamble.
  • the master node and the selected sensor mobile terminals store the specific reserved preamble in memory. Therefore, when a primary user transmission is detected by a mobile terminal, the mobile terminal sends an uplink request message, comprising the reserved preamble, to the master node. If the mobile terminal does not receive an acknowledgement indicating receipt of the uplink message from the master node within a specified time period, the mobile terminal will re-transmit the uplink request message at a higher transmission power.
  • the master node When the master node receives and decodes the uplink request message, it compares the received preamble with the reserved preamble stored in memory. If the received preamble matches the stored preamble reserved for notifying detection of a primary user transmission, then the master node immediately ceases the granting of uplink resources to other mobile terminals within the licensed frequency band (B) pending receipt of the primary user signal level measurements from the notifying sensor mobile terminal, thus helping to prevent interference to the primary user transmissions in the licensed frequency band (B).
  • the master node responds to the initial RACH message by sending a resource allocation message to the sensor mobile terminal.
  • the resources allocated by the master node will typically be in a frequency band outside the licensed frequency band (B), but they may be within the licensed frequency band (B) if desired.
  • the sensor mobile terminal After having been allocated the uplink resources, the sensor mobile terminal sends a message comprising the primary user signal measurements to the master node, initiates a timer and begins monitoring a physical downlink control channel (PDCCH) for a response from the master node within a pre-determined time period set by the timer.
  • PDCCH physical downlink control channel
  • the master node In response to receiving the primary user signal measurements, the master node sends a contention resolution message back to the sensor mobile terminal, which contention resolution message provides an acknowledgement to the sensor mobile terminal that the primary user signal measurements have been received. If the master node does not receive the primary user signal measurements within a defined time period, then the master node may resume allocating uplink resources within the licensed frequency band (B) to the mobile terminals.
  • B licensed frequency band
  • the sensor mobile terminal If the sensor mobile terminal does not receive the contention resolution message within a pre-determined time period, it assumes that the master node has not received the sent primary user measurements and then starts the notification process again by sending the master node the reserved preamble in another RACH attempt. If, however, the contention resolution message is received within the pre-determined time period, then the sensor mobile terminal stops transmitting in the licensed frequency band (B) (if it has not already done so).
  • the master node In response to receiving the primary user signal measurements, as well as sending the contention resolution message to the sensor mobile terminal, the master node begins to selectively control, based on the received primary user measurements, each mobile terminal operating within the licensed frequency band (B), as described above with reference to Fig. 4, and more particularly as follows.
  • the master node determines, based on the received signal
  • the master node controls that mobile terminal to cease transmission in the licensed frequency band (B).
  • the master node may arrange for a hand-off of the mobile terminal to another frequency band.
  • the licensed band represents a television channel
  • the master node may arrange for the selected mobile terminal to hand-off to another television channel. In this manner, the selected mobile terminal may experience continued services with the master node whilst allowing the primary user priority use of the licensed frequency band (B).
  • the master node determines, based on the received signal
  • the master node controls the mobile terminal to limit it's transmission power in the licensed frequency band (B).
  • the master node determines that a mobile terminal would not be likely to cause interference to a primary user (for example, because the mobile terminal is outside of a determined transmission range of the primary user), then the mobile terminal is allowed to continue operation in the licensed frequency band (B).
  • the mobile terminal wishes to establish a communications session with the master node using the contention-based RACH technique when the mobile terminal has not detected a primary user transmission.
  • the mobile terminal should not use the reserved preamble.
  • the mobile terminal will use a randomly generated preamble to initiate the RACH procedure.
  • the mobile terminal must therefore check that the randomly generated preamble is not the same as the reserved preamble. If it is determined that the randomly generated preamble matches the reserved preamble, then the mobile terminal proceeds to generate another preamble.
  • the master node will assign two unique reserved preambles to each of the mobile terminals. One is reserved for notifying primary user apparition and the other is used for normal non-contention based RACH procedures. This embodiment operates similarly to the contention based embodiment except that each mobile terminal is allocated a different reserved preamble. Operation in this mode may only be practical where there are a small number of sensor terminals as there will normally be a limited number of preambles that can be reserved.
  • MAC PDU than a control element to send the primary user transmission information, such as in a suitable field of the header or sub-headers. Some of these fields may be sent to a higher level for processing without departing from the scope of the claims.
  • the transmission power of some mobile terminals was limited in order to avoid interference.
  • directional antennas may be used by the mobile terminals (and the master node) and the transmission direction of the transmitted signals may be changed to avoid interference with the primary user. In this way, the master node and the mobile terminals can continue using the licensed band by directing their signals away from the primary transmitter (while outside its coverage area).
  • nodes may comprise any kind of communications node or device, including access points and user devices such as, for example, mobile telephones, personal digital assistants, laptop computers, web browsers, etc.
  • the software modules may be provided in compiled or un-compiled form and may be supplied to the cognitive node as a signal over a computer network, or on a recording medium. Further, the functionality performed by part or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred as it facilitates the updating of the node in order to update its functionality. Similarly, although the above embodiments employed transceiver circuitry, at least some of the functionality of the transceiver circuitry can be performed by software.
  • the present invention can be materialized by a program for causing a computer such as a CPU (Central Processing Unit) to execute the processes shown in Figs. 4 and 5.
  • a computer such as a CPU (Central Processing Unit) to execute the processes shown in Figs. 4 and 5.
  • CPU Central Processing Unit
  • Non-transitory computer readable media include any type of tangible storage media.
  • Examples of non-transitory computer readable media include magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.), optical magnetic storage media (e.g. magneto-optical disks), CD-ROM, CD-R (compact disc recordable), CD-R/W (compact disc rewritable), and semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).
  • the program may be provided to a computer using any type of transitory computer readable media. Examples of transitory computer readable media include electric signals, optical signals, and electromagnetic waves. Transitory computer readable media can provide the program to a computer via a wired communication line (e.g. electric wires, and optical fibers) or a wireless communication line.

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Abstract

L'invention concerne un système de radiocommunication cognitif comprenant un noeud maître et une pluralité de terminaux mobiles. Le noeud maître comprend des moyens de réception de données de transmission d'utilisateur principal provenant d'au moins un des noeuds mobiles (5) et indiquant une intensité de signal d'une transmission d'utilisateur principal ; des moyens d'obtention de données de position pour chaque noeud mobile (5) ; des moyens d'estimation d'une zone (17) de chevauchement de transmission possible entre le noeud maître (3) et l'utilisateur principal (4) au moyen des données de transmission d'utilisateur principal reçues et des données de position obtenues ; des moyens de comparaison de l'emplacement de chaque noeud mobile (5) avec la zone estimée (17) de chevauchement de transmission possible ; et des moyens de commande du fonctionnement des noeuds mobiles (5) en fonction d'un résultat de la comparaison afin d'éviter toute interférence avec l'utilisateur principal (4) par le noeud maître (3) et les noeuds mobiles (5).
PCT/JP2012/070713 2011-08-23 2012-08-07 Système de communication WO2013027637A2 (fr)

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JP2017503397A (ja) * 2013-12-11 2017-01-26 クアルコム，インコーポレイテッド 免許不要周波数帯を使用するネットワーク展開における負荷分散

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JP7031827B2 (ja) * 2017-10-20 2022-03-08 株式会社国際電気通信基礎技術研究所 通信調停装置、端末装置、コンピュータに実行させるためのプログラム、プログラムを記録したコンピュータ読み取り可能な記録媒体およびデータ構造
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WO2013027637A3 (fr) 2013-04-18
GB2494007A (en) 2013-02-27
GB201114597D0 (en) 2011-10-05
GB201204041D0 (en) 2012-04-18
JP5835468B2 (ja) 2015-12-24
GB2493939A (en) 2013-02-27

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