WO2022056703A1

WO2022056703A1 - Data retransmission delay reduction

Info

Publication number: WO2022056703A1
Application number: PCT/CN2020/115497
Authority: WO
Inventors: Yan Wang; Miao Fu; Hao Zhang; Jian Li; Wei He
Original assignee: Qualcomm Incorporated
Priority date: 2020-09-16
Filing date: 2020-09-16
Publication date: 2022-03-24

Abstract

A base station is described. The base station includes a memory and a processor in electronic communication with the memory. The processor is configured to determine that a user equipment (UE) initiated a random access channel (RACH) procedure in a connected state. The processor is also configured to trigger a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.

Description

DATA RETRANSMISSION DELAY REDUCTION

FIELD OF DISCLOSURE

The present disclosure relates generally to electronic devices. More specifically, the present disclosure relates to reduction of data retransmission delay caused by performing a random access channel (RACH) procedure in a connected state.

BACKGROUND

In the last several decades, the use of electronic devices has become common. In particular, advances in electronic technology have reduced the cost of increasingly complex and useful electronic devices. Cost reduction and consumer demand have proliferated the use of electronic devices such that they are practically ubiquitous in modern society. As the use of electronic devices has expanded, so has the demand for new and improved features of electronic devices. More specifically, electronic devices that perform new functions and/or that perform functions faster, more efficiently, or with higher quality are often sought after.

Some electronic devices (e.g., cellular phones, smartphones, laptop computers, etc. ) communicate with other electronic devices. For example, electronic devices may transmit and/or receive radio frequency (RF) signals to communicate. Improving electronic device communication may be beneficial.

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc. ) . Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems, to name a few.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless nodes (e.g., BSs and/or UEs) to communicate on a municipal, national, regional, and even global level. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) . To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in NR and LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The processor may be configured to determine that the UE initiated the RACH procedure in a connected state based on a cell radio network temporary identifier (C-RNTI) included in a message 3 (msg3) of the RACH procedure received from the UE. In some examples, a MAC entity may be configured to receive the msg3 including the C-RNTI. The MAC entity may also match the C-RNTI to a specific UE in the connected state. The MAC entity may further send an indication to an RLC entity to trigger the RLC status report from the UE when UL scheduling resumes after the RACH.

The processor may be configured to trigger the RLC status report from the UE by setting a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure. The processor may be configured to set the polling bit by setting a P field of the first DL RLC data PDU to 1.

The processor may be configured to retransmit a number of missed RLC data PDUs based on the RLC status report received from the UE.

In some examples, the base station does not configure an enableStatusReportSN-Gap parameter for the UE. In some examples, the base station performs half-duplex communication with the UE. In some examples, the base station communicates with the UE according to a Narrowband Internet of Things (NB-IoT) standard.

A method performed by a base station is also described. The method includes determining that a UE initiated a RACH procedure in a connected state. The method also includes triggering an RLC status report from the UE in response to UL scheduling for the UE after the RACH procedure.

A non-transitory tangible computer-readable medium storing computer-executable code is also described. The computer-readable medium includes code for causing a processor to determine that a UE initiated a RACH procedure in a connected state. The computer-readable medium also includes code for causing the processor to trigger an RLC status report from the UE in response to UL scheduling for the UE after the RACH procedure.

An apparatus is also described. The apparatus includes means for determining that a UE initiated a RACH procedure in a connected state. The apparatus also includes means for triggering an RLC status report from the UE in response to UL scheduling for the UE after the RACH procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram conceptually illustrating an example wireless communication network in which data retransmission delay reduction may be performed;

FIG. 2 illustrates example components of a base station (BS) and a user equipment (UE) in which data retransmission delay reduction may be performed;

FIG. 3 is an example frame format for new radio (NR) , in accordance with certain aspects of the present disclosure;

FIG. 4 is a call flow diagram illustrating a problem of long transmission delays when transmitting downlink data to a narrow band UE;

FIG. 5 is a flow diagram illustrating example operations for wireless communication by a base station, in accordance with certain aspects of the present disclosure;

FIG. 6 is a call flow diagram illustrating example operations for avoiding long data transmission delays caused by a random access channel (RACH) procedure in connected state; and

FIG. 7 illustrates a wireless node that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for avoiding long data transmission delays caused by a random access channel (RACH) procedure in a connected state. For example, in some cases, a base station may determine that a user equipment (UE) initiated a random access channel (RACH) procedure in a connected state. The base station may trigger a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure. In some cases, the base station may trigger the RLC status report from the UE by setting a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure. The base station may retransmit a number of missed RLC data PDUs based on the RLC status report received from the UE.

The following description provides examples of avoiding long data transmission delays caused by RACH in a connected state in communication systems, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs.

The techniques described herein may be used for various wireless networks and radio technologies. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or new radio (e.g., 5G NR) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR access may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond) , massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC) . These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe. NR supports beamforming and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

As used herein, the term “layer” may refer to a layer or sub-layer of a communication protocol stack. Examples of layers (in ascending order, for instance) may include a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer. In some examples, the RLC layer may include functions such as automatic repeat request (ARQ) , segmentation of data, and/or reassembly of data, etc.

Some configurations of the systems and methods disclosed herein may be utilized with single or multiple receive (Rx) links. For example, the systems and methods disclosed herein may be utilized with a single Long-Term Evolution (LTE) link, multiple LTE links, a single Fifth Generation (5G) or New Radio (NR) link, multiple 5G or NR links, an LTE link and 5G link, Evolved Universal Mobile Telecommunications Service (UMTS) Terrestrial Radio Access Network (E-UTRAN) New Radio-Dual Connectivity (ENDC) , multiple radio access technology (RAT) links, multiple carriers, multiple bearers, etc.

It should be noted that some examples of the systems and methods described herein may be utilized and/or implemented with one, two, or more links. For example, an electronic device may receive data (e.g., packet data) on two or more links in some cases and/or approaches. For instance, an electronic device may receive data on two cellular (e.g., LTE, 5G) links and a Wi-Fi link. In another example, an electronic device may receive data on multiple Wi-Fi links and one or more cellular (e.g., LTE, 5G) links. In yet another example, an electronic device may receive data on a cellular (e.g., LTE, 5G) link, on a personal area network (PAN) (e.g., Bluetooth) link, and on a Wi-Fi link. Other variations are possible (e.g., two or more wireless local area network (WLAN) links, two or more PAN links, a combination of WLAN, cellular, and/or PAN links, etc. ) .

Various configurations are now described with reference to the Figures, where like reference numbers may indicate functionally similar elements. The systems and methods as generally described and illustrated in the Figures herein could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of several configurations, as represented in the Figures, is not intended to limit scope, as claimed, but is merely representative of the systems and methods.

FIG. 1 illustrates an example wireless communication network 100 in which data retransmission delay reduction may be performed. For example, the wireless communication network 100 may be an NR system (e.g., a 5G NR network) . As shown in FIG. 1, the wireless communication network 100 may be in communication with a core network 132. The core network 132 may in communication with one or more base stations (BSs) 110 and/or user equipment (UE) 120 in the wireless communication network 100 via one or more interfaces.

As illustrated in FIG. 1, the wireless communication network 100 may include a number of BSs 110a-z (each also individually referred to herein as BS 110 or collectively as BSs 110) and other network entities. A BS 110 may provide communication coverage for a particular geographic area, sometimes referred to as a “cell” , which may be stationary or may move according to the location of a mobile BS 110. In some examples, the BSs 110 may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces (e.g., a direct physical connection, a wireless connection, a virtual network, or the like) using any suitable transport network. In the example shown in FIG. 1, the

BSs

110a, 110b and 110c may be macro BSs for the

macro cells

102a, 102b and 102c, respectively. The BS 110x may be a pico BS for a pico cell 102x. The

BSs

110y and 110z may be femto BSs for the

femto cells

102y and 102z, respectively. A BS may support one or multiple cells. A network controller 130 may couple to a set of BSs 110 and provide coordination and control for these BSs 110 (e.g., via a backhaul) .

The BSs 110 communicate with UEs 120a-y (each also individually referred to herein as UE 120 or collectively as UEs 120) in the wireless communication network 100. The UEs 120 (e.g., 120x, 120y, etc. ) may be dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. Wireless communication network 100 may also include relay stations (e.g., relay station 110r) , also referred to as relays or the like, that receive a transmission of data and/or other information from an upstream station (e.g., a BS 110a or a UE 120r) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE 120 or a BS 110) , or that relays transmissions between UEs 120, to facilitate communication between devices.

According to certain aspects, a BS 110 may be configured for avoiding long data transmission delays caused by performing a random access channel (RACH) procedure with a UE in a connected state, as described herein. For example, as shown in FIG. 1, a BS 110a may include a status report module 122. The status report module 122 may be configured to perform the operations illustrated in FIGs. 5-6, as well as other operations described herein for avoiding long data transmission delays caused by RACH in a connected state. As used herein, the term “connected state” refers to the state of a UE. In some examples, when data is being sent or communication is taking place then the UE is in a connected state. This is compared to an idle state (also referred to as idle mode) when the UE does not have data to send. In the “connected state” the UE may keep its transmitter and/or receiver ON (e.g., the UE’s radio is in the ON state) .

FIG. 2 illustrates example components of a BS 110a and a UE 120a (e.g., in the wireless communication network 100 of FIG. 1) , which may be used to implement aspects of the present disclosure.

At the BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical hybrid ARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , etc. The data may be for the physical downlink shared channel (PDSCH) , etc. A medium access control (MAC) -control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH) , a physical uplink shared channel (PUSCH) , or a physical sidelink shared channel (PSSCH) .

The processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, such as for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , and channel state information reference signal (CSI-RS) . A transmit (TX) multiple-input multiple- output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) in transceivers 232a-232t. Each modulator in transceivers 232a-232t may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators in transceivers 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE 120a, the antennas 252a-252r may receive the downlink signals from the BS 110a and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator in transceivers 254a-254r may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the demodulators in transceivers 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120a to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at UE 120a, a transmit processor 264 may receive and process data (e.g., for the physical uplink shared channel (PUSCH) ) from a data source 262 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS) ) . The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the modulators (MODs) in transceivers 254a-254r (e.g., for SC-FDM, etc. ) , and transmitted to the BS 110a. At the BS 110a, the uplink signals from the UE 120a may be received by the antennas 234, processed by the modulators in transceivers 232a-232t, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 120a. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The

memories

242 and 282 may store data and program codes for BS 110a and UE 120a, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

Antennas 252,

processors

266, 258, 264, and/or controller/processor 280 of the UE 120a and/or antennas 234,

processors

220, 230, 238, and/or controller/processor 240 of the BS 110a may be used to perform the various techniques and methods described herein. For example, as shown in FIG. 2, the controller/processor 240 of the BS 110a may include a status report module 281 that is configured to perform the operations illustrated in FIGs. 5-6, as well as other operations described herein for avoiding long data transmission delays caused by RACH in a connected state. Although shown at the controller/processor, other components of the UE 120a and BS 110a may be used to perform the operations described herein.

NR may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. NR may support half-duplex operation using time division duplexing (TDD) . OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth into multiple orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers may be dependent on the system bandwidth. The minimum resource allocation, called a resource block (RB) , may be 12 consecutive subcarriers. The system bandwidth may also be partitioned into subbands. For example, a subband may cover multiple RBs. NR may support a base subcarrier spacing (SCS) of 15 KHz and other SCS may be defined with respect to the base SCS (e.g., 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. ) .

FIG. 3 is a diagram showing an example of a frame format 300 for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots (e.g., 1, 2, 4, 8, 16, …slots) depending on the SCS. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols) depending on the SCS. The symbol periods in each slot may be assigned indices. A mini-slot, which may be referred to as a sub-slot structure, refers to a transmit time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols) . Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission and the link direction for each subframe may be dynamically switched. The link directions may be based on the slot format. Each slot may include DL/UL data as well as DL/UL control information.

Some example techniques for avoiding long transmission delays are described herein. Narrowband Internet-of-Things (NB-IoT) is a technology being standardized by the IEEE 3GPP standards body. This technology is a narrowband radio technology specially designed for the Internet-of-Things. Some of NB-IoT design focuses on indoor coverage, low cost devices, long battery life, and scenarios involving large numbers of devices. NB-IoT technology may be deployed “in-band” , utilizing resource blocks within an existing spectrum such as the long term evolution (LTE) spectrum or the Global System for Mobile communications (GSM) spectrum. In addition, NB-IoT technology may be deployed in the unused resource blocks within a carrier guard-band (e.g., an LTE carrier) , or for “standalone” deployment, NB-IoT technology can be deployed in a dedicated spectrum (e.g., dedicated for NB-IoT operation) rather than one of the existing spectrums.

Recently, certain global suppliers of cellular IoT modules have reported a serious problem in their NB-IoT modules (e.g., a NB-IoT user equipment) resulting in downlink (DL) radio link control (RLC) data protocol data units (PDUs) of a DL data transmission being routinely lost and DL RLC retransmission of these lost data PDUs not occurring in a timely manner. Consequently, in some cases, the DL data transmission was delayed for over 30 seconds and, after many unnecessary retransmissions by a base station, an upper layer of the narrow band user equipment (NB UE) was not able to tolerate the delay any longer and aborted the session/connection.

In some cases, the reason why so many DL RLC data PDUs were lost may be due to the NB UE missing relevant DL grants during a connected mode random access channel (RACH) procedure for uplink (UL) scheduling. In some cases, the base station communicates with the UE according to a Narrowband Internet of Things (NB-IoT) standard. In some cases, the NB UE may miss relevant DL grants for the DL data transmission transmitted by the base station because the NB-IoT specification may not require NB UE to simultaneously monitor a narrowband physical downlink control channel (NPDCCH) UE-specific search space (USS) and Type2-NPDCCH common search space (CSS) . Additionally, due to their inherent hardware limitations, it may be difficult for some NB UEs to implement the concurrent USS and CSS monitoring. Additionally, in some cases, the NB UE may miss relevant DL grants for the DL data transmission because the NB UE may need to disable receiving during transmission of message 1 (msg1) and/or message 3 (msg3) of the RACH procedure due to an inherent half-duplex limitation of the NB-IoT system. Additionally, the NB UE may miss the relevant DL grants for the DL data transmission, in some cases, if the DL data transmission happens on a non-anchor carrier and the UE tunes to an anchor carrier for the RACH procedure in the connected state. In such cases, since the NB UE is tuned to the anchor carrier, the NB UE may miss the DL grants on the non-anchor carrier.

Further, a reason for a delay in DL RLC retransmission of the lost RLC data PDUs may be due to a delay associated with the base station requesting an RLC status report related to the DL data transmission. For example, generally, when a DL data transmission is segmented into separate data PDUs (e.g., each with a different sequence number (SN) ) and transmitted by a base station to a UE, the base station may need to know whether those data PDUs have been received by the UE. To indicate whether the data PDUs have been received, the UE may transmit acknowledgement (ACK) information indicating whether certain data PDUs have been received by the UE. The UE may determine which data PDUs have been received (and/or which data PDUs have been missed) based on the SN associated with each data PDU. Accordingly, the ACK information may indicate the data PDUs that have been received based on the SN number of the data PDUs that have been received by the UE. One way of transmitting this ACK information may include transmitting a separate ACK for each received data PDU. However, transmitting a separate ACK for each received data PDU may significantly increase overhead in the network.

Accordingly, an RLC status report may be used to carry acknowledgement information (e.g., ACK and/or negative ACK (NACK) information) corresponding to a plurality of data PDUs. The RLC status report may be triggered periodically by the base station by transmitting an acknowledgement mode (AM) data PDU to the UE that includes a polling request. The polling request may be represented by a polling bit (P bit) that is set to one (e.g., “1” ) . Accordingly, in response to receiving an AM data PDU with a polling request, the UE may transmit the RLC status report carrying the acknowledgement information (e.g., ACK, NACK, etc. ) related to the DL data transmission.

However, the request and transmission of an RLC status report (e.g., to indicate which RLC data PDUs have been received and/or which RLC data PDUs have been missed) may be delayed, in some cases, because the standards may not require NB RLC transmission (Tx) side (e.g., the base station in the example above) to set the P bit until both a Tx and/or a retransmission (reTx) buffer are empty or a polling window stalls. Additionally, the standards may make the “detection of reception failure” status report optional and may not describe how to detect the reception failure clearly. Moreover, the network may not configure the UE with the parameter “enableStatusReportSN-Gap” (e.g., a parameter that periodically schedules the UE to transmit a status report) , preventing the UE from triggering the status report upon the detection that certain PDUs have not been received (e.g., missed) .

Accordingly, generally, for any unscheduled uplink activity on NB UE side, like RACH for UL scheduling in the scenario described above, the base station/network may not be aware of such uplink activity. Thus, if the base station continues to transmit DL grants during such unscheduled uplink activity by the NB UE, the NB UE is likely to miss the DL grant due to the inherent limitation of half-duplex. Accordingly, such missed DL grants may, as noted above, possibly result in long transmission delays and unnecessary upper layer retransmission, such as Transmission Control Protocol (TCP) reTx, which may waste radio resources and/or increase the latency of communication between the UE and BS. Additionally, in some cases, because NB UE is not able to timely finish the data transmission (e.g., receive the data PDUs, reorder the data PDUs, and flush the reordered data PDUs to a higher layer of the NB UE) , the NB UE may stay in a connected state for a much longer time. A prolonged connected state of a UE may lead to higher power consumption by the UE. For cellular IoT devices with limited power supplies (e.g., batteries) , power consumption is a concern.

FIG. 4 is a call flow diagram illustrating the problem of long transmission delays when transmitting DL data to a NB UE. In FIG. 4, a UE 120a may communicate with a base station (e.g., eNB, gNB) 110a.

In some examples, communication between the UE 120a and the base station 110a may occur between the RLC layer of the UE 120a and the RLC layer of the base station 110a. In some cases, a higher layer in a wireless network may wish to transmit a first downlink (DL) transmission control protocol (TCP) packet to the UE 120a (e.g., which may comprise a NB UE) . Accordingly, the higher layer may send the first DL TCP packet to the RLC layer of the base station 110a. In some examples, the RLC layer of the base station 110a may segment the TCP packet into a plurality of different RLC data PDUs, each RLC data PDU being associated with a unique sequence number (SN) . Thereafter, as illustrated at 402, the RLC layer of the BS 110a may send an RLC data PDU with a SN equal to ‘x’ to the RLC layer of the UE 120a.

Thereafter, at 404, the RLC layer of the BS 110a may continue to transmit the plurality of RLC data PDUs with SNs equal to x+1 through x+n corresponding to the first DL TCP packet. However, in some cases, the UE 120a may miss receiving one or more of the RLC data PDUs corresponding to SNs equal to x+1 through x+n, as shown at 406. For example, in some cases, as noted above, the UE 120a may miss these RLC data PDUs due to a lower layer RACH procedure. For example, in some cases, as noted above, due to performing a lower layer RACH procedure, the UE 120a may miss one or more DL grants associated with these RLC data PDUs and therefore may not be able to receive these RLC data PDUs.

However, at this point in time, since a RLC status report has not been requested by the base station 110a and/or network, the base station 110a may continue to transmit RLC data PDUs corresponding to the first DL TCP packet. For example, as illustrated at 408 and 410, the RLC layer of the BS 110a may continue transmitting RLC data PDUs with SNs equal to x+n+1 and x+n+2.

Thereafter, the higher layer of the network may wish to transmit one or more additional DL TCP packet, which may be sent to the RLC layer of the base station 110a for transmission to the RLC layer of the UE 120a. The RLC layer of the base station 110a may again segment the one or more additional DL TCP packet into a plurality of RLC data PDUs and begin transmitting the RLC data PDUs to the RLC layer of the UE 120a at 412. For example, as illustrated at 412, the RLC layer of base station BS 110a may transmit an RLC data PDU with SN equal to ‘y’ . Additionally, as illustrated, the RLC layer of the BS 110a may include a polling request (e.g., P=1) in the RLC data PDU with SN equal to y (e.g., since a buffer at the base station 110a may be empty after transmitting the first DL TCP packet) .

Thereafter, as illustrated at 414, after receiving the polling request, the UE 120a may transmit a RLC status report, which may include acknowledgement information related to the PDUs (e.g., identified in the acknowledgement information by their SNs) with SNs up to ‘y’ . For example, in some cases the RLC status report may indicate that the PDUs with SNs equal to x+1 through x+n were missed (e.g., not received) by the UE 120a. Accordingly, in response to the RLC status report and after already having begun transmitting the PDUs corresponding to the second DL TCP packet, the RLC layer of the base station 110a may then begin retransmission of the RLC data PDUs with SNs equal to x+1 through x+n, as illustrated at 416. Only after receiving the retransmitted RLC data PDUs with SNs equal to x+1 through x+n may the RLC layer of the UE 120a reorder the PDUs to form a reordered data unit and send that reordered data unit to the upper layer of the UE 120a.

As can be seen, due to the RLC status report being requested so late, long transmission delays may be experienced by the UE 120a when the UE 120a misses PDUs (e.g., due to missing DL grants) . Further, radio resources may be wasted by unnecessary many unnecessary retransmissions.

Therefore, aspects of the present disclosure provide techniques for avoiding long data transmission delays caused by a RACH procedure in connected state as well as unnecessary retransmissions. For example, in some cases, a RACH-event-based RLC status report mechanism may be introduced to trigger an RLC status report in response to UL scheduling for the UE 120a after the RACH procedure. This may accelerate the RLC data retransmission when detecting DL RLC data PDU loss after RACH in the connected state. For example, such techniques may allow the base station 110a to determine that the UE 120a initiated a RACH procedure in a connected mode. The base station 110a may then proactively transmit, to the UE 120a, a polling request. Accordingly, by proactively transmitting the polling request, the base station 110a may reduce transmission delays and wasted resources due to unnecessary retransmissions, as described above.

FIG. 5 is a flow diagram illustrating example operations 500 for wireless communication, for example, for avoiding long data transmission delays caused by a RACH procedure in connected state as well as unnecessary retransmissions, in accordance with certain aspects of the present disclosure. The operations 500 may be performed, for example, by a wireless node (e.g., such as a base station 110a in the wireless communication network 100) . Operations 500 may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor 240 of FIG. 2) . Further, the transmission and reception of signals by the base station 110a in operations 500 may be enabled, for example, by one or more antennas (e.g., antennas 234 of FIG. 2) . In certain aspects, the transmission and/or reception of signals by the base station 110a may be implemented via a bus interface of one or more processors (e.g., controller/processor 240) obtaining and/or outputting signals.

The operations 500 may begin, at 502, by determining that a user equipment (UE) initiated a RACH procedure in a connected state.

At 504, the wireless node triggers an RLC status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.

As noted above, aspects of the present disclosure provide techniques for avoiding long data transmission delays caused by a RACH procedure in connected state as well as unnecessary retransmissions.

FIG. 6 is a call flow diagram illustrating example operations for avoiding long data transmission delays caused by a RACH procedure in connected state, in accordance with certain aspects of the present disclosure. In FIG. 6, a UE 120a may communicate with a base station (e.g., eNB, gNB) 110a.

In some examples, communication between the UE 120a and the base station 110a may occur between the RLC layer of the UE 120a and the RLC layer of the base station 110a. In some cases, the UE 120a may be a narrow band (NB) UE and may not be configured with the parameter “enableStatusReportSN-Gap” that schedules the UE to transmit the status report. In some cases, the UE 120a is incapable of simultaneously monitoring a common search space (e.g., a Type2-NPDCCH common search space) and/or a user search space (e.g., NPDCCH UE-specific search space) . Additionally, in some cases, the UE 120a is only capable of half-duplex operation. For example, the UE 120a may disable reception during the message 1 (msg1) and/or message 3 (msg3) transmission period due to the half-duplex limitation of the NB-IoT system.

At some point in time, an upper layer of a wireless network may wish to transmit a first DL TCP packet to the UE 120a (e.g., wireless node) . Thereafter, the upper layer may forward the DL TCP packet to an RLC layer of the base station 110a. The RLC layer of the base station 110a may then segment the DL TCP packet into a plurality of data packets (e.g., RLC data PDUs) and may transmit the plurality of data packets to the UE 120a. The UE may then receive, from the base station 110a, the plurality of data packets (e.g., RLC data PDUs) . As noted above, each data packet may be associated with a different sequence number (SN) .

For example, as illustrated at 602, the base station 110a may send (and the UE 120a may receive) a first data packet (e.g., corresponding to the first DL TCP packet) with an SN equal to x. However, after receiving the first data packet at 602, the RLC layer of the base station 110a may transmit data packets with SNs equal to x+1 through x+n, as shown at 604, which may be missed (e.g., not received) by the UE 120a. For example, as illustrated at 606, the UE 120a may not receive the data packets with SNs equal to x+1 through x+n, in some cases, due to performing a random access channel (RACH) procedure in a connected state. In some cases, the UE 120a may perform the RACH procedure for UL scheduling.

Thereafter, in some cases, the base station 110a may determine that the UE 120a initiated the RACH procedure in a connected state. For example, in some cases, the base station 110a may determine that the UE 120a initiated the RACH procedure in a connected state based on a Cell Radio Network Temporary Identifier (C-RNTI) included in the message 3 (msg3) of the RACH procedure received from the UE 120a. In some examples, the media access control (MAC) entity of the base station 110a may receive the msg3 including the C-RNTI of the UE 120a and then match the C-RNTI to a specific UE in the connected state.

As illustrated at 608, the base station may trigger an RLC status report from the UE 120a in response to UL scheduling for the UE 120a after the RACH procedure. For example, the MAC entity of the base station 110a may send an indication to the RLC entity of the base station 110a to trigger the RLC status report from the UE when UL scheduling resumes after the RACH. When the base station 110a transmits the next RLC data PDU at 606 (e.g., the data packet with an SN equal to x+n+1) , the RLC entity may set the P field (e.g., the polling bit) of the RLC data PDU to “1” .

Accordingly, after RACH succeeds in the connected state, the base station 110a may proactively trigger an RLC status report from the UE 120a by setting a polling bit to “1” . In some cases, the RLC status report may include acknowledgement information for at least one of the received plurality of data packets or the one or more missing data packets. For example, at 610 the UE 120a may send the RLC status report with a negative acknowledgement (NACK) for the data packets with SNs equal to x+1 through n+n. For example, the UE 120a may transmit the RLC status report to the base station 110a in the next scheduled uplink transport block, as illustrated at 610.

Thereafter, at 612 the base station 110a may retransmit (and the UE 120a may receive) the one or more missed RLC data PDUs (e.g., the data packets with SNs equal to x+1 through x+n) based, at least in part, on the RLC status report received from the UE 120a. For example, in response to receiving the RLC status report, the base station 110a may determine the one or more packets missed by the UE 120a (e.g., the data packets with SNs equal to x+1 through x+n) and may retransmit the one or more missing data packets. Thereafter, once the UE 120a has received, the one or more missing data packets that were retransmitted by the base station 110a, the UE 120a may reorder the received data packets and received retransmitted data packets to form a reordered data unit (e.g., DL TCP packet) . The UE 120a may then forward the reordered data unit to a higher layer of the UE 120a.

Accordingly, since the base station 110a is able to proactively trigger the RLC status report (e.g., at a time sooner than when the UE would normally be instructed to transmit the status report) , the UE 120a may be able to receive the one or more missed packets sooner, reducing transmission delays and reducing the number of unnecessary retransmissions. Additionally, since the UE 120a is able to receive the one or more missed packets sooner, the UE 120a may not have to be continually powered on for extended periods of time waiting to receive the one or more data packets, allowing the UE 120a to transition to a power saving mode (e.g., an off state of a discontinuous reception mode or idle mode) sooner to save power.

FIG. 7 illustrates a wireless node 700 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIGs. 5-6. The wireless node 700 includes a processing system 702 coupled to a transceiver 708 (e.g., a transmitter and/or a receiver) . The transceiver 708 is configured to transmit and receive signals for the wireless node 700 via an antenna 710, such as the various signals as described herein. The processing system 702 may be configured to perform processing functions for the wireless node 700, including processing signals received and/or to be transmitted by the wireless node 700.

The processing system 702 includes a processor 704 coupled to a computer-readable medium/memory 712 via a bus 706. In certain aspects, the computer-readable medium/memory 712 is configured to store instructions (e.g., computer-executable code) that when executed by the processor 704, cause the processor 704 to perform the operations illustrated in FIGs. 5-6, or other operations for performing the various techniques discussed herein for avoiding long data transmission delays caused by random access channel (RACH) in a connected state. In certain aspects, computer-readable medium/memory 712 stores code 714 for determining, code 716 for triggering, code 718 for receiving, code 720 for matching, code 722 for sending, code 724 for setting, code 726 for retransmitting, and code 728 for performing.

In some cases, the code 714 for determining may include code for determining that a user equipment (UE) initiated a RACH procedure in a connected state.

In some cases, the code 716 for triggering may include code for triggering a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.

In some cases, the code 718 for receiving may include code for receiving a message 3 (msg3) of the RACH procedure from the UE. The msg3 may include a cell radio network temporary identifier (C-RNTI) of the UE.

In some cases, the code 720 for matching may include code for matching the C-RNTI to a specific UE in the connected state.

In some cases, the code 722 for sending may include code for sending an indication to an RLC entity of the base station to trigger the RLC status report from the UE when UL scheduling resumes after the RACH.

In some cases, the code 724 for setting may include code for setting a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure. Setting the polling bit may include setting a P field of the first DL RLC data PDU to “1” .

In some cases, the code 726 for retransmitting may include code for retransmitting a number of missed RLC data PDUs based on the RLC status report received from the UE.

In some cases, the code 728 for performing may include code for comprising performing a random access channel (RACH) procedure with the UE in a connected state.

In certain aspects, the processor 704 may include circuitry configured to implement the code stored in the computer-readable medium/memory 712, such as for performing the operations illustrated in FIGs. 5-6, as well as other operations described herein for avoiding long data transmission delays caused by RACH in a connected state. For example, the processor 704 includes circuitry 734 for determining, circuitry 736 for triggering, circuitry 738 for receiving, circuitry 740 for matching, circuitry 742 for sending, circuitry 744 for setting, circuitry 746 for retransmitting, and circuitry 748 for performing.

In some cases, the circuitry 734 for determining may include code for determining that a user equipment (UE) initiated a RACH procedure in a connected state.

In some cases, the circuitry 736 for triggering may include code for triggering a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.

In some cases, the circuitry 738 for receiving may include code for receiving a message 3 (msg3) of the RACH procedure from the UE. The msg3 may include a cell radio network temporary identifier (C-RNTI) of the UE.

In some cases, the circuitry 740 for matching may include code for matching the C-RNTI to a specific UE in the connected state.

In some cases, the circuitry 742 for sending may include code for sending an indication to an RLC entity of the base station to trigger the RLC status report from the UE when UL scheduling resumes after the RACH.

In some cases, the circuitry 744 for setting may include code for setting a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure. Setting the polling bit may include setting a P field of the first DL RLC data PDU to “1” .

In some cases, the circuitry 746 for retransmitting may include code for retransmitting a number of missed RLC data PDUs based on the RLC status report received from the UE.

In some cases, the circuitry 748 for performing may include code for comprising performing a random access channel (RACH) procedure with the UE in a connected state.

The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR) , 3GPP Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , single-carrier frequency division multiple access (SC FDMA) , time division synchronous code division multiple access (TD-SCDMA) , and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as NR (e.g. 5G RA) , Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) . LTE and LTE-A are releases of UMTS that use E UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . NR is an emerging wireless communications technology under development.

In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a NB subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and BS, next generation NodeB (gNB or gNodeB) , access point (AP) , distributed unit (DU) , carrier, or transmission reception point (TRP) may be used interchangeably. A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) , UEs for users in the home, etc. ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS.

A UE may also be referred to as a mobile station, a wireless node, a wireless communications node, a wireless device, a wireless communications device, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE) , a cellular phone, a smart phone, a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc. ) , an entertainment device (e.g., a music device, a video device, a satellite radio, etc. ) , a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs) , and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a c c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for. ”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal (see FIG. 1) , a user interface (e.g., keypad, display, mouse, joystick, etc. ) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory) , flash memory, ROM (Read Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable Programmable Read-Only Memory) , EEPROM (Electrically Erasable Programmable Read-Only Memory) , registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared (IR) , radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and

disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media) . In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal) . Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein, for example, instructions for performing the operations described herein and illustrated in FIGs. 5-6, as well as other operations described herein for avoiding long data transmission delays caused by RACH in a connected state.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc. ) , such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

A base station, comprising:

a memory;

a processor in electronic communication with the memory, wherein the processor is configured to:

determine that a user equipment (UE) initiated a random access channel (RACH) procedure in a connected state; and

trigger a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.
The base station of claim 1, wherein the processor is configured to determine that the UE initiated the RACH procedure in a connected state based on a cell radio network temporary identifier (C-RNTI) included in a message 3 (msg3) of the RACH procedure received from the UE.
The base station of claim 2, wherein a MAC entity is configured to:

receive the msg3 including the C-RNTI;

matches the C-RNTI to a specific UE in the connected state; and

sends an indication to an RLC entity to trigger the RLC status report from the UE when UL scheduling resumes after the RACH.
The base station of claim 1, wherein the processor is configured to trigger the RLC status report from the UE by setting a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure.
The base station of claim 4, the processor is configured to set the polling bit by setting a P field of the first DL RLC data PDU to 1.
The base station of claim 1, wherein the processor is configured to retransmit a number of missed RLC data PDUs based on the RLC status report received from the UE.
The base station of claim 1, wherein the base station does not configure an enableStatusReportSN-Gap parameter for the UE.
The base station of claim 1, wherein the base station performs half-duplex communication with the UE.
The base station of claim 1, wherein the base station communicates with the UE according to a Narrowband Internet of Things (NB-IoT) standard.
A method performed by a base station, comprising:

determining that a user equipment (UE) initiated a random access channel (RACH) procedure in a connected state; and

triggering a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.
The method of claim 10, wherein determining that the UE initiated the RACH procedure in a connected state is based on a cell radio network temporary identifier (C-RNTI) included in a message 3 (msg3) of the RACH procedure received from the UE.
The method of claim 11, further comprising:

receiving the msg3 including the C-RNTI;

matching the C-RNTI to a specific UE in the connected state; and

sending an indication to an RLC entity to trigger the RLC status report from the UE when UL scheduling resumes after the RACH.
The method of claim 10, wherein triggering the RLC status report from the UE comprises setting a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure.
The method of claim 13, wherein setting the polling bit comprises setting a P field of the first DL RLC data PDU to 1.
The method of claim 10, further comprising retransmitting a number of missed RLC data PDUs based on the RLC status report received from the UE.
The method of claim 10, wherein the base station does not configure an enableStatusReportSN-Gap parameter for the UE.
The method of claim 10, wherein the base station performs half-duplex communication with the UE.
The method of claim 10, wherein the base station communicates with the UE according to a Narrowband Internet of Things (NB-IoT) standard.
A non-transitory tangible computer-readable medium storing computer-executable code, comprising:

code for causing a processor to determine that a user equipment (UE) initiated a random access channel (RACH) procedure in a connected state; and

code for causing the processor to trigger a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.
The computer-readable medium of claim 19, further comprising code for causing the processor to determine that the UE initiated the RACH procedure in a connected state based on a cell radio network temporary identifier (C-RNTI) included in a message 3 (msg3) of the RACH procedure received from the UE.
The computer-readable medium of claim 20, wherein a MAC entity is configured to:

receive the msg3 including the C-RNTI;

matches the C-RNTI to a specific UE in the connected state; and

sends an indication to an RLC entity to trigger the RLC status report from the UE when UL scheduling resumes after the RACH.
The computer-readable medium of claim 19, wherein the code for causing the processor to trigger the RLC status report from the UE comprises code for causing the processor to set a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure.
The computer-readable medium of claim 22, the code for causing the processor to set the polling bit comprises code for causing the processor to set a P field of the first DL RLC data PDU to 1.
The computer-readable medium of claim 19, further comprising code for causing the processor to retransmit a number of missed RLC data PDUs based on the RLC status report received from the UE.
An apparatus, comprising:

means for determining that a user equipment (UE) initiated a random access channel (RACH) procedure in a connected state; and

means for triggering a radio link control (RLC) status report from the UE in response to uplink (UL) scheduling for the UE after the RACH procedure.
The apparatus of claim 25, wherein the means for determining that the UE initiated the RACH procedure in a connected state are based on a cell radio network temporary identifier (C-RNTI) included in a message 3 (msg3) of the RACH procedure received from the UE.
The apparatus of claim 26, further comprising:

means for receiving the msg3 including the C-RNTI;

means for matching the C-RNTI to a specific UE in the connected state; and

means for sending an indication to an RLC entity to trigger the RLC status report from the UE when UL scheduling resumes after the RACH.
The apparatus of claim 25, wherein the means for triggering the RLC status report from the UE comprises means for setting a polling bit in a first downlink (DL) RLC data protocol data unit (PDU) transmitted to the UE when UL scheduling resumes after the RACH procedure.
The apparatus of claim 28, wherein the means for setting the polling bit comprise means for setting a P field of the first DL RLC data PDU to 1.
The apparatus of claim 25, further comprising means for retransmitting a number of missed RLC data PDUs based on the RLC status report received from the UE.