Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/0006—Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
  • H04L27/2601—Multicarrier modulation systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0001—Arrangements for dividing the transmission path
  • H04L5/0003—Two-dimensional division
  • H04L5/0005—Time-frequency
  • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A) or DMT
  • H04L5/001—Time-frequency the frequencies being orthogonal, e.g. OFDM(A) or DMT the frequencies being arranged in component carriers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/003—Arrangements for allocating sub-channels of the transmission path
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/003—Arrangements for allocating sub-channels of the transmission path
  • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
  • H04L5/005—Allocation of pilot signals, i.e. of signals known to the receiver of common pilots, i.e. pilots destined for multiple users or terminals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
  • H04W72/044—Wireless resource allocation based on the type of the allocated resource
  • H04W72/0446—Resources in time domain, e.g. slots or frames
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/12—Wireless traffic scheduling
  • H04W72/1215—Wireless traffic scheduling for collaboration of different radio technologies
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/08—Non-scheduled access, e.g. ALOHA
  • H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/08—Non-scheduled access, e.g. ALOHA
  • H04W74/0833—Random access procedures, e.g. with 4-step access
• • 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
  • H04W74/00—Wireless channel access
  • H04W74/08—Non-scheduled access, e.g. ALOHA
  • H04W74/0833—Random access procedures, e.g. with 4-step access
  • H04W74/0836—Random access procedures, e.g. with 4-step access with 2-step access

Definitions

• aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to uplink procedures for long term evolution (LTE)/LTE- Advanced (LTE-A) communication systems with unlicensed spectrum.
• LTE long term evolution
• LTE-A LTE- Advanced
• Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and the like. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources.
• UTRAN Universal Terrestrial Radio Access Network
• the UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP).
• UMTS Universal Mobile Telecommunications System
• 3GPP 3rd Generation Partnership Project
• multiple-access network formats include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDM A) networks, and Single-Carrier FDMA (SC-FDMA) networks.
• CDMA Code Division Multiple Access
• TDMA Time Division Multiple Access
• FDMA Frequency Division Multiple Access
• OFDM A Orthogonal FDMA
• SC-FDMA Single-Carrier FDMA
• a wireless communication network may include a number of base stations or node Bs that can support communication for a number of user equipments (UEs).
• a UE may communicate with a base station via downlink and uplink.
• the downlink (or forward link) refers to the communication link from the base station to the UE
• the uplink (or reverse link) refers to the communication link from the UE to the base station.
• a base station may transmit data and control information on the downlink to a
• a UE may receive data and control information on the uplink from the UE.
• a transmission from the base station may encounter interference due to transmissions from neighbor base stations or from other wireless radio frequency (RF) transmitters.
• RF radio frequency
• a transmission from the UE may encounter interference from uplink transmissions of other UEs communicating with the neighbor base stations or from other wireless RF transmitters. This interference may degrade performance on both the downlink and uplink.
• a method of wireless communication includes generating, at a UE, one or more uplink signals for transmission to a serving base station, wherein the UE is configured to transmit communication signals to the serving base station over at least unlicensed spectrum and receive communication signals from the serving base station, determining, by the UE, a non-clear channel assessment (non-CCA) subframe for transmission of at least one of the one or more uplink signals, and transmitting, by the UE over an unlicensed band, the at least one of the one or more uplink signals in the non-CCA subframe.
• non-CCA non-clear channel assessment
• a method of wireless communication includes identifying, by a serving base station configured for communication over at least unlicensed spectrum, a non-CCA subframe for reception of at least one uplink signal, and receiving, at the serving base station, over an unlicensed band one or more uplink signals from a UE in the non-CCA subframe.
• an apparatus configured for wireless communication includes means for peneratin p at a T TF. one or more unlink si gnal s for transmission to a serving base station, wherein the UE is configured to transmit communication signals to the serving base station over at least an unlicensed spectrum and receive communication signals from the serving base station.
• the apparatus further includes means for determining, by the UE, a non-CCA subframe for transmission of at least one of the one or more uplink signals.
• the apparatus also comprises means for transmitting, by the UE over an unlicensed band, the at least one of the one or more uplink signals in the non-CCA subframe.
• an apparatus configured for wireless communication includes means for identifying, by a serving base station configured for communication over at least an unlicensed spectrum, a non-CCA subframe for reception of at least one uplink signal.
• the apparatus additionally includes means for receiving, at the serving base station, over an unlicensed band one or more uplink signals from a UE in the non-CCA subframe.
• FIG. 1 shows a diagram that illustrates an example of a wireless communications system according to various embodiments.
• FIG. 2A shows a diagram that illustrates examples of deployment scenarios for using LTE in an unlicensed spectrum according to various embodiments.
• FIG. 2B shows a diagram that illustrates another example of a deployment scenario for using LTE in an unlicensed spectrum according to various embodiments.
• FIG. 3 shows a diagram that illustrates an example of carrier aggregation when using LTE concurrently in licensed and unlicensed spectrum according to various embodiments.
• FIG. 4 is a block diagram conceptually illustrating a design of a base station/eNB and a UE configured according to one aspect of the present disclosure.
• FIG. 5 is a block diagram illustrating a transmission timeline for an LTE/LTE-A deployment with unlicensed spectrum configured according to one aspect of the present disclosure.
• FIG. 6 is a block diagram illustrating a transmission timeline in an LTE/LTE-A deployment with unlicensed spectrum configured according to one aspect of the present disclosure.
• FIG. 7 is a block diagram illustrating a system bandwidth of an LTE/LTE-A deployment with unlicensed spectrum configured according to one aspect of the present disclosure.
• FIGs. 8A and 8B are functional block diagrams illustrating example blocks executed to implement one aspect of the present disclosure.
• FIG. 9 is a block diagram illustrating a transmission timeline in an LTE/LTE-A communication system with unlicensed spectrum configured according to one aspect of the present disclosure.
• FIG. 10 is a block diagram illustrating a transmission timeline of an LTE/LTE-A
• FIG. 11A is a call flow diagram illustrating a call flow in an LTE/LTE-A communication system with unlicensed spectrum between an eNB and UE configured according to one aspect of the present disclosure.
• FIG. 11B is a call flow diagram illustrating a call flow in an LTE/LTE-A communication system with unlicensed spectrum between the eNB and UE, configure according to one aspect of the present disclosure.
• FIG. 12 is a block diagram illustrating a combined random access response message from a base station configured according to one aspect of the present disclosure.
• FIGs. 13A and 13B are functional block diagrams illustrating example blocks executed to implement one aspect of the present disclosure.
• FIGs. 14A and 14B are functional block diagrams illustrating example blocks executed to implement one aspect of the present disclosure.
• a new carrier type (NCT) based on LTE/LTE-A in an unlicensed spectrum may be compatible with carrier-grade WiFi, making LTE/LTE-A with unlicensed spectrum an alternative to WiFi.
• LTE/LTE-A with unlicensed spectrum may leverage LTE concepts and may introduce some modifications to physical layer (PHY) and media access control (MAC) aspects of the network or network devices to provide efficient operation in the unlicensed spectrum and to meet regulatory requirements.
• the unlicensed spectrum may range from 600 Megahertz (MHz) to 6 Gigahertz (GHz), for example.
• LTE/LTE-A with unlicensed spectrum may perform significantly better than WiFi.
• LTE/LTE-A with unlicensed spectrum may perform significantly better than WiFi.
• LTE/LTE-A with unlicensed spectrum may perform better than WiFi in other scenarios such as when LTE/LTE-A with unlicensed spectrum is mixed with WiFi (for single or multiple operators).
• an LTE/LTE-A network on an unlicensed spectrum may be configured to be synchronous with a LTE network on the licensed spectrum.
• LTE/LTE-A networks with unlicensed spectrum deployed on a given channel by multiple SPs may be configured to be synchronous across the multiple SPs.
• One approach to incorporate both the above features may involve using a constant timing offset between LTE/LTE-A with and without unlicensed spectrum for a given SP.
• An LTE/LTE-A network with unlicensed spectrum may provide unicast and/or multicast services according to the needs of the SP.
• LTE/LTE-A network with unlicensed spectrum may operate in a bootstrapped mode in which LTE cells act as anchor and provide relevant unlicensed band cell information (e.g., radio frame timing, common channel configuration, system frame number or SFN, etc.). In this mode, there may be close interworking between LTE/LTE-A with and without unlicensed spectrum.
• the bootstrapped mode may support the supplemental downlink and the carrier aggregation modes described above.
• the PHY-MAC layers of the LTE/LTE-A network with unlicensed spectrum may operate in a standalone mode in which the LTE/LTE-A network with unlicensed spectrum operates independently from an LTE network.
• CDMA Code Division Multiple Access
• TDMA Time Division Multiple Access
• FDMA Frequency Division Multiple Access
• OFDMA Frequency Division Multiple Access
• SC-FDMA SC-FDMA
• a CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc.
• CDMA2000 covers IS- 2000, IS-95, and IS-856 standards.
• IS-2000 Releases 0 and A are commonly referred to as CDMA2000 IX, IX, etc.
• IS-856 (TIA-856) is commonly referred to as CDMA2000 lxEV-DO, High Rate Packet Data (HRPD), etc.
• UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA.
• a TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM).
• GSM Global System for Mobile Communications
• An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc.
• UMB Ultra Mobile Broadband
• E-UTRA Evolved UTRA
• Wi-Fi Wi-Fi
• WiMAX IEEE 802.16
• IEEE 802.20 Flash-OFDM
• UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS).
• UMTS Universal Mobile Telecommunication System
• LTE and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA.
• UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project” (3GPP).
• CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2" (3GPP2).
• the techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies.
• the description below describes an LTE system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE applications.
• the system 100 includes base stations (or cells) 105, communication devices 115, and a core network 130.
• the base stations 105 may communicate with the communication devices 115 under the control of a base station controller (not shown), which may be part of the core network 130 or the base stations 105 in various embodiments.
• Base stations 105 may communicate control information and/or user data with the core network 130 through backhaul links 132.
• the base stations 105 may communicate, either directly or indirectly, with each other over backhaul links 134, which may be wired or wireless communication links.
• the system 100 may support operation on multiple carriers (waveform signals of different frequencies).
• Multi-carrier transmitters can transmit modulated signals simultaneously on the multiple carriers.
• each communication link 125 may be a multi-carrier signal modulated according to the various radio technologies described above.
• Each modulated signal may be sent on a different carrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, data, etc.
• the base stations 105 may wirelessly communicate with the devices 115 via one or more base station antennas. Each of the base station 105 sites may provide communication coverage for a respective geographic area 110.
• base stations 105 may be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a basic service set (BSS), an extended service set (ESS), a NodeB, eNodeB (eNB), Home NodeB, a Home eNodeB, or some other suitable terminology.
• the coverage area 110 for a base station may be divided into sectors making up only a portion of the coverage area (not shown).
• the system 100 may include base stations 105 of different types (e.g., macro, micro, and/or pico base stations). There may be overlapping coverage areas for different technologies.
• the system 100 is an LTE/LTE-A network that supports one or more communication modes of operation or deployment scenarios using unlicensed spectrum.
• the system 100 may support wireless communications using an unlicensed spectrum and an access technology different from LTE/LTE-A with unlicensed spectrum, or a licensed spectrum and an access technology different from LTE/LTE-A.
• the terms evolved Node B (eNB) and user equipment (UE) may be generally used to describe the base stations 105 and devices 115, respectively.
• the system 100 may be a Heterogeneous LTE/LTE-A network with or without unlicensed spectrum in which different types of eNBs provide coverage for various geographical regions.
• each eNB 105 may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cell.
• Small cells such as pico cells, femto cells, and/or other types of cells may include low power nodes or LPNs.
• a macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider.
• a pico cell would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider.
• a femto cell would also generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, and the like).
• An eNB for a macro cell may be referred to as a macro eNB.
• An eNB for a pico cell may be referred to as a pico eNB.
• an eNB for a femto cell may be referred to as a femto eNB or a home eNB.
• An eNB may support one or multiple (e.g., two, three, four, and the like) cells.
• the core network 130 may communicate with the eNBs 105 via a backhaul 132
• the eNBs 105 may also communicate with one another, e.g., directly or indirectly via backhaul links 134 (e.g., X2, etc.) and/or via backhaul links 132 (e.g., through core network 130).
• the system 100 may support synchronous or asynchronous operation.
• the eNBs may have similar frame and/or gating timing, and transmissions from different eNBs may be approximately aligned in time.
• the eNBs may have different frame and/or gating timing, and transmissions from different eNBs may not be aligned in time.
• the techniques described herein may be used for either synchronous or asynchronous operations.
• the UEs 115 are dispersed throughout the system 100, and each UE may be stationary or mobile.
• a UE 115 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.
• a UE 115 may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like.
• PDA personal digital assistant
• a UE may be able to communicate with macro eNBs, pico eNBs, femto eNBs, relays, and the like.
• the communications links 125 shown in system 100 may include uplink (UL) transmissions from a mobile device 115 to a base station 105, and/or downlink (DL) transmissions, from a base station 105 to a mobile device 115.
• the downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions.
• the downlink transmissions may be made using a licensed spectrum, an unlicensed spectrum, or both.
• the uplink transmissions may be made using a licensed spectrum, an unlicensed spectrum, or both.
• LTE/LTE-A with unlicensed spectrum may be supported including a supplemental downlink (SDL) mode in which LTE downlink capacity in a licensed spectrum may be offloaded to an unlicensed spectrum, a carrier aggregation mode in which both LTE downlink and uplink capacity may be offloaded from a licensed spectrum to an unlicensed spectrum, and a standalone mode in which LTE downlink and uplink communications between a base station (e.g., eNB) and a UE may take place in an unlicensed spectrum.
• Base stations 105 as well as UEs 115 may support one or more of these or similar modes of operation.
• OFDMA communications signals may be used in the communications links 125 for LTE downlink transmissions in an unlicensed spectrum
• SC-FDMA communications signals may be used in the communications links 125 for LTE uplink transmissions in an unlicensed spectrum. Additional details regarding the implementation of LTE/LTE-A deployment scenarios or modes of operation with unlicensed spectrum in a system such as the system 100, as well as other features and functions related to the operation of LTE/LTE-A with unlicensed spectrum, are provided below with reference to FIGS. 2 A - 14B. [0039] Turning next to FIG. 2A, a diagram 200 shows examples of a supplemental downlink mode and of a carrier aggregation mode for an LTE/LTE-A network that supports communications using unlicensed spectrum.
• the diagram 200 may be an example of portions of the system 100 of FIG. 1.
• the base station 105-a may be an example of the base stations 105 of FIG. 1
• the UEs 115-a may be examples of the UEs 115 of FIG. 1.
• the base station In the example of a supplemental downlink mode in diagram 200, the base station
• the 105-a may transmit OFDMA communications signals to a UE 115-a using a downlink 205.
• the downlink 205 is associated with a frequency Fl in an unlicensed spectrum.
• the base station 105-a may transmit OFDMA communications signals to the same UE 115-a using a bidirectional link 210 and may receive SC-FDMA communications signals from that UE 115-a using the bidirectional link 210.
• the bidirectional link 210 is associated with a frequency F4 in a licensed spectrum.
• the downlink 205 in the unlicensed spectrum and the bidirectional link 210 in the licensed spectrum may operate concurrently.
• the downlink 205 may provide a downlink capacity offload for the base station 105-a.
• the downlink 205 may be used for unicast services (e.g., addressed to one UE) services or for multicast services (e.g., addressed to several UEs).
• This scenario may occur with any service provider (e.g., traditional mobile network operator or MNO) that uses a licensed spectrum and needs to relieve some of the traffic and/or signaling congestion.
• MNO mobile network operator
• the base station In one example of a carrier aggregation mode in diagram 200, the base station
• the 105-a may transmit OFDMA communications signals to a UE 115-a using a bidirectional link 215 and may receive SC-FDMA communications signals from the same UE 115-a using the bidirectional link 215.
• the bidirectional link 215 is associated with the frequency Fl in the unlicensed spectrum.
• the base station 105-a may also transmit OFDMA communications signals to the same UE 115-a using a bidirectional link 220 and may receive SC-FDMA communications signals from the same UE 115-a using the bidirectional link 220.
• the bidirectional link 220 is associated with a frequency F2 in a licensed spectrum.
• the bidirectional link 215 may provide a downlink and uplink capacity offload for the base station 105-a.
• this scenario may occur with any service provider (e.g., MNO) that uses a licensed spectrum and needs to relieve some of the traffic and/or signaling congestion.
• MNO service provider
• the base station In another example of a carrier aggregation mode in diagram 200, the base station
• the 105-a may transmit OFDMA communications signals to a UE 115-a using a bidirectional link 225 and may receive SC-FDMA communications signals from the same UE 115-a using the bidirectional link 225.
• the bidirectional link 225 is associated with the frequency F3 in an unlicensed spectrum.
• the base station 105-a may also transmit OFDMA communications signals to the same UE 115-a using a bidirectional link 230 and may receive SC-FDMA communications signals from the same UE 115-a using the bidirectional link 230.
• the bidirectional link 230 is associated with the frequency F2 in the licensed spectrum.
• the bidirectional link 225 may provide a downlink and uplink capacity offload for the base station 105-a. This example and those provided above are presented for illustrative purposes and there may be other similar modes of operation or deployment scenarios that combine LTE/LTE-A with and without unlicensed spectrum for capacity offload.
• an operational configuration may include a bootstrapped mode (e.g., supplemental downlink, carrier aggregation) that uses the LTE primary component carrier (PCC) on the licensed spectrum and the secondary component carrier (SCC) on the unlicensed spectrum.
• PCC primary component carrier
• SCC secondary component carrier
• control for LTE/LTE-A with unlicensed spectrum may be transported over the LTE uplink (e.g., uplink portion of the bidirectional link 210).
• LBT listen-before-talk
• CSMA carrier sense multiple access
• LBT may be implemented on the base station (e.g., eNB) by, for example, using a periodic (e.g., every 10 milliseconds) clear channel assessment (CCA) and/or a grab-and-relinquish mechanism aligned to a radio frame boundary.
• CCA clear channel assessment
• data and control may be communicated in LTE
• LTE/LTE-A LTE/LTE-A with unlicensed spectrum
• the carrier aggregation mechanisms supported when using LTE/LTE-A with unlicensed spectrum may fall under a hybrid frequency division duplexing-time division duplexing (FDD-TDD) carrier aggregation or a TDD-TDD carrier aggregation with different symmetry across component carriers.
• FDD-TDD frequency division duplexing-time division duplexing
• FIG. 2B shows a diagram 200-a that illustrates an example of a standalone mode for LTE/LTE-A with unlicensed spectrum.
• the diagram 200-a may be an example of portions of the system 100 of FIG. 1.
• the base station 105-b may be an example of the base stations 105 of FIG. 1 and the base station 105-a of FIG. 2A
• the UE 115-b may be an example of the UEs 115 of FIG. 1 and the UEs 115-a of FIG. 2A.
• the base station 105-b may transmit OFDMA communications signals to the UE 115-b using a bidirectional link 240 and may receive SC-FDMA communications signals from the UE 115-b using the bidirectional link 240.
• the bidirectional link 240 is associated with the frequency F3 in an unlicensed spectrum described above with reference to FIG. 2A.
• the standalone mode may be used in non-traditional wireless access scenarios, such as in-stadium access (e.g., unicast, multicast).
• the typical service provider for this mode of operation may be a stadium owner, cable company, event hosts, hotels, enterprises, and large corporations that do not have licensed spectrum.
• an operational configuration for the standalone mode may use the PCC on the unlicensed spectrum.
• LBT may be implemented on both the base station and the UE.
• FIG. 3 a diagram 300 illustrates an example of carrier aggregation when using LTE concurrently in licensed and unlicensed spectrum according to various embodiments.
• the carrier aggregation scheme in diagram 300 may correspond to the hybrid FDD-TDD carrier aggregation described above with reference to FIG. 2A.
• This type of carrier aggregation may be used in at least portions of the system 100 of FIG. 1.
• this type of carrier aggregation may be used in the base stations 105 and 105-a of FIG. 1 and FIG. 2A, respectively, and/or in the UEs 115 and 115-a of FIG. 1 and FIG. 2A, respectively.
• an FDD FDD-LTE
• a first TDD TDD1
• another FDD FDD-LTE
• TDD1 results in a DL:UL ratio of 6:4, while the ratio for TDD2 is 7:3.
• the different effective DL:UL ratios are 3: 1, 1:3, 2:2, 3: 1, 2:2, and 3: 1.
• This example is presented for illustrative purposes and there may be other carrier aggregation schemes that combine the operations of LTE/LTE-A with and without unlicensed spectrum.
• FIG. 4 shows a block diagram of a design of a base station/eNB 105 and a UE
• a transmit processor 420 may receive data from a data source 412 and control information from a controller/processor 440.
• the control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid automatic repeat request indicator channel (PHICH), physical downlink control channel (PDCCH), etc.
• the data may be for the physical downlink shared channel (PDSCH), etc.
• the transmit processor 420 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively.
• the transmit processor 420 may also generate reference symbols, e.g., for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal.
• a transmit (TX) multiple-input multiple-output (MIMO) processor 430 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 432a through 432t. Each modulator 432 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream.
• MIMO multiple-input multiple-output
• Each modulator 432 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 432a through 432t may be transmitted via the antennas 434a through 434t, respectively.
• the antennas 452a through 452r may receive the downlink signals from the eNB 105 and may provide received signals to the demodulators (DEMODs) 454a through 454r, respectively.
• Each demodulator 454 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples.
• Each demodulator 454 mav further nro ess the. irmut sarrmles (e. P for OFDM eic ⁇ to obtain received symbols.
• a MIMO detector 456 may obtain received symbols from all the demodulators 454a through 454r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.
• a receive processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 115 to a data sink 460, and provide decoded control information to a controller/processor 480.
• a transmit processor 464 may receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from a data source 462 and control information (e.g., for the physical uplink control channel (PUCCH)) from the controller/processor 480.
• the transmit processor 464 may also generate reference symbols for a reference signal.
• the symbols from the transmit processor 464 may be precoded by a TX MIMO processor 466 if applicable, further processed by the demodulators 454a through 454r (e.g., for SC-FDM, etc.), and transmitted to the eNB 105.
• the uplink signals from the UE 115 may be received by the antennas 434, processed by the modulators 432, detected by a MIMO detector 436 if applicable, and further processed by a receive processor 438 to obtain decoded data and control information sent by the UE 115.
• the processor 438 may provide the decoded data to a data sink 439 and the decoded control information to the controller/processor 440.
• the controllers/processors 440 and 480 may direct the operation at the eNB 105 and the UE 115, respectively.
• the controller/processor 440 and/or other processors and modules at the eNB 105 may perform or direct the execution of various processes for the techniques described herein.
• the controllers/processor 480 and/or other processors and modules at the UE 115 may also perform or direct the execution of the functional blocks illustrated in FIGs. 8A-8B and 13A-13B, and/or other processes for the techniques described herein.
• the memories 442 and 482 may store data and program codes for the eNB 105 and the UE 115, respectively.
• a scheduler 444 may schedule UEs for data transmission on the downlink and/or uplink.
• LTE/LTE-A with unlicensed spectrum various adaptations may be desirable in order to accommodate LTE operations over an unlicensed band with efficiency and a little change from the current LTE standards as possible.
• various uplink procedures may be adapted for LTE operations with unlicensed spectrum in LTE/LTE-A deployments with unlicensed spectrum.
• uplink communications that may be important for guaranteed transmission include: sounding reference signals (SRS), which are used in power control and uplink/downlink scheduling, scheduling request (SR), channel state information (CSI) feedback, uplink discovery signals for peer to peer communications, physical random access channel (PRACH), physical uplink shared channel (PUSCH) (e.g., initial PUSCH transmission as part of RACH procedures).
• SRS sounding reference signals
• SR scheduling request
• CSI channel state information
• PRACH physical random access channel
• PUSCH physical uplink shared channel
• This guaranteed transmission opportunity may be applicable to standalone LTE/LTE-A deployments with unlicensed spectrum, as well as potentially to carrier aggregation (CA) deployments.
• CA carrier aggregation
• LTE/LTE-A with unlicensed spectrum may also provide additional opportunistic transmission of uplink signals as well.
• the additional uplink signals that may be opportunistically transmitted in CCA-based subframes may provide additional signal instances that may be received at the associated base stations more frequently than the fixed period.
• the UE detects a clear CCA, then it may transmit uplink signals at some point before the expiration of the clear period.
• the transmission stream are guaranteed to be available for a predetermined duration, such as 5-10 ms.
• the associated base stations may receive certain uplink signals more frequently.
• inter-frequency status should be based on the guaranteed transmission subframes.
• the uplink and downlink autonomous transmi ssions mav he. se.narate.1v mana ged A ordin plv each mav have different periodicities and/or different subframe offsets.
• the uplink and downlink autonomous transmissions may be jointly managed.
• uplink autonomous transmissions may operate in a slave configuration to the downlink autonomous transmissions.
• the joint management may, thus, include the same periodicity and/or correlated subframe offsets.
• Aspects that jointly manage the autonomous transmissions may offer more efficient operations as linking the downlink and uplink operations typically results in improved system performance.
• LTE/LTE-A deployments with unlicensed spectrum that use WIFI nodes operate under a 5% flexible transmission budget.
• the 5% flexible transmission budget prevents a WIFI node from autonomously transmitting more than 5% within any 50 ms period.
• one aspect of the present disclosure suggests a fixed periodicity of 80 ms for guaranteed transmissions.
• the 5% flexible transmission budget requirements are measured over a 50 ms period.
• the fixed period for guaranteed transmissions may also be set to 50 ms.
• 80 ms offers the benefit of being more evenly divisible or comparable to many different system parameters, a shorter period, such as 50 ms would provide more opportunities for guaranteed operations.
• Other times may be considered as well, e.g., 60 ms, 70 ms, and the like.
• FIG. 5 is a block diagram illustrating a transmission timeline 50 for an LTE/LTE-
• Transmission timeline 50 illustrates the downlink guaranteed transmissions for LTE/LTE-A with unlicensed spectrum (LTE-US) eNB 500 and the uplink guaranteed transmission for LTE-US UEl 501 which are jointly managed.
• the uplink guaranteed transmissions from LTE-US UE2 502 and LTE-US U3 503 are transmitted according to different periodicities and offsets than the transmissions from LTE-US UEl 501.
• the different periodicities and offsets may be due to different discontinuous reception (DRX) operations, due to load balancing/interference coordination, or the like.
• DRX discontinuous reception
• the uplink guaranteed transmissions of LTE-US UEl 501 are slaved to the downlink guaranteed transmissions of LTE-US eNB 500.
• LTE-US eNB 500 sends its downlink guaranteed transmission and LTE-US UEl 501 sends its corresponding uplink guaranteed transmission a time, Tl, after the downlink transmission.
• Tl time
• Each of LTE-US eNB 500 and T .TF.-T TS T TF.1 501 transmit their resne tiv cmarantee.H transmissions at the. same, fixed period, such as, for example, 50 ms, 60 ms, 80 ms, or the like.
• Tl after which LTE-US UEl 501 sends its uplink guaranteed transmission, it may be beneficial to have Tl ⁇ T2, to facilitate fast random access procedure.
• LTE-US UEl 501 The processing time of LTE-US UEl 501 allows LTE-US UEl 501 to receive the downlink guaranteed transmission from LTE-US eNB 500 at 504 and send uplink guaranteed transmissions at 506. Over time T2, LTE-US eNB 500 may process SR, CSI feedback, and the like, received at 506, and send downlink guaranteed transmission 505. LTE-US UE 501 may then transmit uplink guaranteed transmission 507 triggered again by the receipt of downlink guaranteed transmission 505.
• the duration of each guaranteed transmission instance in the uplink may be the same or different than that of the downlink guaranteed transmission.
• the downlink guaranteed transmission occupies 4 symbols over 2 subframes.
• the uplink guaranteed transmission may also occupy 4 symbols over 2 subframes.
• the uplink transmissions may be single carrier frequency division multiple access (SC-FDMA) signals, signals based on multi-cluster resource allocation where each cluster is contiguous resource allocation, signals based on interleaved resource allocation, signals based on OFDM, etc.
• SC-FDMA single carrier frequency division multiple access
• a transmission duration of 7 symbols over 1 slot may be a more natural duration than the 4 symbols duration.
• uplink guaranteed transmissions may have a duration of 4 symbols over 2 subframes, while other aspects may use other durations, such as 7 symbols over 1 slot.
• Other durations are possible as well, e.g., 6 symbols.
• FIG. 6 is a block diagram illustrating a transmission timeline 60 in an LTE/LTE-
• LTE-US UEl 600 - LTE-US UE4 603 represent uplink guaranteed transmissions at fixed intervals.
• LTE-US UEl 600 and LTE-US UE2 602 transmit their respective guaranteed transmissions at the same time and interval.
• the guaranteed transmissions of LTE-US UEl 600 and LTE-US UE2 602 are frequency division multiplexed (FDM) into FDM transmission 604.
• FDM frequency division multiplexed
• the guaranteed transmissions from LTE-US UE3 602 and LTE-US UE4 603 are also transmitted at the same time and interval and mav also he.
• the FDM transmission 604 and the FDM transmission of LTE-US UE3 602 and LTE-US UE4 603 may then each be time division multiplexed (TDM) 605.
• TDM time division multiplexed
• TDM within a subframe may be realized via TDM within a subframe (different symbols in a subframe, or different slots in a subframe), TDM across subframes (different subframes for different deployments), FDM within a symbol, or a combination thereof.
• One of the uplink signals that may be sent by UEs using the guaranteed transmission subframes identified in LTE/LTE-A deployments with unlicensed spectrum are PRACH/RACH signals. Random access procedures allow for the UE to connect to a new cell whether connecting initially on startup or connecting on handover.
• the RACH resources may be managed through various levels of multiplexing.
• FIG. 7 is a block diagram illustrating a system bandwidth 70 of an LTE/LTE-A deployment with unlicensed spectrum configured according to one aspect of the present disclosure. As illustrated, system bandwidth 70 is divided into 100 physical resource blocks.
• the multiplexing of PRACH may be based on frequency division multiplexing (FDM) and/or code division multiplexing (CDM).
• FDM frequency division multiplexing
• CDM code division multiplexing
• the entire 100 PRBs are be grouped into 10 groups, of 10 PRBs each.
• Each group may be interleaved in frequency to span at least 80% of system bandwidth 70.
• PRACH Group 1 occupies every tenth PRB, e.g., PRBs 1, 11, 21, and 91.
• each PRACH is assigned to only one PRACH group.
• PRACH for different UEs may be multiplexed using CDM within a single group.
• the PRACH Group 1 instances are illustrated, in the alternative, with PRACH from both UE1 and UE2.
• the PRACH signaling from UE1 and UE2 are combined through CDM in a single PRACH group.
• an LTE/LTE-A UE with unlicensed spectrum generates a random access request for connecting to a cell.
• the UE transmits the random access request to a base station over a first carrier of a plurality of carriers operated in a cell serviced by the serving base station.
• an LTE/LTE-A base station with unlicensed spectrum receives the random access request from the UE over the first carrier of a plurality of carriers available in the cell.
• the UE monitors the plurality of carriers for a random access response to connect to the cell.
• the LTE/LTE-A base station with unlicensed spectrum generates a random access response, in response to the random access request.
• the LTE/LTE-A base station with unlicensed spectrum directs transmission of the random access response to the UE over another carrier of the plurality of carriers.
• PRACH may be initiated on a first carrier, while the UE monitors a different carrier, either along with or instead of the first carrier, for any random access response.
• FIG. 9 is a block diagram illustrating a transmission timeline 90 in an LTE/LTE-A communication system with unlicensed spectrum configured according to one aspect of the present disclosure.
• Timeline 90 illustrates downlink transmission opportunities from LTE-US eNB 900 and uplink transmission opportunities from LTE-US UE 901.
• LTE-US UE 901 may transmit uplink RACH either through guaranteed RACH transmission opportunities at non-CCA subframes 911 and 916 or non-guaranteed RACH transmission opportunities at CCA subframes 910, 912-915, and 917 after receiving a CCA clear signal.
• LTE-US eNB 900 may send random access response (RAR) messages also either through guaranteed RAR transmission opportunities at non-CCA subframes 902 and 907 or non-guaranteed RAR transmission opportunities at CCA subframes 903-906, 908, and 909 after receiving a CCA clear si cmal Guaranteed transmission onnortnnities of R ACH and R AR messa ges occur at the fixed period associated with guaranteed transmissions (e.g., 50 ms, 60 ms, 80 ms, etc.).
• the set of subframes for RACH opportunities can be maintained by an eNB.
• PRACH format is sufficient. Due to reduced coverage range for LTE/LTE-A nodes with unlicensed spectrum, PRACH may occupy a fraction of a subframe. For example, the PRACH request may only be provided in one slot or one or more symbols (similar to PRACH format 4).
• the actual channel can be similar to PUSCH (or PUCCH) for the case of simplified RACH procedure, since it contains some payload.
• a UE transmits the random access request and then waits for a certain response window before a RACH re-transmission is triggered. Each successive re-transmission is also ramped up with power.
• the reasoning for the retransmission/power ramp-up process is to conserve power, by not transmitting RACH at its maximum power, and gradually increasing the power of the re-transmissions in case the targeted base station simply cannot reliably receive and interpret the random access request.
• This RACH re-transmission process may involve multiple transmissions until the UE receives the corresponding random access response, and these multiple transmissions may have power ramp-ups with a step size (including OdB or no power ramp-ups) configurable by an LTE/LTE-A base station with unlicensed spectrum.
• a step size including OdB or no power ramp-ups
• the UE in order to determine whether to perform a re-transmission of PRACH in an LTE/LTE-A deployment with unlicensed spectrum, the UE should be capable of distinguishing the following two transmissions states of a cell: State 1 is an incapable transmission state in which the cell does not have a chance to transmit the response within a given response window.
• the base station In the incapable transmission state, the base station has not had an opportunity within the response window to transmit a random access response because there either has been no guaranteed transmission subframes (non-CCA subframes) or the base station has not been able to detect a clearance during a CCA, non- guaranteed subframe.
• State 2 is a capable state in which the cell has had chance to transmit the response within the given response window, either because it has had a guaranteed subframe or has detected clearance on a CCA subframe, but the UE has still not received the response.
• the UE may not receive the response because of various reasons, such as the eNB failing to receive the request message, or even the UE failin p to receive, the resnonse from the base station et [0070]
• the UE should be able to detect these two states and take different actions accordingly.
• the detection may be based on detection of channel usage pilot signals (CUPS), sometimes referred to as channel usage beacon signals (CUBS), cell-specific reference signals (CRS), channel state information reference signals (CSTRS), etc. If the UE detects one of these reference signals, that means that the base station has been able to make transmissions, which means that it has either had a guaranteed subframe or a CCA-cleared subframe.
• CUPS channel usage pilot signals
• CRS cell-specific reference signals
• CSTRS channel state information reference signals
• the UE would, therefore determine that the base station is in State 2, the capable transmission state, and would trigger re-transmission after the response window has expired without receiving a random access response.
• the UE fails to detect any reference signal transmissions from the base station, that may mean that the base station has not encountered either a guaranteed subframe or a CCA- cleared subframe. In this situation, the UE would determine that the base station is in State 1, the incapable transmission state. In State 1, the UE should not attempt retransmissions and should extending the response window for the base station to be able to respond. If the extended response window again passes with the UE having received the response, then the UE may attempt re-transmissions.
• LTE-US UE 901 transmits an initial random access request at guaranteed subframe 911 and begins to monitor for a random access response from LTE-US eNB 900.
• the first RAR transmission opportunity arises at non- guaranteed subframe 903.
• LTE-US eNB 900 does not detect a CCA-clear. Therefore, LTE-US eNB 900 is incapable of any transmissions.
• LTE-US UE 901 w continues to monitor during the response window for the random access response.
• LTE-US eNB 900 fails to detect a CCA-clear.
• LTE-US UE 901 does not receive a random access response message.
• the response window ends for LTE-US UE 901 at the time associated with non-guaranteed subframe 905.
• LTE-US UE 901 has not detected any reference signals from LTE-US eNB 900 since transmitting the initial random access request at subframe 911.
• LTE-US UE 901, therefore, determines that LTE-US eNB 900 is in an incapable transmission state and, accordingly, extends the response window and associate re-transmission time gap.
• LTE-US eNB 900 still does not send a random access response message to LTE-US UE 901.
• UE 901 With the occurrence of the guaranteed subframe 907, UE 901 now determines that T .TF.-TTS e.NR 900 i s in a anahle transmi ssion state, hut because, it still has not received a random access response from LTE-US eNB 900, LTE-US UE 901 triggers a retransmission and ramp-up of transmission power at guaranteed subframe 916. As such, the PRACH re-transmission process is updated for the LTE/LTE-A deployment with unlicensed spectrum to save unnecessary re-transmission and ramp-up of PRACH transmission power.
• LTE/LTE-A UEs with unlicensed spectrum can look for the random access response in both guaranteed and non-guaranteed subframes.
• the response window can take into account the differences among three different subframe types at the LTE/LTE-A base station with unlicensed spectrum: guaranteed subframes; CCA-cleared non-guaranteed subframes; and CCA-not-cleared non-guaranteed subframes.
• the UE may monitor the response starting from N-ms after PRACH transmission and keep monitoring until the end of a guaranteed subframe, or alternatively, either a CCA-cleared non-guaranteed subframe or a guaranteed subframe.
• CUPS/CUB s may be used for both channel synchronization and channel reservation. After determining that unlicensed spectrum is available (e.g., by performing a successful CCA), a base station may fill each of the CCA slots following its performance of a successful CCA with CUPS/CUBs.
• the CUPS/CUBS may include one or more signals that are detectable by other devices to let the other devices know the unlicensed spectrum (or at least a channel thereof) has been reserved for use by another device.
• CUPS/CUBs may be detected by both LTE and WiFi devices. Unlike most LTE signals, however, which begin at a subframe boundary, CUPS/CUBS may begin at an OFDM symbol boundary. That is, a device that performs a CCA for the channel after another device begins to transmit CUPS/CUBS on the channel may detect the energy of the CUPS/CUBS and determine that the channel is currently unavailable.
• aspects of the present disclosure set the response window or time gap between re-transmissions to take into account the extended response window. For example, one possibility is to determine the time gap based on first subframe (or frame) that the base station has a chance to respond, either due to encountering a guaranteed subframe or CCA cleared non-guaranteed subframe.
• FIG. 10 is a block diagram illustrating a transmission timeline 1000 of an LTE-
• LTE-US 1001 has been in an idle mode for at least 50 ms before the first illustrated guaranteed transmission opportunity at non-CCA subframe 1002. Because LTE-US UE 1001 has been in an idle mode for this period of time, when LTE-US UE 1001 desires to connect to the cell after non-CCA subframe 1002, it may immediately transmit the random access request at the next available transmission opportunity, which is CCA subframe 1003. While LTE-US UE 1001 would normally be required to first receive a CCA clear before transmitting uplink signals on CCA subframe 1003, because of the substantial idle period, LTE-US UE 1001 is able to transmit the random access request on CCA subframe 1003 without first obtaining the CCA clear.
• LTE-US UE 1001 may need to make adjustments to the guaranteed transmissions in order to adjust to the normal offset. For a subsequent transmission opportunity, LTE-US UE 1001 would not be able to transmit again within 50 ms of the initial random access transmission.
• non-CCA subframe 1004 is within 50 ms from CCA subframe 1003. If LTE-US UE 1001 were to transmit additional uplink signals or random access re-transmissions at non-CCA subframe 1004, it may then violate the 5% duty cycle flexible transmission limit within the 50 ms period. In such a circumstance, LTE-US UE 1001 may skip transmission on the guaranteed subframe completely. It should be noted, however, that LTE-US UE 1001 may perform a CCA request to determine whether or not such transmissions would, in fact, violate the 5% limit. If LTE-US UE 1001 were to receive a CCA clear, then it could then transmit the additional uplink signals or re-transmitted random access requests.
• Non- CCA subframe. 1 05 lies outsid of the. 50 ms window from CCA subfram 1 0 hut also does not match the offset that starts from CCA subframe 1003. Accordingly, LTE- US UE 1001 may adjust the offset for guaranteed transmission for regular operations, in order to begin guaranteed transmissions at non-CCA subframe 1005.
• the first message, Msg 1, includes the PRACH by UE;
• the second message, Msg 2 includes the RAR response by the base station;
• the fourth message, Msg 4 includes connection setup information from the base station, which may contain RRC connection setup and the like.
• RRC radio resource control
• FIG. 11A is a call flow diagram 1100 illustrating a call flow in an LTE/LTE- A communication system with unlicensed spectrum between an eNB 1101 and UE 1102 configured according to one aspect of the present disclosure.
• UE 1102 sends a combined random access request message that includes the random access request and initial PUSCH transmission.
• eNB 1101 having received the random access request with the initial PUSCH information, responds with a combined random access response message that includes the random access response to UE 1102 and additional connection setup information, such as the RRC connection setup message.
• the 2-step simplified RACH procedure provides a much more efficient process.
• Msg 3 which was included by UE 1102 in the combined random access request message
• Msg 4 which was included by eNB 1101 in the combined random access response message.
• the initial PUSCH waits for acknowledgment that comes with the Msg 4 connection setup information.
• UE 1102 may continue monitoring the response window for re-transmission and power ramp-ups of the RACH requests.
• alternative aspects of the present disclosure provide for a 3-step simplified RACH procedure. FIG.
• FIG. 1 IB is a call flow diagram 1105 illustrating a call flow in an LTE/LTE- A communication system with unlicensed spectrum between the eNB 1101 and UE 1 1 ? onfi cmre accordin g to one. asne t of the. nresent di sclosure. Similar to the. ?-ster> simplified procedure from FIG. 11A, at time 1103, UE 1102 sends a combined random access request message that includes the random access request and initial PUSCH transmission. At time 1106, eNB 1101, having received the random access request with the initial PUSCH information, sends a random access response message which simply acknowledges the random access request of the combined message at time 1103, such that re-transmissions and power ramp-ups can be stopped. At time 1107, eNB 1101 sends the additional connection setup information. Thus, the potential latency between Msg 3 and Msg 4 is addressed by splitting the messages from eNB 1101 in response to the combined random access request message.
• the 2-step simplified RACH procedure illustrated in FIG. 11A is sufficient, as the material of Msg 4, combined into the second message at 1104 may not be necessary, which would prevent the latency issue from arising.
• the latency between Msg 3 and Msg 4 would be large, it may be more efficient to opt for the 3-step simplified RACH procedure illustrated in FIG. 11B.
• the combined random access request message at 1103 is sent by UE 1102 containing at least the UE identifier (UE ID), such as, for example, the international mobile station equipment identity (IMEI) number. Additionally, UE 1102 may derive a PRACH group and a sequence within the group for transmission of the combined random access request. This derivation can be purely random or, alternatively, based on various information, such as the UE ID, which may be embedded in the random access request. Moreover, in additional aspects, the cyclic redundancy check (CRC) of the combined message should not be scrambled using UE ID, as eNB 1101 would not yet have access to the UE ID.
• UE ID UE identifier
• IMEI international mobile station equipment identity
• Additional aspects may also provide more specific information in the combined random access response message send by eNB 1101 at 1104.
• eNB 1101 may respond with the cell radio network temporary identifier (C-RNTI) assignment, etc.
• C-RNTI cell radio network temporary identifier
• the latency between step 1 and step 2 can be large (e.g., for initial access, and can be tens of milliseconds) or small (e.g., for handover).
• the second message (e.g., the combined random access response message) of the simplified 2-Step RACH process may be transmitted as a unicast or multicast transmission.
• Unicast transmissions may be less overhead-efficient compared with multi-cast. If transmitted as a unicast message, the UE IDs may be used to scramble the entire combined random access response message. In multicast, however, the message will contain information for more than one UE. UE IDs may, therefore, be part of the payload in the message. To improve security of the UE- specific information in the multi-cast, the portion of the message containing the UE- specific information may be scrambled with the UE ID corresponding to the UE to which the information is directed.
• the combined random access response message may be organized into two portions: a common information portion that includes information that may be shared by multiple UEs, and the UE-specific portion, which includes sets of UE-specific information arranged by the UE to which the information relates.
• FIG. 12 is a block diagram illustrating a combined random access response message 1200 from a base station configured according to one aspect of the present disclosure.
• Combined random access response message 1200 includes common information portion 1201, which contains various information that may be common to two or more UEs which are associated with a RACH procedure at the base station, and UE-specific information portion 1202, which contains various UE-specific information. For example, as illustrated in FIG.
• UE-specific information portion 1202 includes specific information for UE_1 1202-1, UE_2 1202-2, through UE_K 1202-K. As noted above, each of the individual UE-specific information subsections 1202-1 - 1202-K, may be scrambled with the associated UE ID. Thus, another UE may not be capable of viewing relevant UE-specific information about another UE.
• the UE will both transmit the combined request message and look for the response message from the eNB in both guaranteed and non-guaranteed subframes.
• FIGs. 13A and 13B are functional block Hia prams that illustrate, examnle blocks executed to imnlp.me.nt one aspect of the present disclosure.
• a base station generates an expedited random access allocation.
• the expedited random access allocation instructs the UE to begin the RACH process without first performing a CCA check on the subframe.
• the base station transmits the expedited random access allocation to the UE either in a CCA subframe (cleared non-guaranteed) or a non-CCA subframe (guaranteed).
• a UE receive the expedited random access allocation from the base station.
• the UE transmits a random access request in a next available subframe without determining whether the next available subframe is a random access designated subframe.
• the UE responds the demand by starting PRACH in a close-by, and what could be a non-regular PRACH subframe.
• Typical random access response grants in LTE contain the following information fields: a 1-bit hopping flag, a 10-bit fixed size resource block assignment, a 4-bit truncated modulation and coding scheme (MCS), a 3-bit transmit power control (TPC) command for scheduled PUSCH, a 1-bit uplink delay, a 1-bit CSI request, and additional information, such as the RRC connection setup information.
• the random access request grant may continue to include most of this information with only slight modifications from LTE implementations. For example, the hopping flag may not be necessary, depending on the uplink multiplexing structure.
• the fixed size resource block assignment may be simplified and/or re-interpreted, for example, to indicate the amount of decimation (e.g., number of combs) and frequency offset in the frequency domain, and/or number of symbols.
• the LTE/LTE-A RAR with unlicensed spectrum grant may still have the truncated MCS, though the number of bits may be reduced from the standard 4-bit field.
• the TPC command for scheduled PUSCH is still included.
• the other RAR grant information such as the uplink delay, CSI request, and the additional grant information may also be included in the LTE/LTE-A RAR with unlicensed spectrum grant information.
• a UE configured for transmission over at least unlicensed spectrum generates uplink signals and determines non-CCA subframes over which to transmit at least some of those generated uplink signals to a serving base station.
• the serving base which is also configured for communication over at least unlicensed spectrum, identifies non-CCA subframes over which it may receive uplink signals and receives any such uplink signals in the non-CCA subframes over the unlicensed band.
• FIG. 14A is a functional block diagram illustrating example blocks executed to implement one aspect of the present disclosure.
• a UE generates one or more uplink signals for transmission to a serving base station.
• the UE of the illustrated aspect is configured to transmit communication signals to a serving base station over at least unlicensed spectrum and to receive communication signals from the serving base station.
• the UE determines a non-CCA subframe for transmission of at least one of the generated uplink signals.
• the UE transmits the uplink signals in the non-CCA subframe over an unlicensed band.
• FIG. 14B is a functional block diagram illustrating example blocks executed to implement one aspect of the present disclosure.
• the serving base station identifies a non-CCA subframe for reception of at least one uplink signal.
• the serving base station of the aspect illustrated in FIG. 14B may serve the UE performing the blocks illustrated in FIG. 14A.
• the serving base station would be configured for communication over at least unlicensed spectrum.
• the serving base station receives one or more uplink signals from a UE in the non-CCA subframe over an unlicensed band.
• FIGs. 8A-8B, 13A-13B, and 14A-14B may comprise processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.
• DSP digital signal processor
• ASIC application specific integrated circuit
• FPGA field programmable gate array
• a general- purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine.
• a processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
• a software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
• An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium.
• the storage medium may be integral to the processor.
• the processor and the storage medium may reside in an ASIC.
• the ASIC may reside in a user terminal.
• the processor and the storage medium may reside as discrete components in a user terminal.
• the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium.
• Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Computer-readable storage media may be any available media that can be accessed by a general purpose or special purpose computer.
• such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.
• a connection may be properly termed a computer-readable medium.
• the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL), then the coaxial cable, fiber optic cable, twisted pair, or DSL, are included in the definition of medium.
• DSL digital subscriber line
• Disk and disc includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
• the term "and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed.
• the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

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