HK1254364B - Listen before talk for cellular in unlicensed band - Google Patents

Description

Listen-before-talk for cellular communications in unlicensed bands

This application is a divisional application of Chinese invention patent application No. 201580027371.1 (PCT International Application No. PCT/US2015/036674), filed on June 19, 2015, with the earliest priority date of June 30, 2014, and entitled “Listen-before-talk for cellular communications in unlicensed bands”.

Priority claim

This application claims the benefit of priority to U.S. application serial number 14/669,736, filed on March 26, 2015, which claims the benefit of priority to U.S. provisional patent application serial number 62/019,316, filed on June 30, 2016, both of which are incorporated herein by reference in their entireties.

Technical Field

Embodiments relate to cellular wireless technology.Some embodiments relate to cellular wireless technology operating in unlicensed communication bands.

Background Art

Cellular technology typically operates in licensed spectrum. Licensed spectrum is a range of frequencies that is exclusively allocated to a specific entity (e.g., a specific wireless carrier) for use. Because the available licensed spectrum is limited and as demand for cellular wireless services increases, the amount of freely allocated spectrum available for use is limited.

Unlike licensed spectrum, various unlicensed spectrums exist that allow entities to use certain frequencies without obtaining legal permission. These frequencies are shared among devices that wish to use them, and the devices using them have protocols that allow them to share the spectrum with other devices. Typically, these unlicensed spectrums are primarily unlicensed for cellular wireless use and are often subject to competition or utilization by other devices.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings (not necessarily drawn to scale), like reference numerals in different views may describe similar components. Like reference numerals with different letter suffixes may represent different instances of similar elements. The accompanying drawings generally illustrate various embodiments discussed in this document by way of example and not limitation.

FIG1A is a timeline of a Listen Before Talk (LBT) method according to some examples of the present disclosure.

FIG1B is a flow chart of an LBT method according to some examples of the present disclosure.

FIG2A is a timeline of an LBT method according to some examples of the present disclosure.

FIG2B is a flow chart of an LBT method according to some examples of the present disclosure.

FIG3 is a flowchart of an LBT method with backoff according to some examples of the present disclosure.

4 is a schematic diagram of a cellular wireless device according to some examples of the present disclosure.

FIG5 is a block diagram illustrating an example of a machine upon which one or more embodiments may be implemented.

DETAILED DESCRIPTION

As demand for licensed spectrum for cellular wireless protocols such as Long Term Evolution (LTE) increases, designers of LTE systems have begun developing the use of these licensed protocols in unlicensed frequencies. The use of cellular and other licensed protocols in unlicensed frequencies presents certain challenges.

For example, cellular wireless devices (e.g., base stations or mobile devices, such as smartphones) utilize licensed channels, which guarantee these devices exclusive use of a particular wireless channel. A "channel" is a frequency band (usually contiguous, but not always) used for wireless communications. Consequently, these cellular protocols are designed with the assumption that they have exclusive access to the frequencies on which they operate. They are generally only concerned with coordination among other devices participating in the same network. For example, in an LTE system, a base station (eNodeB) typically coordinates transmissions and receptions from one or more user equipment (UEs) associated with the eNodeB. The eNodeB generally does not consider other users in other networks when scheduling the transmission and reception of data. If a cellular wireless network were to begin transmitting in an unlicensed channel without modification, the cellular wireless device would continue to transmit and receive. This would prevent other devices from utilizing the channel.

In contrast, devices operating in unlicensed channels must consider not only devices operating in a single network (e.g., controlled by a single operator) but also devices operating in many different networks and devices operating using other protocols. For example, devices operating according to wireless protocols such as the 802.11 standard (Wi-Fi) defined by the Institute of Electrical and Electronics Engineers (IEEE) must consider not only devices in their own network (i.e., Basic Service Set—BSS) but also devices in other BSSs, and even devices running other protocols, before determining whether to use the wireless medium.

Therefore, what is needed is a method for adapting a cellular wireless protocol to operate in an unlicensed channel in a manner that allows the cellular wireless protocol to share the unlicensed channel with other devices. Some examples disclose systems, machine-readable media, methods, and cellular wireless devices that implement a Listen-Before-Talk (LBT) reception scheme for devices operating according to a cellular wireless protocol in an unlicensed channel. The cellular wireless device can use the cellular wireless protocol in an unlicensed channel after the LBT access scheme has determined that a channel in an unlicensed band (a defined frequency range in a specific spectrum) is idle for a specific period of time.

As used herein, a "cellular wireless device" is any device that operates in accordance with a cellular wireless protocol. A "cellular wireless protocol" is a wireless protocol that defines a cellular wireless network that is distributed over land areas called cells, each of which is served by at least one fixed-location transceiver (called a cell site or base station). These cell sites are interconnected to provide wireless service over a wide geographic area. Example cellular wireless protocols that may be suitable for transmission in an unlicensed channel include cellular wireless protocols in accordance with one of the LTE family of standards promulgated by the Third Generation Partnership Project (3GPP), the Universal Mobile Telecommunications System (UMTS) family of standards promulgated by 3GPP, the Global System for Mobile Communications (GSM) family of standards, and the like. A cellular wireless device may be a base station such as a NodeB or eNodeB, or may be a mobile device such as a user equipment (UE).

Cellular wireless devices can use the licensed band to control transmissions on unlicensed channels and other parameters used. This can include obtaining CSI feedback, scheduling decisions on PDCCH, etc.

Example transmissions by cellular wireless devices on unlicensed channels include transmissions supporting one or more of the following layers: Layer 1, Layer 2, Layer 3, and other layers of these cellular protocols, such as the physical (PHY) layer, the medium access control (MAC) layer, the radio link control (RLC) layer, the packet data convergence protocol (PDCP) layer, and the radio resource control (RRC) layer. Channels for transmission on unlicensed frequencies may include any uplink data channel, uplink control channel, downlink data channel, and downlink control channel. Examples include one or more of the following: physical downlink shared channel (PDSCH), physical uplink shared channel (PUSCH), physical downlink control channel (PDCCH), and physical uplink control channel (PUCCH).

In some examples, a cellular wireless device such as a cellular base station (e.g., an eNodeB) can provide uplink and downlink capabilities to a cell in a licensed spectrum, and also provide a supplemental downlink (SDL) channel in an unlicensed spectrum. The SDL channel can carry one or more LTE channels (e.g., PDSCH). LBT technology can be applied to the SDL channel to ensure that the unlicensed channel is idle and free of interference. In other examples, for uplink channels on the unlicensed spectrum, the UE can be a cellular wireless device that implements the LBT mechanism. In some examples, the SDL can be scheduled on the PDCCH on the primary (licensed) frequency. For example, the UE can be scheduled on the PDCCH of the licensed frequency to receive data on the SDL PDSCH on the unlicensed frequency (i.e., using cross-carrier scheduling). In some examples, the PDCCH that schedules the unlicensed channel can be sent on the unlicensed channel.

To operate in the unlicensed spectrum, aspects of the cellular network protocol may be modified in one or more ways (e.g., as disclosed herein). For example, a LBT access scheme may be implemented in the cellular wireless protocol by a cellular wireless device. In some examples, a cellular wireless device implementing the LBT access mode for the unlicensed band may listen to the channel for a channel listening time (e.g., a predetermined period of time). If the channel is idle for the channel listening time, the cellular wireless device may consider the channel available.

In some examples, the cellular wireless device may determine that a channel is idle by comparing the average detected power on the channel during the channel listening time with a predetermined power level threshold. If the average detected power is below the power level threshold, the channel may be considered available for transmission; otherwise, if the average detected power is above the power level threshold, the channel may be considered busy.

Alternatively, instead of using the average detected power for the entire channel listening time, the cellular wireless device may be considered busy if the detected channel power at any point during the channel listening time exceeds a power level threshold. Otherwise, the cellular wireless device may consider the channel available if the detected channel power at any point during the channel listening time does not exceed the power level threshold.

Once the cellular wireless device determines that the medium is available, the cellular wireless device can immediately transmit in the asynchronous mode. In other examples, in the synchronous mode, in response to determining that the wireless medium is available, the cellular wireless device can reserve the medium using a medium reservation technique and wait for a subframe boundary of the cellular wireless protocol before transmitting.

Turning now to FIG. 1A , a timeline 1000 is shown of a cellular wireless device operating asynchronously in an unlicensed channel using a LBT mechanism. The device measures the power level of the channel for a channel sense time 1010. In FIG. 1A , the channel sense time 1010 is Wμs. In some examples, the device determines the idleness of the medium by performing carrier sensing (CS) for the channel sense time 1010 and measuring the average power received during this period. If the average power received during this period is below a power level threshold (e.g., -62 dBm), the cellular wireless device may consider the medium idle and available for transmission. In some examples, this method of detecting that the medium is idle differs from the method of Wi-Fi carrier sensing. In Wi-Fi carrier sensing, Wi-Fi devices use both energy detection and channel detection mechanisms. If a Wi-Fi device uses a signal detection mechanism to detect a Wi-Fi signal, the Wi-Fi device assumes that the channel is occupied. In some examples, the LBT method disclosed herein uses only an energy detection mechanism and not a Wi-Fi signal detection mechanism.

Once the medium is idle, the cellular wireless device may optionally transmit a subscription message (RSRV) 1020. The subscription message may be any transmission designed to trigger the channel sensing mechanism of one or more protocols operating on the unlicensed channel to detect that the channel is busy. An example of a subscription message 1020 may be a simple transmission above a certain power level designed to trigger other devices to detect the energy on the channel and determine based on the energy that the channel is not idle.

In some examples, the message may be specific to a wireless protocol operating in an unlicensed band. For example, a Wi-Fi message may be transmitted by a cellular wireless device on an unlicensed channel. The subscription message may reserve the channel for transmission by the cellular wireless device. In some examples, the message may be a Wi-Fi Request-To-Send (RTS) or Clear-To-Send (CTS) message. These messages may be sent by modifying the cellular wireless protocol circuitry to send messages for other protocols, or by adding protocol circuitry that sends messages for other protocols (e.g., adding a Wi-Fi chip to an eNodeB). The RTS or CTS message may have a duration field that may specify the duration for which the cellular wireless device needs to occupy the unlicensed channel.

The RTS/CTS message may be transmitted to one or more cellular wireless devices. The RTS/CTS message may be broadcast to the intended UE. The intended UE may detect whether the channel is idle. The RTS/CTS message may be transmitted in a time or frequency multiplexed manner.

The cellular wireless device may then transmit using the cellular protocol 1030. The cellular wireless device may transmit one or more uplink or downlink cellular wireless channels carrying control data or user data. In some examples, the cellular wireless device may transmit one or more radio subframes.

FIG1B illustrates an example method 1100 for a cellular wireless device employing an asynchronous LBT mechanism according to some examples of the present disclosure. At operation 1110, the cellular wireless device senses a channel for a channel listening time (e.g., W μs). At operation 1120, the cellular wireless device determines whether the channel is idle. In some examples, the cellular wireless device determines whether the channel is idle by determining whether the average received power during the channel listening time is below a power level threshold. If the channel is deemed not idle, the device may return and repeat operations 1110 and 1120 until the channel is deemed idle. At operation 1130, the cellular wireless device may transmit data during the transmission opportunity (TXOP). In some examples, the cellular wireless device may send a subscription message before transmitting the data at operation 1130. In some examples, W may be 34 μs.

Turning now to FIG. 2A , a timeline 2000 is shown of a cellular wireless device operating synchronously in an unlicensed channel using the LBT mechanism. The device senses that the medium is idle for a channel listening time 2010. In FIG. 2A , the channel listening time 2010 is W μs. In some examples, the device determines that the medium is idle by performing carrier sensing (CS) for the channel listening time 2010 and measuring the average power received. If the average power received during this period is below a power level threshold, the cellular wireless device may consider the medium idle.

Once the medium is idle, the cellular wireless device may send a reservation message (RSRV) 2020. In some examples, the reservation message 2020 may be a message from another wireless protocol (e.g., a Wi-Fi message) and may be sent by the cellular wireless device. The message may reserve the wireless medium for transmission by the cellular wireless device. In some examples, the message may be a CTS or RTS message. These messages may be sent by modifying the cellular wireless protocol circuitry to transmit messages for the other protocol, or by adding protocol circuitry to transmit messages for the other protocol (e.g., adding a Wi-Fi chip to an eNodeB).

In the scenario of FIG2A , the reservation message 2020 reserves the wireless medium for the cellular wireless device for a desired transmission opportunity (TXOP) 2040 and an amount of time to transmit data at a synchronized time (e.g., sufficient time to wait for a subframe boundary). For example, the reservation message 2020 may be the sum of the TXOP (transmission 2040) plus the idle period 2030, which is the period of time that elapses before the start of the next subframe of the cellular wireless protocol.

FIG2B illustrates an example method 2100 for a cellular wireless device employing a synchronous LBT mechanism according to some examples of the present disclosure. At operation 2110, the cellular wireless device senses a channel for a channel listening time (e.g., W μs). At operation 2120, the cellular wireless device determines whether the channel is idle. In some examples, the cellular wireless device determines whether the channel is idle by determining whether the average received power during the channel listening time is below a power level threshold. If the channel is deemed not idle, the device may return and repeat operations 2110 and 2120 until the channel is deemed idle. At operation 2130, the cellular wireless device aligns to a subframe and transmits data during a transmission opportunity. In some examples, before transmitting data at operation 2130, the cellular wireless device may send a subscription message.

In some examples, LBT techniques may include a backoff process to avoid conflicts when there are a large number of transmitters. FIG3 illustrates an example method of an LBT technique including a backoff process. At operation 3010, the cellular wireless device senses the channel for a channel listening time. If the average received power is not below a power level threshold at operation 3020, the cellular wireless device may continue to sense the channel at operation 3010. If the average received power is below the power level threshold at operation 3020, and if the cellular wireless device determines that a backoff is not implemented at operation 3030, the cellular wireless device may transmit data during the transmission opportunity at operation 3040. As noted with respect to FIG1 and FIG2, the cellular wireless device may send a subscription message, and in some embodiments, may align to a subframe boundary.

If the cellular wireless device determines at operation 3030 that a backoff operation should be implemented, the cellular wireless device may calculate a random backoff contention window (CW) between an absolute minimum (MIN) value and a current maximum (CWT) at operation 3050. The CWT may initially be set to the MIN level. At operation 3060, the cellular wireless device may decrement the contention window CW. At operation 3070, it is determined whether the CW is zero. If the CW is zero, the cellular wireless device may proceed to operation 3040 to transmit data on an unlicensed channel. If the CW is not zero at operation 3070, the cellular wireless device senses the channel for X μs at operation 3080. In some examples, X is 9 μs. X and W may be the same value or different values. In some examples, the MIN may be 3 and the MAX may be 1023.

If the received power is below the predetermined threshold at operation 3090, the cellular wireless device decrements the CW at operation 3060, and the cellular wireless device repeats operations 3070, 3080, and 3090 until the CW is zero (at which point the cellular wireless device transmits on the unlicensed channel at operation 3040) or until the received power is not below the threshold at operation 3090. If the received power is not below the threshold at operation 3090, the cellular wireless device returns to operation 3010 at operation 3095. In some examples, the threshold power level at operation 3090 may be the same as or different from the threshold power level at operation 3020. In some examples, the threshold may be -62 dBm. Once the CW is zero, the backoff process may be considered successful.

Once the data has been transmitted at operation 3040, in some examples, the cellular wireless device may determine whether a collision occurred during the transmission. To accomplish this, in some examples, the cellular wireless device may calculate a transport block error (TBE) rate at operation 3100. At operation 3110, the TBE may be compared to a predetermined error threshold. In some examples, the predetermined error threshold may be 0.5. If the TBE is below the predetermined error threshold, the cellular wireless device may conclude that the transmission was successful and was not subject to interference. In this case, at operation 3120, the current maximum value CWT may be set to the MIN value, which may be used the next time a CW is determined. The process ends at this point until the next time the cellular wireless device has data to transmit and the process begins again at operation 3010. If the TBE is above or equal to the predetermined threshold, the cellular wireless device may set the current maximum value CWT to twice the previous CWT, but not exceeding the global maximum value MAX, at operation 3130. Since the cellular wireless device will attempt to retransmit the block with errors, a new fallback CW is selected at operation 3050 and the fallback process repeats.

Unlike Wi-Fi, the LBT mechanism disclosed herein, in some examples, utilizes transport block error measurements. Cellular wireless protocols specifically define TBE, but generally speaking, TBE is a measure of the success of data transmission over the air at the physical/MAC layer level. For LTE, a transmission is considered successful if the transport block is successfully decoded. Successful decoding occurs when the cyclic redundancy check (CRC) calculated by the receiver matches the CRC sent in the transport block. TBE is a percentage or ratio of successful blocks. Conversely, Wi-Fi assumes that a collision is indicated if an acknowledgment for a packet is not received.

As already noted, in some examples, to prevent other wireless devices from accessing the medium, the cellular wireless device may transmit a subscription message at operation 3040. Also, at operation 3040, the cellular wireless device may wait for a cellular subframe boundary before transmitting.

Turning now to FIG4 , a schematic diagram of a cellular wireless device 4000 is shown according to the following example. Cellular wireless device 4000 can be any device capable of communicating using a licensed cellular protocol. Cellular wireless device 4000 can be a nodeB, eNodeB, UE, base transceiver station (BTS), Wi-Fi access point, mobile phone, smartphone, desktop computer, laptop computer, medical device (e.g., heart rate monitor, blood pressure monitor, etc.), wearable device (e.g., computing glasses, smartwatch), etc.

The cellular wireless device 4000 may include a first wireless transceiver 4030, a second wireless transceiver 4040, and control circuitry 4020 for controlling the first and second wireless transceivers. The first wireless transceiver 4030 may operate on an unlicensed channel and, in some examples, may implement a wireless protocol other than a cellular wireless protocol. In some examples, the first wireless transceiver 4030 may implement a protocol that operates on an unlicensed channel, such as the IEEE 802.11 wireless protocol, the Bluetooth wireless protocol, the Bluetooth Low Energy (BLE) wireless protocol, the Zigbee wireless protocol, and the like. In some examples, the first wireless transceiver 4030 may determine whether the unlicensed channel is occupied by other traffic. In some examples, the first wireless transceiver 4030 may detect the power level on the unlicensed channel and, if the average power level over a predetermined time period is below a specified threshold, the control circuitry 4020 may determine that the channel is unoccupied. If the average power level over the predetermined time period is above a specified threshold, the control circuitry 4020 may determine that the channel is occupied. If the channel is occupied, the control circuit 4020 may instruct the first wireless transceiver 4030 to continue sensing the channel until the average power level received within a predetermined time period is below a predetermined threshold.

Once the channel is deemed unoccupied, the control circuitry 4020 may control the backoff process. The control circuitry 4020 may cooperate with the first transceiver 4030 to implement the operations of FIG3 , such as selecting a random contention window, decrementing the contention window, sensing the channel for X μs using the first transceiver 4030, determining whether the backoff period has ended or whether activity was sensed on the channel during the backoff period, and signaling the first transceiver 4030 to again determine whether the medium is idle by detecting the power level on the unlicensed channel for a channel listening period. Once the control circuitry and the first transceiver determine that the channel is idle again, the control circuitry 4020 may restart and implement the backoff process again.

The second wireless transceiver 4040 can implement a cellular wireless protocol and can generally transmit on licensed frequencies. Example cellular wireless protocols may include the Long Term Evolution (LTE) family of standards promulgated by the Third Generation Partnership Project (3GPP), the Universal Mobile Telecommunications System (UMTS) family of standards promulgated by 3GPP, the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard known as Worldwide Interoperability for Microwave Access (WiMAX), and the like. The second wireless transceiver 4040 can provide cellular wireless protocols for one or more protocol layers to enable communication. For example, if the cellular wireless device 4000 is an eNodeB, the second transceiver 4040 provides functionality to implement the eNodeB. If the cellular wireless device 4000 is a UE, the second transceiver 4040 provides functionality to connect to a cellular network and transmit data over the network. The second transceiver 4040 can utilize licensed bandwidth and may also include circuitry to send and receive data across unlicensed bandwidth.

The control circuitry 4020 may control the first transceiver 4030 and the second transceiver 4040. When the control circuitry 4020 determines that the unlicensed channel should be used for the cellular wireless protocol, the control circuitry 4020 may use the first transceiver 4030 to determine when the channel is idle and, in some examples, reserve the channel using a channel reservation message via the first transceiver 4030. Once the channel is idle, the control circuitry 4020 may instruct the first transceiver 4030 or the second transceiver 4040 to transmit on the unlicensed band.

In some examples, the cellular wireless device 4000 may send a subscription message on an unlicensed channel. In some examples, the subscription message may have a duration field that may be set to the duration of the cellular data transmission (e.g., a subframe). In some examples, the cellular wireless device 4000 may not begin transmitting until a subframe boundary. In these examples, if the subscription message is not sent, the subscription message may have a duration equal to the duration of the cellular data transmission plus the amount of time until the next subframe boundary.

After the transmission, the control circuit 4020 may determine whether the transmission was successful. In some examples, the transmission may be considered successful if the TBE measurement is below a predetermined threshold. If the TBE measurement is below the predetermined threshold, the contention window for the next transmission may be set to a minimum contention window value (MIN) by setting the maximum value used for random selection (e.g., at operation 3050 of FIG. 3 ) to a minimum value (MIN).

If the TBE measurement is not below a predetermined threshold, the next contention window may be doubled and a backoff process may be initiated to resend data.

5 shows a block diagram of an example machine 5000 on which any one or more of the techniques (e.g., methodologies) discussed herein may be implemented. In alternative embodiments, the machine 5000 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 5000 may operate as a server machine, a client machine, or both in a server-client network environment. In an example, the machine 5000 may operate as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. The machine 5000 may be a cellular wireless device, a wireless device, or the like. Example cellular wireless devices include an eNodeB, a UE, a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile phone, a web appliance, a network router, a switch or a bridge, or any machine capable of executing (sequentially or otherwise) instructions specifying an action to be taken by the machine. Further, while a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, e.g., cloud computing, Software as a Service (SaaS), and other computer cluster configurations.

The examples described herein may include, or may operate on, logic, or multiple components, modules, circuit systems, or mechanisms. Modules and circuits are tangible entities (e.g., hardware) that can perform specified operations and can be configured or arranged in some manner. In an example, a circuit can be arranged in a specified manner (e.g., internally or relative to an external entity, such as other circuits) as a circuit system. In an example, one or more computer systems (e.g., independent client or server computer systems) or one or more hardware processors, in whole or in part, can be configured to operate to perform a specified operation through firmware or software (e.g., instructions, application components, or applications).

Thus, the term "circuitry" is understood to encompass a tangible entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., temporarily) configured (e.g., programmed) to operate in a specific manner or to perform some or all of any of the operations described herein. Considering an example where the circuitry is temporarily configured, at any given moment, each circuit needs to be instantiated. For example, where the circuitry includes a general-purpose hardware processor configured using software, the general-purpose hardware processor can be configured as different circuits at different times. The software can accordingly configure the hardware processor to constitute a specific circuit at one instance in time and to constitute a different circuit at a different instance in time.

The machine (e.g., a computer system) 5000 may include a hardware processor 5002 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 5001, and a static memory 5006, some or all of which may communicate with each other via an interconnection link (e.g., a bus) 5008. The machine 5000 may also include a display unit 5010, an alphanumeric input device 5012 (e.g., a keyboard), and a user interface (UI) navigation device 5014 (e.g., a mouse). In an example, the display unit 5010, the input device 5012, and the UI navigation device 5014 may be a touch screen display. The machine 5000 may also include a storage device (e.g., a drive unit) 5016, a signal generating device 5018 (e.g., a speaker), a network interface device 5020, and one or more sensors 5021 (e.g., a global positioning system (GPS) sensor, a compass, an accelerometer, or other sensors). The machine 5000 may include an output controller 5028 (e.g., a serial (e.g., universal serial bus (USB)), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC)), etc.) connection) to control or communicate with one or more peripheral devices (e.g., a printer, a card reader, etc.).

The storage device 5016 may include a machine-readable medium 5022 on which is stored one or more sets of data structures or instructions 5024 (e.g., software) that implement (or are utilized by) any one or more of the techniques or functionality described herein. The instructions 5024 may also reside, at least partially, within the main memory 5001, within the static memory 5006, or within the hardware processor 5002 during execution by the machine 5000. In an example, one or any combination of the hardware processor 5002, the main memory 5001, the static memory 5006, or the storage device 5016 may constitute a machine-readable medium.

Although the machine-readable medium 5022 is shown as a single medium, the term "machine-readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store one or more instructions 5024.

The term "machine-readable medium" may include any medium that can perform the following activities: store, encode or carry instructions for execution by the machine 5000, and these instructions cause the machine 5000 to perform any one or more of the techniques disclosed herein; or store, encode or carry data structures used by or associated with such instructions. Machine-readable media may include non-transitory machine-readable media. Machine-readable media is not a transient propagation signal. Non-limiting examples of machine-readable media may include solid-state memory, and optical and magnetic media. Specific examples of machine-readable media may include: non-volatile memory such as semiconductor memory devices (e.g., electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)) and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; random access memory (RAM); and CD-ROM disks and DVD-ROM disks.

Instructions 5024 may also be sent or received over a communication network 5026 using a transmission medium via the network interface device 5020 using any of a number of transmission protocols (e.g., frame relay, Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Hypertext Transfer Protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), a mobile phone network (e.g., a cellular network), a plain old telephone (POTS) network, and wireless data networks (e.g., the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards (referred to as IEEE), the IEEE 802.16 family of standards (referred to as IEEE), the IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, and others). In an example, the network interface device 5020 may include one or more physical jacks (e.g., Ethernet, coaxial, or telephone jacks) or one or more antennas to connect to the communication network 5026. In an example, the network interface device 5020 may include multiple antennas to enable wireless communication using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) technology. The term "transmission medium" shall be taken to include any intangible medium that can store, encode, or carry instructions for execution by the machine 5000, and includes digital or analog communication signals or other intangible media to facilitate communication of such software.

Additional Notes and Non-Limiting Examples

Example 1 includes a subject matter (e.g., a device, an apparatus, or a machine) comprising: a first transceiver that transmits and receives in an unlicensed channel using a first wireless protocol; a second transceiver that transmits and receives in an authorized channel according to a cellular wireless protocol; a controller that: determines, via the first transceiver, that an average energy of the unlicensed channel within a predetermined time period is lower than a predetermined threshold, and in response: sends a wireless reservation message on the unlicensed channel via the first transceiver to reserve the unlicensed channel for transmission of a supplemental downlink (SDL) physical downlink shared channel (PDSCH); schedules at least one user equipment (UE) served by an eNodeB to receive data on the SDLPDSCH in the unlicensed channel via a physical downlink control channel (PDCCH) on the authorized channel sent by the second transceiver; and sends the SDLPDSCH over the unlicensed channel at a cellular subframe boundary via the first transceiver.

In Example 2, the subject matter of Example 1 can include, wherein the cellular wireless protocol is the Long Term Evolution (LTE) or Long Term Evolution-Advanced (LTE-A) family of standards defined by the 3rd Generation Partnership Project (3GPP).

In Example 3, the subject matter of any one of Examples 1 to 2 may include, wherein the first wireless protocol is a protocol according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 protocol.

In Example 4, any of Examples 1 to 3 may include, wherein the wireless subscription message is one of: a cancel-to-send (CTS) message or a request-to-send (RTS) message.

In Example 5, the subject matter of any one of Examples 1 to 4 may include, wherein the controller implements a fallback process, and the controller does not send the subscription message, schedule the UE, and send the SDL PDSCH until the fallback process is successful.

In Example 6, the subject matter of any one of Examples 1 to 5 may include, wherein the backoff length is determined based on a previous transmission.

In Example 7, the subject matter of any one of Examples 1 to 6 may include, wherein the unlicensed channel is a channel in an Industrial, Scientific, and Medical (ISM) band.

In Example 8, the subject matter of any one of Examples 1 to 7 may include, wherein the cellular subframe boundary is the start of an LTE or LTE-A subframe.

In Example 9, the subject matter of any one of Examples 1 to 8 may include, wherein the wireless reservation message includes a duration field set to a time that is at least a sum of a time required to reach a start of a subframe boundary and a time required to transmit the SDL PDSCH.

In Example 10, the subject matter of any one of Examples 1 to 9 may include, wherein the second transceiver is configured to provide the PDCCH in a granted channel.

Example 11 includes a subject matter (e.g., an apparatus, a device, or a machine) comprising: sensing a first channel for a predetermined time period, the first channel being a wireless channel that is not exclusively authorized for cellular wireless communication; determining that an average received power of the first channel indicates that the first channel is idle during the predetermined time period; and in response to determining that the first channel is idle: scheduling at least one user equipment (UE) served by an eNodeB to receive data on a physical downlink shared channel (PDSCH) sent on the first channel; transmitting the schedule to the UE via a control channel on a second channel, the second channel being a wireless channel authorized for cellular wireless communication; and sending the PDSCH on the first channel via a first transceiver.

In Example 12, the subject matter of Example 11 may include, wherein the instructions configure the eNodeB to at least: transmit a subscription message on the first channel in response to determining that the first channel is idle.

In Example 13, the subject matter of any one of Examples 11 to 12 may include, wherein the subscription message is a message defined in accordance with one of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards.

In Example 14, the subject matter of any one of Examples 11 to 13 may include, wherein the reservation message has a duration field that is at least as large as the sum of a time until a subframe boundary and a time required to transmit the subframe.

In Example 15, the subject matter of any one of Examples 11 to 14 may include, wherein the operation of transmitting the PDSCH comprises the operation of waiting until a subframe boundary of the eNodeB to transmit.

In Example 16, the subject matter of any one of Examples 11 to 15 may include, wherein the instructions further configure the eNodeB to implement a fallback procedure before scheduling the UE.

In Example 17, the subject matter of any one of Examples 11 to 16 may include, wherein the eNodeB operates according to one of Long Term Evolution (LTE) or Long Term Evolution-Advanced (LTE-A) radio protocols.

Example 18 includes a subject matter (e.g., a method, an apparatus for performing an action, a machine-readable medium comprising instructions that, when executed by a machine, cause the machine to perform the action, or an apparatus for performing the following operations), the subject matter comprising: at an eNodeB: determining, via a first transceiver, that an average energy of a first channel over a predetermined time period is lower than a predetermined threshold, the first channel being a wireless channel that is not exclusively authorized for cellular wireless communication, and in response: selecting a random backoff period; determining that the average energy of the first channel over the backoff period is lower than a second threshold; scheduling at least one user equipment (UE) served by the eNodeB to receive data on a supplemental downlink (SDL) physical downlink shared channel (PDSCH) on the first channel; transmitting the scheduling to the UE by sending a physical downlink control channel (PDCCH) on a second channel by a second transceiver, the second channel being a wireless channel authorized for cellular wireless communication; and sending an SDL PDSCH via the first transceiver over an unauthorized channel at a cellular subframe boundary.

In Example 19, the subject matter of Example 18 may include providing the PDSCH on the second channel.

In Example 20, the subject matter of any one of Examples 18 to 19 may include, wherein the unlicensed channel is a frequency between 2.4 GHz and 2.5 GHz.

In Example 21, the subject matter of any one of Examples 18 to 20 may include sending the wireless subscription message on the first channel.

In Example 22, the subject matter of any one of Examples 18 to 21 may include, wherein the wireless subscription message is a broadcast message.

In Example 23, the subject matter of any one of Examples 18 to 22 may include, wherein the wireless subscription message is a cancel-send (CTS) message.

In Example 24, the subject matter of any one of Examples 18 to 23 may include, wherein the CTS message is sent in a time multiplexed or frequency multiplexed manner.

In Example 25, the subject matter of any one of Examples 18 to 24 may include, wherein the wireless subscription message has a duration field set to a value of at least a time until a subframe boundary plus a time necessary to transmit a PDSCH subframe.

In Example 26, the subject matter of any one of Examples 18 to 25 may include, wherein the predetermined threshold and the second threshold are the same value.

In Example 27, the subject matter of any one of Examples 18 to 26 may include, wherein the predetermined threshold and the second threshold are different values.

Example 28 includes a subject matter (e.g., an apparatus, a device, or a machine) comprising: an apparatus for determining, via a first transceiver, that an average energy of a first channel over a predetermined time period is below a predetermined threshold, the first channel being a wireless channel that is not exclusively authorized for cellular wireless communication, and in response: an apparatus for selecting a random backoff period; an apparatus for determining that the average energy of the first channel over the backoff period is below a second threshold; an apparatus for scheduling at least one user equipment (UE) served by an eNodeB to receive data on a supplemental downlink (SDL) physical downlink shared channel (PDSCH) on the first channel; an apparatus for transmitting the schedule to the UE by sending a physical downlink control channel (PDCCH) on a second channel by a second transceiver, the second channel being a wireless channel authorized for cellular wireless communication; and an apparatus for sending an SDL PDSCH via the first transceiver over an unauthorized channel at a cellular subframe boundary.

In Example 29, the subject matter of Example 28 may include means for providing the PDSCH on the second channel.

In Example 30, the subject matter of any one of Examples 28 to 29 may include, wherein the unlicensed channel is a frequency between 2.4 GHz and 2.5 GHz.

In Example 31, the subject matter of any one of Examples 28 to 30 may include means for sending a wireless subscription message on a first channel.

In Example 32, the subject matter of any one of Examples 28 to 31 may include, wherein the wireless subscription message is a broadcast message.

In Example 33, the subject matter of any one of Examples 28 to 32 may include, wherein the wireless subscription message is a cancel-send (CTS) message.

In Example 34, the subject matter of any one of Examples 28 to 33 may include, wherein the wireless subscription message has a duration field set to a value of at least a time until a subframe boundary plus a time necessary to transmit a PDSCH subframe.

In Example 35, the subject matter of any one of Examples 28 to 34 may include, wherein the predetermined threshold and the second threshold are the same value.

In Example 36, the subject matter of any one of Examples 28 to 35 may include, wherein the predetermined threshold and the second threshold are different values.

Example 37 includes a subject matter (e.g., a device, an apparatus, or a machine) comprising: one or more processors configured to: sense a first channel for a predetermined time period, the first channel being a wireless channel that is not exclusively authorized for cellular wireless communication; determine that an average received power of the first channel indicates that the first channel is idle during the predetermined time period; and in response to determining that the first channel is idle: schedule at least one user equipment (UE) served by an eNodeB to receive data on a physical downlink shared channel (PDSCH) sent on the first channel; transmit the schedule to the UE via a control channel on a second channel, the second channel being a wireless channel authorized for cellular wireless communication; and send the PDSCH on the first channel via a first transceiver.

In Example 38, the subject matter of Example 37 may include, wherein the one or more processors are configured to: send the subscription message on the first channel in response to determining that the first channel is idle.

In Example 39, the subject matter of any one of Examples 37 to 38 may include, wherein the subscription message is a message defined in accordance with one of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards.

In Example 40, the subject matter of any one of Examples 37 to 39 may include, wherein the reservation message has a duration field that is at least as large as the sum of a time until a subframe boundary and a time required to transmit the subframe.

In Example 41, the subject matter of any one of Examples 37 to 40 may include, wherein the operation of transmitting the PDSCH comprises the operation of waiting until a subframe boundary of the eNodeB to transmit.

In Example 42, the subject matter of any one of Examples 37 to 41 may include, wherein the instructions further configure the eNodeB to implement a fallback procedure before scheduling the UE.

In Example 43, the subject matter of any one of Examples 37 to 42 may include, wherein the eNodeB operates in accordance with one of Long Term Evolution (LTE) or Long Term Evolution-Advanced (LTE-A) radio protocols.

Claims (21)

1. An apparatus for an evolved Node B (eNodeB) configured to operate in unlicensed spectrum and apply a listen-before-tell (LBT) approach before performing a transmission, the apparatus comprising: Memory; The processing circuit is configured as follows: The transceiver circuitry is configured to sense that the channel will be idle during a time slot of a predetermined period, the channel being in the unlicensed spectrum; If the channel is sensed to be idle during the time slot of the predetermined time period, the processing circuit is further configured to: Set a random competition window CW value and store the CW value in the memory, the CW value being between the absolute minimum value CW _min and the current maximum value CWT of CW; The transceiver circuit is configured to sense the channel reaching an additional time slot period when the CW value is greater than zero; and For each of the additional time slots, when the channel is sensed to be idle, the CW value is decreased until the CW value reaches zero; and After the channel is sensed to be idle during the time slot of the predetermined period and after the CW value is zero, physical downlink shared channel (PDSCH) data is transmitted on the channel. 2. The apparatus of claim 1, wherein the additional time slot period corresponds to a time slot in an additional predetermined time period, and wherein the processing circuitry: The transceiver circuitry is configured to continuously sense the channel until a busy time slot is detected, or until all time slots in the additional predetermined time period are detected as idle. 3. The apparatus of claim 2, wherein, after detecting a busy time slot, the processing circuit further: Configure the transceiver circuitry to sense that the channel will be idle during the time slot of the predetermined time period; and If the channel is sensed to be idle during the time slot of the predetermined time period, then: Set the random CW value; and The transceiver circuit is configured to repeatedly sense the channel for an additional time slot period when the CW value is greater than zero. 4. The apparatus of claim 1, wherein if the average power detected during a plurality of time slots for the predetermined time period is lower than a power level threshold, the processing circuit determines that the channel is idle during the plurality of time slots. 5. The apparatus of claim 4, wherein the power level threshold is -62 dBm. 6. The apparatus of claim 1, wherein each time slot is 9 µs. 7. The apparatus of claim 1, wherein the processing circuit is further configured to: Calculate the Transport Block Error Rate (TBE). If the TBE rate is lower than a predetermined threshold, then the CWT is set to the CW _min ; or If the TBE rate is higher than or equal to the predetermined threshold, then the CWT is set to twice the previous CWT and not exceeding the global maximum value CW _max . 8. The apparatus of claim 7, wherein the CW _min is 3 and the CW _max is 1023. 9. The apparatus of claim 7, wherein the CW _min and the CW _max correspond to the number of time slot periods, and The predetermined time period corresponds to at least a predetermined number of time slots. 10. The apparatus of claim 1, wherein the processing circuit causes a reservation message to be transmitted on the channel in response to determining that the channel is idle, wherein the reservation message has a duration field, the value of which is at least the sum of the time up to the subframe boundary and the time required to transmit the subframe. 11. A non-transitory computer-readable medium storing instructions that, when executed by the processing circuitry of an evolved NodeB (eNodeB), cause the following operations to be performed: The eNodeB is configured to operate in unlicensed spectrum and apply Listen-Before-Speak (LBT) before transmitting: The eNodeB's transceiver circuitry senses that the channel will be idle during a predetermined time slot period in the unlicensed spectrum; If the channel is sensed to be idle during the time slot of the predetermined time period, then: The processing circuit sets a random competition window CW value, which is between the absolute minimum value of CW, CW _min , and the current maximum value of CW, CWT. The transceiver circuit senses the channel reaching another time slot when the CW value is greater than zero; and By the processing circuitry, for each of the additional time slots, when the channel is sensed to be idle, the CW value is decreased until the CW value reaches zero; and The transceiver circuit encodes Physical Downlink Shared Channel (PDSCH) data for transmission on the channel after the channel is sensed to be idle during the time slot of the predetermined time period and after the CW value is zero. 12. The non-transitory computer-readable medium of claim 11, wherein the additional time slot period corresponds to a time slot in an additional predetermined time period, and wherein the operation further comprises: The transceiver circuitry continuously senses the channel until a busy time slot is detected, or until all time slots in the other predetermined time period are detected as idle. 13. The non-transitory computer-readable medium of claim 12, wherein, after detecting a busy time slot, the operation further comprises: The transceiver circuit senses that the channel will be idle during the time slot of the predetermined time period; and If the channel is sensed to be idle during the time slot of the predetermined time period, then: The CW value is set by the processing circuit; and The transceiver circuit repeatedly senses the channel during additional time slots when the CW value is greater than zero. 14. The non-transitory computer-readable medium of claim 11, wherein if the average power detected during a plurality of time slots for the predetermined time period is lower than a power level threshold, the processing circuit determines that the channel is idle during the plurality of time slots. 15. The non-transitory computer-readable medium of claim 14, wherein the power level threshold is -62 dBm. 16. The non-transitory computer-readable medium of claim 11, wherein each time slot is 9 µs. 17. The non-transitory computer-readable medium of claim 11, wherein the operation further comprises: Calculate the Transport Block Error Rate (TBE). If the TBE rate is lower than a predetermined threshold, then the CWT is set to the CW _min ; or If the TBE rate is higher than or equal to the predetermined threshold, then the CWT is set to twice the previous CWT and not exceeding the global maximum value CW _max . 18. The non-transitory computer-readable medium of claim 17, wherein the CW _min is 3 and the CW _max is 1023. 19. The non-transitory computer-readable medium of claim 17, wherein the CW _min and the CW _max correspond to the number of time slot periods, and The predetermined time period corresponds to at least a predetermined number of time slots. 20. The non-transitory computer-readable medium of claim 11, wherein the operation further comprises: The transceiver circuit transmits a reserved message on the channel in response to determining that the channel is idle, wherein the reserved message has a duration field, the value of which is at least the sum of the time up to the subframe boundary and the time required to transmit the subframe. 21. An apparatus for an evolved Node B (eNodeB) configured to operate in unlicensed spectrum and apply a listen-before-tell (LBT) protocol before transmitting, the apparatus comprising: A means for sensing that a channel will be idle during a time slot of a predetermined period, the channel being in the unlicensed spectrum; If the channel is sensed to be idle during the time slot of the predetermined time period, the device includes: A means for setting a random competition window CW value and storing the CW value in memory, the CW value being between the absolute minimum value CW _min and the current maximum value CWT of CW; A means for sensing the channel reaching another time slot when the CW value is greater than zero; and Means for decreasing the CW value until the CW value reaches zero when the channel is sensed to be idle during each of the additional time slots; and A means for encoding Physical Downlink Shared Channel (PDSCH) data for transmission on the channel after the channel is sensed to be idle during the time slot of the predetermined time period and after the CW value is zero.