WO2017136079A1

WO2017136079A1 - Low latency in wireless communication system

Info

Publication number: WO2017136079A1
Application number: PCT/US2016/069525
Authority: WO
Inventors: Hong He; Seunghee Han; Alexei Davydov; Christian Ibars Casas; Gang Xiong
Original assignee: Intel IP Corporation
Priority date: 2016-02-02
Filing date: 2016-12-30
Publication date: 2017-08-10
Also published as: EP3411986A1

Abstract

Technologies described herein provide mechanisms and formats to accomplish short transmission time interval (S-TTI) length in wireless communication systems. In one implementation, logic is to: identify S-TTI length based on which to allocate resources of a channel of a radio access network cell; based on the S-TTI length, determine a low latency resource block (LLRB) size according to which to allocate resources of the channel and a demodulation reference signal (DMRS) pattern according to which to transmit DMRSs to user equipment (UE) via the channel; and generate the DMRSs for transmission to the UE using resources identified based on the DMRS pattern. Other embodiments are described and claimed.

Description

LOW LATENCY IN WIRELESS COMMUNICATION SYSTEM

RELATED CASE

This application claims priority to United States Provisional Patent Application Number 62290283, titled "Low Latency Operation In A Wireless Communication System," filed February 2, 2016, the entirety of which is hereby incorporated by reference.

TECHNICAL FIELD

Embodiments herein generally relate to communications between devices in broadband wireless communications networks.

BACKGROUND

Packet data latency is a key performance metric in modern communication systems. Packet data latency is not only important for perceived responsiveness of a communication system, but it is also a parameter that influences system throughput. Given the rapid increase in network traffic volume due to increased connectivity of electronic devices, techniques to reduce packet data latency are needed to increase responsiveness, robustness and throughput of various communications systems, particularly wireless communications systems.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates a block diagram of a system, in accordance with some exemplary embodiments.

FIG. 2 illustrates details of a low latency resource block (LLRB) structure, in accordance with some exemplary embodiments.

FIG. 3 illustrates an exemplary LLRB, which illustrates an exemplary LLRB structure in one short transmission time interval (S-TTI) period, in accordance with some exemplary embodiments.

FIGS. 4A-4C illustrate demodulation reference signal (DMRS) patterns, in accordance with some exemplary embodiments.

FIGS. 5A-5D illustrate alternative DMRS patterns, in accordance with some exemplary embodiments.

FIG. 6 illustrates another alternative DMRS patterns, in accordance with some exemplary embodiments.

FIG. 7 illustrates another alternative DMRS patterns, in accordance with some exemplary embodiments.

FIGS. 8A-8B illustrate alternative DMRS patterns, in accordance with some exemplary embodiments. FIG. 9 illustrates example components of an electronic device.

FIG. 10 illustrates an embodiment of a storage medium.

FIG. 11 illustrates a first exemplary process.

FIG. 12 illustrates a second exemplary process.

DETAILED DESCRIPTION

Before some embodiments are disclosed and described, it is to be understood that the claimed subject matter is not limited to the particular structures, process operations, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. The same reference numerals in different drawings represent the same element.

Numbers provided in flow charts and processes are provided for clarity in illustrating operations and do not necessarily indicate a particular order or sequence.

An initial overview of technology embodiments is provided below and then specific technology embodiments are described in further detail later. This initial summary is intended to aid readers in understanding the technology more quickly, but is not intended to identify key features or essential features of the technology nor is it intended to limit the scope of the claimed subject matter.

In general, wireless mobile communication technology uses various standards and protocols to transmit data between a node (e.g., a transmission station) and a wireless device (e.g., a mobile device). Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include, for example, the third generation partnership project (3GPP) long term evolution (LTE), among others. In 3GPP radio access network (RAN) LTE systems, the node in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) system is referred to as an evolved Node B (eNodeB or eNB), which communicates with a wireless device, commonly referred to as user equipment (UE). A downlink (DL) transmission can be a communication from the node (e.g., eNodeB) to the wireless device (e.g., UE), and an uplink (UL) transmission can be a communication from the wireless device to the node.

Typically, one or more UEs are scheduled resources for communicating with one or more eNodeB s over at least one UL channel, such as a physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), or the like. LTE uses OFDM in the DL and Discrete Fourier Transform (DFT)-spread OFDM in the UL. The basic LTE downlink physical resource can be viewed as a time-frequency resource grid. The time-frequency resource grid is divided into one millisecond subframes referred to as a Transmission Time Interval (TTI). A TTI is a fundamental parameter of the air interface and it refers to the length of an independently decodable transmission on the radio link.

Each subframe of an OFDM based communication system includes OFDM symbols. For normal cyclic prefix (NCP) length, for example, a subframe includes fourteen OFDM symbols. A subframe has only 12 OFDM symbols if an extended CP (ECP) is used. In the frequency domain, the physical resources are divided into adjacent subcarriers with a spacing of 15 kHz. The smallest element of the time-frequency resource grid is a resource element (RE). A resource element includes one OFDM subcarrier during one OFDM symbol interval. LTE resource elements are grouped into resource blocks (RBs), which in its most common configuration includes 12 subcarriers and 7 OFDM symbols (one slot) for NCP. Thus, a RB typically includes 84 REs. The two RBs occupying the same set of 12 subcarriers in a given radio subframe (2 slots) are referred to as an RB pair, which includes REs if a normal CP is used.

Packet data latency is a key performance metric in today's communication systems. Packet data latency is important not only for the perceived responsiveness of the system; it is also a parameter that influences the throughput. HTTP/TCP is the dominating application and transport layer protocol suite used on the internet today. For instance, the typical size of HTTP based transactions over the internet is in the range of a few tens of Kbytes up to 1 Mbyte. In this size range, the TCP slow start period is a significant part of the total transport period of the packet stream.

The transmission of a request, grant, or data is done in subframe portions with a TTI. The TTI length will have an impact both on a time for transmitting over air and on processing time in transmitter and receivers.

Various embodiments disclosed herein may relate to long term evolution-advanced (LTEa) and/or LTE-advanced pro, and/or fifth generation (5G) system information (SI). A massive multiple input and multiple output (MIMO) may be applied in the 5G system to enhance the coverage and improve the spectrum efficiency. In a massive MIMO system, an eNodeB may maintain a plurality of transmitting (Tx) and receiving (Rx) beams. Meanwhile the UE may also maintain a plurality of Tx and Rx beams, to include UL and DL beams.

Embodiments herein may enable short TTI (S-TTI) operations that make it possible to reduce the reference signaling overhead and packet latency. This may be achieved by: (1) a S- TTI length based low latency resource block (LLRB) used for resource allocation of shortened physical downlink shared channel (S-PDSCH) or shortened physical downlink control channel (S-PDCCH) to address the issue of unnecessary protocol overheads; (2) demodulation reference signal (DMRS) patterns to reduce the demodulation latency of PDSCH and balancing the DMRS overhead in a relatively short TTI (e.g., 2-symbols S-TTI) and channel estimation performance. More specifically, DMRS for demodulation in S-TTI n may be transmitted in S-TTI n or earlier S-TTI (e.g., S-TTI n-l); and/or (3) Time-domain S-TTI bundling or DMRS clusters type based DMRS transmission to reduce the DMRS overhead.

In some embodiment, a LTE system may be modified in a first mode to support MIMO transmission in one or more S-TTI lengths. This may include techniques to determine whether a reference signal (RS) pattern, based on a low latency resource block (LLRB) structure providing reduced overhead, is to be used for at least one channel, which is based on at least in part on a TTI length or a S-TTI length. Further, the LTE system may transmit to a UE over the at least one channel using a LLRB-based RS pattern with reduced overhead.

FIG. 1 illustrates a block diagram of a communication system 100, in accordance with some exemplary embodiments. In general, the communication system 100 may utilize various techniques that may involve transmission of data over one or more wireless connections using one or more wireless mobile broadband technologies. For example, various embodiments may involve transmissions over one or more wireless connections according to one or more 3rd Generation Partnership Project (3GPP), 3GPP Long Term Evolution (LTE), and/or 3GPP LTE- Advanced (LTE- A) technologies and/or standards, including their revisions, progeny and variants. By way of example and not limitation, certain embodiments are directed to 3GPP LTE systems as defined by 3GPP LTE series of standards, which include without limitation 3GPP Technical Specification (TS) 21.101 V12.0.2 (2016-12) titled "Technical Specification Group Services and System Aspects; Technical Specifications and Technical Reports for a UTRAN- based 3GPP system (Release 12)," dated December 2016; 3GPP TS 21.101 V13.0.0 (2016-12) titled "Technical Specification Group Services and System Aspects; Technical Specifications and Technical Reports for a UTRAN-based 3GPP system (Release 13)," dated December 2016; 3GPP TS 22.011 V14.4.0 (2016-12) titled "Technical Specification Group Services and System Aspects; Service accessibility (Release 14)," dated December 2016; 3GPP TS 22.115 V15.0.0 (2016-12) titled "Technical Specification Group Services and System Aspects; Service aspects; Charging and billing (Release 15)," dated December 2016; including their revisions, progeny and variants. It may be appreciated, however, that embodiments may be applicable to other wireless communication systems as well. Embodiments are not limited in this context.

Various embodiments may additionally or alternatively involve transmissions according to one or more Global System for Mobile Communications (GSM)/Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS)/High Speed Packet Access (HSPA), and/or GSM with General Packet Radio Service (GPRS) system (GSM/GPRS) technologies and/or standards, including their revisions, progeny and variants.

Examples of wireless mobile broadband technologies and/or standards may also include, without limitation, any of the Institute of Electrical and Electronics Engineers (IEEE) 802.16 wireless broadband standards such as IEEE 802.16m and/or 802.16p, International Mobile

Telecommunications Advanced (IMT-ADV), Worldwide Interoperability for Microwave Access (WiMAX) and/or WiMAX II, Code Division Multiple Access (CDMA) 2000 (e.g., CDMA2000 lxRTT, CDMA2000 EV-DO, CDMA EV-DV, and so forth), High Performance Radio

Metropolitan Area Network (HIPERMAN), Wireless Broadband (WiBro), High Speed

Downlink Packet Access (HSDPA), High Speed Orthogonal Frequency-Division Multiplexing (OFDM) Packet Access (HSOPA), High-Speed Uplink Packet Access (HSUPA) technologies and/or standards, including their revisions, progeny and variants.

Some embodiments may additionally or alternatively involve wireless communications according to other wireless communications technologies and/or standards. Examples of other wireless communications technologies and/or standards that may be used in various

embodiments may include, without limitation, other IEEE wireless communication standards such as the IEEE 802.11, IEEE 802.11a, IEEE 802.11b, IEEE 802.11 g, IEEE 802.11η, IEEE 802. Hu, IEEE 802.1 lac, IEEE 802.1 lad, IEEE 802.11af, and/or IEEE 802.11ah standards, High-Efficiency Wi-Fi standards developed by the IEEE 802.11 High Efficiency WLAN (HEW) Study Group, Wi-Fi Alliance (WFA) wireless communication standards such as Wi-Fi, Wi-Fi Direct, Wi-Fi Direct Services, Wireless Gigabit (WiGig), WiGig Display Extension (WDE), WiGig Bus Extension (WBE), WiGig Serial Extension (WSE) standards and/or standards developed by the WFA Neighbor Awareness Networking (NAN) Task Group, machine-type communications (MTC) standards such as those embodied in 3GPP Technical Report (TR) 23.887, 3GPP Technical Specification (TS) 22.368, and/or 3 GPP TS 23.682, and/or near-field communication (NFC) standards such as standards developed by the NFC Forum, including any revisions, progeny, and/or variants of any of the above. The embodiments are not limited to these examples.

In addition to transmission over one or more wireless connections, the techniques disclosed herein may involve transmission of content over one or more wired connections through one or more wired communications media. Examples of wired communications media may include a wire, cable, metal leads, printed circuit board (PCB), backplane, switch fabric, semiconductor material, twisted-pair wire, co-axial cable, fiber optics, and so forth. The embodiments are not limited in this context. As shown in FIG. 1, in some exemplary embodiments, communication system 100 may include one or more wireless communication devices capable of communicating content, data, information and/or signals via a wireless medium. For example, communication system 100 may include one or more wireless communication nodes, e.g., node 110, and one or more mobile devices, e.g., including mobile devices 120 and 130. The node 110 may comprise or be implemented as, for example, an eNodeB for an LTE system. The mobile devices 120, 130 may comprise or be implemented as, for example, UEs for an LTE system. The wireless medium may include, for example, a radio channel, a cellular channel, an RF channel, a Wireless Fidelity (WiFi) channel, an IR channel, a LTE channel, an OFDM channel, an OFDMA channel, and the like. One or more elements of communication system 100 may optionally communicate over any suitable wired communication links.

In some exemplary embodiments, node 110, mobile device 120 and/or mobile device 130 may be configured to communicate over one or more wireless communication frequency bands. For example, node 110, mobile device 120 and/or mobile device 130 may communicate over a first frequency band and over a second frequency band. In some embodiments, the first frequency band may be higher than the second frequency band. In some embodiments, the first frequency band may be lower than the second frequency band.

In some exemplary embodiments, node 110 may include or may perform the

functionality of an infrastructure station, a base station (BS), an access point (AP), a WiFi node, a WiMax node, a cellular node, an eNodeB, a station, a hot spot, a network controller, and the like. In some exemplary embodiments, mobile devices 120 and/or 130 may include, for example, a UE, a mobile computer, a laptop computer, a notebook computer, a tablet computer, an Ultrabook™ computer, a mobile internet device, a handheld computer, a handheld device, a storage device, a PDA device, a handheld PDA device, an on-board device, an off-board device, a hybrid device (e.g., combining cellular phone functionalities with PDA device functionalities), a consumer device, a vehicular device, a non-vehicular device, a portable device, a mobile phone, a cellular telephone, a PCS device, a mobile or portable GPS device, a DVB device, a relatively small computing device, a non-desktop computer, an Ultra Mobile Device (UMD), an Ultra Mobile PC (UMPC), a Mobile Internet Device (MID), a video device, an audio device, an A/V device, a gaming device, a media player, a Smartphone, or the like.

In some exemplary embodiments, node 110, mobile device 120 and/or mobile device 130 may include one or more wireless communication units to perform wireless communication over the one or more wireless communication frequency bands between node 110, mobile device 120 and/or mobile device 130 and/or with one or more other wireless communication devices. For example, node 110 may include a first wireless communication unit 112 configured to communicate over the first frequency band, and a second wireless communication unit 114 configured to communicate over the second frequency band; mobile device 120 may include a first wireless communication unit 122 configured to communicate over the first frequency band, and a second wireless communication unit 124 configured to communicate over the second frequency band; and/or mobile device 130 may include a first wireless communication unit 132 configured to communicate over the first frequency band, and a second wireless communication unit 134 configured to communicate over the second frequency band.

In some exemplary embodiments, wireless communication units 112, 114, 122, 124, 132 and 134 may include, or may be associated with, one or more antennas. In one example, wireless communicate unit 112 may be associated with one or more antennas 108; wireless communicate unit 114 may be associated with one or more antennas 107; wireless communicate unit 122 may be associated with one or more antennas 128; wireless communicate unit 124 may be associated with one or more antennas 127; wireless communicate unit 132 may be associated with one or more antennas 138; and/or wireless communication unit 134 may be associated with one or more antennas 137.

Antennas 108, 107, 128, 127, 138 and/or 137 may include any type of antennas suitable for transmitting and/or receiving wireless communication signals, blocks, frames, transmission streams, packets, messages and/or data. For example, antennas 108, 107, 128, 127, 138 and/or 137 may include any suitable configuration, structure and/or arrangement of one or more antenna elements, components, units, assemblies and/or arrays. Antennas 108, 107, 128, 127, 138 and/or 137 may include, for example, antennas suitable for directional communication, e.g., using beamforming techniques. For example, antennas 108, 107, 128, 127, 138 and/or 137 may include a phased array antenna, a multiple element antenna, a set of switched beam antennas, and/or the like. In some embodiments, antennas 108, 107, 128, 127, 138 and/or 137 may implement transmit and receive functionalities using separate transmit and receive antenna elements. In some embodiments, antennas 108, 107, 128, 127, 138 and/or 137 may implement transmit and receive functionalities using common and/or integrated transmit/receive elements.

In some exemplary embodiments, mobile devices 120 and/or 130 may also include, for example, a processor 191, an input unit 192, an output unit 193, a memory unit 194, and a storage unit 195; and/or node 101 may also include, for example, one or more of a processor 111, a memory unit 117, and a storage unit 115. Node 110, mobile device 120 and/or mobile device 130 may optionally include other suitable hardware components and/or software components. In some exemplary embodiments, some or all of the components of node 110, mobile device 120 and/or mobile device 130 may be enclosed in a common housing or packaging, and may be interconnected or operably associated using one or more wired or wireless links. In other embodiments, components of node 110 may be distributed among multiple or separate devices.

Processor 111 and/or processor 191 include, for example, a processor, a microprocessor, a

Central Processing Unit (CPU), a Digital Signal Processor (DSP), one or more processor cores, a single-core processor, a dual-core processor, a multiple-core processor, a microprocessor, a host processor, a controller, a plurality of processors or controllers, a chip, a microchip, one or more circuits, circuitry, a logic unit, an Integrated Circuit (IC), an Application-Specific IC (ASIC), or any other suitable multi-purpose or specific processor or controller. For example, processor 111 executes instructions, for example, of an Operating System (OS) of node 110 and/or of one or more suitable applications.

Memory unit 117 and/or memory unit 194 include, for example, a Random Access Memory (RAM), a Read Only Memory (ROM), a Dynamic RAM (DRAM), a Synchronous DRAM (SD-RAM), a flash memory, a volatile memory, a non- volatile memory, a cache memory, a buffer, a short term memory unit, a long term memory unit, or other suitable memory units. Storage unit 115 and/or storage unit 195 include, for example, a hard disk drive, a floppy disk drive, a Compact Disk (CD) drive, a CD-ROM drive, a DVD drive, or other suitable removable or non-removable storage units. For example, memory unit 117 and/or storage unit 115, for example, may store data processed by node 101.

Input unit 192 includes, for example, a keyboard, a keypad, a mouse, a touch-screen, a touch-pad, a track-ball, a stylus, a microphone, or other suitable pointing device or input device. Output unit 193 includes, for example, a monitor, a screen, a touch-screen, a flat panel display, a Cathode Ray Tube (CRT) display unit, a Liquid Crystal Display (LCD) display unit, a plasma display unit, one or more audio speakers or earphones, or other suitable output devices.

In some exemplary embodiments, mobile device 120 and node 110 may establish a wireless communication link 105 for communication between mobile device 120 and node 110 over a frequency band. For example, mobile device 120 and node 110 may establish link 105, e.g., upon entering of mobile device 120 into a cell controlled by node 110.

In some exemplary embodiments, mobile device 130 and node 110 may establish a wireless communication link 135 for communication between mobile device 130 and node 110 over a frequency band. For example, mobile device 130 and node 110 may establish link 135, e.g., upon entering of mobile device 130 into a cell controlled by node 110. In some exemplary embodiments, node 110 may include a wireless communication controller 116 configured to control wireless communication unit 114 to communicate information over a frequency band, e.g., via antennas 107. In some exemplary embodiments, mobile device 120 may include a wireless communication controller 126 configured to control wireless communication unit 124 to communicate information over a frequency band, e.g., via antennas 127. In some exemplary embodiments, controller 116 may control wireless communication unit 114 to communicate information between node 110 and mobile device 120, and to establish a link 103 between node 110 and mobile device 120. In some exemplary embodiments, controller 126 may control wireless communication unit 124 to communicate information between mobile device 120 and node 110, and to establish link 103 between node 110 and mobile device 120.

In some exemplary embodiments, mobile device 130 may include a wireless communication controller 136 configured to control wireless communication unit 134 to communicate information over a frequency band, e.g., via antennas 137. In some exemplary embodiments, controller 136 may control wireless communication unit 134 to communicate information between mobile device 130 and node 110, and to establish a link 133 between node 110 and mobile device 130. In some exemplary embodiments, controller 116 may control wireless communication unit 114 to communicate information between node 110 and mobile device 130, and to establish link 133 between node 110 and mobile device 130.

In some exemplary embodiments, controller 116 may control wireless communication unit 114 to communicate information between node 110 and mobile devices 120 and 130; and to control mobile devices 120 and 130 to establish a link 123 between mobile device 120 and mobile device 130.

In some exemplary embodiments, links 103, 123 and/or 133 may include a direct link, e.g., a P2P link, for example, to enable direct communication between node 110, mobile device 120 and/or mobile device 130. In some exemplary embodiments, links 103, 123 and/or 133 may include a wireless beamformed link.

In one example, the information communicated between node 110 and mobile device 120 may include information with respect to node 110, e.g., supported transmission power levels of node 110, one or more modulation orders of node 110, a number of antennas of antennas 108, a number of antenna elements per antenna of antennas 108, and/or a beamforming capability of wireless communication unit 112; and/or capability information with respect to mobile device 120, e.g., wireless communication unit 122, supported transmission power levels of device 120, one or more modulation orders of device 120, a number of antennas of antennas 128, a number of antenna elements per antenna of antennas 128, and/or a beamforming capability of wireless communication unit 122.

In another example, the information communicated between node 110 and mobile device 120, e.g., via link 105, and/or between node 110 and mobile device 130, e.g., via link 135, to establish link 123, may include information with respect to mobile device 120; and/or information with respect to mobile device 130, e.g., whether device 130 includes e.g., wireless communication unit 132, supported transmission power levels of device 130, one or more modulation orders of device 130, a number of antennas of antennas 138, a number of antenna elements per antenna of antennas 138, and/or a beamforming capability of wireless

communication unit 132.

In some exemplary embodiments, the information with respect to a device may include location information corresponding to a location of the device. In one example, the information communicated between node 110 and mobile device 120 may include location information corresponding to a location of node 110, e.g., a location Fix of node 110; and/or location information corresponding to a location of mobile device 120, e.g., a location Fix of mobile device 120. In one example, the information communicated between node 110 and mobile device 120 may include location information corresponding to a location of node 110, e.g., a location Fix of node 110; and/or location information corresponding to a location of mobile device 120, e.g., a location Fix of mobile device 120. In another example, the information communicated between node 110 and mobile device 120, and between node 110 and mobile device 130, e.g., before establishing link 123, may include location information corresponding to a location of device 120, e.g., a location Fix of device 120; and/or location information corresponding to a location of mobile device 130, e.g., a location Fix of mobile device 130.

In one example, node 110 and mobile device 120 may communicate, e.g., before establishing link 103, e.g., via link 105, information including the transmission power levels of node 110 and/or device 120; the modulation orders of node 110 and/or device 120; the number of antennas of antennas 108 and/or 208; the number of antenna elements per antenna of antennas 108 and/or 208; the beamforming capability of wireless communication units 112 and/or 122; and/or the location information corresponding to the location of mobile device 120 and/or node 110.,

In some exemplary embodiments, control information corresponding to links 103, 123 and/or 133, e.g., a DMRS; link adaptation, error control, beamforming adjustments, signal quality feedback and/or the like may be communicated via links 103, 123 and/or 133. Some exemplary embodiments, e.g., the communication system 100, may be used in conjunction with one or more types of wireless communication signals and/or systems, for example, Radio Frequency (RF), Infra-Red (IR), Frequency-Division Multiplexing (FDM), OFDM, Time-Division Multiplexing (TDM), Time-Division Multiple Access (TDM A), Extended TDMA (E-TDMA), General Packet Radio Service (GPRS), extended GPRS, Code- Division Multiple Access (CDMA), Wideband CDMA (WCDMA), CDMA 2000, single-carrier CDMA, multi-carrier CDMA, Multi-Carrier Modulation (MDM), Discrete Multi-Tone (DMT), Bluetooth®, Global Positioning System (GPS), Wi-Fi, Wi-Max, ZigBee™, Ultra- Wideband (UWB), Global System for Mobile communication (GSM), 2G, 2.5G, 3G, 3.5G, 4G, Fifth Generation (5G) mobile networks, 3GPP, Long Term Evolution (LTE), LTE advanced (LTE-A), Enhanced Data rates for GSM Evolution (EDGE), or the like. Other embodiments may be used in various other devices, systems and/or networks.

The communication system 100 and various exemplary embodiments may include logical channels that are classified into Control Channels and Traffic Channels. Logical control channels may include a broadcast control channel (BCCH), which is the downlink channel for broadcasting system control information, a paging control channel (PCCH), which is the downlink channel that transfers paging information, a multicast control channel (MCCH), which is a point-to-multipoint downlink channel used for transmitting multimedia broadcast and multicast service (MB MS) scheduling and control information for one or several multicast traffic channels (MTCHs). Generally, after establishing radio resource control (RRC) connection, MCCH is only used by the UE that receive MBMS. Dedicated control channel (DCCH) is another logical control channel that is a point-to-point bi-directional channel transmitting dedicated control information, such as user-specific control information used by the user equipment having an RRC connection. Common control channel (CCCH) is also a logical control channel that may be used for random access information. Logical traffic channels may comprise a dedicated traffic channel (DTCH), which is a point-to-point bi-directional channel dedicated to one user equipment for the transfer of user information. Also, a multicast traffic channel (MTCH) may be used for point-to-multipoint downlink transmission of traffic data.

Furthermore, the communication system 100 and various exemplary embodiments may additionally include logical transport channels that are classified DL and UL. The DL transport channels may include a broadcast channel (BCH), a downlink shared data channel (DL-SDCH), a multicast channel (MCH) and a Paging Channel (PCH). The UL transport channels may include a random access channel (RACH), a request channel (REQCH), an uplink shared data channel (UL-SDCH) and a plurality of physical channels. The physical channels may also include a set of downlink and uplink channels.

The DL physical channels may include at least one of DMRS, a common pilot channel (CPICH), a synchronization channel (SCH), a common control channel (CCCH), a shared downlink control channel (SDCCH), a multicast control channel (MCCH), a shared uplink assignment channel (SUACH), an acknowledgement channel (ACKCH), a downlink physical shared data channel (DL-PSDCH), an uplink power control channel (UPCCH), a paging indicator channel (PICH), a load indicator channel (LICH), a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), S-PDCCH, a physical hybrid ARQ indicator channel (PHICH), a physical downlink shared channel (PDSCH), S-PDSCH, and a physical multicast channel (PMCH). The UL physical channels may include at least one of a physical random access channel (PRACH) and/or xPRACH, a channel quality indicator channel (CQICH), an acknowledgement channel (ACKCH), an antenna subset indicator channel (ASICH), a shared request channel (SREQCH), an uplink physical shared data channel (UL-PSDCH), a broadband pilot channel (BPICH), a physical uplink control channel (PUCCH) and a physical uplink shared channel (PUSCH).

One or more embodiments may use a communication frame structure or subframe that includes one or more of the above-indicated DL physical channels and/or UL physical channels. Moreover, the communication frame structure or subframe may include additional parameters. Such parameters may include an xSRS or SRS, a BRRS, a guard period (GP), DMRS pattern, and the like.

In one implementation, LLRB size may be included in downlink control information (DCI). The LLRB size may be based on S-TTI and a reference length associated with DMRSs.

Embodiments herein may enable short TTI (S-TTI) operations that make it possible to reduce the reference signaling overhead and packet latency. This may be achieved by: (1) S-TTI length based LLRB used for resource allocation of S-PDSCH or S-PDCCH to address the issue of unnecessary protocol overheads; (2) DMRS patterns to reduce the demodulation latency of PDSCH and balance the DMRS overhead in a rather S-TTI (e.g. 2-symbols S-TTI) and channel estimation performance. More specifically, DMRS for demodulation in S-TTI n may be transmitted in S-TTI n or earlier S-TTI (e.g. S-TTI n-l); (3) Time-domain S-TTI bundling or DMRS clusters type based DMRS transmission to reduce the DMRS overhead.

Some embodiments may relate to wireless communication is provided to support MIMO transmission in S-TTI length for LTE systems. The technique may include determining if a RS pattern based on a LLRB structure providing reduced overhead is to be used for at least one channel, based on at least in part on TTI length; and transmitting to a wireless node using the at least one channel using LLRB based RS pattern with reduced overhead.

Some embodiments may relate to wireless communication is provided to support MIMO transmission in S-TTI length for LTE systems. The technique may include determining if a RS pattern based on an LLRB structure providing reduced overhead is to be used for at least one channel, based on at least in part on S-TTI length; and transmitting to a wireless node using the at least one channel using LLRB based RS pattern with reduced overhead.

FIG. 2 illustrates details of an LLRB structure that may be used to describe the mapping

DL S— TI of certain physical channels to REs for S-TTI operations. One LLRB 300 is defined as N_sy7^_b consecutive OFDM symbols in the time domain and K x N^c consecutive subcarriers in frequency domain, where N^_y^_b ^{7 7} denotes the number of OFDM symbols in an S-TTI and N^c denotes the resource block size in the frequency domain in a Rel-13 LTE system (e.g., N^c ⁼ 12). The K in a LLRB may be a function of -Vj¾^_7Ti.

In accordance to certain aspect, each LLRB may include K consecutive RBs in frequency domain, where K = [ NR_ef,_smboi / N_sy^_b ] or [ NR_ef,_smboi / N_sy^_b ] and NR_ef,_smboi denotes NRefismboi■ The K value may be semi-statically configurable in Radio Resource Control (RRC) signaling, and/or dynamically indicated by way of DCI formats, or is fixed in accordance with a specification. For example, an S-TTI length of 7 may be associated with an LLRB size of 2; or an S-TTI length of 2 may be associated with an LLRB size of 6; or an S-TTI length of 1 may be associated with an LLRB size of 12.

In one implementation, K= 1 may be allowed for signaling to provide a way for the eNodeB to disable the LLRB scaling mechanism for S-TTI. Furthermore, in one

implementation, for example, NR_ef,smboi is equal to 14 or 12 for NCP and 12 or 10 for an extended cyclic prefix (ECP).

FIG. 3 illustrates an exemplary LLRB, which illustrates an exemplary LLRB structure in one S-TTI period. The exemplary LLRB shown in FIG.3 conceptually illustrates an LLRB structure in one S-TTI period (N_syi^_b ) of 7 symbols, 2 symbols and 1 symbol. It is noted that this particular LLRB structure is shown for purpose of explanation, and is not intended to be in any way limiting. With NR_ef,_smboi = 12 for the 2-symbols S-TTI case, one LLRB 420 may include 6 consecutive RBs in the frequency domain and 2 symbols in the time domain to provide the almost same number of REs as one RB 400 in a Rel-13 LTE system for S-TTI transmission. This design can effectively avoid the unnecessary RLC segmentations for a given payload to remove the substantial protocol overhead to some extent. In addition, it effectively reduces the RA field size in DCI formats. The RB 440 can be used for normal UEs without enabling S-TTI operation.

When the communication system 100 is implemented as an LTE system, each UE may be semi-statically configured with a DL transmission mode. There are ten different transmission modes (TMs) defined for LTE, wherein TMs 1-6 rely on CRS and TM 7-10 rely on UE specific DMRS. To balance the trade-off between channel estimation and rate-loss due to DMRS overhead, DMRS-based TMs may be conditionally supported depending on the S-TTI length (e.g., S-TTI length dependent TMs support). Since CRS for up to 4 antenna ports may be present in every subframe to meet the backward compatibility requirement, DMRS-based TM may be not supported for relatively short S-TTI (e.g. 1-symbol STTI). Instead, CRS-based TMs may be used. A disadvantage of this may be that the performance of rather short S-TTI may be limited by the available CRS antenna ports. Alternatively, the implemented TM the presence of corresponding DMRS in a rather short TTI may be dynamically indicated via PDCCH, such as based on the number of configured CRS ports and the channel experienced by a particular UE.

To overcome the foregoing and to make it possible to support DMRS-based TM in any S-

TTI configuration, block diagrams of DMRS pattern according to several embodiments are illustrated in FIGS. 4A-4C. Referring to the figures, LLRB 500, 501 and 502 are defined by N symbols periods by S subcarriers. Each LLRB 500, 501 and 502 includes DMRS REs 512, with the remaining REs 513 available for data symbols and other symbols. Although the illustrated embodiments illustrate DMRS cluster comprising 2 or 4 REs, DMRS clusters of any appropriate size may be utilized according to alternative embodiments.

In one embodiment as depicted in FIG. 4A, to minimize the latency for the

demodulation of the associated data in RE 513, DMRS REs 512 are placed at the first symbol of LLRB 500 (e.g., symbol 1 in FIG. 4A). DMRS symbols are arranged in contiguous DMRS clusters 503, 504 and 505. In this design, each cluster spans F contiguous subcarriers within the first symbol. Each cluster is comprised of a fixed and same RE numbers. The F DMRS REs in each cluster may be used for channel estimation for up to F layers that are orthogonally multiplexed in a FDM or CDM manner.

In another embodiment, as shown in FIG. 4B, DRMS REs 512 are located in contiguous DMRS cluster 506, 507 and 508 with each cluster spanning multiple symbol periods starting from the first symbol (e.g., symbol 1 in FIG. 4B) of LLRB 501 and one subcarrier.

In yet another embodiment, as shown in FIG. 4C, each cluster spans F contiguous subcarriers in the first M symbols period. The F M DMRS REs in one cluster 509 may be used for channel estimation for up to F x M spatial layers. In some embodiments, the DMRS pattern utilized may be fixed in the relevant specification. Alternatively, the DMRS pattern may be semi-statically configured for a UE by higher layers based on a channel that an UE is using. For high-speed UEs (e.g., vehicular based), for example, the DMRS pattern in FIG. 4A may be suitable. For low speed UEs, however, the DMRS pattern of FIG. 4B may be suitable. For example, an eNodeB may identify a high- mobility UE by receiving a high mobility indicator from the UE or based on measurement at the eNodeB side. Then, the eNodeB may send DMRS patterns illustrated in FIG. 4A or 4C to the high mobility UE.

DMRS clusters may be symmetric with respect to the center subcarrier of the LLRB region. The symmetry of DMRS clusters may provide improved channel estimation

performance. In one implementation, the DMRS clusters may be spaced approximately equally across frequency in the symbol periods. In the embodiments depicted in FIG. 4A-4C, subcarriers at the edges of one LLBR region (e.g., subcarrier 5 and/or 1), may be included as part of the DMRS REs in a cluster.

Alternative DMRS patterns may be utilized according to various embodiments. In particular, FIGS. 5A-5D illustrate various DMRS patterns or clusters 600 that may be used for the DMRS-based DL transmission in S-TTI configurations with different symbol periods. In particular implementations, the DMRS patterns cover 12 subcarries in two symbol periods. Each DMRS pattern may include eight DMRS REs 610 on subcarrier 3/4/8/9 in two symbol periods, with the remaining REs 620 available for data symbols or control symbols.

As depicted in FIGS. 5 A, 5B, the patterns 600 may be used in the first 2 symbol periods within a LLRB. For a 1-symbol S-TTI configuration, a punctured structure in symbol 0 can be used (as shown in FIG.6D). Such unified DMRS patterns 600 may, however, result in substantial RS overhead for some rather short S-TTI configurations. For example, the DMRS overhead per LLRB is increased from 9.5% for 7-symbols S-TTI to 33.3% for 2-symbols S-TTI case.

Alternatively, to solve this problem, the DMRS cluster density in the frequency domain can be deceased for a shorter S-TTI by increasing the subcarriers number between two contiguous DMRS clusters.

As an embodiment illustrated in FIGS. 5A, 5C, to maintain the same DMRS overhead within a LRRB (e.g. 16 REs) for 7-symbols and 3-symbols S-TTI cases, the space in the frequency domain between two consecutive DMRS clusters may be increased from 4 to 10 subcarriers. As estimation accuracy can depend on the number of DMRS clusters over which the channel parameters are estimated. Estimating the channel over an insufficient number of DMRS clusters may lead to inaccurate channel parameters. Thus, the density of DMRS cluster in the frequency domain may be properly selected and a relatively increased DMRS overhead is expected for a shorter S-TTI. For the 7-symbols S-TTI configuration, one more DMRS may be further inserted in the last OFDM symbols 5 and 6. Alternatively, the DMRS symbols may be moved to 2 and 3 or 2 and 4, in order to avoid a collision with a CRS transmission.

In accordance with an embodiment, the DMRS REs 610 may also be arranged to support spatial multiplexing techniques such as MIMO and/or Spatial Division Multiple Access

(SDMA). In one design, Q DMRS REs (e.g. Q=4) in a DMRS cluster 630 may be used for channel estimation for up to Q spatial channels. The corresponding DMRS REs associated with Q layers may be multiplexed in Frequency-Division Multiplex (FDM) and/or Time-Division Multiplex (TDM) in Q set of frequencies over 1 or 2 symbol periods. For example, four antenna ports indexing K to K+3 to support rank 4 transmission may use FDM/TDM RE "a", "b", "c", "d" in each cluster, respectively. Alternatively, DMRS over a set of UEs within one cluster or two contiguous clusters in a Code-Division Multiplex (CDM) manner can be also considered. For example, referring to DMRS cluster 630, for PDSCHs transmitted at MIMO rank 2 and below, a spreading factor of 2 (SF2) may be used, whereby DMRS symbols are spread across two consecutive REs in a DMRS cluster either in time (e.g. REs pair <a, b> or <c,d>) or in frequency (e.g. REs pair <a,c> or <b,d>). For PDSCH transmitted at MIMO rank 3 or 4, a spreading factor of 4 may be used, whereby DMRS symbols are spread across a set of REs <a,b,c,d> in a DMRS cluster in both time and frequency.

It should be noted that the first OFDM symbol or other symbols used for DMRS REs in the figures may be shifted in time domain to avoid collision with legacy CRS and max legacy PDCCH region of 4 OFDM symbols to ensure the backward compatible. Also, DMRS for S- TTIs may have to limit to non-CRS OFDM symbols to completely avoid the collision with legacy CRS taking into account the cell dependent shift. This design would result in the various DMRS pattern in S-TTIs depending on the presence of CRS and legacy PDCCH region.

In the design disclosed above, the DMRS clusters in a LLRB n is used for the demodulation of PDSCH transmitted in the LLRB n itself. As depicted in FIG. 4A-4C as an example, one disadvantage of this solution is that demodulation of S-TTI n would be delayed until receipt of the 1 or 2 symbol having the DMRS presence in order to obtain channel estimations, thereby delaying an acknowledgement (ACK) and/or negative ACK (NACK).

Some embodiments herein may provide enhancements with respect to the

aforementioned DMRS clusters designs, to further reduce the channel estimation latency.

Accordingly, DMRS clusters used for PDSCH transmitted in S-TTI n+l may be transmitted in S- TTI n. For example, in the embodiment illustrated in FIG. 6, a DMRS cluster 710 in S-TTI n may be used for PDSCH demodulation in S-TTI n+l, while DMRS cluster 720 in S-TTI n+l is used for PDSCH demodulation in S-TTI n+2, and so forth.

Data transmission rate-matching around the DMRS 710 in LLRB 700 may be used. For example, when a PDSCH is mapped to the REs, it may only be mapped to those REs not occupied by the DMRS REs 710. Alternatively, data transmission in LLRB 700 may be punctured in locations with the DMRS REs 710. In one example of signaling the presence of DMRS 710 to support rate-matching operation, DCI formats may be used to indicate whether DMRS 710 for next S-TTI n+l may be present or not in an explicit or implicit manner.

Embodiments of the disclosure herein provide techniques in which RS overhead may be dynamically reduced based upon a number of criteria and yet reduced packet latency and reliable demodulation of the transmitted data are provided. In accordance to an aspect to reduce DMRS overhead, a concept of S-TTIs bundling in time is disclosed.

In one implementation as illustrated in FIG. 7, S-TTIs bundling window 800 of size N comprise of S-TTI n to S-TTI n+N-l. In one embodiment, the S-TTIs bundling window size may be fixed to be equal to one subframe in LTE system (e.g., 1 ms). Alternatively, the S-TTIs bundling window size may be semi-statically configurable by higher layers based on UE feedback or network measurement (e.g., on mobility speed of a particular UE). Additionally, the S-TTIs bundling window size may be dynamically configured by PDCCH.

The DMRS clusters using pattern 804 in each LLRB may be only present in the first S- TTI 801 within S-TTIs bundling window 800. Alternatively, a subset of DMRS clusters in the first S-TTI 801 may be also present in other additional S-TTIs of the bundling window 800. The rationale is that subsequent S-TTI may utilize not only their own DMRS clusters, but also the DMRS clusters of earlier S-TTIs to improve the channel estimation performance and so the DMRS density can be reduced, assuming a single pre-coder is selected for all S-TTIs in a bundling window for a given UE.

In one design, the DMRS pattern implemented in S-TTI 802 and 803 may be identical, such as by using DMRS pattern 805. In yet another implementation, the DMRS pattern used in consecutive S-TTIs within a bundling window may be varied. As illustrated in FIG.7, DMRS pattern 805, 806 and 807 may be used in three consecutive S-TTIs n +1, n+2 and n+3 to help improve frequency granularity of DMRS. In another implementation, the one or more subsequent S-TTIs provides more DMRS reductions than that of a previous subframe. The MCS may be also varied across S-TTs in a bundling window due to more utilizable DMRS clusters for later S-TTIs. In addition, this mechanism may be limited to some channels only (e.g., PDSCH). A fixed DMRS pattern such as DMRS pattern 804 may be used for PDCCH in S-TTIs due to lack of hybrid automatic repeat request (hybrid ARQ or HARQ) operations. HARQ operations typically include a combination of high-rate forward error-correcting coding and ARQ error- control.

In some embodiments, DMRS clusters in a LLRB may be divided into different DMRS cluster types to provide a way of reduced DMRS overhead. As depicted in FIG.8A, DMRS clusters in LLRB 900 comprise Type-1 DMRS cluster 901 and 903, and Type-2 DMRS cluster 902. Type-1 DMRS clusters 901 and 903 may be kind of baseline DMRS clusters that are by default present. One or more Type-2 DMRS clusters 902 may be UE specifically added to deal with smaller channel coherence bandwidth in addition to Type-1 DMRS clusters. In one example, the Type-2 DMRS clusters may be present in the same symbol(s) that include the Type-1 DMRS clusters. Additionally or alternatively, the Type-2 DMRS clusters 902 may be present in symbols that do not include Type-1 DMRS clusters 901 and 903 to increase DMRS time density for a high-mobility UE. The presence of Type-2 DMRS clusters may by indicated by RRC messaging or PDCCH in an explicit or implicit way. As shown in FIG. 8B in one PRB, it is possible to move the first and last two blocks by 1 RE to the middle, so the gap between three DMRS blocks is 2 REs.

FIG.8B shows one embodiment of implementing RB group based DMRS pattern design for S-TTIs. In the illustrated example, PDSCH 950 comprises RBs 908-916, wherein RB 908- 910 forms RB group 905, and RB 911-913 forms RB group 906 and RB 914-916 forms RB group 907. DMRS clusters may be present in a subset of RB of a RB group while other RBs in the cluster (e.g., RB 908 and 910) do not include DMRS clusters. DMRS presence in one RB (e.g., RB 909) may be used for demodulation of PDSCH in the RBs 908-910. RB group size may be fixed in specification or semi-statically configured by RRC signaling or dynamically indicated on PDCCH. Within a RB group, it is expected that same precoding may be applied to all RBs. In one implementation, the RB group size is same as the size of precoding RB groups, such as defined in the LTE Rel-10 specification. Note that the other RB (e.g., RB 908 or 910) in one RB group may be selected for DMRS transmission.

Other DMRS implementations may be used according to various embodiments. In one implementation, for example, DMRS symbols (for low latency) are placed by one or two OFDM symbols right after a legacy PDCCH region or a PDSCH starting symbol indicated by higher layer signaling. In addition, search space for DMRS may be defined in frequency domain. By doing so, a UE can estimate channel in the DMRS search space. Once a UE knows the scheduling after decoding S-PDCCH, the estimation can be used for data demodulation transmitted on S-PDSCH. Thus, only one or two symbols in the very first symbols are typically needed within a subframe for DMRS transmission.

In another implementation, DMRS is defined in S-PDCCH region only. Therefore, there is no DMRS or a less DMRSs transmitted in S-PDSCH compared to that in S-PDCCH region. The regions for S-PDCCH and S-PDSCH can be shared or overlapped. One option would be to limit the DMRS in S-PDCCH region only, and after blind decoding, the channel estimation for S-PDCCH can be reused for S-PDSCH.

UE-specific S-PDCCH search space may be defined. S-PDSCH can be scheduled within S-PDCCH search space. S-PDSCH may be scheduled in a subset of S-PDCCH search space.

FIG. 9 illustrates example components of an electronic device 900. In embodiments, the electronic device 900 may, implement, be incorporated into, or otherwise be a part of a UE, a node such as an eNodeB, some other equipment capable of performing similar operations, or some combination thereof. In some embodiments, the UE device 900 may include application circuitry 902, baseband circuitry 904, Radio Frequency (RF) circuitry 906, front-end module (FEM) circuitry 908 and one or more antennas 910, coupled together at least as shown.

As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be

implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware. Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software.

The application circuitry 902 may include one or more application processors. For example, the application circuitry 902 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with and/or may include memory/storage (e.g., memory/storage 904g or 906e) and may be configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems to run on the system.

The baseband circuitry 904 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 904 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry 906 and to generate baseband signals for a transmit signal path of the RF circuitry 906. Baseband processing circuity 904 may interface with the application circuitry 902 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 906. For example, in some embodiments, the baseband circuitry 904 may include a second generation (2G) baseband processor 904a, third generation (3G) baseband processor 904b, fourth generation (4G) baseband processor 904c, and/or other baseband processor(s) 904d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 904 (e.g., one or more of baseband processors 904a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 906. The radio control functions may include, but are not limited to, signal modulation/demodulation,

encoding/decoding, radio frequency shifting, etc. In some embodiments,

modulation/demodulation circuitry of the baseband circuitry 904 may include Fast-Fourier Transform (FFT), precoding, and/or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 904 may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry 904 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 904e of the baseband circuitry 904 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 904f. The audio DSP(s) 904f may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 904 and the application circuitry 902 may be implemented together such as, for example, on a system on a chip (SOC). In some embodiments, the baseband circuitry 904 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 904 may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 904 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

The baseband circuitry 904 may be coupled with and/or may include memory/storage (e.g., memory/storage 904g) and may be configured to execute instructions stored in the memory/storage to enable various, processes, applications to run.

RF circuitry 906 may enable communication with wireless networks using modulated electromagnetic radiation through a non- solid medium. In various embodiments, the RF circuitry 906 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 906 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 908 and provide baseband signals to the baseband circuitry 904. RF circuitry 906 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 904 and provide RF output signals to the FEM circuitry 908 for transmission.

In some embodiments, the RF circuitry 906 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 906 may include mixer circuitry 906a, amplifier circuitry 906b and filter circuitry 906c. The transmit signal path of the RF circuitry 906 may include filter circuitry 906c and mixer circuitry 906a. RF circuitry 906 may also include synthesizer circuitry 906d for synthesizing a frequency for use by the mixer circuitry 906a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 906a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 908 based on the synthesized frequency provided by synthesizer circuitry 906d. The amplifier circuitry 906b may be configured to amplify the down-converted signals and the filter circuitry 906c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 904 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 906a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect. In some embodiments, the mixer circuitry 906a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 906d to generate RF output signals for the FEM circuitry 908. The baseband signals may be provided by the baseband circuitry 904 and may be filtered by filter circuitry 906c. The filter circuitry 906c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 906a of the receive signal path and the mixer circuitry 906a of the transmit signal path may include two or more mixers and may be arranged for quadrature down conversion and/or up conversion respectively. In some embodiments, the mixer circuitry 906a of the receive signal path and the mixer circuitry 906a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 906a of the receive signal path and the mixer circuitry 906a may be arranged for direct down conversion and/or direct up conversion, respectively. In some embodiments, the mixer circuitry 906a of the receive signal path and the mixer circuitry 906a of the transmit signal path may be configured for superheterodyne operation.

In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 906 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 904 may include a digital baseband interface to communicate with the RF circuitry 906.

In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 906d may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 906d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

The synthesizer circuitry 906d may be configured to synthesize an output frequency for use by the mixer circuitry 906a of the RF circuitry 906 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 906d may be a fractional N/N+l synthesizer.

In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 904 or the applications processor 902 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 902.

Synthesizer circuitry 906d of the RF circuitry 906 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 906d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some

embodiments, the RF circuitry 906 may include an IQ/polar converter.

Front-end module (FEM) circuitry 908 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 910, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 906 for further processing. FEM circuitry 908 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 906 for transmission by one or more of the one or more antennas 910.

In some embodiments, the FEM circuitry 908 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 906). The transmit signal path of the FEM circuitry 908 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 906), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 910.

In some embodiments, the electronic device 900 may include additional elements such as, for example, memory/storage, display, camera, sensor, and/or input/output (I/O) interface. For example, the RF circuitry 906 may be coupled with and/or may include memory/storage (e.g., memory/storage 906e) and may be configured to execute instructions stored in the memory/storage .

In embodiments where the electronic device 900 is, implements, is incorporated into, or is otherwise part of a UE, the RF circuitry 906 may receive a long term evolution (LTE) subframe that includes a BRRS. The baseband circuitry 904 may be to determine a value of the BRRS and switch a DL Tx beam based on the value of the BRRS.

In embodiments where the electronic device 900 implements part of an eNodeB, network node, or cellular base station, RF circuitry 906 may be receive a LTE subframe that includes extended sounding RS (xSRS), such as used in 5G wireless systems. The baseband circuitry 904 may determine a value of the xSRS within the LTE subframe and refine an UL Rx beam based on the value of the xSRS.

FIG. 10 illustrates an embodiment of a storage medium 1000. The storage medium 1000 may comprise an article of manufacture. In one embodiment, the storage medium 1000 may comprise any non-transitory computer readable medium or machine readable medium, such as an optical, magnetic or semiconductor storage. The storage medium may store various types of computer executable instructions, such as instructions 1002 to implement one or more of logic flows described herein. Examples of a computer readable or machine readable storage medium may include any tangible media capable of storing electronic data, including volatile memory or non- volatile memory, removable or non-removable memory, erasable or non-erasable memory, writeable or re-writeable memory, and so forth. Examples of computer executable instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, object-oriented code, visual code, and the like. The embodiments are not limited in this context.

In some embodiments, the electronic device of FIG. 9 may be configured to perform one or more processes, techniques, and/or methods as described herein, or portions thereof. One such process 1100 is depicted in FIG. 11. For example, the process may include, at 1102, identifying a short transmission time interval (S-TTI) length based on which to allocate resources of a channel of a radio access network cell. At 1104, the process may further include based on the S- TTI length, determining a low latency resource block (LLRB) size according to which to allocate resources of the channel and a demodulation reference signal (DMRS) pattern according to which to transmit DMRSs to user equipment (UE) via the channel. At 1106, the process may further include generating the DMRSs for transmission to the UE using resources identified based on the DMRS pattern.

In some embodiments, the electronic device of FIG. 9 may be configured to perform one or more processes, techniques, and/or methods as described herein, or portions thereof. One such process 1200 is depicted in FIG. 12. For example, the process may include, at 1202, identifying a short transmission time interval (S-TTI) length and a low latency resource block (LLRB) size governing resource allocation for communications over a channel of a cell served by an evolved node B (eNodeB). At 1204, the process may further include identifying a demodulation reference signal (DMRS) pattern applicable to DMRS transmissions to the UE via the channel. At 1206, accessing the channel to receive DMRSs from the eNodeB via a set of resources identified based on the DMRS pattern.

Various embodiments may be implemented using hardware elements, software elements, or a combination of both. Examples of hardware elements may include processors,

microprocessors, circuits, circuit elements (e.g., transistors, resistors, capacitors, inductors, and so forth), integrated circuits, application specific integrated circuits (ASIC), programmable logic devices (PLD), digital signal processors (DSP), field programmable gate array (FPGA), logic gates, registers, semiconductor device, chips, microchips, chip sets, and so forth. Examples of software may include software components, programs, applications, computer programs, application programs, system programs, machine programs, operating system software, middleware, firmware, software modules, routines, subroutines, functions, methods, procedures, software interfaces, application program interfaces (API), instruction sets, computing code, computer code, code segments, computer code segments, words, values, symbols, or any combination thereof. Determining whether an embodiment is implemented using hardware elements and/or software elements may vary in accordance with any number of factors, such as desired computational rate, power levels, heat tolerances, processing cycle budget, input data rates, output data rates, memory resources, data bus speeds and other design or performance constraints.

One or more aspects of at least one embodiment may be implemented by representative instructions stored on a machine-readable medium which represents various logic within the processor, which when read by a machine causes the machine to fabricate logic to perform the techniques described herein. Such representations, known as "IP cores" may be stored on a tangible, machine readable medium and supplied to various customers or manufacturing facilities to load into the fabrication machines that actually make the logic or processor. Some embodiments may be implemented, for example, using a machine-readable medium or article which may store an instruction or a set of instructions that, if executed by a machine, may cause the machine to perform a method and/or operations in accordance with the embodiments. Such a machine may include, for example, any suitable processing platform, computing platform, computing device, processing device, computing system, processing system, computer, processor, or the like, and may be implemented using any suitable combination of hardware and/or software. The machine -readable medium or article may include, for example, any suitable type of memory unit, memory device, memory article, memory medium, storage device, storage article, storage medium and/or storage unit, for example, memory, removable or nonremovable media, erasable or non-erasable media, writeable or re-writeable media, digital or analog media, hard disk, floppy disk, Compact Disk Read Only Memory (CD-ROM), Compact Disk Recordable (CD-R), Compact Disk Rewriteable (CD-RW), optical disk, magnetic media, magneto-optical media, removable memory cards or disks, various types of Digital Versatile Disk (DVD), a tape, a cassette, or the like. The instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, encrypted code, and the like, implemented using any suitable high-level, low- level, object-oriented, visual, compiled and/or interpreted programming language.

Numerous specific details have been set forth herein to provide a thorough understanding of the embodiments. It will be understood by those skilled in the art, however, that the embodiments may be practiced without these specific details. In other instances, well-known operations, components, and circuits have not been described in detail so as not to obscure the embodiments. It can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments.

Some embodiments may be described using the expression "coupled" and "connected" along with their derivatives. These terms are not intended as synonyms for each other. For example, some embodiments may be described using the terms "connected" and/or "coupled" to indicate that two or more elements are in direct physical or electrical contact with each other. The term "coupled," however, may also mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other.

Unless specifically stated otherwise, it may be appreciated that terms such as

"processing," "computing," "calculating," "determining," or the like, refer to the action and/or processes of a computer or computing system, or similar electronic computing device, that manipulates and/or transforms data represented as physical quantities (e.g., electronic) within the computing system's registers and/or memories into other data similarly represented as physical quantities within the computing system's memories, registers or other such information storage, transmission or display devices. The embodiments are not limited in this context.

It should be noted that the methods described herein do not have to be executed in the order described, or in any particular order. Moreover, various activities described with respect to the methods identified herein can be executed in serial or parallel fashion.

Although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combinations of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description. Thus, the scope of various embodiments includes any other applications in which the above compositions, structures, and methods are used.

What has been described above includes examples of the disclosed architecture, system, devices, processes, structure, and functions. It is, of course, not possible to describe every conceivable combination of components and/or methodologies, but one of ordinary skill in the art may recognize that many further combinations and permutations are possible. Accordingly, the novel architecture is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. The detailed disclosure now turns to providing examples that pertain to further embodiments. The examples provided below are not intended to be limiting.

Example 1 may include a method of wireless communication, comprising: determining if a shorten TTI (S-TTI) length providing reduced latency is to be used for at least one channel; determining the low latency resource block (LLRB) size used for resource allocation of one channel based on at least partially the determined shorten TTI length; communicating with a wireless node using the at least one channel based on the determined the RB size and DMRS pattern corresponding to the determined TTI length.

Example 2 may include the method of example 1 and/or other examples herein, whereinthe determining the LLRB size used for resource allocation of one channel includes: one low latency resource block (LLRB) providing reduced latency comprises of N consecutive symbols in the time domain and S consecutive carriers, wherein the N denotes the number of OFDM symbols in the determined S-TTI and the resource block size in the frequency domain in a Rel-13 LTE system.

Example 3 may include the method of example 2 and/or other examples herein, wherein the value of K is determined according to the number of symbols in the determined S-TTI includes: Wherein N denotes the number of symbols in the determined S-TTI, and denotes the reference number of symbols. The value of may be fixed in specification or semi-statically configurable in Radio Resource Control (RRC) message and/or dynamically indicated by means of Downlink Control Information (DCI) formats on PDCCH transmitted in a S-TTI.

Example 4 may include the method of example 1 and/or other examples herein, wherein the DMRS pattern used for channel estimation for a S-TTI n includes: the plurality of DMRS patterns comprise DMRS clusters; and DMRS resource elements (REs) in each cluster are placed at the first OFDM symbol of the S-TTI n using a plurality of subcarrier in frequency.

Example 5 may include the method of example 4 and/or other examples herein, further comprising: a plurality of subcarrier in frequency includes subcarrier at the edges of one LLRB.

Example 6 may include the method of example 4 and/or other examples herein, further comprising: one DMRS cluster comprising 2 consecutive subcarriers in 2 symbol periods is used to support rank 4 transmission by spreading DMRS symbols with spreading factor of 4.

Example 7 may include the method of example 4 and/or other examples herein, further comprising: the DMRS cluster density in the frequency domain is varied for different S-TTI length configuration to ensure same amount of REs are used for DMRS in a LLRB independent of S-TTI length.

Example 8 may include the method of example 4 and/or examples herein, further comprising: the DMRS cluster density in the frequency domain is same for different S-TTI length configuration by using a single unified DMRS pattern in the first one or two symbols of a LLRB.

Example 9 may include the method of example 8 and/or other examples herein, where in the single unified DMRS pattern includes: a unified DMRS pattern covers 12 subcarriers in 2 symbol periods, wherein eight DMRS REs are arranged on subcarrier 3/4/8/9 in the first 2 symbol periods.

Example 10 may include the method of example 4 and/or other examples herein, further comprising: symbol used for DMRS REs in an S-TTI may be shifted in time domain to avoid collision with legacy CRS and max legacy PDCCH region. Example 11 may include the method of example 1 and/or other examples herein, wherein the DMRS pattern used for channel estimation for a S-TTI n includes: DMRS clusters used for channel estimation in S-TTI n is transmitted in an earlier S-TTI n-1.

Example 12 may include the method of example 1 and/or other examples herein, wherein the DMRS pattern providing reduced RS overhead further comprising: determining a S-TTIs time bundling window of size N comprising N consecutive S-TTIs; and transmitting, by the eNodeB , the DMRS in the first S-TTI that are used for the demodulation in the subsequent S- TTs within the same S-TTIs bundling window.

Example 13 may include the method of example 12 and/or other examples herein, further comprising: the size of S-TTIs bundling window may be fixed to be one subframe in LTE system (e.g. 1ms), or it may be semi-statically configurable by higher layers based on UE feedback or NW measurement (e.g. on mobility speed of a particular UE) or dynamically configured by PDCCH.

Example 14 may include the method of example 12 and/or other examples herein, further comprising: a subset of DMRS clusters in the first S-TTI of a bundling window may be also present in other S-TTIs of the bundling window.

Example 15 may include the method of example 14 and/or other examples herein, wherein DMRS clusters in other S-TTIs of a bundling window may be identical or may be varied.

Example 16 may include the method of example 1 and/or other examples herein, wherein the DMRS pattern providing reduced RS overhead further comprising: dividing the DMRS clusters in one LLRB into two types; and identify a UE under a channel condition with smaller channel coherence bandwidth; and transmitting Type-1 DMRS clusters in each LLRB; and sending the additional Type-2 DMRS clusters to the identified UE.

Example 17 may include an apparatus comprising means to perform one or more elements of a method described in or related to any of examples 1-16, or any other method or process described herein.

Example 18 may include one or more non-transitory computer-readable media comprising instructions to cause an electronic device, upon execution of the instructions by one or more processors of the electronic device, to perform one or more elements of a method described in or related to any of examples 1-16, or any other method or process described herein.

Example 19 may include an apparatus comprising logic, modules, and/or circuitry to perform one or more elements of a method described in or related to any of examples 1-16, or any other method or process described herein. Example 20 may include a method, technique, or process as described in or related to any of examples 1-16, or portions or parts thereof.

Example 21 may include an apparatus comprising: one or more processors and one or more computer readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform the method, techniques, or process as described in or related to any of examples 1-16, or portions thereof.

Example 22 may include a method of communicating in a wireless network as shown and described herein.

Example 23 may include a system for providing wireless communication as shown and described herein.

Example 24 may include a device for providing wireless communication as shown and described herein.

Example 25. An apparatus, comprising: a memory; and logic for an evolved node B (eNodeB), at least a portion of the logic implemented in circuitry coupled to the memory, the logic to: identify a short transmission time interval (S-TTI) length based on which to allocate resources of a channel of a radio access network cell; based on the S-TTI length, determine a low latency resource block (LLRB) size according to which to allocate resources of the channel and a demodulation reference signal (DMRS) pattern according to which to transmit DMRSs to user equipment (UE) via the channel; and generate the DMRSs for transmission to the UE using resources identified based on the DMRS pattern.

Example 26. The apparatus of example 25, the DMRS pattern to comprise multiple DMRS resource element (RE) clusters.

Example 27. The apparatus of example 26, each DMRS RE cluster to span a same number of orthogonal frequency-division multiplexing (OFDM) symbols.

Example 28. The apparatus of any of examples 25 to 26, each DMRS RE cluster to span a same number of subcarriers.

Example 29. The apparatus of any of examples 25 to 28, the logic to generate a radio resource control (RRC) message for transmission to the UE, the RRC message to comprise information indicating the DMRS pattern.

Example 30. The apparatus of any of examples 25 to 29, the logic to generate a radio resource control (RRC) message for transmission from the eNodeB , the RRC message to comprise information indicating the LLRB size. Example 31. The apparatus of any of examples 25 to 30, the logic to generate downlink control information (DCI) for transmission from the eNodeB, the DCI to comprise information indicating the LLRB size.

Example 32. The apparatus of any of examples 25 to 31, the logic to determine the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.

Example 33. The apparatus of example 32, the S-TTI length to comprise a first number of orthogonal frequency-division multiplexing (OFDM) symbols, the reference length to comprise a second number of OFDM symbols.

Example 34. The apparatus of any of examples 32 to 33, the logic to generate a radio resource control (RRC) message for transmission from the eNodeB, the RRC message to comprise information indicating the reference length.

Example 35. The apparatus of any of examples 32 to 34, the logic to generate downlink control information (DCI) for transmission from the eNodeB, the DCI to comprise information indicating the reference length.

Example 36. The apparatus of any of examples 25 to 35, the S-TTI length to comprise one orthogonal frequency-division multiplexing (OFDM) symbol.

Example 37. The apparatus of example 36, the LLRB size to comprise twelve resource blocks (RBs).

Example 38. The apparatus of any of examples 25 to 35, the S-TTI length to comprise two orthogonal frequency-division multiplexing (OFDM) symbols.

Example 39. The apparatus of example 38, the LLRB size to comprise six resource blocks (RBs).

Example 40. The apparatus of any of examples 25 to 35, the S-TTI length to comprise seven orthogonal frequency-division multiplexing (OFDM) symbols.

Example 41. The apparatus of example 40, the LLRB size to comprise two resource blocks (RBs).

Example 42. The apparatus of any of examples 25 to 42, the channel to comprise a shortened physical downlink shared channel (S-PDSCH).

Example 43. The apparatus of any of examples 25 to 42, the channel to comprise a shortened physical downlink control channel (S-PDCCH).

Example 44. An apparatus, comprising: a memory; and logic for user equipment (UE), at least a portion of the logic implemented in circuitry coupled to the memory, the logic to: identify a short transmission time interval (S-TTI) length and a low latency resource block (LLRB) size governing resource allocation for communications over a channel of a cell served by an evolved node B (eNodeB); identify a demodulation reference signal (DMRS) pattern applicable to DMRS transmissions to the UE via the channel; and access the channel to receive DMRSs from the eNodeB via a set of resources identified based on the DMRS pattern.

Example 45. The apparatus of example 44, the logic to identify the LLRB size based on information comprised in a radio resource control (RRC) message received from the eNodeB.

Example 46. The apparatus of example 44, the logic to identify the LLRB size based on downlink control information (DCI) received from the eNodeB.

Example 47. The apparatus of any of examples 44 to 46, the logic to identify the LLRB size based on the S-TTI length.

Example 48. The apparatus of example 47, the logic to identify the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.

Example 49. The apparatus of example 48, the S-TTI length to comprise a first number of orthogonal frequency-division multiplexing (OFDM) symbols, the reference length to comprise a second number of OFDM symbols.

Example 50. The apparatus of any of examples 48 to 49, the logic to identify the reference length based on information comprised in a radio resource control (RRC) message received from the eNodeB.

Example 51. The apparatus of any of examples 40 to 50, the logic to identify the reference length based on downlink control information (DCI) received from the eNodeB.

Example 52. The apparatus of any of examples 44 to 51 , the logic to identify the DMRS pattern based on information comprised in a radio resource control (RRC) message received from the eNodeB.

Example 53. The apparatus of any of examples 44 to 52, the DMRS pattern to comprise multiple DMRS resource element (RE) clusters.

Example 54. The apparatus of example 53, each DMRS RE cluster to span a same number of orthogonal frequency-division multiplexing (OFDM) symbols.

Example 55. The apparatus of any of examples 53 to 54, each DMRS RE cluster to span a same number of subcarriers.

Example 56. The apparatus of any of examples 44 to 55, the S-TTI length to comprise one orthogonal frequency-division multiplexing (OFDM) symbol.

Example 57. The apparatus of example 56, the LLRB size to comprise twelve resource blocks (RBs).

Example 58. The apparatus of any of examples 44 to 55, the S-TTI length to comprise two orthogonal frequency-division multiplexing (OFDM) symbols. Example 59. The apparatus of example 58, the LLRB size to comprise six resource blocks (RBs).

Example 60. The apparatus of any of examples 44 to 55, the S-TTI length to comprise seven orthogonal frequency-division multiplexing (OFDM) symbols.

Example 61. The apparatus of example 60, the LLRB size to comprise two resource blocks (RBs).

Example 62. The apparatus of any of examples 44 to 61, the channel to comprise a shortened physical downlink shared channel (S-PDSCH).

Example 63. The apparatus of any of examples 44 to 61, the channel to comprise a shortened physical downlink control channel (S-PDCCH).

Example 64. An apparatus, comprising: a memory; and logic for an evolved node B (eNodeB), at least a portion of the logic implemented in circuitry coupled to the memory, the logic to: identify a short transmission time interval (S-TTI) length based on which to allocate resources of a channel of a radio access network cell; based on the S-TTI length, determine a low latency resource block (LLRB) size according to which to allocate resources of the channel and a demodulation reference signal (DMRS) pattern according to which to transmit DMRSs to user equipment (UE) via the channel; and generate the DMRSs for transmission to the UE using resources identified based on the DMRS pattern.

Example 65. The apparatus of example 64, the DMRS pattern to comprise multiple DMRS resource element (RE) clusters.

Example 66. The apparatus of example 65, each DMRS RE cluster to span a same number of orthogonal frequency-division multiplexing (OFDM) symbols.

Example 67. The apparatus of any of examples 64 to 65, each DMRS RE cluster to span a same number of subcarriers.

Example 68. The apparatus of any of examples 64 to 67, the logic to generate a radio resource control (RRC) message for transmission to the UE, the RRC message to comprise information indicating the DMRS pattern.

Example 69. The apparatus of any of examples 64 to 68, the logic to generate a radio resource control (RRC) message for transmission from the eNodeB , the RRC message to comprise information indicating the LLRB size.

Example 70. The apparatus of any of examples 64 to 69, the logic to generate downlink control information (DCI) for transmission from the eNodeB, the DCI to comprise information indicating the LLRB size. Example 71. At least one machine -readable storage medium comprising instructions that when executed by a computing device, cause the computing device to: identify a short transmission time interval (S-TTI) length based on which to allocate resources of a channel of a radio access network cell; based on the S-TTI length, determine a low latency resource block (LLRB) size according to which to allocate resources of the channel and a demodulation reference signal (DMRS) pattern according to which to transmit DMRSs to user equipment (UE) via the channel; and generate the DMRSs for transmission to the UE using resources identified based on the DMRS pattern.

Example 72. The at least one machine -readable storage medium of example 71, the DMRS pattern to comprise multiple DMRS resource element (RE) clusters.

Example 73. The at least one machine -readable storage medium of example 71, each DMRS RE cluster to span a same number of orthogonal frequency-division multiplexing (OFDM) symbols.

Example 74. The at least one machine -readable storage medium of any of examples 71 to 73, each DMRS RE cluster to span a same number of subcarriers.

Example 75. The at least one machine -readable storage medium of any of examples 71 to 74, the computing device to generate a radio resource control (RRC) message for transmission to the UE, the RRC message to comprise information indicating the DMRS pattern.

Example 76. The at least one machine -readable storage medium of any of examples 72 to 75, the computing device to generate a radio resource control (RRC) message for transmission from the eNodeB, the RRC message to comprise information indicating the LLRB size.

Example 77. The at least one machine -readable storage medium of examples 72 to 76, the computing device to generate downlink control information (DCI) for transmission from the eNodeB , the DCI to comprise information indicating the LLRB size.

Example 78. The at least one machine -readable storage medium of example 72 to 76, the computing device to determine the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.

Example 79. An apparatus, comprising: a memory; and logic for user equipment (UE), at least a portion of the logic implemented in circuitry coupled to the memory, the logic to: identify a short transmission time interval (S-TTI) length and a low latency resource block (LLRB) size governing resource allocation for communications over a channel of a cell served by an evolved node B (eNodeB); identify a demodulation reference signal (DMRS) pattern applicable to DMRS transmissions to the UE via the channel; and access the channel to receive DMRSs from the eNodeB via a set of resources identified based on the DMRS pattern. Example 80. The apparatus of example 79, the logic to identify the LLRB size based on information comprised in a radio resource control (RRC) message received from the eNodeB.

Example 81. The apparatus of example 79, the logic to identify the LLRB size based on downlink control information (DCI) received from the eNodeB.

Example 82. The apparatus of any of examples 79 to 81, the logic to identify the LLRB size based on the S-TTI length.

Example 83. The apparatus of example 79, the logic to identify the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.

Example 84. At least one machine -readable storage medium comprising instructions that when executed by a computing device, cause the computing device to: identify a short transmission time interval (S-TTI) length and a low latency resource block (LLRB) size governing resource allocation for communications over a channel of a cell served by an evolved node B (eNodeB); identify a demodulation reference signal (DMRS) pattern applicable to DMRS transmissions to the UE via the channel; and access the channel to receive DMRSs from the eNodeB via a set of resources identified based on the DMRS pattern.

Example 85. The at least one machine -readable storage medium of example 84, the computing device to identify the LLRB size based on information comprised in a radio resource control (RRC) message received from the eNodeB.

Example 86. The at least one machine -readable storage medium of example 84, the computing device to identify the LLRB size based on downlink control information (DCI) received from the eNodeB.

Example 87. The at least one machine -readable storage medium of any of example 84 to 86, the computing device to identify the LLRB size based on the S-TTI length.

Example 88. The at least one machine -readable storage medium of example 84, the computing device to identify the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.

It is emphasized that the Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate preferred embodiment. In the appended claims, the terms "including" and "in which" are used as the plain- English equivalents of the respective terms "comprising" and "wherein," respectively.

Moreover, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

CLAIMS What is claimed is:

1. An apparatus, comprising:

a memory; and

logic for an evolved node B (eNodeB), at least a portion of the logic implemented in circuitry coupled to the memory, the logic to:

identify a short transmission time interval (S-TTI) length based on which to allocate resources of a channel of a radio access network cell;

based on the S-TTI length, determine a low latency resource block (LLRB) size according to which to allocate resources of the channel and a demodulation reference signal (DMRS) pattern according to which to transmit DMRSs to user equipment (UE) via the channel; and

generate the DMRSs for transmission to the UE using resources identified based on the DMRS pattern.

2. The apparatus of claim 1, the DMRS pattern to comprise multiple DMRS resource element (RE) clusters.

3. The apparatus of claim 2, each DMRS RE cluster to span a same number of orthogonal frequency-division multiplexing (OFDM) symbols.

4. The apparatus of any of claims 2 to 3, each DMRS RE cluster to span a same number of subcarriers.

5. The apparatus of any of claims 1 to 4, the logic to generate a radio resource control (RRC) message for transmission to the UE, the RRC message to comprise information indicating the DMRS pattern.

6. The apparatus of any of claims 1 to 5, the logic to generate a radio resource control (RRC) message for transmission from the eNodeB, the RRC message to comprise information indicating the LLRB size.

7. The apparatus of any of claims 1 to 6, the logic to generate downlink control information (DCI) for transmission from the eNodeB, the DCI to comprise information indicating the LLRB size.

8. At least one machine-readable storage medium comprising instructions that when

executed by a computing device, cause the computing device to:

identify a short transmission time interval (S-TTI) length based on which to allocate resources of a channel of a radio access network cell; based on the S-TTI length, determine a low latency resource block (LLRB) size according to which to allocate resources of the channel and a demodulation reference signal (DMRS) pattern according to which to transmit DMRSs to user equipment (UE) via the channel; and

9. The at least one machine-readable storage medium of claim 8, the DMRS pattern to comprise multiple DMRS resource element (RE) clusters.

10. The at least one machine-readable storage medium of claim 8, each DMRS RE cluster to span a same number of orthogonal frequency-division multiplexing (OFDM) symbols.

11. The at least one machine-readable storage medium of any of claims 8 to 10, each DMRS RE cluster to span a same number of subcarriers.

12. The at least one machine-readable storage medium of any of claims 1 to 4, the computing device to generate a radio resource control (RRC) message for transmission to the UE, the RRC message to comprise information indicating the DMRS pattern.

13. The at least one machine-readable storage medium of any of claims 9 to 12, the

computing device to generate a radio resource control (RRC) message for transmission from the eNodeB, the RRC message to comprise information indicating the LLRB size.

14. The at least one machine-readable storage medium of claims 9 to 13, the computing device to generate downlink control information (DCI) for transmission from the eNodeB, the DCI to comprise information indicating the LLRB size.

15. The at least one machine-readable storage medium of claims 9 to 13, the computing device to determine the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.

16. An apparatus, comprising:

a memory; and

logic for user equipment (UE), at least a portion of the logic implemented in circuitry coupled to the memory, the logic to:

identify a short transmission time interval (S-TTI) length and a low latency resource block (LLRB) size governing resource allocation for communications over a channel of a cell served by an evolved node B (eNodeB);

identify a demodulation reference signal (DMRS) pattern applicable to DMRS transmissions to the UE via the channel; and access the channel to receive DMRSs from the eNodeB via a set of resources identified based on the DMRS pattern.

17. The apparatus of claim 16, the logic to identify the LLRB size based on information comprised in a radio resource control (RRC) message received from the eNodeB.

18. The apparatus of claim 16, the logic to identify the LLRB size based on downlink control information (DCI) received from the eNodeB.

19. The apparatus of any of claims 16 to 18, the logic to identify the LLRB size based on the S-TTI length.

20. The apparatus of claim 16, the logic to identify the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.

21. At least one machine-readable storage medium comprising instructions that when

executed by a computing device, cause the computing device to:

identify a demodulation reference signal (DMRS) pattern applicable to DMRS transmissions to the UE via the channel; and

access the channel to receive DMRSs from the eNodeB via a set of resources identified based on the DMRS pattern.

22. The at least one machine-readable storage medium of claim 21, the computing device to identify the LLRB size based on information comprised in a radio resource control (RRC) message received from the eNodeB.

23. The at least one machine-readable storage medium of claim 21, the computing device to identify the LLRB size based on downlink control information (DCI) received from the eNodeB.

24. The at least one machine-readable storage medium of any of claims 21 to 23, the

computing device to identify the LLRB size based on the S-TTI length.

25. The at least one machine-readable storage medium of claim 21, the computing device to identify the LLRB size based on the S-TTI length and a reference length associated with the DMRSs.