WO2015077915A1 - Procédés et appareil d'améliorations de capacité pour voix sur évolution à long terme - Google Patents

Procédés et appareil d'améliorations de capacité pour voix sur évolution à long terme Download PDF

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Publication number
WO2015077915A1
WO2015077915A1 PCT/CN2013/087834 CN2013087834W WO2015077915A1 WO 2015077915 A1 WO2015077915 A1 WO 2015077915A1 CN 2013087834 W CN2013087834 W CN 2013087834W WO 2015077915 A1 WO2015077915 A1 WO 2015077915A1
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Prior art keywords
transmissions
scheduling
volte
capacity
transmission
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PCT/CN2013/087834
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English (en)
Inventor
Minghai Feng
Chao Wei
Bo Chen
Jilei Hou
Neng Wang
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Qualcomm Incorporated
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Priority to PCT/CN2013/087834 priority Critical patent/WO2015077915A1/fr
Publication of WO2015077915A1 publication Critical patent/WO2015077915A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/52—Allocation or scheduling criteria for wireless resources based on load

Definitions

  • Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to techniques for capacity enhancements for voice over internet protocol long-term evolution (VoLTE) calls.
  • VoIP voice over internet protocol long-term evolution
  • Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the 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, 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)/LTE-Advanced systems and orthogonal frequency division multiple access (OFDMA) systems.
  • CDMA code division multiple access
  • TDMA time division multiple access
  • FDMA frequency division multiple access
  • 3GPP 3rd Generation Partnership Project
  • LTE Long Term Evolution
  • LTE-Advanced systems orthogonal frequency division multiple access
  • a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals.
  • Each terminal communicates with one or more base stations via transmissions on the forward and reverse links.
  • the forward link (or downlink) refers to the communication link from the base stations to the terminals
  • the reverse link (or uplink) refers to the communication link from the terminals to the base stations.
  • This communication link may be established via a single-input single-output, multiple-input single-output or a multiple-input multiple-output (MIMO) system.
  • MIMO multiple-input multiple-output
  • a wireless communication network may include a number of base stations that can support communication for a number of wireless devices.
  • Wireless devices comprise user equipments (UEs) and remote devices.
  • UE user equipments
  • a UE is a device that operates under direct control by humans. Some examples of UEs include cellular phones, smart phones, personal digital assistants (PDAs), wireless modems, handheld devices, tablets, laptop computers, netbooks, smartbooks, ultrabooks, etc.
  • PDAs personal digital assistants
  • a remote device is a device that operates without being directly controlled by humans. Some examples of remote devices include sensors, meters, location tags, etc.
  • a remote device may communicate with a base station, another remote device, or some other entity.
  • Machine type communication refers to communication involving at least one remote device on at least one end of the communication.
  • Certain aspects of the present disclosure provide a method for wireless communications by a base station (BS).
  • the method generally includes determining whether capacity for the BS to handle voice over internet protocol over long term evolution (VoLTE) calls is limited by at least one of uplink (UL) transmission resources, downlink (DL) transmission resources, or physical downlink control channel (PDCCH) resources, and scheduling at least one of UL transmissions, DL transmissions, or PDCCHs based on the determination.
  • UL uplink
  • DL downlink
  • PDCCH physical downlink control channel
  • the apparatus generally includes at least one processor configured to determine whether capacity for the BS to handle voice over internet protocol over long term evolution (VoLTE) calls is limited by at least one of uplink (UL) transmission resources, downlink (DL) transmission resources, or physical downlink control channel (PDCCH) resources, and schedule at least one of UL transmissions, DL transmissions, or PDCCHs based on the determination, and a memory coupled with the at least one processor.
  • VoLTE voice over internet protocol over long term evolution
  • the apparatus generally includes means for determining whether capacity for a BS to handle voice over internet protocol over long term evolution (VoLTE) calls is limited by at least one of uplink (UL) transmission resources, downlink (DL) transmission resources, or physical downlink control channel (PDCCH) resources, and means for scheduling at least one of UL transmissions, DL transmissions, or PDCCHs based on the determination.
  • VoLTE voice over internet protocol over long term evolution
  • Certain aspects of the present disclosure provide a computer program product comprising a non-transitory computer-readable medium comprising instructions.
  • the instructions are generally executable by a computer to cause the computer to determine whether capacity for a BS to handle voice over internet protocol over long term evolution (VoLTE) calls is limited by at least one of uplink (UL) transmission resources, downlink (DL) transmission resources, or physical downlink control channel (PDCCH) resources, and schedule at least one of UL transmissions, DL transmissions, or PDCCHs based on the determination.
  • VoLTE voice over internet protocol over long term evolution
  • FIG. 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with certain aspects of the present disclosure.
  • FIG. 2 shows a block diagram conceptually illustrating an example of a base station in communication with a UE in a wireless communications network, in accordance with certain aspects of the present disclosure.
  • FIG. 3 is a block diagram conceptually illustrating an example of a frame structure in a wireless communications network, in accordance with certain aspects of the present disclosure.
  • FIG. 4 is a block diagram conceptually illustrating two exemplary subframe formats with the normal cyclic prefix.
  • FIG. 5 illustrates an example list of downlink/uplink (DL/UL) configurations in a frame in the TDD-LTE standard, in accordance with certain aspects of the present disclosure.
  • FIG. 6 illustrates VoLTE capacity of an FDD cell, in accordance with certain aspects of the present disclosure.
  • FIG. 7 illustrates VoLTE capacity of a TDD cell, in accordance with certain aspects of the present disclosure.
  • FIG. 8 illustrates VoLTE capacity of an FDD cell, in accordance with certain aspects of the present disclosure.
  • FIG. 9 illustrates example operations for wireless communications by a BS, in accordance with certain aspects of the present disclosure.
  • aspects of the present disclosure provided techniques for enhancing uplink coverage.
  • a CDMA network may implement a radio technology such as universal terrestrial radio access (UTRA), cdma2000, etc.
  • UTRA includes wideband CDMA (WCDMA), time division synchronous CDMA (TD-SCDMA), and other variants of CDMA.
  • cdma2000 covers IS-2000, IS-95 and IS-856 standards.
  • a TDMA network may implement a radio technology such as global system for mobile communications (GSM).
  • GSM global system for mobile communications
  • An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA), ultra mobile broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc.
  • E-UTRA evolved UTRA
  • UMB ultra mobile broadband
  • IEEE 802.11 Wi-Fi
  • WiMAX IEEE 802.16
  • Flash-OFDM® Flash-OFDM
  • UTRA and E-UTRA are part of universal mobile telecommunication system (UMTS).
  • 3GPP Long Term Evolution (LTE) and LTE- Advanced (LTE-A), in both frequency division duplex (FDD) and time division duplex (TDD), are new releases of UMTS that use E-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink.
  • LTE Long Term Evolution
  • LTE-A LTE- Advanced
  • FDD frequency division duplex
  • TDD time division duplex
  • UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named "3rd Generation Partnership Project” (3 GPP).
  • 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 wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques are described below for LTE/LTE-Advanced, and LTE/LTE- Advanced terminology is used in much of the description below.
  • FIG. 1 shows a wireless communication network 100, which may be an LTE network or some other wireless network.
  • Wireless network 100 may include a number of evolved Node Bs (eNBs) 110 and other network entities.
  • eNB evolved Node Bs
  • An eNB is an entity that communicates with UEs and may also be referred to as a base station, a Node B, an access point, etc.
  • Each eNB may provide communication coverage for a particular geographic area.
  • the term "cell" can refer to a coverage area of an eNB and/or an eNB subsystem serving this coverage area, depending on the context in which the term is used.
  • An eNB may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells.
  • a macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions.
  • a pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions.
  • a femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG)).
  • CSG closed subscriber group
  • 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).
  • HeNB home eNB
  • an eNB 110a may be a macro eNB for a macro cell 102a
  • an eNB 110b may be a pico eNB for a pico cell 102b
  • an eNB 110c may be a femto eNB for a femto cell 102c.
  • An eNB may support one or multiple (e.g., three) cells.
  • the terms "eNB", “base station” and “cell” may be used interchangeably herein.
  • Wireless network 100 may also include relay stations.
  • a relay station is an entity that can receive a transmission of data from an upstream station (e.g., an eNB or a UE) and send a transmission of the data to a downstream station (e.g., a UE or an eNB).
  • a relay station may also be a UE that can relay transmissions for other UEs.
  • a relay station 1 lOd may communicate with macro eNB 110a and a UE 120d in order to facilitate communication 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.
  • Wireless network 100 may be a heterogeneous network that includes eNBs of different types, e.g., 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 impact on interference in wireless network 100.
  • macro eNBs may have a high transmit power level (e.g., 5 to 40 Watts) whereas pico eNBs, femto eNBs, and relay eNBs may have lower transmit power levels (e.g., 0.1 to 2 Watts).
  • a network controller 130 may couple to a set of eNBs and may provide coordination and control for these eNBs.
  • Network controller 130 may communicate with the eNBs via a backhaul.
  • the eNBs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.
  • UEs 120 may be dispersed throughout wireless network 100, and each UE may be stationary or mobile.
  • a UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, 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 computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a smart phone, a netbook, a smartbook, an ultrabook, etc.
  • PDA personal digital assistant
  • WLL wireless local loop
  • a solid line with double arrows indicates desired transmissions between a UE and a serving eNB, which is an eNB designated to serve the UE on the downlink and/or uplink.
  • a dashed line with double arrows indicates potentially interfering transmissions between a UE and an eNB.
  • FIG. 2 shows a block diagram of a design of base station/eNB 110 and UE 120, which may be one of the base stations/eNBs and one of the UEs in FIG. 1.
  • Base station 110 may be equipped with T antennas 234a through 234t
  • UE 120 may be equipped with antennas 252a through 252r, where in general T > 1 andR > 1 .
  • 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 CQIs received from the UE, process (e.g., encode and modulate) the data for each UE based on the MCS(s) selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for SRPI, etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols.
  • MCS modulation and coding schemes
  • Processor 220 may also generate reference symbols for reference signals (e.g., the CRS) and synchronization signals (e.g., the PSS and SSS).
  • a transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream.
  • TX transmit
  • MIMO multiple-input multiple-output
  • MIMO multiple-input multiple-output
  • Each modulator 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.
  • antennas 252a through 252r may receive the downlink signals from base station 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively.
  • Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) its received signal to obtain input samples.
  • Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols.
  • a MIMO detector 256 may obtain received symbols from all demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.
  • a receive processor 258 may 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.
  • a channel processor may determine RSRP, RSSI, RSRQ, CQI, etc.
  • a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, etc.) from controller/processor 280. 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 modulators 254a through 254r (e.g., for SC-FDM, OFDM, etc.), and transmitted to base station 110.
  • control information e.g., for reports comprising 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 modulators 254a through 254r (e.g., for SC-FDM, OFDM, etc.), and transmitted to base station 110.
  • the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a 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.
  • Base station 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244.
  • Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.
  • Controllers/processors 240 and 280 may direct the operation at base station 110 and UE 120, respectively.
  • Processor 240 and/or other processors and modules at base station 110, and/or processor 280 and/or other processors and modules at UE 120, may perform or direct processes for the techniques described herein.
  • Memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively.
  • a scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.
  • the base station 110 may be configured to determine a bundling size based at least in part on a data allocation size and precode data in bundled contiguous resource blocks of the determined bundling size, wherein resource blocks in each bundle may be precoded with a common precoding matrix. That is, reference signals such as UE-RS and/or data in the resource blocks may be precoded using the same precoder.
  • the power level used for the UE-RS in each RB (resource block) of the bundled RBs may also be the same.
  • the UE 120 may be configured to perform complementary processing to decode data transmitted from the base station 110. For example, the UE 120 may be configured to determine a bundling size based on a data allocation size of received data transmitted from a base station in bundles of contiguous resource blocks (RBs), wherein at least one reference signal in resource blocks in each bundle are precoded with a common precoding matrix, estimate at least one precoded channel based on the determined bundling size and one or more reference signals (RSs) transmitted from the base station, and decode the received bundles using the estimated precoded channel.
  • RBs resource blocks
  • RSs reference signals
  • FIG. 3 shows an exemplary frame structure 300 for FDD in LTE.
  • the transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames.
  • Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms)) and may be partitioned into 10 sub frames with indices of 0 through 9.
  • Each sub frame may include two slots.
  • Each radio frame may thus include 20 slots with indices of 0 through 19.
  • Each slot may include L symbol periods, e.g., seven symbol periods for a normal cyclic prefix (as shown in FIG. 3) or six symbol periods for an extended cyclic prefix.
  • the 2L symbol periods in each subframe may be assigned indices of 0 through 2L-1.
  • an eNB may transmit 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.
  • PSS primary synchronization signal
  • SSS secondary synchronization signal
  • the PSS and SSS may be transmitted in symbol periods 6 and 5, respectively, in sub frames 0 and 5 of each radio frame with the normal cyclic prefix, as shown in FIG. 3.
  • the PSS and SSS may 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.
  • CRS cell-specific reference signal
  • the CRS may be transmitted in certain symbol periods of each subframe and may be used by the UEs to perform channel estimation, channel quality measurement, and/or other functions.
  • the eNB may also transmit a physical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 of certain radio frames.
  • PBCH physical broadcast channel
  • the PBCH may carry some system information.
  • the eNB may transmit other system information such as system information blocks (SIBs) on a physical downlink shared channel (PDSCH) in certain subframes.
  • SIBs system information blocks
  • PDSCH physical downlink shared channel
  • the eNB may transmit control information/data on a 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.
  • FIG. 4 shows two exemplary subframe formats 410 and 420 with the normal cyclic prefix.
  • the available time frequency resources may be partitioned into resource blocks.
  • Each resource block may cover 12 subcarriers in one slot and may include a number of resource elements.
  • Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value.
  • Subframe format 410 may be used for two antennas.
  • a CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7 and 11.
  • a reference signal is a signal that is known a priori by a transmitter and a receiver and may also be referred to as pilot.
  • a CRS is a reference signal that is specific for a cell, e.g., generated based on a cell identity (ID).
  • ID cell identity
  • FIG. 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 symbols may be transmitted on that resource element from other antennas.
  • Subframe format 420 may be used with four antennas.
  • a 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.
  • a CRS may be transmitted on evenly spaced subcarriers, which may be determined based on cell ID.
  • CRSs may be transmitted on the same or different subcarriers, depending on their cell IDs.
  • resource elements not used for the CRS may be used to transmit data (e.g., traffic data, control data, and/or other data).
  • E-UTRA Evolved Universal Terrestrial Radio Access
  • An interlace structure may be used for each of the downlink and uplink for FDD in LTE.
  • Q interlaces with indices of 0 through Q - 1 may be defined, where Q may be equal to 4, 6, 8, 10, or some other value.
  • Each interlace may include sub frames that are spaced apart by Q frames.
  • interlace q may include sub frames q, q + Q, q + 2Q, etc., where q e ⁇ 0, ..., Q - 1 ⁇ .
  • the wireless network may support hybrid automatic retransmission request (HARQ) for data transmission on the downlink and uplink.
  • HARQ hybrid automatic retransmission request
  • a transmitter e.g., an eNB
  • a receiver e.g., a UE
  • all transmissions of the packet may be sent in subframes of a single interlace.
  • each transmission of the packet may be sent in any subframe.
  • a UE may be located within the coverage of multiple eNBs. One of these eNBs may be selected to serve the UE. The serving eNB may be selected based on various criteria such as received signal strength, received signal quality, pathloss, etc. Received signal quality may be quantified by a signal-to-noise-and-interference ratio (SINR), or a reference signal received quality (RSRQ), or some other metric.
  • SINR signal-to-noise-and-interference ratio
  • RSRQ reference signal received quality
  • the UE may operate in a dominant interference scenario in which the UE may observe high interference from one or more interfering eNBs.
  • FIG. 5 illustrates an example list of the downlink/uplink configurations in a TDD-LTE frame 402 according to the LTE standard.
  • D, U, and S indicate Downlink, Uplink and Special subframes 406, respectively.
  • the special subframe S may include DwPTS 410, GP 412, and UpPTS 414 fields.
  • several DL/UL configurations with 5 ms switch point periodicity and 10 ms switch point periodicity may be chosen for an TDD-LTE frame 402.
  • the configurations with 5ms switch point periodicity may include two special subframes within a frame, while configurations with 10ms switch point periodicity may include one special sub frame within a frame.
  • the configurations 0, 1, and 2 may have two identical 5 ms half- frames 404 within a 10ms TDD-LTE frame 402. Although seven configurations are shown in FIG. 5, a larger or smaller number of configurations and/or different configurations may be employed by the present methods and apparatus.
  • VoLTE Voice over internet protocol
  • DS Dynamic Scheduling
  • SPS Semi-Persistent Scheduling
  • Dynamic scheduling allows usage of frequency resources on an "as needed” basis, but requires using physical downlink control channels (PDCCHs) to notify UEs of UL and DL grants, and therefore may be capacity limited by the available PDCCH resources.
  • PDCCHs physical downlink control channels
  • Semi-Persistent Scheduling is not limited by PDCCH resources, but the scheduling gain from "as needed” scheduling is also not available.
  • UL and DL balance may also limit VoLTE capacity, in that UEs engaged in VoLTE typically require an end to end delay budget for a call, and PDCCH resources are shared between UL and DL.
  • FIG. 6 illustrates results of an FDD study.
  • the FDD capacity analysis conclusions were that capacity under dynamic scheduling is control channel limited, capacity under SPS is data channel limited, and overall system VoLTE capacity is uplink limited.
  • FIG. 7 illustrates results of a TDD study.
  • the TDD study reached conclusions similar to the conclusions of the FDD study.
  • the TDD capacity analysis conclusions were that capacity under dynamic scheduling is control channel limited, capacity under SPS is data channel limited, and overall system VoLTE capacity is uplink limited. Because the overall VoLTE system capacity is uplink limited, there is no need to utilize transmission mode 7 (TM7) in DL, rather than transmission mode 2 (TM2). Using TM7 to increase DL capacity will not improve the system capacity, due to the UL capacity bottleneck.
  • TM7 transmission mode 7
  • TM2 transmission mode 2
  • DS VoLTE could be further improved by assigning more PDCCH resource to either UL or DL.
  • SPS VoLTE could be further improved by utilizing semi-static rate control for both UL and DL.
  • DL and UL balance could be improved by balancing PDCCH resources between UL and DL and balancing delay budget between UL and DL.
  • FIG. 8 illustrates results of a first technique for enhancing VoLTE system capacity, wherein dynamic scheduling (DS) is used for UL transmissions of VoLTE calls, while semi-persistent scheduling (SPS) of DL transmissions for VoLTE calls.
  • DS dynamic scheduling
  • SPS semi-persistent scheduling
  • a second technique for enhancing VoLTE system capacity is utilizing dynamic scheduling (DS) for DL transmissions of VoLTE calls, while semi-persistent scheduling (SPS) is used for UL transmissions of VoLTE calls.
  • DS dynamic scheduling
  • SPS semi-persistent scheduling
  • a majority of PDCCH resources are assigned for DL DS. This technique may be more useful for DL capacity limited scenarios. Considering DL is the bottleneck for VoLTE capacity from the perspective of data channels, assigning more PDCCH resources for DL grants and applying DL DS can help to improve DL capacity performance more than some other techniques.
  • a third technique for enhancing VoLTE system capacity is static rate control for SPS, wherein a base station (BS) performs static rate allocation for a UE based on the UE's static conditions.
  • a BS may allocate a high MCS index for a UE with good channel conditions, while allocating low MCS index for other UEs with worse channel conditions.
  • the channel condition used for determining the allocations may be path- loss, distance from cell center, other channel conditions, or a combination of these conditions.
  • a fourth technique for enhancing VoLTE system capacity is semi-static rate control for SPS, wherein rates and physical resource block (PRB) allocations for VoLTE calls are semi-statically controlled.
  • a BS may initially allocate a conservative MCS and number of PRBs for a UE, e.g. MCS 10 and 2 PRBs.
  • PHR power headroom
  • the BS may allocate an increased MCS index that is a higher rate and a decreased number of PRBs, e.g. MCS 18 and 1 PRB for the VoLTE UE.
  • the BS may allocate the high MCS index for the SPS UL transmissions of that UE, otherwise the BS may fall back to the initial MCS index allocation for the UE.
  • CQI channel quality indicator
  • the BS may allocate an increased MCS index that is a higher rate and a decreased number of PRBs.
  • the BS may allocate the high MCS index for the SPS DL transmissions of that UE, otherwise the BS may decrease the MCS index allocation.
  • a fifth technique for enhancing VoLTE system capacity is to use DS to override SPS scheduling, when needed.
  • the scheduler of the BS may override SPS in the transmission time interval (TTI) by dynamically scheduling this UE via PDCCH.
  • TTI transmission time interval
  • the BS may return to scheduling the UE by SPS.
  • a sixth technique for enhancing VoLTE system capacity is improved utilization of PDCCH resources.
  • both UL and DL are DS, but a BS may allocate more PDCCH resources for UL in a sub-frame sending an UL grant to better balance UL and DL capacity, and improve the final system VoLTE UE capacity.
  • DL grants may be sent in sub-frames without UL grants.
  • a seventh technique for enhancing VoLTE system capacity is to improve a balance of UL and DL delay budgets for each VoLTE call.
  • FIG. 9 illustrates example operations 900 for wireless communications by a base station (BS), in accordance with certain aspects of the present disclosure.
  • the operations 900 may be used to accomplish any of the techniques discussed above.
  • the operations 900 may begin at 902 by determining whether capacity for the BS to handle voice over internet protocol over long term evolution (VoLTE) calls is limited by at least one of uplink (UL) transmission resources, downlink (DL) transmission resources, or physical downlink control channel (PDCCH) resources.
  • the BS may schedule at least one of UL transmissions, DL transmissions, or PDCCHs based on the determination.
  • the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions.
  • the means may include various hardware and/or software/firmware component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor.
  • ASIC application specific integrated circuit
  • those operations may be performed by any suitable corresponding counterpart means-plus- function components
  • 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/firmware module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, phase change 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 combinations 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.
  • a 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/DVD 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. Also, any connection is properly termed a computer-readable medium.
  • 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.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Certains aspects de la présente invention concernent généralement des communications sans fil et, plus particulièrement, des techniques d'améliorations de capacité pour des appels voix sur IP sur évolution à long terme (VoLTE).
PCT/CN2013/087834 2013-11-26 2013-11-26 Procédés et appareil d'améliorations de capacité pour voix sur évolution à long terme WO2015077915A1 (fr)

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CN111971916A (zh) * 2018-04-23 2020-11-20 瑞典爱立信有限公司 用于重复的时域分配
CN113812198A (zh) * 2019-05-13 2021-12-17 高通股份有限公司 保证分组延迟预算

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CN101547135A (zh) * 2008-03-25 2009-09-30 中兴通讯股份有限公司 用于无线通信系统的上行调度方法
CN102257864A (zh) * 2008-12-16 2011-11-23 诺基亚公司 在通信系统中避免下行链路控制信道覆盖限制的系统和方法

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CN101547135A (zh) * 2008-03-25 2009-09-30 中兴通讯股份有限公司 用于无线通信系统的上行调度方法
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CN111971916A (zh) * 2018-04-23 2020-11-20 瑞典爱立信有限公司 用于重复的时域分配
CN111971916B (zh) * 2018-04-23 2023-08-22 瑞典爱立信有限公司 用于传送传输块重复的方法、无线设备、基站、介质和系统
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CN113812198B (zh) * 2019-05-13 2024-04-05 高通股份有限公司 保证分组延迟预算

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