Commanded physical random access channel resource management

Abstract

Generally speaking, certain aspects of the present disclosure relate to wireless communications, and more particularly, to transmission resource management for a scheduled physical random access channel (PRACH) signal. An example method performed by a base station generally includes: providing an indication of a set of transmission resources within a narrowband region of a wider system bandwidth for a first user equipment (UE) to transmit a scheduled physical random access channel (PRACH) signal; and sending a command to the first UE to transmit the scheduled PRACH.

Description

[0001] This application is a divisional application of a Chinese patent application filed on May 10, 2017, with application number 201780028935.2 (PCT / US2017 / 031897), and invention name “Commanded Physical Random Access Channel Resource Management”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Application No. 15 / 591,082, filed on May 9, 2017, which claims the benefit of U.S. Provisional Application No. 62 / 336,548, filed on May 13, 2016, which is assigned to the assignee of the present application and is expressly incorporated herein by reference in its entirety. Technical Field

[0004]

[0006] Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to transmission resource management for commanded Physical Random Access Channel (PRACH) signals. Background Art

[0005] Wireless communication systems are widely deployed to provide various types of communication content, such as voice and data. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE), including Advanced LTE systems and Orthogonal Frequency Division Multiple Access (OFDMA) systems.

[0006] Typically, a wireless multiple access communication system is capable of supporting communications for multiple wireless terminals simultaneously. Each terminal communicates with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the base station to the terminal, and the reverse link (or uplink) refers to the communication link from the terminal to the base station. The communication link can be established via a single-input single-output, multiple-input single-output, or multiple-input multiple-output (MIMO) system.

[0007] A wireless communication network may include multiple base stations capable of supporting communications for multiple wireless devices. The wireless devices may include user equipment (UE). Some UEs may be considered machine type communication (MTC) UEs, which may include remote devices that can communicate with a base station, another remote device, or some other entity. Machine type communication (MTC) may refer to communications involving at least one remote device on at least one end of the communication, and may include forms of data communications involving one or more entities that do not necessarily require human interaction. MTC UEs may include UEs capable of MTC communications with an MTC server and / or other MTC devices via, for example, a public land mobile network (PLMN). Summary of the Invention

[0008] The systems, methods, and devices of the present disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the disclosure as expressed by the claims that follow, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description," one will understand how the features of the present disclosure provide advantages, including improved communication between access points and stations in a wireless network.

[0009] Certain aspects of the present disclosure provide a method for wireless communications by a base station (BS), the method generally comprising: providing an indication of a scheduled physical random access channel (PRACH) region including a set of transmission resources within a narrowband region of a wider system bandwidth for sending a scheduled PRACH signal by a first user equipment (UE); and sending a first command to the first UE to send the scheduled PRACH.

[0010] Certain aspects of the present disclosure provide a method for wireless communications by a user equipment (UE), the method generally including: receiving a command from a base station (BS) to send a scheduled physical random access channel (PRACH) to the BS; obtaining an indication of a scheduled PRACH region including a set of transmission resources within a narrowband region of a wider system bandwidth for sending the scheduled PRACH signal to the BS; and sending the PRACH signal to the BS using the indicated transmission resources.

[0011] Certain aspects of the present disclosure provide an apparatus for wireless communications, the apparatus generally comprising: a processing system configured to provide an indication of a scheduled physical random access channel (PRACH) region comprising a set of transmission resources within a narrowband region of a wider system bandwidth for transmission of a scheduled PRACH signal by a first user equipment (UE); and to send a first command to the first UE to send the scheduled PRACH signal; and a memory coupled to the processor.

[0012] Certain aspects of the present disclosure provide an apparatus for wireless communications, the apparatus generally including: a processing system configured to: receive a command from a base station (BS) to transmit a scheduled physical random access channel (PRACH) to the BS; obtain an indication of a scheduled PRACH region including a set of transmission resources within a narrowband region of a wider system bandwidth for transmitting the scheduled PRACH signal to the BS; and transmit the PRACH signal to the BS using the indicated transmission resources; and a memory coupled to the processor.

[0013] Certain aspects of the present disclosure provide an apparatus for wireless communications, the apparatus generally comprising: means for providing an indication of a scheduled physical random access channel (PRACH) region comprising a set of transmission resources within a narrowband region of a wider system bandwidth for transmitting a scheduled PRACH signal by a first user equipment (UE); and means for sending a first command to the first UE to transmit the scheduled PRACH.

[0014] Certain aspects of the present disclosure provide an apparatus for wireless communications, the apparatus generally comprising: means for receiving a command from a base station (BS) to send a scheduled physical random access channel (PRACH) to the BS; means for obtaining an indication of a scheduled PRACH region including a set of transmission resources within a narrowband region of a wider system bandwidth, for sending a scheduled PRACH signal to the BS; and means for sending the PRACH signal to the BS using the indicated transmission resources.

[0015] Certain aspects of the present disclosure provide a computer-readable medium for wireless communications, the computer-readable medium including instructions that, when executed by a processing system, cause the processing system to perform operations. The operations generally include providing an indication of a scheduled physical random access channel (PRACH) region including a set of transmission resources within a narrowband region of a wider system bandwidth for a first user equipment (UE) to transmit a scheduled PRACH signal; and sending a first command to the first UE to transmit the scheduled PRACH.

[0016] Certain aspects of the present disclosure provide a computer-readable medium for wireless communications, the computer-readable medium including instructions that, when executed by a processing system, cause the processing system to perform operations. The operations generally include: receiving a command from a base station (BS) to transmit a scheduled physical random access channel (PRACH) to the BS; obtaining an indication of a scheduled PRACH region including a set of transmission resources within a narrowband region of a wider system bandwidth for transmitting the scheduled PRACH signal to the BS; and transmitting the PRACH signal to the BS using the indicated transmission resources.

[0017] Numerous other aspects are provided, including methods, apparatus, systems, computer program products, and processing systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be obtained by reference to the aspects, some aspects of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only certain typical aspects of the present disclosure and are therefore not to be considered limiting of its scope, as the description may admit to other equally effective aspects.

[0019] Figure 1 is a block diagram conceptually illustrating an example wireless communication network in accordance with certain aspects of the present disclosure.

[0020] Figure 2 is a block diagram conceptually illustrating an example of an evolved Node B (eNB) in communication with a user equipment (UE) in a wireless communication network, in accordance with certain aspects of the present disclosure.

[0021] Figure 3 is a block diagram conceptually illustrating an example frame structure for a particular radio access technology (RAT) for use in a wireless communication network, in accordance with certain aspects of the present disclosure.

[0022] Figure 4 Example subframe formats for a downlink with a normal cyclic prefix are shown in accordance with certain aspects of the present disclosure.

[0023] Figure 5A and 5B An example of MTC coexistence within a broadband system, such as LTE, is shown, in accordance with certain aspects of the present disclosure.

[0024] Figure 6 An exemplary mapping of DL narrowband regions to UL narrowband regions is shown, in accordance with certain aspects of the present disclosure.

[0025] Figure 7An example physical random access channel (PRACH) signal is schematically illustrated in accordance with certain aspects of the present disclosure.

[0026] Figure 8 Schematic illustration of a set of resources reserved for a PRACH signal, in accordance with certain aspects of the present disclosure.

[0027] Figure 9 Schematic illustration of a set of resources reserved for a PRACH signal, in accordance with certain aspects of the present disclosure.

[0028] Figure 10 Schematic illustration of a set of resources reserved for a PRACH signal, in accordance with certain aspects of the present disclosure.

[0029] Figure 11 Schematic illustration of a set of resources reserved for a PRACH signal, in accordance with certain aspects of the present disclosure.

[0030] Figure 12 Schematically illustrating a set of resources reserved for data transmission and scheduled PRACH signals, in accordance with certain aspects of the present disclosure.

[0031] Figure 13 Example operations are illustrated that may be performed by a BS for wireless communications in accordance with certain aspects of the present disclosure.

[0032] Figure 13A Shows that it can be performed in Figure 13 An example unit of operation is shown in FIG.

[0033] Figure 14 Example operations are illustrated that may be performed by a UE for wireless communications in accordance with certain aspects of the present disclosure.

[0034] Figure 14A Shows that it can be performed in Figure 14 An example unit of operation is shown in FIG. DETAILED DESCRIPTION

[0035] Aspects of the present disclosure provide techniques and apparatus for scheduling physical random access channel (PRACH) signals for devices with limited communication resources, such as low-cost (LC) machine type communication (MTC) devices and LC-enhanced MTC (eMTC) devices. MTC and eMTC devices can receive MTC physical downlink control channel (MPDCCH) transmissions carrying paging messages and RAR messages. MTC and eMTC devices can attempt to decode MPDCCH candidates in a search space of time and frequency transmission resources. The MPDCCH can be transmitted in a common search space (CSS). A base station can transmit the MPDCCH conveying paging and RAR messages in a CSS selected at least in part based on the receiving UE's coverage enhancement (CE) level and / or the subband used by the UE when transmitting the physical random access channel (PRACH). To improve coverage for certain devices, such as MTC and eMTC devices, "bundling" can be used, where certain transmissions can be sent as a bundle of transmissions, e.g., including the same information transmitted over multiple subframes.

[0036] Therefore, as will be described in more detail below, the techniques presented herein can allow cells to send and MTC devices to receive bundled paging and RAR messages to achieve up to 15 dB CE. Additionally, in situations where a cell needs to send both paging and RAR messages in one subframe, the techniques presented herein can allow cells to send and MTC devices to receive both paging and RAR messages, sometimes referred to as collisions between paging and RAR messages.

[0037] The technology described herein can be used for various wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single carrier FDMA (SC-FDMA) networks, etc. The terms "network" and "system" are generally used interchangeably. A CDMA network can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes wideband CDMA (W-CDMA), time division synchronous CDMA (TD-SCDMA), and other variants of CDMA. cdma2000 includes IS-2000, IS-95, and IS-856 standards. A TDMA network can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks can implement radio technologies such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash OFDM, and the like. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A), in both Frequency Division Duplex (FDD) and Time Division Duplex (TDD), are versions of UMTS that use OFDMA on the downlink and SC-FDMA on the uplink. 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). An example of an emerging telecommunication standard is New Radio (NR), for example, 5G radio access. NR is a set of enhancements to the LTE mobile standard published by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and using OFDMA with a cyclic prefix (CP) on the downlink (DL) and uplink (UL) to better integrate with other open standards, as well as supporting beamforming, MIMO antenna technology, and carrier aggregation. Some next-generation, NR, or 5G networks may include multiple base stations, each of which simultaneously supports communications with multiple communication devices (e.g., UEs). In an LTE or LTE-A network, a collection of one or more base stations may define an eNode B (eNB).In other examples (e.g., in next-generation or 5G networks), a wireless multiple-access communication system may include multiple distributed units (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with multiple central units (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a collection of one or more distributed units in communication with the central unit may define an access node (e.g., a new radio base station (NR BS), a new radio node B (NR NB), a network node, a gNB, etc.). A base station or DU may communicate with a collection of UEs on downlink channels (e.g., for transmissions from the base station or to the UE) and uplink channels (e.g., for transmissions from the UE to the base station or distributed unit). The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, certain aspects of these techniques are described below for LTE / LTE-A, and LTE / LTE-A terminology is used in much of the description below. LTE and LTE-A are generally referred to as LTE.

[0038] Figure 1 An exemplary wireless communication network 100 is shown having a base station (BS) and user equipment (UE) in which aspects of the present disclosure may be practiced.

[0039] For example, one or more paging procedure enhancements may be supported for certain UEs (e.g., LC MTC UEs, LC eMTC UEs, etc.) in the wireless communication network 100. According to the techniques presented herein, a BS and a LC UE in the wireless communication network 100 may be able to determine which narrowband area the LC UE should monitor for bundled paging messages sent from a BS in the wireless communication network 100 based on the available system bandwidth supported by the wireless communication network 100. Furthermore, according to the techniques presented herein, a BS and / or a LC UE in the wireless communication network 100 may be able to determine and / or adjust a bundling size for paging messages based on one or more triggers in the wireless communication network 100.

[0040] The wireless communication network 100 may be an LTE network or some other wireless network. The wireless communication network 100 may include multiple evolved Node Bs (eNBs) 110 and other network entities. An eNB is an entity that communicates with user equipment (UE) and may also be referred to as a base station, Node B, access point (AP), etc. Each eNB may provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to the coverage area of an eNB and / or the eNB subsystem serving that coverage area, depending on the context in which the term is used.

[0041] An eNB may provide communication coverage for macro cells, pico cells, femto cells, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access by UEs with a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG)). 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 (HeNB). In Figure 1 In the example shown in FIG, eNB 110a may be a macro eNB for macro cell 102a, eNB 110b may be a pico eNB for pico cell 102b, and eNB 110c may be a femto eNB for femto cell 102c. An eNB may support one or more (e.g., three) cells. The terms "eNB," "base station," and "cell" may be used interchangeably herein.

[0042] The wireless communication network 100 may also include a relay station. A relay station is an entity that can receive transmissions of data from an upstream station (e.g., an eNB or UE) and send transmissions of data to a downstream station (e.g., a UE or eNB). A relay station may also be a UE that can relay transmissions for other UEs. Figure 1 In the example shown in FIG, a relay (station) eNB 110d may communicate with macro eNB 110a and UE 120d to facilitate communications between eNB 110a and UE 120d. A relay station may also be referred to as a relay eNB, a relay base station, a relay, etc.

[0043] The wireless communication network 100 may be a heterogeneous network that includes different types of eNBs, such as macro eNBs, pico eNBs, femto eNBs, relay eNBs, etc. These different types of eNBs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless communication network 100. For example, a macro eNB may have a high transmit power level (e.g., 5 to 40 W), while a pico eNB, a femto eNB, and a relay eNB may have a lower transmit power level (e.g., 0.1 to 2 W).

[0044] The network controller 130 may be coupled to a set of eNBs and may provide coordination and control for these eNBs. The network controller 130 may communicate with the eNBs via a backhaul. The eNBs may also communicate with each other directly or indirectly, for example, via a wireless or wired backhaul.

[0045] UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless communication network 100, and each UE may be fixed or mobile. UEs may also be referred to as access terminals, terminals, mobile stations (MSs), subscriber units, stations (STAs), etc. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop, a cordless phone, a wireless local loop (WLL) station, a tablet, a smartphone, a netbook, a smartbook, an ultrabook, a navigation device, a gaming device, a camera, an in-vehicle device, a drone, a robot / robotic device, a wearable device (e.g., a smartwatch, smart clothing, a smart wristband, a smart ring, a smart wristband, smart glasses, virtual reality goggles), etc. MTC UEs include devices such as sensors, meters, monitors, location tags, drones, trackers, robots / robotic devices, etc. A UE may be implemented as an Internet of Everything (IoE) or Internet of Things (IoT) (e.g., Narrowband Internet of Things (NB-IoT)) device.

[0046] One or more UEs 120 in a wireless communication network 100 (e.g., an LTE network) may also be low-cost (LC), low data rate devices, such as, for example, LC MTC UEs, LC eMTC UEs, and the like. In an LTE network, LC UEs may coexist with legacy and / or improved UEs and may have one or more capabilities that are limited when compared to other UEs (e.g., non-LC UEs) in the wireless network. For example, when compared to legacy and / or improved UEs in an LTE network, the LC UE may operate using one or more of the following: a reduction in maximum bandwidth (relative to legacy UEs), a single receive radio frequency (RF) chain, a reduction in peak rate, a reduction in transmit power, rank 1 transmission, half-duplex operation, and the like. As used herein, devices with limited communication resources (such as MTC devices, eMTC devices, and the like) are generally referred to as LC UEs. Similarly, legacy devices such as legacy and / or improved UEs (e.g., in LTE) are generally referred to as non-LC UEs.

[0047] Figure 2 is a block diagram of a design of a BS / eNB 110 and a UE 120, where the BS / eNB 110 and the UE 120 may be Figure 11 and UE 120. BS 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T≧1 and R≧1.

[0048] At BS 110, a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based on a channel quality indicator (CQI) received from the UE, process (e.g., encode and modulate) the data for each UE based on the MCS selected for the UE, and provide data symbols for all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and control information (e.g., CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols. The processor 220 may also generate reference symbols for reference signals (e.g., common reference signals (CRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). A transmit (TX) multiple-input, multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on data symbols, control symbols, overhead symbols, and / or reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each MOD 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.

[0049] At UE 120, antennas 252a through 252r can receive downlink signals from BS 110 and / or other base stations and can provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each DEMOD 254 can condition (e.g., filter, amplify, downconvert, and digitize) its received signal to obtain input samples. Each DEMOD 254 can also process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 can obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols, and, if applicable, provide detected symbols. A receive processor 258 can process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller / processor 280. The channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), CQI, and the like.

[0050] On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information from a controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.). Processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 (if applicable), further processed by MODs 254a through 254r (e.g., for SC-FDM, OFDM, etc.), and transmitted to BS 110. At BS 110, uplink signals from UE 120 and other UEs may be received by antenna 234, processed by DEMOD 232, detected by MIMO detector 236 (if applicable), and further processed by receive processor 238 to obtain decoded data and control information sent by UE 120. Processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller / processor 240. BS 110 may include a communication unit 244 and communicate with network controller 130 via communication unit 244. Network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0051] The controller / processors 240 and 280 may direct the operations at the BS 110 and the UE 120, respectively. For example, the controller / processor 240 and / or other processors and modules at the BS 110 may perform or direct the operations in Figure 13Similarly, the controller / processor 280 and / or other processors and modules at the UE 120 may perform or direct the operations shown in Figure 14 The operations shown in FIG and / or processes for the techniques described herein. Memories 242 and 282 may store data and program codes for BS 110 and UE 120, respectively. Scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0052] Figure 3 An exemplary frame structure 300 for FDD in LTE is shown. The transmission timeline for each of the downlink and uplink may be divided into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms)) and may be divided into 10 subframes with indices from 0 to 9. Each subframe may include two slots. Thus, each radio frame may include 20 slots with indices from 0 to 19. Each slot may include L symbol periods, e.g., seven symbol periods for a normal cyclic prefix (e.g., 1 symbol period for a cyclic prefix). Figure 2 ) or six symbol periods for an extended cyclic prefix. The 2L symbol periods in each subframe may be assigned indices from 0 to 2L-1.

[0053] In LTE, the eNB may send a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) on the downlink in the center 1.08 MHz of the system bandwidth for each cell supported by the eNB. Figure 3In subframes 0 and 5 of each radio frame shown with a normal cyclic prefix (CP), the PSS and SSS are transmitted in symbol periods 6 and 5, respectively. The PSS and SSS can be used by UEs for cell search and acquisition. The eNB may transmit a cell-specific reference signal (CRS) across the system bandwidth for each cell supported by the eNB. The CRS may be transmitted in specific symbol periods of each subframe and may be used by the UE to perform channel estimation, channel quality measurement, and / or other functions. The BS may also transmit a physical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 of a specific radio frame. The PBCH may carry some system information. The eNB may transmit other system information, such as system information blocks (SIBs), on the physical downlink shared channel (PDSCH) in specific subframes. The BS may transmit control information / data on the physical downlink control channel (PDCCH) in the first B symbol periods of a subframe, where B may be configurable for each subframe. The eNB may transmit traffic data and / or other data on the PDSCH in the remaining symbol periods of each subframe. The eNB may send control information / data on the enhanced physical downlink control channel (EPDCCH) in any symbol period of the subframe.

[0054] The PSS, SSS, CRS, and PBCH in LTE are described in 3GPP TS 36.211, titled "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation," which is publicly available.

[0055] Figure 4 Two example subframe formats 410 and 420 with a normal cyclic prefix for the downlink are shown. The available time-frequency resources for the downlink can be divided into resource blocks. Each resource block can include 12 subcarriers in a time slot and can include multiple resource elements. Each resource element can include one subcarrier in a symbol period and can be used to transmit one modulation symbol, which can be a real or complex value.

[0056] Subframe format 410 may be used for an eNB equipped with two antennas. CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7, and 11. A reference signal is a signal known as a priori for the transmitter and receiver and may also be referred to as a pilot signal. CRS is a cell-specific reference signal, generated, for example, based on a cell identity (ID). Figure 4, for a given resource element with label Ra, a modulation symbol may be transmitted on that resource element from antenna a, and no modulation symbol may be transmitted on that resource element from other antennas. Subframe format 420 may be used for an eNB equipped with four antennas. CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7, and 11, and from antennas 2 and 3 in symbol periods 1 and 8. For both subframe formats 410 and 420, CRS may be transmitted on equally spaced subcarriers, which may be determined based on the cell ID. Different eNBs may transmit their CRS on the same or different subcarriers, depending on their cell IDs. For both subframe formats 410 and 420, resource elements not used for CRS may be used to transmit data (e.g., traffic data, control data, and / or other data).

[0057] In LTE, an interlace structure can be used for each link in the FDD downlink and uplink. For example, Q interlaces with indices from 0 to Q-1 can be defined, where Q can be equal to 4, 6, 8, 10, or some other value. Each interlace can include subframes spaced at a fixed distance from Q frames. In particular, interlace q can include subframes q, q+Q, q+2Q, etc., where q∈{0,...,Q-1}.

[0058] Wireless networks may support hybrid automatic repeat request (HARQ) for data transmission on the downlink and uplink. With HARQ, a transmitter (e.g., eNB 110) may not send one or more transmissions of a packet until the packet is correctly decoded by a receiver (e.g., UE 120) or some other termination condition is encountered. With synchronous HARQ, all transmissions of a packet may be sent in a subframe of a single interlace. With asynchronous HARQ, each transmission of a packet may be sent in any subframe.

[0059] A UE may be located within the coverage area of multiple eNBs. One of these eNBs may be selected to serve the UE. The serving BS may be selected based on various criteria such as received signal strength, received signal quality, path loss, etc. Received signal quality may be quantified by signal to interference plus noise ratio (SINR), reference signal received quality (RSRQ), or some other metric. The UE may operate in a significant interference scenario, in which the UE may observe strong interference from one or more interfering eNBs.

[0060] As mentioned above, one or more UEs in a wireless communication network (eg, wireless communication network 100 ) may be devices with limited communication resources, eg, LC UEs, compared to other (non-LC) devices in the wireless communication network.

[0061] In some systems, for example, in LTE Rel-13, LC UEs may be restricted to specific narrowband allocations within the available system bandwidth (e.g., no more than six resource blocks (RBs)). However, the LC UE may be able to re-tune (e.g., operate and / or camp on) to a different narrowband region within the available system bandwidth of the LTE system, for example, to coexist within the LTE system.

[0062] As another example of coexistence within an LTE system, an LC UE may be able to (repeatedly) receive a legacy physical broadcast channel (PBCH) (e.g., an LTE physical channel that typically carries parameters that can be used for initial access to a cell) and support one or more legacy physical random access channel (PRACH) formats. For example, an LC UE may be able to receive a legacy PBCH with one or more additional repetitions of the PBCH across multiple subframes. As another example, an LC UE may be able to send one or more repetitions of the PRACH (e.g., utilizing one or more supported PRACH formats) to an eNB in an LTE system. The PRACH may be used to identify the LC UE. Furthermore, the number of repeated PRACH attempts may be configured by the eNB.

[0063] The LC UE may also be a link budget constrained device and may operate in different operating modes based on its link budget constraints (e.g., a different amount of repeated messages may be required to be sent to or from the LC UE). For example, in some cases, the LC UE may operate in a normal coverage mode in which there are almost no repetitions (e.g., the amount of repetitions required for the UE to successfully receive and / or send messages may be low or may not even require repetitions). Alternatively, in some cases, the LC UE may operate in a coverage enhancement (CE) mode in which there may be a large number of repetitions. For example, for a 328-bit payload, the LC UE in CE mode may require 150 or more repetitions of the payload in order to successfully receive the payload.

[0064] In some cases, for example, also for LTE Rel-13, the LC UE may have limited capabilities with respect to its reception of broadcast and unicast transmissions. For example, the maximum transport block (TB) size for broadcast transmissions received by the LC UE may be limited to 1000 bits. Additionally, in some cases, the LC UE may not be able to receive more than one unicast TB in a subframe. In some cases (e.g., for the CE mode and normal mode described above), the LC UE may not be able to receive more than one broadcast TB in a subframe. Additionally, in some cases, the LC UE may not be able to receive both unicast TBs and broadcast TBs in a subframe.

[0065] For MTC, LC UEs coexisting in an LTE system may also support new messages for certain procedures such as paging, random access procedures, etc. (e.g., as opposed to the traditional messages used in LTE for these procedures). In other words, these new messages for paging, random access procedures, etc. may be separate from messages used for similar procedures associated with non-LC UEs. For example, compared to traditional paging messages used in LTE, an LC UE may be able to monitor and / or receive paging messages that a non-LC UE may not be able to monitor and / or receive. Similarly, compared to traditional random access response (RAR) messages used in traditional random access procedures, an LC UE may be able to receive RAR messages that may or may not be received by a non-LC UE. The new paging and RAR messages associated with the LC UE may also be repeated one or more times (e.g., "bundled"). In addition, different numbers of repetitions (e.g., different bundle sizes) for the new messages may be supported.

[0066] Example MTC coexistence within broadband systems

[0067] As mentioned above, MTC and / or eMTC operations may be supported in wireless communication networks (e.g., co-existing with LTE or some other RAT). Figure 5A and 5B An example is shown of how LC UEs in MTC operation can coexist within a broadband system such as LTE.

[0068] As in Figure 5A As shown in the example frame structure in , subframes 510 associated with MTC and / or eMTC operations may be time division multiplexed (TDM) with regular subframes 520 associated with LTE (or some other RAT).

[0069] Additionally or alternatively, as in Figure 5BAs shown in the example frame structure in , one or more narrowband areas 560, 562 used by LC UEs in MTC can be frequency division multiplexed within the wider bandwidth 550 supported by LTE. Multiple narrowband areas can be supported for MTC and / or eMTC operations, where each narrowband area spans a bandwidth of no more than a total of 6 RBs. In some cases, each LC UE in MTC operation can operate within one narrowband area (e.g., 1.4 MHz or 6 RBs) at a time. However, at any given time, the LC UE in MTC operation can be re-tuned to other narrowband areas in the wider system bandwidth. In some examples, multiple LC UEs can be served by the same narrowband area. In other examples, multiple LC UEs can be served by different narrowband areas (e.g., each narrowband area spans 6 RBs). In other examples, different combinations of LC UEs can be served by one or more of the same narrowband areas and / or one or more different narrowband areas.

[0070] LC UE can operate (e.g., monitor / receive / transmit) in a narrowband region for various operations. Figure 5B As shown in FIG, a first narrowband region 560 (e.g., wideband data spanning no more than 6 RBs) of a subframe 552 may be monitored by one or more LC UEs for PSS, SSS, PBCH, MTC signaling, or paging transmissions from a BS in a wireless communication network. Regions 556 and 558 may be used by the BS to transmit data to other UEs (e.g., non-LC UEs). Also as in FIG. Figure 5B As shown in FIG, the BS may use the second narrowband region 562 of subframe 554 (e.g., also wideband data spanning no more than 6 RBs) to transmit RACH messages or data previously configured by the BS in signaling to the LC UE and / or one or more of the other LC UEs. After monitoring the first narrowband region, the LC UE may have been retuned to the second narrowband region for reception. Region 559 may be used by the BS to transmit data to other UEs (e.g., non-LC UEs).

[0071] Although the examples described herein assume a narrowband of 6 RBs, those skilled in the art will recognize that the techniques presented herein can also be applied to narrowband regions of different sizes.

[0072] Example narrowband management for MTC

[0073] As mentioned above, in some systems, such as LTE Rel-12, narrowband operation for MTC (e.g., eMTC) may be supported. Cells supporting narrowband operation for MTC may have different system bandwidths for downlink (DL) and uplink (UL) operations. Cells with different DL and UL system bandwidths (SB) may organize the DL system bandwidth into narrowband regions in a manner different from the manner used to organize the UL system bandwidth into narrowband regions. Therefore, aspects of the present disclosure provide techniques for organizing the DL system bandwidth and the UL system bandwidth into narrowband regions.

[0074] Cells supporting narrowband operation for MTC and legacy UEs can receive legacy PUCCH transmissions from legacy UEs. Legacy PUCCH transmissions can be sent at either or both edges of the cell's UL system bandwidth. Therefore, aspects of the present disclosure provide techniques for reserving transmission resources included in the UL narrowband region for use by legacy PUCCH transmissions. Similar reservations can also be applied to DL narrowband regions used by other legacy DL signals or channels.

[0075] Cells supporting narrowband operation for MTC may also support the transmission of a sounding reference signal (SRS). The currently defined minimum bandwidth for SRS transmission is four RBs. However, as mentioned above, the bandwidth of the narrowband region is six RBs. In narrowband operation based on six RBs, the fact that six RBs cannot be divided evenly by four RBs presents a challenge in managing SRS transmission using four RBs. Therefore, aspects of the present disclosure provide techniques for allocating transmission resources for SRS transmission in cells supporting narrowband operation (e.g., for MTC).

[0076] A cell operating with FDD may have a DL system bandwidth that is different from the UL system bandwidth of the cell. For example, a cell may perform DL operations in a system bandwidth of 10 MHz and UL operations in a system bandwidth of 5 MHz. To support MTC operations and MTC UEs, a cell may organize the DL system bandwidth and the UL system bandwidth into narrowband regions or narrowband areas. The eNB or other BS controlling the cell may allocate the DL narrowband area to the MTC UE for the MTC UE to monitor the signal from the eNB. Similarly, the eNB (or other BS) may allocate the UL narrowband area to the MTC UE for use by the MTC when transmitting UL signals. In this example, the cell may organize the DL system bandwidth into eight DL narrowband areas and simultaneously organize the UL system bandwidth into four UL narrowband areas.

[0077] When a BS (e.g., an eNB or a cell) supports MTC UEs with a cell's DL system bandwidth and UL system bandwidth organized into narrowband regions, the BS can establish a mapping between the DL narrowband regions and the UL narrowband regions so that allocating a DL narrowband region to an MTC UE also means allocating the UL narrowband region to the MTC UE. Having this mapping allows the BS to simplify scheduling of resources in the cell. For example, the BS can expect to send ACK / NAK for transmissions in the DL narrowband region to the MTC UE in the corresponding UL narrowband region. Similarly, the MTC UE monitors DL transmissions in the DL narrowband region allocated to the MTC UE and responds with transmissions in the corresponding UL narrowband region.

[0078] According to aspects of the present disclosure, a technology for mapping UL and DL narrowband areas by a BS is provided. The BS can determine the minimum size of the UL system bandwidth and the DL system bandwidth supported by the BS, determine the number of narrowband areas that can be organized in the determined size, and then organize both the DL system bandwidth and the UL system bandwidth in the number of narrowband areas. The BS can then map each DL narrowband area to one UL narrowband area. For example, a cell can perform DL operations in a 10 MHz system bandwidth and perform UL operations in a 5 MHz system bandwidth. In this example, the BS can determine that the minimum size of the UL system bandwidth and the DL system bandwidth is 5 MHz, and then determine that the BS can organize four narrowband areas in the 5 MHz system bandwidth. Still in this example, the BS can then organize four DL narrowband areas in the DL system bandwidth and four UL narrowband areas in the UL system bandwidth, and map each DL narrowband area to one UL narrowband area.

[0079] Figure 6 An exemplary mapping 600 of DL narrowband regions to UL narrowband regions as described above is shown. Such a mapping may be performed by Figure 1 Although the eNB 110a in Figure 6The DL system bandwidth 610 and UL system bandwidth 650 are shown as being within the same frequency range, but are in different frequency ranges in a cell using FDD. The DL system bandwidth 610 is 10 MHz, or 510 RBs wide, and the UL system bandwidth 650 is 5 MHz, or 2105 RBs wide. A base station supporting MTC UEs while operating both the DL system bandwidth 610 and the UL system bandwidth 650 may determine that the UL system bandwidth 650 is smaller than the DL system bandwidth 610 (the 5 MHz size of the UL system bandwidth 650 is the minimum size of the UL system bandwidth 650 and the DL system bandwidth 610). The base station may then determine that it can organize four narrowband regions 652, 654, 656, and 658 based on the UL system bandwidth 650. The base station may then determine that the four narrowband regions are organized based on the DL system bandwidth, and organize the DL narrowband regions 612, 614, 616, and 618 based on the DL system bandwidth. The BS may then map the DL narrowband zone 612 to the UL narrowband zone 652 , the DL narrowband zone 614 to the UL narrowband zone 654 , the DL narrowband zone 616 to the UL narrowband zone 656 , and the DL narrowband zone 618 to the UL narrowband zone 658 .

[0080] Example commands for physical random access channel resource management

[0081] As mentioned above, LC MTC UEs were introduced in LTE Rel-12. Additional enhancements may be made in LTE Release 13 (Rel-13) to support MTC operations. For example, an MTC UE may be able to operate (e.g., monitor, transmit, and receive) in a narrowband region of 1.4 MHz or 6 RBs within a wider system bandwidth (e.g., 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz). As a second example, a base station and an MTC UE may support up to 20 dB of coverage enhancement (CE) through some techniques (e.g., bundling). Coverage enhancement may also be referred to as coverage extension and range extension.

[0082] When a UE needs to connect to a cell to which the UE is not currently connected, the UE and the cell engage in a message exchange called a random access channel (RACH) procedure. In an example RACH procedure, the UE sends a physical random access channel (PRACH) signal (sometimes referred to as message 1 (Msg1) of the RACH procedure) in a set of transmission resources reserved for PRACH signals (sometimes referred to as a PRACH area), and the cell then responds to the PRACH signal with a random access response (RAR) message (sometimes referred to as message 2 (Msg2) of the RACH procedure) carried on a downlink shared channel (DL-SCH). The UE responds to the RAR message with an RRC connection request message (sometimes referred to as message 3 (Msg3) of the RACH procedure), and the cell responds to Msg3 with a contention resolution message (sometimes referred to as message 4 (Msg4) of the RACH procedure. The UE then connects to the cell.

[0083] In current (eg, LTE Rel-12) wireless technologies, a PRACH signal transmitted by an MTC device includes a first group of 4 symbols using a first hopping pattern and a second group of 4 symbols using the first hopping pattern but offset from the first group by a random group hopping value.

[0084] Figure 7 An exemplary PRACH signal 700 according to aspects of the present disclosure is schematically illustrated. Four symbols 702a-702d in a first group 704a are transmitted (e.g., by a UE), then random group hopping is applied, and a second group 704b of symbols 702e-702h having the same hopping pattern as in the first group is transmitted (e.g., by a UE). Curve 706 illustrates the correspondence between symbol 702a in group 704a and symbol 702e in group 704b. Similarly, symbol 702b corresponds to symbol 702f, symbol 702c corresponds to symbol 702g, and symbol 702d corresponds to symbol 702h.

[0085] PRACH signal (e.g., Figure 7 The tone spacing of the PRACH signal 700 shown in FIG may be 3.75 kHz. The symbols in the PRACH signal may use a cyclic prefix (CP) of 66.7 microseconds (μs) or 266.7 μs, both of which are different from the CP length used for data transmission in LTE systems.

[0086] When a UE starts a random access procedure, it randomly selects a resource (e.g., a tone) from the resources reserved for PRACH signal transmission in the cell and uses the resource to send the PRACH signal. The UE can determine which resources in the cell are reserved for PRACH signals by receiving and decoding one or more system information blocks (SIBs) sent by the cell.

[0087] Figure 8 8 is a schematic illustration of a set of resources 800 (e.g., a PRACH region) reserved (e.g., by a BS, by a cell) for PRACH signals according to aspects of the present disclosure. Frequency region 802 is a set of tones to be used by a UE that intends Msg3 of a RACH procedure to be a single-tone message. For example, an MTC UE may select resources from frequency region 802 when transmitting Msg1 of a RACH procedure so that the MTC UE may transmit a single-tone Msg3 after receiving Msg2 from the cell. Frequency region 804 is a set of tones to be used by a UE that intends Msg3 of a RACH procedure to be a multi-tone message. A cell may select resources reserved for PRACH signals from a wider system bandwidth, and the cell may send an indication of the resources reserved for PRACH signals in one or more SIBs.

[0088] A UE may sometimes be in connected mode with a serving cell but lose synchronization (e.g., uplink synchronization) with the UE's serving cell. When the UE loses synchronization with the serving cell, the serving BS (e.g., serving eNB) may request the UE to send a PRACH signal by sending a PDCCH to the UE indicating that the UE should send a PRACH signal. In current (e.g., LTE Rel-12) wireless technologies, the UE may randomly select resources for the PRACH signal from the resources reserved for the PRACH signal by the serving cell. Due to the randomness of the selection, the commanded PRACH signal (i.e., the PRACH signal sent by the UE on the randomly selected resources) may conflict with PRACH signals from other UEs (e.g., UEs connected to the eNB, other UEs commanded to send PRACH signals).

[0089] A UE with an active receiver (e.g., the receiver is not powered off) typically monitors PDCCH (e.g., EPDCCH, MPDCCH) in one or more search spaces. The UE typically monitors at least one common search space (CSS) and can be configured to monitor a UE-specific search space (UESS). A search space comprises a set of consecutive groups of control channel elements (CCEs). The UE uses an identifier of the UE (e.g., a radio network temporary identifier (RNTI)) when determining whether any of the groups in the search space contains a PDCCH directed at the UE. Monitoring of the PDCCH is further described in 3GPP TS 36.213, "Evolved Universal Terrestrial Radio Access (E-UTRA)", which is publicly available and incorporated herein by reference.

[0090] According to aspects of the present disclosure, a BS (e.g., an eNB) may allocate specific resources for transmission of a PRACH signal to a UE, and the BS may command the UE to transmit the PRACH signal. For example, when the eNB determines to command (e.g., direct) the UE to transmit a PRACH signal (e.g., when the UE has lost synchronization with a cell served by the eNB and serving the UE), the eNB serving the UE may allocate tones to the UE for the UE to use in transmitting the PRACH signal.

[0091] According to aspects of the present disclosure, a BS (e.g., eNB) may instruct a UE to use specific resources in a PRACH region configured (e.g., reserved) by the BS. When doing so, the BS may send signaling instructing other UEs not to use the specific resources for sending PRACH signals.

[0092] According to aspects of the present disclosure, a BS (eg, an eNB) may command a UE to use resources in a data region (eg, Figure 5B The wideband data region 556, 558, 559 shown in FIG2 is used to transmit PRACH signals. When transmitting PRACH signals in the data region, different CPs and tone spacings (e.g., as mentioned above) of the PRACH signals from data signals (e.g., data signals transmitted by other UEs in the cell) may cause interference between the PRACH signals and the data signals. In addition, frequency hopping within a group and random group hopping (as mentioned above with reference to FIG2 ) may cause interference between the PRACH signals and the data signals. Figure 7 described) may result in transmission resources being wasted (eg, not used for data transmission or PRACH signals).

[0093] According to aspects of the present disclosure, a cell (e.g., a BS serving the cell) may divide a set of resources reserved for PRACH signals into three regions, including a first region reserved for UEs that intend to make Msg3 a single-tone message, a second region reserved for UEs that intend to make Msg3 a multi-tone message, and a third region for UEs that send scheduled PRACH signals (e.g., PRACH signals sent in response to a command such as a PDCCH from an eNB).

[0094] As mentioned above, Figure 9 FIG1 is a schematic illustration of a resource set 900 (e.g., a PRACH region) reserved for PRACH signals, divided into three regions. Frequency region 902 is the set of tones to be used by UEs transmitting unscheduled PRACH signals with the intent that Msg3 of a RACH procedure be a single-tone message. Frequency region 904 is the set of tones to be used by UEs transmitting unscheduled PRACH signals with the intent that Msg3 of a RACH procedure be a multi-tone message. Frequency region 906 is the set of tones to be used by UEs transmitting scheduled PRACH signals.

[0095] According to aspects of the present disclosure, a BS (e.g., an eNB) may transmit (e.g., in an SIB) an additional parameter to indicate a region of transmission resources reserved for scheduled PRACH signals. For example, the BS may transmit an indication of a first region of transmission resources reserved for PRACH signals, and the additional parameter may be an offset from one of the boundaries of the first region, wherein the offset indicates a second region within the first region for scheduled PRACH signals.

[0096] According to aspects of the present disclosure, a base station (e.g., an eNB) may configure a semi-static resource partitioning for a cell, including a region of transmission resources reserved for scheduled PRACH signals in response to a PDCCH command. The resource partitioning may be referred to as semi-static because the resource partitioning is not effective until reconfigured by the base station (e.g., for a cell and / or base station). PRACH signals ordered by PDCCH are relatively rare events, and a semi-statically allocated set of resources for scheduled PRACH signals may often go unused, potentially resulting in a waste of transmission resources.

[0097] In aspects of the present disclosure, a BS (e.g., an eNB) may periodically update (e.g., change) a semi-static resource partitioning for a cell and send signaling (e.g., in an SIB or MIB) about the updated resource partitioning. For example, the BS may determine the semi-static resource partitioning for the cell and send an indication of the resource partitioning. In this example, the BS may also determine a period for updating the resource partitioning and send an indication of the period. Still in this example, after the period has passed, the BS may determine whether to update the semi-static resource partitioning, and if the determination is to update the resource partitioning, the BS may send an indication of the new (e.g., changed) resource partitioning. UEs in the cell may activate their receivers based on the period indicated by the BS to receive updates to the semi-static resource partitioning, if any.

[0098] According to aspects of the present disclosure, a BS (e.g., an eNB) may configure dynamic resource partitioning, including reserving a region of transmission resources for a scheduled PRACH signal at or near the time when the BS is about to send a PDCCH to command one or more UEs to send a scheduled PRACH signal. The resource partitioning may be referred to as dynamic because the resource partitioning is changed in response to the BS detecting that one or more UEs should send a scheduled PRACH signal (e.g., the UE has lost synchronization), and the change in resource partitioning is effective for a predetermined time period. When the eNB intends to command a UE to send a scheduled PRACH signal, the eNB may dynamically change the configuration of the PRACH resources and send signaling (e.g., in an SIB) containing the PRACH resource change for a period (e.g., 4 ms).

[0099] As mentioned above, Figure 10 FIG2 is a schematic illustration of a set of resources 1000 (e.g., PRACH regions) reserved for PRACH signals, divided into three regions and dynamically updated over time. Frequency regions 1002a-1002g are the set of tones to be used by UEs transmitting unscheduled PRACH signals at different times and intending Msg3 of a RACH procedure to be a single-tone message. Frequency regions 1004a-1004g are the set of tones to be used by UEs transmitting unscheduled PRACH signals at different times and intending Msg3 of a RACH procedure to be a multi-tone message. Frequency regions 1006a-1006c are the set of tones to be used by UEs transmitting scheduled PRACH signals at indicated times at different times, dynamically configured by the BS.

[0100] According to aspects of the present disclosure, a base station (e.g., an eNB) may change the resources reserved for a PRACH signal at a limited set of times (e.g., at certain system frame numbers (SFNs)). The base station may signal the limited set of times, for example, by including an indication of the time in one or more SIBs. A UE may receive the signaling and determine the set of times at which the UE may change the resources reserved for the PRACH signal. Additionally or alternatively, the set of times may be determined by the base station and the UE based on standards and / or specifications.

[0101] According to aspects of the present disclosure, if a first random access attempt made by a UE fails (e.g., the eNB does not respond to a PRACH signal from the UE), the UE may check the SIB contents (e.g., for changes to the resources reserved for the PRACH signal) before sending a second PRACH attempt, if the attempt is after a possible SIB change of the resources reserved for the PRACH signal. For example, the UE sends a first PRACH signal to the BS in a random access attempt, and the random access attempt fails. In this example, the UE has information about a set of times at which the BS may change the resources reserved for the PRACH signal. Still in this example, if one of the times in the set of times occurs before the UE makes a second random access attempt, the UE may check the SIB contents received since the first random access attempt to determine whether the BS has changed the resources reserved for the PRACH signal. Still in this example, if the BS has changed the resources reserved for the PRACH signal, the UE may determine the resources for sending the PRACH signal for the second random access attempt based on the SIB contents.

[0102] According to aspects of the present disclosure, resource partitioning for a PRACH signal for a PDCCH command may occur only at certain times, e.g., every 1024 frames. According to these aspects, the eNB may send semi-static time information in signaling (e.g., in one or more SIBs). Whenever the eNB determines that a UE needs to send a PRACH signal, the eNB may send a PDCCH command to the UE to cause the UE to send the PRACH signal, and the UE may wait to send the scheduled PRACH until after a change in the resources reserved for the PRACH signal occurs and makes the resources available for the scheduled PRACH signal, which may be many subframes later. For example, the BS may send a PDCCH to the UE commanding the UE to send the PRACH signal at a time such as Figure 10 The UE sends the PRACH signal at time 1008 shown in FIG. 1 , the UE may wait until time 1010 to send the commanded PRACH signal because the resources reserved for the PRACH signal change at time 1010 and the UE may use resource 1006 c for sending the commanded PRACH signal.

[0103] As mentioned above, Figure 11 is shown by BS (e.g., Figure 1 1 is a schematic illustration of an exemplary timeline 1100 of a set of resources (e.g., PRACH regions) reserved for PRACH signals at a particular time, divided into three regions by an eNB 110 shown in FIG. Frequency region 1102 is to be used by a UE (e.g., UE 110) that transmits an unscheduled PRACH signal to the BS at a different time and intends for Msg3 of the RACH procedure to be a single tone. Figure 1 1100). The frequency region 1104 is the set of tones used by a UE transmitting an unscheduled PRACH signal to the base station, intending for Msg3 of the RACH procedure to be multi-tone information. Frequency region 1106 is the set of tones used by a UE transmitting a scheduled PRACH signal at the indicated time. In the example, at time 1110, the eNB transmits a PDCCH requesting the UE to transmit a scheduled PRACH signal. Because resources for the scheduled PRACH signal are not allocated until time 1112 in the exemplary timeline, the UE does not transmit the scheduled PRACH signal requested in the PDCCH at time 1110 until time 1112.

[0104] According to aspects of the present disclosure, when the number of UEs that need PDCCH commands to transmit PRACH signals is greater than the number that can be accommodated by resources reserved for scheduled PRACH signals, a BS (e.g., an eNB) may not transmit PDCCH commands for all UEs that need PDCCH commands to transmit PRACH signals, and the BS may allow the remaining UEs to transmit PRACH signals in randomly selected resources. That is, the BS may determine that a first group of UEs and a second group of UEs need to transmit PRACH signals (e.g., the UEs have lost uplink synchronization), and the BS may transmit PDCCH commands to the first group of UEs so that the first group of UEs transmit PRACH signals in resources reserved for scheduled PRACH signals (e.g., Figure 11 1106) and the BS may not send a command to send a PRACH signal to the second group of UEs. When the UE determines that the UE needs to send a PRACH signal (for example, the UE determines that the UE has lost synchronization with the BS), each UE in the second group may send a PRACH signal on the randomly selected resources.

[0105] According to aspects of the present disclosure, when the number of UEs requiring PDCCH commands to transmit PRACH signals is greater than the number that can be accommodated by resources reserved for scheduled PRACH signals, a BS (e.g., an eNB) may transmit a PDCCH command for the remaining UEs indicating that those UEs should use random PRACH resources instead of scheduled PRACH resources. That is, the BS may determine that a first group of UEs and a second group of UEs need to transmit PRACH signals (e.g., the UEs have lost uplink synchronization), and the BS may transmit a PDCCH command according to aspects of the present disclosure that causes the UEs in the first group to transmit PRACH signals in resources reserved for scheduled PRACH signals, and the BS may transmit a PDCCH command to the UEs in the second group according to previously known techniques, causing each UE in the second group to transmit a PRACH signal on resources randomly selected by the UE.

[0106] According to aspects of the present disclosure, a base station (e.g., an eNB) may utilize a portion of the data region of the system bandwidth for scheduled PRACH signals. That is, the base station may reserve resources for scheduled PRACH signals in the data region of the system bandwidth rather than in the PRACH region. Additionally or alternatively, the base station may include, in a PDCCH commanding a UE to transmit a scheduled PRACH signal, an indication of resources in the data region of the system bandwidth to be used by the UE when transmitting the PRACH signal.

[0107] As mentioned above, Figure 12 is a schematic diagram showing the time intervals at which a BS (e.g., Figure 1 12 illustrates an exemplary timeline 1200 of a set of resources reserved for data transmission and scheduled PRACH signals, as shown in FIG. 12. Frequency region 1202 is a set of tones to be used for data transmission at different times. Frequency region 1204 is a set of tones to be used by a UE sending a scheduled PRACH signal at the indicated time. At time 1210, the BS sends a request to the UE (e.g., Figure 1 120a) and UE1, shown in FIG. 1210b, transmit a PDCCH for a scheduled PRACH signal. Similarly, at times 1212 and 1214, the BS transmits a PDCCH requesting the other UEs, UE2, and UE3, to transmit scheduled PRACH signals. Because resources are not allocated for the scheduled PRACH signal until time 1216, the UEs, UE1, UE2, and UE3, do not transmit the scheduled PRACH signal until time 1216.

[0108] According to aspects of the present disclosure, when a data region (e.g., Figure 12When sending a scheduled PRACH signal in area 1204 shown in FIG, the UE may disable random group hopping (e.g., in Figure 7 Disabling random group hopping may avoid wasting some transmission resources.

[0109] According to aspects of the present disclosure, a BS (e.g., an eNB) may defer sending a PDCCH commanding scheduled PRACH signals or send those PDCCHs immediately, but allow UEs to defer transmission of PRACH signals until they are grouped to send scheduled PRACH signals together in time. Deferring scheduled PRACH signals and grouping UEs may avoid wasting some transmission resources.

[0110] According to aspects of the present disclosure, a cell may allocate some tones as guard tones between the region used for scheduled PRACH signals and the remaining data region. Allocating tones as guard tones may reduce interference between data transmissions and scheduled PRACH signals. For example, such interference may be caused by a difference in CP between data transmissions and scheduled PRACH signals.

[0111] According to aspects of the present disclosure, an eNB that divides a data region into resources for data and resources for scheduled PRACH signals may dynamically divide the data region. An eNB that dynamically divides a data region into resources for data and resources for scheduled PRACH signals may add a time for transmission of the scheduled PRACH signal to a PDCCH commanding the scheduled PRACH signal.

[0112] According to aspects of the present disclosure, the data region is divided into resources for data and resources for scheduled PRACH signals (e.g., Figure 12 A BS (e.g., an eNB) that semi-statically partitions the data region into resources for data and resources for scheduled PRACH signals (e.g., regions 1202 and 1204 shown in FIG. 1 ) may semi-statically perform resource partitioning only at specific times (e.g., specific subframes). A BS that semi-statically partitions the data region into resources for data and resources for scheduled PRACH signals may send an indication of the semi-statically selected times in signaling from the BS (e.g., in an SIB). The partitioning may be referred to as semi-static because the partitioning is configured to occur at known times and repeat over time until the BS announces (e.g., in an SIB) a change to the partitioning (e.g., a change in time, a change in the repetition interval, a change in the selected resources).

[0113] Figure 13 It is shown that a BS (e.g., Figure 1Example operations 1300 for wireless communications may be performed by an eNodeB 110a in FIG. Operations 1300 may be performed by a BS to command a UE to transmit a scheduled PRACH signal.

[0114] Operations 1300 begin at block 1302, where a BS provides an indication of a scheduled physical random access channel (PRACH) region comprising a set of transmission resources within a narrowband region of a wider system bandwidth for sending a scheduled PRACH signal by a first user equipment (UE).

[0115] Operations 1300 continue at block 1304 where the BS sends a first command to the first UE to send a scheduled PRACH.

[0116] Figure 14 shows that a UE (e.g., Figure 1 1400 for wireless communication. For example, operations 1400 may be performed by the UE to send a scheduled PRACH signal. Operations 1400 may be considered as an additional example of operations described above. Figure 13 A supplement to operation 1300.

[0117] Operations 1400 begin at block 1402, where the UE receives a command from a base station (BS) to send a scheduled physical random access channel (PRACH) signal to the BS.

[0118] Operations 1400 continue at block 1404 where the UE obtains an indication of a scheduled PRACH region comprising a set of transmission resources within a narrowband region of a wider system bandwidth for use in sending a scheduled PRACH signal to a BS.

[0119] At block 1406, the UE sends a PRACH signal to the BS using the indicated transmission resources.

[0120] The steps of the method or algorithm described in conjunction with the disclosure herein may be directly embodied in hardware, a software module executed by a processor or processing system, or a combination thereof. The software module may be present in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, PCM (phase change memory), registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and / or write information to the storage medium. In an alternative, the storage medium may be an integral part of the processor. The processor, processing system, and / or storage medium may be present in an ASIC. The ASIC may be present in a user terminal. In an alternative, the processor and storage medium may be present in a user terminal as discrete components. Typically, where there are operations shown in the figures, those operations may have corresponding corresponding units plus functional components, which have similar numbering. For example, Figure 13 The operations 1300 shown in FIG. 13 correspond to Figure 13A The unit 1300A shown in FIG. Figure 14 The operations 1400 shown in FIG. 14 correspond to Figure 14A 1400A shown in FIG. For example, the means for determining, the means for executing, the means for transmitting, the means for receiving, the means for sending, the means for applying, the means for providing, the means for selecting, the means for using, the means for updating, the means for obtaining, the means for scheduling, the means for evaluating, and / or the means for measuring may include one or more processors or other elements, e.g. Figure 2 The transmit processor 264, controller / processor 280, receive processor 258, and / or antenna 252 of the user equipment 120 shown in FIG. Figure 2 1. The transmit processor 220, receive processor 238, controller / processor 240, and / or antenna 234 of the base station 110 are shown in FIG.

[0121] In one or more exemplary designs, the functions described can be implemented in hardware, software, or a combination thereof. If implemented in software, these functions can be stored or sent as one or more instructions or codes on a computer-readable medium. Computer-readable media include both computer storage media and communication media, and communication media include any media that helps to transfer a computer program from one place to another. Storage media can be any available media that can be accessed by a general-purpose or special-purpose computer. By way of example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used to carry or store desired program code units in the form of an instruction or data structure and any other media that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. In addition, any connection is suitably referred to as a computer-readable medium. For example, if a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared, radio, and microwave) is used to transmit software from a website, server, or other remote source, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of medium. Disks and optical discs, as used herein, include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and optical discs reproduce data optically using lasers. Combinations of the above are also included within the scope of non-transitory computer-readable and processor-readable media. Software should be broadly construed to mean instructions, instruction sets, code, code segments, program code, programs, subroutines, software modules, applications, software applications, software packages, firmware, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or other terms.

[0122] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless specified otherwise or clear from the context, phrases such as "X employs A or B" are intended to mean any of the natural inclusive permutations. That is, for example, the phrase "X employs A or B" is satisfied by any of the following instances: X employs A; X employs B; or X employs both A and B. As used herein, references to elements in the singular are not intended to mean "one and only one," but rather "one or more" unless specifically stated otherwise. For example, the articles "a" and "an," as used in this application and the appended claims, should generally be understood to mean "one or more," unless specified otherwise or clear from the context to be directed to the singular. Unless specifically stated otherwise, the term "some" refers to one or more. A phrase referring to "at least one" of a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to encompass: a, b, c, ab, ac, bc, and abc, as well as any combination of multiples of the same elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc or any other ordering of a, b, and c). As used herein, including in the claims, when the term "and / or" is used in a list of two or more items, it means that any one of the listed items can be used alone, or any combination of two or more of the listed items can be used. For example, if a combination is described as including components A, B, and / or C, the combination can include only A; only B; only C; A and B combined; A and C combined; B and C combined; or A, B, and C combined.

[0123] The previous description of the present disclosure is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication performed by a user equipment (UE), comprising: receiving a command from a base station BS to send a scheduled physical random access channel PRACH signal to the BS; obtaining an indication of a scheduled PRACH region for transmitting a scheduled PRACH signal to the base station, the scheduled PRACH region comprising a set of transmission resources within a narrowband region of a wider system bandwidth, wherein the scheduled PRACH region is a subset of PRACH resources indicated by the base station and reserved for PRACH signals based on the command, and the indication comprises a parameter indicating a starting offset of the scheduled PRACH signal from a boundary of the scheduled PRACH region in the PRACH resources; as well as The scheduled PRACH signal is sent to the BS using transmission resources in the scheduled PRACH region.

2. The method according to claim 1, wherein The scheduled PRACH region is semi-statically updated.

3. The method according to claim 2, wherein: Semi-static updates occur periodically.

4. The method according to claim 2, further comprising: An indication of a time for the semi-static update is received in a system information block (SIB).

5. The method according to claim 1, wherein The scheduled PRACH region is dynamically updated.

6. The method according to claim 5, further comprising: An indication of a dynamic update is received in a system information block (SIB).

7. The method according to claim 1, wherein The scheduled PRACH region is a subset of a set of data transmission resources.

8. The method according to claim 1, further comprising: obtaining an indication by the UE to disable random group hopping when sending the scheduled PRACH signal; as well as Wherein, sending the scheduled PRACH signal includes sending the scheduled PRACH signal without using group hopping.

9. The method according to claim 1, wherein: The command indicates a time for the UE to send the scheduled PRACH signal.

10. A method for wireless communication performed by a base station BS, comprising: providing an indication of a scheduled PRACH region for transmitting a scheduled PRACH signal by a user equipment (UE), the scheduled PRACH region comprising a set of transmission resources within a narrowband region of a wider system bandwidth, wherein the scheduled PRACH region is a subset of PRACH resources indicated by the base station and reserved for PRACH signals based on a command, and the indication comprises a parameter indicating a starting offset of the scheduled PRACH signal from a boundary of the scheduled PRACH region in the PRACH resources; and The command is sent to the UE to send a scheduled PRACH signal using transmission resources in the scheduled PRACH region.

11. The method according to claim 10, further comprising: The scheduled PRACH region is semi-statically updated.

12. The method according to claim 11, wherein Semi-statically updating the PRACH region includes periodically semi-statically updating the scheduled PRACH region.

13. The method according to claim 12, further comprising: An indication of the time for semi-static updates is sent in the System Information Block (SIB).

14. The method according to claim 10, further comprising: Determining to command the UE to send the scheduled PRACH signal; as well as The scheduled PRACH region is dynamically updated based on the determination.

15. The method according to claim 14, further comprising: The indication of the dynamic update is sent in the System Information Block (SIB).

16. The method according to claim 10, wherein The scheduled PRACH region is a subset of a set of data transmission resources.

17. The method according to claim 10, further comprising: An indication is sent to the UE to disable random group hopping when sending the scheduled PRACH signal.

18. An apparatus for wireless communication, comprising: At least one processor configured to: receiving a command from a base station BS to send a scheduled physical random access channel PRACH signal to the BS; obtaining an indication of a scheduled PRACH region for transmitting a scheduled PRACH signal to the BS, the scheduled PRACH region comprising a set of transmission resources within a narrowband region of a wider system bandwidth, wherein the scheduled PRACH region is a subset of PRACH resources indicated by the BS and reserved for PRACH signals based on the command, and the indication comprises a parameter indicating a starting offset of the scheduled PRACH signal from a boundary of the scheduled PRACH region in the PRACH resources; and sending the scheduled PRACH signal to the BS using transmission resources in the scheduled PRACH region; and A memory is coupled to the at least one processor.

19. The device according to claim 18, wherein The scheduled PRACH region is semi-statically updated.

20. The apparatus according to claim 18, wherein The scheduled PRACH region is dynamically updated.

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