HK1249327B - Device for contention free uplink synchornization - Google Patents

Description

Apparatus for contention-free uplink synchronization

Background Art

Wireless mobile communication technologies use various standards and protocols to transmit data between nodes (e.g., transmission stations) and wireless devices (e.g., mobile devices). Some wireless devices communicate using orthogonal frequency division multiple access (OFDMA) in uplink (UL) transmissions and single-carrier frequency division multiple access (SC-FDMA) in downlink (DL) transmissions. Standards and protocols that use orthogonal frequency division multiplexing (OFDM) for signal transmission include the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE), the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standards (e.g., 802.16e, 802.16m), commonly referred to in the industry as WiMAX (Worldwide Interoperability for Microwave Access), and the IEEE 802.11 standard, commonly referred to in the industry as WiFi.

In a 3GPP radio access network (RAN) LTE system, a node may be a combination of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also commonly referred to as an evolved Node B, enhanced Node B, or eNB) and a Radio Network Controller (RNC), which communicates with wireless devices referred to as user equipment (UE). Downlink (DL) transmissions may be communications from a node (e.g., an eNB) to a wireless device (e.g., a UE), and uplink (UL) transmissions may be communications from a wireless device to a node.

In LTE, data can be sent from the eNB to the UE via the Physical Downlink Shared Channel (PDSCH). The Physical Uplink Control Channel (PUCCH) can be used to confirm that the data was received. The downlink and uplink channels or transmissions can use time division duplexing (TDD) or frequency division duplexing (FDD).

Depending on the type of communication, the over-the-air latency of 3GPP LTE communications can be on the order of tens of milliseconds. This latency may be sufficient for voice and audio/video communications. However, the latency of current 3GPP LTE systems may be detrimental to future 5G systems.

Summary of the Invention

According to a first aspect of the present disclosure, a user equipment (UE) is provided, which is configured to achieve low-latency synchronization with a base station under the control of one or more processors and memories. The UE is configured to sense whether any physical uplink shared channel (PUSCH) is idle for a predetermined time period; provide a unique UE identity in a PUSCH transmission; and transmit a PUSCH transmission in one of the idle PUSCH channels in the absence of an uplink grant from the base station for contention-free communication with the base station for uplink synchronization.

According to a second aspect of the present disclosure, a base station is provided, which is operable under the control of one or more processors and memories to perform contention-free uplink (UL) synchronization with a user equipment (UE). The base station is configured to: after sensing an idle physical uplink shared channel (PUSCH) channel for a predetermined period of time, process a PUSCH transmission received from the UE without sending an uplink grant to the UE; process a unique UE identifier in the PUSCH transmission received by the base station; and determine the identity of the UE for contention-free UL synchronization using the unique UE identifier in the PUSCH transmission.

According to a third aspect of the present disclosure, there is provided an apparatus for achieving low-latency synchronization with a base station. The apparatus comprises: means for sensing whether any uplink shared channel (PUSCH) is idle for uplink (UL) synchronization with the base station for a predetermined time period; means for providing a unique UE identification in a PUSCH transmission; and means for transmitting a PUSCH transmission in one of the idle PUSCH channels for contention-free communication with the base station for uplink synchronization in the absence of an UL grant received from the base station.

According to a fourth aspect of the present disclosure, there is provided an apparatus for achieving low-latency synchronization with a user equipment (UE). The apparatus comprises: means for processing a physical uplink shared channel (PUSCH) transmission received from a UE after sensing an idle PUSCH channel for a predetermined time period; means for processing a unique UE identifier in a PUSCH transmission received by a base station; means for determining the identity of the UE for contention-free UL synchronization by the unique UE identifier in the PUSCH transmission in the absence of an uplink (UL) grant transmitted to the UE; and means for performing blind UE detection based on a demodulation reference signal (DMRS).

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which together illustrate, by way of example, the features of the present invention; and wherein:

FIG1 illustrates a device-to-device (D2D) discovery area within an LTE operating area according to an example;

2 illustrates a diagram of radio frame resources (e.g., a resource grid) for downlink (DL) transmissions including a legacy physical downlink control channel (PDCCH) according to an example;

3 shows a frame design for a physical uplink shared control channel (PUSCH) transmission based on listen before talk (LBT) according to an embodiment of the present technology;

FIG4 illustrates a subframe design for a physical uplink shared control channel (PUSCH) transmission based on listen before talk (LBT) according to an embodiment of the present technology;

5 shows a design of a physical uplink shared control channel (PUSCH) transmission based on listen-before-talk (LBT) with subframe-level total time interval (TTI) in accordance with an embodiment of the present technology;

6 shows a design of a physical uplink shared control channel (PUSCH) transmission based on listen-before-talk (LBT) with preamble signaling in accordance with an embodiment of the present technology;

7 shows a design of a physical uplink shared control channel (PUSCH) transmission based on listen-before-talk (LBT) with an LTB contention region in accordance with an embodiment of the present technology.

FIG8 depicts a flow diagram of a method for achieving low latency between a user equipment (UE) and an anchor enhanced Node B (eNB) according to an embodiment of the present technology;

FIG9 depicts a flow diagram of an additional method for achieving contention-free uplink (UL) synchronization between an anchor enhanced Node B (eNB) and a user equipment (UE) in accordance with an embodiment of the present technology;

FIG10 shows a diagram of a wireless device (eg, UE) according to an example.

11 illustrates a diagram of example components of a wireless device (eg, user equipment "UE") apparatus according to an example.

12 shows a diagram of a node (eg, eNB) and a wireless device (eg, UE) according to an example.

Reference may now be made to the exemplary embodiments illustrated, and specific language may be used herein to describe the same, but it will be understood that this is not intended to limit the scope of the technology.

DETAILED DESCRIPTION

Before disclosing and describing the present technology, it should be understood that the technology is not limited to the specific structures, processing actions, or materials disclosed herein, but extends to equivalents thereof, as recognized by professionals in the relevant fields. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting. The same reference numerals in different figures represent the same elements. The numbers provided in the flow charts and processes are provided for clarity of the actions and operations and do not necessarily indicate a particular order or sequence.

Example Embodiments

The following provides an initial overview of the technology embodiments, and then describes specific technology embodiments in more detail later. This preliminary overview is intended to help readers understand the technology more quickly, but is not intended to identify the key features or essential features of the technology, nor is it intended to limit the scope of the claimed subject matter.

Reducing the air interface latency of 3GPP Radio Access Network (RAN) LTE systems is crucial for enabling new services and improving the performance of existing technologies in advanced wireless communication systems. For example, reducing the round-trip time (RTT) air interface latency target for the upcoming 5G 3GPP Radio Access Network (RAN) LTE system to 1ms (millisecond) can enable new services and improve the performance of existing technologies. An RTT of 1ms is significantly lower than what can be supported by 3GPP LTE Rel.12. Therefore, one option for reducing data plane latency to a value close to the constraints of the 5G 3GPP Radio Access Network (RAN) LTE system is to reduce the total transmission time interval (TTI), where the TTI is currently 1ms for 3GPP Radio Access Network (RAN) LTE systems. However, the RTT data plane latency constraint does not guarantee an overall end-to-end latency reduction. Specifically, for uplink transmissions, the total latency of small packet transmissions is mainly the control plane (C-plane) latency in the idle state. When the UE is in the idle state, the UE does not have a radio resource control (RRC) connection. C-plane latency can be measured as the time it takes for a UE (User Equipment) to transition from an idle state to an active state.

Therefore, the solution provided by this technology uses physical uplink shared control channel (PUSCH) transmission based on listen before talk (LBT) to reduce C-plane latency and provide grant-free PUSCH transmission.

In one aspect, the present technology provides a process for reducing latency and performing low-latency communications in uplink PUSCH transmissions. In one aspect, low latency can be achieved by removing the scheduling authorization constraints of the current 3GPP Radio Access Network (RAN) LTE system design in 3GPP LTE Rel.8, 9, 10, 11 or 12, while the PUSCH transmission is based on carrier sensing. In one example, a frequency division duplex (FDD) configuration can be considered and used for the present technology. In other aspects, it should be noted that the present technology can be used in RRC non-connected mode (i.e., idle) and/or time division duplex (TDD) configuration. It can be assumed that the UE is time-frequency synchronized with the associated eNB.

In one aspect, LBT-based PUSCH transmissions may be classified as contention-based PUSCH transmissions, where each UE may sense the channel (or medium) for a specified duration before transmitting on the allocated resources. If the channel is sensed to be idle, the wireless device (e.g., UE) may be allowed to transmit only on the allocated resources that are sensed to be idle. Thus, the present technology enables the UE to send data directly without the involvement of the eNB (i.e., without receiving an UL grant from the eNB), thereby reducing latency. It should be noted that careful consideration may need to be given to reducing the probability of collisions (particularly when two or more UEs are not transmitting at the same time), thereby reducing errors in PUSCH transmissions. In one example, in order for the eNB to determine from which UE the PUSCH transmission was sent, a UE identification (ID) may be included in the PUSCH transmission or outside of the PUSCH transmission. The UE ID may be a cell radio network transmission identity (C-RNTI) or a new type of RNTI, which may be encoded as part of the uplink (UL) shared channel (SCH) (UL-SCH) and/or may be masked on the cyclic redundancy check (CRC) for the UL-SCH.

In one aspect, the technology provides contention-free physical uplink shared control channel (PUSCH) transmissions using a listen-before-talk procedure. In one example, an apparatus of a user equipment (UE) may have circuitry including one or more processors configured to achieve low-latency synchronization with an anchor enhanced node (eNB) by: sensing whether any physical uplink shared channel (PUSCH) is idle for uplink (UL) synchronization with the anchor eNB for a predetermined period of time, providing a unique UE identity in the PUSCH transmission, and/or transmitting the PUSCH transmission in one of the idle PUSCH channels for contention-free communication with the anchor eNB for uplink synchronization.

Additional techniques are provided for contention-free uplink (UL) synchronization between an anchor enhanced Node B (eNB) and a user equipment (UE). The anchor eNB has circuitry, including one or more processors, that can receive a Physical Uplink Shared Channel (PUSCH) transmission from a UE for UL synchronization after the UE senses whether the PUSCH channel is idle for the anchor eNB for a predetermined period of time. The eNB circuitry can also receive a unique UE identifier in the PUSCH transmission and/or determine the identity of the UE using the unique UE identifier in a PUSCH subframe design for LBT CH transmissions and PUSCH transmissions for contention-free UL synchronization.

FIG1 illustrates an exemplary anchor-booster network architecture 100. Anchor-booster network architecture 100 is a form of heterogeneous network. Anchor-booster network architecture 100 may include at least one anchor evolved Node B (eNB) 104 and at least one booster eNB 106 (e.g., an mmWave small eNB or another type of low-power (i.e., small) eNB). Anchor eNB 104 may be associated with an anchor cell, a macro cell, or a primary cell. Booster eNB 106 may be associated with a booster cell, a small cell, or a secondary cell. Booster eNB 106 may operate in the same or a different frequency band as anchor eNB 104.

Anchor eNB 104 can be a high-transmit power eNB used to provide coverage and connectivity over a relatively large geographic area. For example, an anchor eNB can cover a cell with a radius of 1 to 10 kilometers or more. Anchor eNB 104 can be responsible for UE mobility, as the coverage area of anchor eNB 104 is typically wider than that of booster eNB 106. Anchor eNB 104 can also be responsible for communicating control information with the UE. In one embodiment, this control information can be communicated using Radio Resource Control (RRC) signaling.

The booster eNB 106 may be a low-transmit power eNB used for traffic offloading (i.e., offloading data transmission) and quality of service (QoS) enhancement. For example, the booster eNB may cover a cell with a radius of tens to hundreds of meters. Both the anchor eNB 104 and the booster eNB 106 may deliver packet data according to the desired QoS. For example, the anchor eNB 104 may deliver delay-sensitive data (e.g., voice over IP (VoIP)) while the booster eNB 106 may deliver delay-tolerant data (e.g., data transferred using the File Transfer Protocol (FTP) or other types of delay-tolerant data).

A user equipment (UE) 108 may be supported by both a booster eNB 106 and an anchor eNB 104 in order to ensure mobility robustness, meet QoS performance, and balance traffic load between the anchor eNB 104 and the booster eNB 106. In other words, the UE 108 may support dual connectivity because the UE may be served by both the booster eNB 106 and the anchor eNB 104. Through this dual connectivity, the anchor eNB 104 may handle control plane signaling and delay-sensitive traffic, while the booster eNB 106 may handle delay-tolerant data plane traffic.

As shown in Figure 1, booster eNB 106 can be deployed under the coverage of anchor eNB 104 and connected to core network 102. Anchor eNB 104 and booster eNB 106 can be connected via an X2 interface or other types of interfaces. Anchor eNB 104 and core network 102 can be connected via an S1 interface. The backhaul link connecting anchor eNB 104 and booster eNB 106 can be ideal or non-ideal, where an "ideal" backhaul link has a latency less than a predetermined value (in milliseconds) and a "non-ideal" backhaul link has a latency greater than a predetermined value. The network operator can select this predetermined value based on the network architecture, geographic operating area, cell density, etc.

Each backhaul technology may be associated with a latency (one-way), throughput, and priority. For example, fiber access 1 may have a latency of 10-30 ms, fiber access 2 may have a latency of 5-10 ms, fiber access 3 may have a latency of 2-5 ms, digital subscriber line (DSL) access may have a latency of 10-60 ms, and wireless backhaul may have a latency of 5-35 ms. In one configuration, the latency associated with fiber access 1, fiber access 2, fiber access 3, DSL access, and wireless backhaul may be greater than a predetermined value and, therefore, be considered a non-ideal backhaul. As another example, fiber may have a latency (one-way) of no more than 2.5 microseconds (μs). In one configuration, the latency associated with fiber may be less than a predetermined value and, therefore, may be considered an ideal backhaul.

The macro/anchor cell can be used as an "umbrella" cell, and the small/boost cell can be added to the UE as a secondary cell. As described in further detail below, the small/boost cell can be added to or removed from the UE via signaling between the UE, the booster eNB, and the anchor eNB. When adding a small/boost cell coordinated between the anchor eNB and the booster eNB, a radio resource control (RRC) message (i.e., a control plane message) can be transmitted to the UE to add the small/boost cell.

FIG2 shows a diagram of radio frame resources (e.g., a resource grid) for downlink (DL) transmission including a traditional physical downlink control channel (PDCCH) according to an example. In this example, a radio frame 200 for transmitting a signal for data can be configured to have a duration Tf of 10 milliseconds (ms). Each radio frame can be segmented or divided into ten subframes 210i, each 2 ms long. Each subframe can also be subdivided into two time slots 220a and 220b, each with a duration Tslot of 0.5 ms. The first time slot (#0) 220a may include a traditional physical downlink control channel (PDCCH) 260 and/or a physical downlink shared channel (PDSCH) 266, and the second time slot (#1) 220b may include data transmitted using the PDSCH. On the one hand, at least a portion of the architectural design of the radio frame 200 may also be applied to single carrier frequency division multiple access (SC-FDMA) in uplink (UL) transmissions, as further described in FIG3 .

Each time slot for a component carrier (CC) used by nodes and wireless devices may include multiple resource blocks (RBs) 230a, 230b, 230i, 230m, and 230n based on the CC frequency bandwidth. A CC may have a carrier frequency with a bandwidth and a center frequency. Each subframe of a CC may include downlink control information (DCI) found in a traditional PDCCH. When using traditional PDCCH, the traditional PDCCH in the control region may include one to three columns of the first OFDM symbol in each subframe or physical RB (PRB). The remaining 11 to 13 OFDM symbols in the subframe (or 14 OFDM symbols when traditional PDCCH is not used) may be allocated to the PDSCH for data (for short or normal cyclic prefix).

The control region may include a physical control format indicator channel (PCFICH), a physical hybrid automatic repeat request (hybrid ARQ) indicator channel (PHICH), and a PDCCH. The number of OFDM symbols used for the PDCCH in the control region may be determined by a control channel format indicator (CFI) transmitted in the physical control format indicator channel (PCFICH). The PCFICH may be located in the first OFDM symbol of each subframe. The PCFICH and PHICH may be scheduled prior to the PDCCH, and therefore the PCFICH and PHICH may be scheduled prior to the PDCCH.

In an example embodiment, each RB (physical RB or PRB) 230i may include 12 15kHz subcarriers 236 (on the frequency axis) and 6 or 7 orthogonal frequency division multiplexing (OFDM) symbols 232 (on the time axis) per time slot. If a short or normal cyclic prefix is used, the RB may use seven OFDM symbols. If an extended cyclic prefix is used, the RB may use six OFDM symbols. Using a short or normal cyclic prefix, a resource block may be mapped to 84 resource elements (REs) 240i; or using an extended cyclic prefix, a resource block may be mapped to 72 REs (not shown). An RE may be a unit of one OFDM symbol 242 multiplied by one subcarrier (i.e., 15kHz) 246.

In the case of quadrature phase shift keying (QPS) modulation, each RE can transmit two bits 250a and 250b of information. Other types of modulation can be used, such as 16-bit quadrature amplitude modulation (QAM) or 64QAM for transmitting a larger number of bits in each RE, or dual phase shift keying (BPSK) modulation for transmitting a smaller number of bits (a single bit) in each RE. RBs can be configured for downlink transmissions from the eNB to the UE, or for uplink transmissions from the UE to the eNB.

The example provided in FIG2 is not intended to be limiting. Other types of OFDM signaling and control information communication may be implemented using the anchor/boost communication scheme. When the booster eNB is a different RAT type than the RAT used by the anchor eNB, the communication scheme shown in the example of FIG2 may or may not be used.

In one aspect, contention-free uplink (UL) synchronization can be achieved by providing: 1) subframe design for PUSCH transmission with LBT; 2) channel access mechanism for PUSCH transmission; 3) preamble design for LBT-based PUSCH transmission; and 4) optimization for efficient PUSCH transmission.

For example, consider the following control plane latency breakdown for uplink (UL) PUSCH transmissions in Table 1 for 3GPP Release 8. For PUSCH transmissions, the total latency incurred to obtain a scheduling grant from the eNode is approximately 9.5ms. This overhead is significant for any acceptable low-latency design.

Table 1. Delays for synchronized UEs

As shown in Table 2, the present technology's contention-free (e.g., grant-free) scheduling for PUSCH transmissions based on carrier sensing and pre-talk listening can be used with latency for asynchronous UEs. Latency for asynchronous UEs can be reduced, and PRACH overhead (i.e., components 1, 2, 3, 4 in Table 2) can also be reduced.

Table 2. Delays for asynchronous UEs

FIG3 illustrates a frame design for a physical uplink shared control channel (PUSCH) transmission 300 based on listen before talk (LBT) according to an embodiment of the present technology. FIG3 depicts the overall radio frame design for a PUSCH transmission 300 based on LBT. It should be noted that the descriptions and embodiments of FIG1 and FIG2 can be used in FIG3. That is, for example, the embodiment described in FIG3 can be applied to the frame structure of FIG2. The embodiment described in FIG3 can also be applied to different frame structures.

For example, in one aspect, at least a portion of the architectural design of the radio frame 200 in Figure 2 can also be applied to single carrier frequency division multiple access (SC-FDMA) in uplink (UL) transmissions, as further described in Figure 3. Therefore, similar to Figure 2, the radio frame design of Figure 3 may include a subframe that may include two time slots (e.g., time slots 220a and 220B of Figure 2). The time for sending a subframe identifier (ID) can be defined as a transmission time interval (TTI). In 3GPP LTE, a subframe can have a length of 1ms and a time slot can have a length of 0.5ms. However, the structure and TTI of the radio frame can vary depending on the communication system. Communication systems with lower latency may have significantly shorter TTI periods.

A time slot 302 (similar to time slots 220a and/or 220b of Figure 2) can include multiple single-carrier frequency division multiple access (SC-FDMA) symbols (e.g., 14 symbols, such as 0 to 13 in the PUSCH transmission 602 shown in Figure 3) in the time domain and multiple resource blocks in the frequency domain. For one resource block (RB230), its horizontal axis represents the time axis and its vertical axis represents the frequency axis. In a single-carrier frequency division multiple access (SC-FDMA) system, a reference signal (RS) can use all frequency resources of one symbol to meet the single-carrier characteristic. In a 3GPP LTE system, RS is not precoded on the uplink. RS can be distinguished from data. The selected type of RS includes a demodulation RS (DMRS) 310 and a sounding RS (SRS). DMRS 310 can be a reference signal for acquiring channel information to demodulate uplink data, and SRS can be a reference signal for measuring the uplink channel.

As described above, at least a portion of the architectural design of the radio frame 200 may also be applicable to single carrier frequency division multiple access (SC-FDMA) in uplink (UL) transmission, as further described in FIG3. That is, dedicated frequency-time resources may be used for LBT-based PUSCH transmission, where the time/frequency resources (e.g., each demodulation reference signal "DMRS") may be configured by higher layer signaling (e.g., RRC signaling).

In FIG3 , at least a portion of the frequency resources can be used for PUSCH transmission 300, as shown by DMRS 310 in columns 4 and 10, while a variable number of resource blocks (RBs) can be used for LBT-based PUSCH transmission 300. As shown in FIG3 , one or more DMRS 310 can be inserted into PUSCH transmission 300. Due to the SC-FDMA transmission scheme, DMRS 310 can occupy the entire OFDM symbol within the PUSCH resource allocation (e.g., in columns 4 and 10). The length of the DMRS sequence can be equal to the number of subcarriers of the allocated resource block. The DMRS used for the physical uplink shared channel (PUSCH) can be cyclically shifted.

Information related to the time/frequency resources used in PUSCH transmission can be transmitted to the UE via RRC signaling. If necessary, in addition to variable resources, fixed resources known in advance to all UEs can also be used. In the case of unconnected RRC, such fixed resources may be used for unauthorized PUSCH transmission. On the one hand, the DMRS sequence can be generated by using a constant envelope zero autocorrelation waveform (CAZAC) sequence. For example, the CAZAC sequence can be a Zadoff-Chu (ZC) sequence. Various ZC sequences can be generated based on the root index and the cyclic shift index. That is, the root index or the cyclic shift index can be the seed value of the ZC sequence. DCI format 0, which provides control information for uplink data transmission, may include a cyclic shift index. The channel can be estimated from multiple terminals by an orthogonal (or quasi-orthogonal) sequence by assigning different cyclic shift indices to these terminals.

Figure 4 shows a subframe design for a physical uplink shared control channel (PUSCH) transmission based on listen before talk (LBT) according to an example. More specifically, Figure 4 depicts a preliminary radio frame design for a PUSCH uplink based on LBT. Figure 4 depicts two UEs such as UE1 and UE2. In addition, Figure 4 describes an operation in which LBT operation may precede PUSCH transmission. As shown in Figures 4-5, LBT may consist of two phases, including a clear channel assessment (CCA) 404 and an extended CCA (ECCA) 406. In Figure 4, DMRS 410, PUSCH transmission 402, and (one or more) reservation signals 414 are also shown for UE1 and UE2. During CCA 404 and ECCA 406, it may be sensed whether the medium (e.g., channel) is idle. If the energy sensed during the duration of CCA 404 and ECCA 406 is less than a certain threshold, the channel may be sensed as idle. The duration of CCA 404 and ECCA 406 depends on the minimum sensing granularity.

In one aspect, the PUSCH transmission 402 may consist of up to 14 symbols (e.g., symbols 0 through 13 of the PUSCH transmission 402 as shown in FIG4 ). The reservation signal may start from a symbol in the subframe preceding the PUSCH transmission (shown as “-1” in FIG4 ) when the SRS 412 is not being transmitted, or from symbol 13 when one symbol is used for the SRS 412. Thus, for LBT-based PUSCH resources, no SRS 414 may be transmitted (e.g., depicted as “punctured/no SRS” for both UE1 and UE2 in FIG4 ), and the PUSCH transmission 402 consisting of 13 symbols may be used to perform LBT in one null symbol. A modulation and coding scheme (MCS) may be used for uplink transmissions that may be known to the UE (e.g., UE1 and/or UE2) and the eNB. In one aspect, the lowest MCS may be used.

On the other hand, for a specified number of symbols M, LBT can be performed starting from symbol 0. Therefore, PUSCH transmission can start from symbol M+1 and end at symbol 14 within the subframe. In this case, SRS can be sent on symbol 14, and puncturing of symbol 14 is not used.

In one aspect, the control signal may be used to send the C_RNTI of the UE (e.g., UE1 or UE2) after completing LBT so that the eNB can determine the identity of the UE (e.g., UE1 or UE2) or the eNB can perform blind UE detection based on the sequence of DMRS 410 transmissions used for a single antenna.

The LBT sensing granularity (slit) can be used as 1/12 of the symbol duration, equivalent to 5.6 microseconds (μs), corresponding to 12 subcarriers in a resource block. CCA 404 can be performed in an implementation for multiple slits known to the UE (e.g., UE1 or UE2), or can be performed by the eNB through signaling. ECCA 406 can span multiple slits determined by a contention window (CW) known to the UE in an implementation, or can be performed by the eNB through signaling. Each UE (e.g., UE1 or UE2) can determine the number of slits by uniformly generating a random number from (1, CW) called a backoff counter. Whenever the channel is sensed as idle, the ECCA counter can be decremented by 1. If the ECCA counter reaches zero, the UE (e.g., UE1 and/or UE2) can send a reserved signal that can consist of random bits to align with the beginning of the symbol and/or the next symbol. If a UE (e.g., UE1 and/or UE2) cannot obtain a clear channel, LBT can be performed in the next subframe using the current counter without generating a new random number. In one aspect, the counter can be regenerated for each transmission attempt. In another aspect, as a design choice, the CCA 404 operation can be skipped entirely. These operations are further described in FIG5 .

FIG5 shows a design of a physical uplink shared control channel (PUSCH) transmission based on listen-before-talk (LBT) with a subframe-level total time interval (TTI) according to an example. It should be noted that the description and embodiments of FIG1-4 can be used in FIG5. In action 510, during CCA and ECCA, it can be sensed (e.g., by using LBT operation) whether a channel medium in wireless communication is idle for a first predetermined time period (e.g., "C" microseconds (μs) or "Cμs"). In action 520, it can be determined whether the energy (e.g., received power) sensed during the CCA and ECCA duration is less than a specified threshold (T _dbm ). If the sensed energy (e.g., received power) during the CCA and ECCA durations is not less than a specified threshold (T _dbm ), then in action 530 , each UE (e.g., UE1 or UE2) may determine the number of slots by uniformly generating a random number from (1, CW), and in action 540 , each time the channel is sensed as idle, the ECCA counter may be decremented by 1, expressed as N=N-1, where N is a random number.

Moving from act 560 to act 570, a determination is made by checking whether the random number (N) is equal to one (1) (e.g., N=1). If not, the channel medium may be sensed for a second predetermined period of time (e.g., "E" microseconds (μs) or "Eμs") to determine whether it is idle. Additionally, returning to act 520, a determination is made by checking whether the random number (N) is equal to one (1) if the energy sensed during the CCA and ECCA durations (e.g., received power) is less than a specified threshold (T _dbm ), as in act 570.

In one aspect, from act 540 or act 550, in act 550, similar to act 520, a determination may be made again to determine whether the energy sensed during the CCA and ECCA durations (e.g., received power) is less than a specified threshold (T _dbm ). If the energy sensed during the CCA and ECCA durations (e.g., received power) is not less than the specified threshold (T _dbm ), each UE may determine the number of slits by uniformly generating a random number from (1, CW). As shown in FIG. 5 , if yes, act 550 moves to and/or returns to act 540. If no, act 550 moves to or returns to act 560.

If the random number (N) is equal to one (1) in action 570, the action moves to action 580, and each UE (e.g., UE1 and/or UE2) can send a reservation signal to align with the beginning of the symbol and/or the next symbol. If the UE (e.g., UE1 and/or UE2) cannot obtain a clear channel, action 580 returns to action 510, and LBT can be performed in the next subframe, however using the current counter without generating a new random number.

6 shows a design of a physical uplink shared control channel (PUSCH) transmission based on listen before talk (LBT) with preamble signaling according to an example. FIG6 depicts additional options for PUSCH transmission based on LBT. Similar to FIG4, the LBT sensing granularity (slot) can be used as 1/12 symbol, which is equivalent to 5.6 microseconds (μs), corresponding to 12 subcarriers in a resource block. In addition, during CCA 604 and ECCA 606, the channel medium in the wireless communication can be sensed (e.g., by using LBT operation) for a predetermined time period. CCA 604 can be performed in an implementation for a plurality of slots known to the UEs (e.g., UE 1, UE 2, and UE 3), or can be performed by the eNB through signaling.

In one aspect, the PUSCH transmission 602 may consist of up to 14 symbols (e.g., symbols 0 to 13 of the PUSCH transmission 602 shown in FIG6 ). In one aspect, the TTI may be maintained at 1 subframe. However, as shown in FIG6 , reducing the granularity to the symbol level may be achieved, where LBT operations may be performed within each symbol, as opposed to performing LBT operations in the last symbol as shown in FIG3 . Therefore, FIG6 includes new additional preamble signaling. The preamble 610 may include a UE RNTI and/or a DMRS-like signal for demodulation. In addition, the DMRS may be removed from the PUSCH transmission burst. The modulation and coding scheme (MCS) may be used for uplink transmissions that may be known to the UE (e.g., UE1, UE2, and/or UE3) and the eNB. The preamble may be used to indicate the length of the transmission (number of symbols or TTI) and the cell identity (e.g., to ignore other cells during LBT), and may also be used for scheduling requests and/or buffer status reports (BSRs) when there is more data to transmit.

It should be noted that, in one aspect, PUSCH transmissions may be retransmitted. First, a PUSCH transmission may be received in error at the eNB. Retransmissions may be performed based on PHICH information. Additional scheduling may also be sent using dedicated resources, where failed PUSCH transmissions may not be retransmitted following the LBT protocol. The Retransmission Request (Hybrid ARQ) Indicator Channel (PHICH) functionality may be replaced by sending an UL grant containing a New Data Indicator (NDI) and switching information indicating whether to flush the UL buffer.

In one aspect, for synchronous operation, if the PHICH indicates an acknowledgment (ACK), the UE is restricted from sending retransmitted PUSCH transmissions. If the PHICH indicates a negative acknowledgment (NACK), the UE may send retransmitted PUSCH, for example, at a specific time location (e.g., retransmit at TTI n+4 when a PHICH is received at TTI n). For frequency division duplex (FDD), the retransmission may be performed with or without the LBT protocol, where "n" is the subframe. For synchronous or asynchronous HARQ operation, if the NDI in the UL grant is toggled, the UE may be restricted from sending retransmitted PUSCH and may flush the UL data buffer. If the NDI in the UL grant is not toggled, the UE may send retransmitted PUSCH at the time and/or frequency location specified by the UL grant. In particular, the time location may be implicitly defined, as in 3GPP LTE Rel. 8-12, for example, in subframe n+4 when a UL grant is received in subframe n. This retransmission can be performed with or without the LBT protocol.

In one aspect, both PHICH and UL grant-based HARQ operations can be considered together. For example, when a UE expects and receives PHICH-based operations, but also receives NDI in an UL grant, the UE can ignore the PHICH indication and follow the NDI in the UL grant. In other words, the NDI can override the PHICH.

7 shows a design of a physical uplink shared control channel (PUSCH) transmission based on listen before talk (LBT) in an LBT contention zone 702 according to an example. It should be noted that a hidden node problem may occur if multiple UEs transmit simultaneously after performing LBT and the PUSCH transmission is not successfully decoded at the eNB 710 due to high interference. If the random number counter used for ECCA using contention windows of different UEs is similar for each different UE, a collision may occur at the eNB 710. Therefore, FIG7 depicts the use of adaptive segmentation of UEs, where each of the UEs belongs to a different contention zone 702 (e.g., zone 1, zone 2, and/or zone 3), and each of the zones belongs to a different contention window. Similar to FIG4 , the LBT sensing granularity (slit) can be used as 1/12 symbol, which is equivalent to 5.6 microseconds (μs), corresponding to 12 subcarriers in a resource block. In addition, during CCA and ECCA, the channel medium in the wireless communication can be sensed (e.g., by using LBT operation) for a predetermined time period.

In one aspect, a semi-static priority of the contention window can be assigned based on latency constraints to each of the contention zones (e.g., Zone 1, Zone 2, and/or Zone 3). If a cell determines a conflict, the eNB can semi-statically change (or increase) the contention window by creating a new zone, or reduce the contention zone, to allow for successful transmission.

8 shows a flow chart of a method for implementing low-latency synchronization between a user equipment (UE) and an anchor enhanced Node B (eNB) according to an example. For example, the functionality of the UE may be implemented as method 800 or the functionality may be executed as instructions on a machine, wherein the instructions are included on at least one computer-readable medium or a non-transitory machine-readable storage medium. As shown in block 810, one or more processors may be configured to sense whether any physical uplink shared channel (PUSCH) is idle for a predetermined time period. As shown in block 820, one or more processors may be configured to provide a unique UE identification in a PUSCH transmission. In action 830, a PUSCH transmission may be transmitted in one of the idle PUSCH channels for contention-free (e.g., unlicensed) communication with the eNB for uplink synchronization.

It should be noted that each of the following items may be included in Figure 8. In other words, each of the following items may be included in each of the actions described in Figure 8 and/or combined with one or more of these actions. One or more processors may be configured to transmit a PUSCH transmission to the anchor eNB in one of the idle PUSCH channels without uplink synchronization scheduling. One or more processors may be configured to sense that the PUSCH channel is idle when the sensed energy is below a predetermined threshold. One or more processors may be configured to detect whether any PUSCH channel is idle during a clear channel assessment (CCA) and an extended CCA (ECCA), where the duration of the CCA or ECCA is based on a minimum sensing granularity. One or more processors may be configured to sense that the PUSCH channel is idle when the energy sensed during the duration of the CCA or ECCA is below a predetermined threshold.

In one aspect, the ECCA may span multiple sensing granularity slits, wherein the number of the multiple sensing granularity slits spanned by the ECCA is determined by the multiple contention windows.

In an aspect, one or more processors may be configured to determine the number of the plurality of sensing granularity slits by generating a random number ranging from 1 to the number of the plurality of sensing granularity slits spanned by the ECCA determined by the contention window, reduce the number of the plurality of sensing granularity slits spanned by the ECCA whenever the PUSCH channel is sensed as idle, and/or reserve one of the PUSCH channels that is idle for transmitting a PUSCH transmission.

In one aspect, the unique UE identifier may be one of: a cell radio network temporary identifier (C-RNTI) and/or a radio network temporary identifier (RNTI). Furthermore, the delivery of the PUSCH transmission may also be performed when the UL packet arrives at a medium access control (MAC) buffer of the UE. The PUSCH transmission may consist of a plurality of symbols corresponding to subcarriers in a resource block, and the one or more processors may be configured to use at least one of the plurality of symbols to sense whether the PUSCH channel is idle, while using the remaining number of symbols in the plurality of symbols for the PUSCH transmission.

In one aspect, the one or more processors may be configured to use a modulation and coding scheme (MCS) for UL transmission, where the MCS may be predefined by a minimum MCS. In one aspect, the one or more processors may be configured to use preamble signaling to sense whether a PUSCH channel is idle.

In another aspect, one or more processors may be configured to transmit a PUSCH transmission in a hybrid automatic repeat request (HARQ) operation, processing the PUSCH transmission for retransmission when the UE receives a negative acknowledgement (NACK) in a physical HARQ indicator channel (PHICH). The retransmission of the PUSCH transmission may be based on an UL grant or based on a new data indicator (NDI) toggled in the UL grant. In one aspect, the one or more processors may be configured to transmit the PUSCH transmission in a configured time or frequency region and/or adaptively partition the UE into different contention zones with different contention windows relative to alternative UEs, wherein each contention zone is dynamically or semi-statically modified (adapted) based on a latency constraint.

FIG9 illustrates a flow chart of an additional method for implementing contention-free uplink (UL) synchronization between an anchor enhanced Node B (eNB) and a user equipment (UE), according to an example. For example, the functionality of the eNB may be implemented as method 900 or the functionality may be executed as instructions on a machine, wherein the instructions are included on at least one computer-readable medium or a non-transitory machine-readable storage medium. One or more processors may be configured to process a Physical Uplink Shared Channel (PUSCH) transmission received from a UE after sensing an idle PUSCH channel for a predetermined time period, as shown in block 910. One or more processors may be configured to receive a unique UE identification (ID) in the PUSCH transmission by the ENodeB, as shown in block 920. The identity of the UE may be determined by the UE unique ID in the PUSCH transmission for contention-free (e.g., grant-free) communication with the eNB for uplink synchronization, as shown in action 930. In one aspect, FIG9 may also perform blind UE detection based on a demodulation reference signal (DMRS).

It should be noted that each of the following items may be included in Figure 9. In other words, each of the following items may be included in each of the actions described in Figure 9 and/or combined with one or more of these actions.

In an aspect, one or more processors may be configured to perform blind UE detection based on a demodulation reference signal (DMRS), process a PUSCH transmission received from the UE in one of idle PUSCH channels without UL synchronization scheduling, process a reservation signal received from the UE to reserve one of multiple PUSCH channels as idle to receive the PUSCH transmission, and/or process a PUSCH transmission received from the UE when an UL packet arrives at a medium access control (MAC) buffer of the UE.

In an aspect, the one or more processors may be configured to use a modulation and coding scheme (MCS) for UL transmission, where the MCS may be predefined by a lowest MCS.

In an aspect, one or more processors may be configured to receive a PUSCH transmission in a hybrid automatic repeat request (HARQ) operation, process a negative acknowledgement (NACK) in a physical HARQ indicator channel for transmission to a UE to trigger the UE to retransmit the PUSCH transmission, process a UL grant or a new data indicator (NDI) toggled in a UL grant for transmission to the UE for retransmission of the PUSCH transmission, and/or process PUSCH transmissions received in a configured time or frequency region.

In an aspect, the one or more processors may be configured to dynamically or semi-statically modify and/or allocate a requisition window for successful reception of a PUSCH transmission by creating a new contention region with a different contention window or reducing a currently used contention region upon determining a cell conflict between the UE and an alternative UE.

10 provides an example diagram of a wireless device 1000, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet computer, a cell phone, or other type of wireless device. In one aspect, the wireless device may include at least one of the following: an antenna, a touch-sensitive display, a speaker, a microphone, a graphics processor, an application processor, internal memory, a non-volatile memory port, and combinations thereof.

The wireless device may include one or more antennas configured to communicate with a node or transmission station (e.g., a base station (BS), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), a remote radio unit (RRU), a central processing module (CPM), or other types of wireless wide area network (WWAN) access points). The wireless device may be configured to communicate using at least one wireless communication standard including 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The wireless device may communicate using a separate antenna for each wireless communication standard or a shared antenna for multiple wireless communication standards. The wireless device may communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN. Various techniques or some aspects thereof or a portion thereof can be in the form of program code (i.e., instructions) embodied in a tangible medium (e.g., a floppy disk, a compact disc read-only memory (CD-ROM), a hard drive, a non-transitory computer-readable storage medium, or any other machine-readable storage medium), wherein when the program code is loaded into a machine such as a computer and executed by it, the machine becomes a device for performing these various techniques. Circuits can include hardware, firmware, program code, executable code, computer instructions, and/or software. Non-transitory computer-readable storage media can be computer-readable storage media that does not include signals. In the case of executing program code on a programmable computer, a computing device can include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage element), at least one input device, and at least one output device. Volatile and non-volatile memory and/or storage element can be random access memory (RAM), erasable programmable read-only memory (EPROM), a flash drive, an optical drive, a magnetic hard drive, a solid-state drive, or other media for storing electronic data. Nodes and wireless devices may also include transceiver modules (i.e., transceivers), counter modules (i.e., counters), processing modules (i.e., processors), and/or clock modules (i.e., clocks) or timer modules (i.e., timers). One or more programs that can implement or utilize the various techniques described herein may use application programming interfaces (APIs), reusable controls, and the like. Such programs may be implemented in high-level procedural or object-oriented programming languages to communicate with computer systems. However, if desired, the program(s) may be implemented in assembly or machine language. In any case, the language may be a compiled or interpreted language, combined with hardware implementation.

As used herein, the term "circuit" may refer to a portion 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 executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the functionality. In some aspects, a circuit may be implemented in one or more software or firmware modules or functionality associated with the circuit may be implemented by one or more software or firmware modules. In some aspects, a circuit may include logic that is at least partially operable in hardware.

The aspects described herein may be implemented into a system using any suitably configured hardware and/or software.

11 illustrates example components of a user equipment (UE) 1100. In some aspects, the UE device 1110 may include application circuitry 1102, baseband circuitry 1004, radio frequency (RF) circuitry 1106, front-end module (FEM) circuitry 1008, and one or more antennas 1101, coupled together at least as shown.

The application circuitry 1102 may include one or more application processors. For example, the application circuitry 1002 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 specialized processors (e.g., graphics processors, application processors, etc.). The processor(s) may include any combination of general-purpose processors and specialized processors (e.g., graphics processors, application processors, etc.). The processor(s) may be coupled to a storage medium 1112 and/or may include a memory/storage device and may be configured to execute instructions stored in the storage medium 1112 to enable various applications and/or operating systems to run on the system.

The baseband circuitry 1104 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1104 may include one or more baseband processors and/or control logic for processing baseband signals received from the receive signal path of the RF circuitry 1106 and generating baseband signals for the transmit signal path of the RF circuitry 1106. The baseband processing circuitry 1104 may interface with the application circuitry 1102 for baseband signal generation and processing and for controlling the operation of the RF circuitry 1106. For example, in some aspects, the baseband circuitry 1104 may include a second generation (2G) baseband processor 1104a, a third generation (3G) baseband processor 1104b, a fourth generation (4G) baseband processor 1104c, and/or one or more other baseband processors 1104d for other existing generations, generations in development, or generations to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 1104 (e.g., one or more of the baseband processors 1104a-d) can handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1106. The radio control functions can include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some aspects, the modulation/demodulation circuitry of the baseband circuitry 1104 can include fast Fourier transform (FFT), precoding, and/or constellation mapping/demapping functions. In some aspects, the encoding/decoding circuitry of the baseband circuitry 1104 can include convolution, tail-biting convolution, turbo, Viterbi, and/or low-density parity check (LDPC) encoder/decoder functions. Aspects of the modulation/demodulation and encoder/decoder functions are not limited to these examples and, in other aspects, can include other suitable functions.

In some aspects, the baseband circuitry 1104 may include elements of a protocol stack, such as elements of an Evolved Universal Terrestrial Radio Access Network (EUTRAN) protocol (including, for example, physical (PHY), medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements). The central processing unit (CPU) 1104e of the baseband circuitry 1104 may be configured to execute elements of the protocol stack for signaling at the PHY, MAC, RLC, PDCP, and/or RRC layers. In some aspects, the baseband circuitry may include one or more audio digital signal processors (DSPs) 1104f. The audio DSP(s) 1104f may include elements for compression/decompression and echo cancellation, and in other aspects may include other suitable processing elements. In some aspects, the components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or arranged on the same circuit board. In some aspects, some or all of the constituent components of the baseband circuitry 1104 and the application circuitry 1102 may be implemented together, for example, on a system on a chip (SOC).

In some aspects, the baseband circuitry 1104 can provide communications compatible with one or more radio technologies. For example, in some aspects, the baseband circuitry 1104 can support communications with the Evolved Universal Terrestrial Radio Access Network (EUTRAN) and/or other wireless metropolitan area networks (WMANs), wireless local area networks (WLANs), and wireless personal area networks (WPANs). In some aspects, the baseband circuitry 1104 is configured to support radio communications of more than one wireless protocol, which can be referred to as multi-mode baseband circuitry.

The RF circuitry 1106 can communicate with a wireless network using modulated electromagnetic radiation via a non-solid medium. In various aspects, the RF circuitry 1106 can include switches, filters, amplifiers, and the like to facilitate communication with the wireless network. The RF circuitry 1106 can include a receive signal path that can include circuitry for down-converting RF signals received from the FEM circuitry 1108 and providing baseband signals to the baseband circuitry 1104. The RF circuitry 1106 can also include a transmit signal path that can include circuitry for up-converting baseband signals provided by the baseband circuitry 1104 and providing an RF output signal to the FEM circuitry 1108 for transmission.

In some aspects, RF circuitry 1106 may include a receive signal path and a transmit signal path. The receive signal path of RF circuitry 1106 may include mixer circuitry 1106a, amplifier circuitry 1106b, and filter circuitry 1106c. The transmit signal path of RF circuitry 1106 may include filter circuitry 1106c and mixer circuitry 1106a. RF circuitry 1106 may also include synthesizer circuitry 1106d for synthesizing frequencies for use by mixer circuitry 1106a in the receive signal path and the transmit signal path. In some aspects, mixer circuitry 1106a in the receive signal path may be configured to downconvert the RF signal received from FEM circuitry 1108 based on the synthesized frequency provided by synthesizer circuitry 1106d. Amplifier circuitry 1106b may be configured to amplify the downconverted signal, and filter circuitry 1106c may be a low-pass filter (LPF) or a band-pass filter (BPF) configured to remove unwanted signals from the downconverted signal to generate an output baseband signal. The output baseband signal can be provided to baseband circuitry 1104 for further processing. In some aspects, the output baseband signal can be a zero-frequency baseband signal, but it does not need to be a zero-frequency baseband signal. In some aspects, the mixer circuitry 1106a of the receive signal path can include a passive mixer, although the scope of the aspects is not limited in this respect.

In some aspects, the mixer circuit 1106a of the transmit signal path can be configured to upconvert an input baseband signal based on a synthesized frequency provided by the synthesizer circuit 1106d to generate an RF output signal for the FEM circuit 1108. The baseband signal can be provided by the baseband circuit 1104 and can be filtered by the filter circuit 1106c. The filter circuit 1106c can include a low pass filter (LPF), although the scope of the aspects is not limited in this respect.

In some aspects, the mixer circuit 1106a of the receive signal path and the mixer circuit 1106a 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 aspects, the mixer circuit 1106a of the receive signal path and the mixer circuit 1106a 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 aspects, the mixer circuit 1106a of the receive signal path and the mixer circuit 1106a of the transmit signal path may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some aspects, the mixer circuit 1106a of the receive signal path and the mixer circuit 1106a of the transmit signal path may be configured for superheterodyne operation.

In some aspects, the output baseband signal and the input baseband signal can be analog baseband signals, although the scope of the aspects is not limited in this respect. In some alternative aspects, the output baseband signal and the input baseband signal can be digital baseband signals. In these alternative aspects, the RF circuitry 1106 can include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry, and the baseband circuitry 1104 can include a digital baseband interface for communicating with the RF circuitry 1106.

In some dual-mode embodiments, 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, synthesizer circuit 1106 d may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, but the scope of the embodiments is not limited in this respect, as other types of frequency synthesizers may be suitable. For example, synthesizer circuit 1106 d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase-locked loop with a frequency divider.

Synthesizer circuit 1106d may be configured to synthesize an output frequency based on the frequency input and the divider control input for use by mixer circuit 1106a of RF circuit 1106. In some embodiments, synthesizer circuit 1106d may be a fractional-N/N+1 synthesizer.

In some embodiments, the frequency input can be provided by a voltage-controlled oscillator (VCO), but the frequency input does not need to be a VCO. Depending on the desired output frequency, the divider control input can be provided by the baseband circuit 1104 or the application processor 1102. In some embodiments, the divider control input (e.g., N) can be determined from a lookup table based on the channel indicated by the application processor 1102.

The synthesizer circuit 1106d of the RF circuit 1106 may include a frequency divider, a delay-locked loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the frequency divider may be a dual-mode frequency 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 N or N+1 (e.g., based on a carry output) 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 decompose the VCO cycle into Nd equal phase groups, 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 circuit 1106d can be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency can be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with a quadrature generator and divider circuit to generate multiple signals at the carrier frequency with multiple different phases relative to each other. In some embodiments, the output frequency can be the LO frequency (fLO). In some embodiments, RF circuit 1106 can include an IQ/polarity converter.

The FEM circuitry 1108 may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas 1110, amplify the received signals, and provide the amplified versions of the received signals to the RF circuitry 1106 for further processing. The FEM circuitry 1108 may also include a transmit signal path that may include circuitry configured to amplify signals provided by the RF circuitry 1106 for transmission to one or more of the one or more antennas 1110.

In some embodiments, the FEM circuitry 1108 may include a TX/RX switch for switching between transmit and receive modes of 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) for amplifying a received RF signal and providing the amplified received RF signal as an output (e.g., to the RF circuitry 1106). The transmit signal path of the FEM circuitry 1108 may include a power amplifier (PA) for amplifying an input RF signal (e.g., provided by the RF circuitry 1106), and one or more filters for generating an RF signal for subsequent transmission (e.g., by one or more of the one or more antennas 1110).

In some embodiments, UE 1100 may include additional elements, such as memory/storage, displays, cameras, sensors, and/or input/output (I/O) interfaces.

FIG12 shows a schematic diagram 1200 of a node 1210 (e.g., an eNB and/or a serving GPRS support node) and a wireless device (e.g., a UE) according to an example. The node may include a base station (BS), a node B (NB), an evolved node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a remote radio unit (RRU), or a central processing module (CPM). In one aspect, the node may be a serving GPRS support node. The node 1210 may include a node device 1212. The node device 1212 or node 1210 may be configured to communicate with a wireless device 1220. The node device 1212 may be configured to implement the described techniques. The node device 1212 may include a processing module 1214 and a transceiver module 1216. In one aspect, the node device 1212 may include the transceiver module 1216 and the processing module 1214, which form circuitry 1218 for the node 1210. In one aspect, the transceiver module 1216 and the processing module 1214 may form the circuitry of the node device 1212. The processing module 1214 may include one or more processors and memory. In one embodiment, the processing module 1222 may include one or more application processors. The transceiver module 1216 may include a transceiver and one or more processors and memory. In one embodiment, the transceiver module 1216 may include a baseband processor.

Wireless device 1220 may include a transceiver module 1224 and a processing module 1222. Processing module 1222 may include one or more processors and memory. In one embodiment, processing module 1222 may include one or more application processors. Transceiver module 1224 may include a transceiver and one or more processors and memory. In one embodiment, transceiver module 1224 may include a baseband processor. Wireless device 1220 may be configured to implement the described techniques. Node 1210 and wireless device 1220 may also include one or more storage media, such as transceiver modules 1216, 1224 and/or processing modules 1214, 1222.

Example

The following examples relate to specific technical embodiments and indicate specific features, elements, or steps that can be used or combined to implement these embodiments.

Example 1 includes a device of a user equipment (UE) for achieving low-latency synchronization with an enhanced Node B (eNB) under the control of one or more processors and memories, the device being configured to: sense whether any physical uplink shared channel (PUSCH) is idle for a predetermined time period; provide a unique UE identifier in a PUSCH transmission; and transmit the PUSCH transmission in one of the idle PUSCH channels for contention-free communication with the eNB for uplink synchronization.

Example 2 includes the apparatus of Example 1, wherein the apparatus is further configured to transmit the PUSCH transmission to the eNB in one of the idle PUSCH channels without uplink synchronization scheduling.

Example 3 includes the apparatus of Example 1 or 2, wherein the apparatus is further configured to sense the PUSCH channel as idle when the sensed energy is below a predetermined threshold.

Example 4 includes the apparatus of Example 1, wherein the apparatus is further configured to perform clear channel assessment (CCA) or extended clear channel assessment (ECCA) for multiple sensing granularity slots known to the UE, or to perform CCA or ECCA by signaling to the eNB.

Example 5 includes the apparatus of Example 1 or 4, wherein the apparatus is further configured to sense whether any of the PUSCH channels is idle during a clear channel assessment (CCA) and an extended CCA (ECCA), wherein the duration of the CCA or ECCA is based on a minimum sensing granularity.

Example 6 includes the apparatus of Example 1 or 5, wherein the apparatus is further configured to sense the PUSCH channel as idle when the sensed energy during the duration of the CCA or ECCA is below a predetermined threshold.

Example 7 includes the apparatus of Example 1 or 5, further configured to: perform ECCA by spanning a plurality of sensing granularity slits, wherein the number of the plurality of sensing granularity slits spanned by the ECCA is determined by a contention window (CW); determine the number of the plurality of sensing granularity slits by generating a random number ranging from 1 to the number of the plurality of sensing granularity slits spanned by the ECCA determined by the CW in a backward-shifted counter manner; and reduce the number of the plurality of sensing granularity slits spanned by the ECCA whenever the PUSCH channel is sensed as idle.

Example 8 includes the apparatus of Example 1 or 7, wherein the apparatus is further configured to:

Whenever the PUSCH channel is sensed as idle, the ECCA counter is decremented by one (1); a reserved signal for alignment with a symbol boundary is sent; and the reserved signal for starting the next symbol is processed for transmission.

Example 9 includes the apparatus of Example 8, wherein the apparatus is further configured to sense whether a current transmission attempt is unsuccessful, wherein the UE continues to perform ECCA in a subsequent subframe using a current count of the ECCA counter without generating a new random number.

Example 10 includes the apparatus of Example 1 or 9, wherein the apparatus is further configured to: sense whether the current transmission attempt is unsuccessful, wherein the UE performs a pre-conversation listening process consisting of CCA and ECCA by regenerating a new backshift counter in the next transmission attempt (e.g., a subsequent subframe); and perform the pre-conversation listening process starting from symbol 0 for a specified number of symbols M, wherein the PUSCH transmission starts from symbol M+1 and ends at symbol 14 within the subframe, wherein M is a positive integer, wherein a channel sounding reference signal (SRS) is sent on symbol 14, wherein truncation of symbol 14 is eliminated.

Example 11 includes the apparatus of Example 1, wherein the apparatus is further configured to reserve an idle one of the PUSCH channels for transmitting the PUSCH transmission.

Example 12 includes the apparatus of Example 1 or 11, wherein the unique UE identity is one of a cell radio network temporary identifier (C-RNTI) or a radio network temporary identifier (RNTI).

Example 13 includes the apparatus of Example 1, wherein transmitting the PUSCH transmission is performed when the UL packet arrives at a medium access control (MAC) buffer of the UE.

Example 14 includes the apparatus of Example 1 or 13, wherein the PUSCH transmission consists of a plurality of symbols corresponding to subcarriers in a resource block, wherein the circuit is further configured to use at least one of the plurality of symbols to sense whether the PUSCH channel is idle, while using a remaining number of the plurality of symbols for the PUSCH transmission.

Example 15 includes the apparatus of Example 1, wherein the apparatus is further configured to use a modulation and coding scheme (MCS) for UL transmission, wherein the MCS can be predefined by a lowest MCS.

Example 16 includes the apparatus of Example 1 or 15, wherein the apparatus is further configured to sense whether the PUSCH channel is idle using preamble signaling.

Example 17 includes the apparatus of Example 1, further configured to sense whether the PUSCH channel is idle using an additional preamble signal, wherein the additional preamble signal includes a radio network temporary identifier (RNTI) and/or a DMRS signal for demodulation, wherein the DMRS signal is removed during the PUSCH transmission pulse.

Example 18 includes the apparatus of Example 1 or 17, wherein the apparatus is further configured to transmit the PUSCH transmission in a hybrid automatic repeat request (HARQ) operation.

Example 19 includes the apparatus of Example 18, wherein the apparatus is further configured to process the PUSCH transmission for retransmission when the UE receives a negative acknowledgement (NACK) in a physical HARQ indicator channel (PHICH).

Example 20 includes the apparatus of Example or 19, wherein the retransmission of the PUSCH transmission is based on the UL grant or based on a new data indicator (NDI) toggled in the UL grant.

Example 21 includes the apparatus of Example 1, wherein the apparatus is further configured to transmit a PUSCH transmission in a configured time or frequency region.

Example 22 includes the apparatus of Example 1 or 21, wherein the apparatus is further configured to adaptively partition the UE into different contention zones having different contention windows relative to alternative UEs, wherein each of the contention zones is dynamically or semi-statically modified according to a latency constraint.

Example 23 includes the apparatus of Example 1, wherein the apparatus comprises at least one of: an antenna, a touch-sensitive display, a speaker, a microphone, a graphics processor, an application processor, a baseband processor, internal memory, a non-volatile memory port, and combinations thereof.

Example 24 includes an apparatus of an anchor enhanced Node B (eNB) operable to achieve contention-free uplink (UL) synchronization with a user equipment (UE), the apparatus being configured to: process a physical uplink shared channel (PUSCH) transmission received from the UE after sensing an idle PUSCH channel for a predetermined time period; receive a unique UE identifier in the PUSCH transmission; and determine the identity of the UE for contention-free UL synchronization via the unique UE identifier in the PUSCH transmission.

Example 25 includes the apparatus of Example 24, wherein the apparatus is further configured to perform blind UE detection based on a demodulation reference signal (DMRS).

Example 26 includes the apparatus of Example 24 or 25, wherein the apparatus is further configured to generate a demodulation reference signal (DMRS) sequence by using a constant envelope zero autocorrelation waveform (CAZAC) sequence, wherein the CAZAC sequence is a Zadoff-Chu (ZC) sequence.

Example 27 includes the apparatus of Example 24, wherein the apparatus is further configured to process a PUSCH transmission received from the UE in one of the idle PUSCH channels without UL synchronization scheduling.

Example 28 includes the apparatus of Example 24 or 27, wherein the apparatus is further configured to process a reservation signal received from the UE, the reservation signal being used to reserve an idle one of the plurality of PUSCH channels for receiving the PUSCH transmission.

Example 29 includes the apparatus of Example 24, wherein the apparatus is further configured to process a PUSCH transmission received from the UE when the UL packet arrives at a medium access control (MAC) buffer of the UE.

Example 30 includes the apparatus of Example 24 or 29, wherein the apparatus is further configured to: use a modulation and coding scheme (MCS) for UL transmission, wherein the MCS can be predefined by a minimum MCS; process a PUSCH transmission received in a hybrid automatic repeat request (HARQ) operation; and process a negative acknowledgement (NACK) in a physical HARQ indicator channel for transmission to a UE to trigger the UE to retransmit the PUSCH transmission.

Example 31 includes the apparatus of Example 24 or 29, wherein the apparatus is further configured to: process an UL grant or a new data indicator (NDI) switched in the UL grant for transmission to the UE to retransmit the PUSCH transmission; process the PUSCH transmission received in the configured time or frequency region; and when a cell conflict between the UE and an alternative UE is determined, dynamically or semi-statically modify or allocate the contention window by creating a new contention area with a different contention window or reducing the contention area currently used for successful reception of the PUSCH transmission.

Example 32 includes an apparatus of a user equipment (UE) for implementing low-latency synchronization with an enhanced Node B (eNB) under the control of one or more processors and memories, the apparatus being configured to: sense whether any physical uplink shared channel (PUSCH) is idle for a predetermined time period; provide a unique UE identifier in a PUSCH transmission; and transmit the PUSCH transmission in one of the idle PUSCH channels for contention-free communication with the eNB for uplink synchronization.

Example 33 includes the apparatus of Example 32, wherein the apparatus is further configured to transmit the PUSCH transmission to the eNB in one of the idle PUSCH channels without uplink synchronization scheduling.

Example 34 includes the apparatus of Example 32, wherein the apparatus is further configured to sense the PUSCH channel as idle when the sensed energy is below a predetermined threshold.

Example 35 includes the apparatus of Example 32, wherein the apparatus is further configured to perform clear channel assessment (CCA) or extended clear channel assessment (ECCA) for multiple sensing granularity slots known to the UE, or to perform CCA or ECCA by signaling to the eNB.

Example 36 includes the apparatus of Example 32, wherein the apparatus is further configured to sense whether any of the PUSCH channels is idle during a clear channel assessment (CCA) and an extended CCA (ECCA), wherein the duration of the CCA or ECCA is based on a minimum sensing granularity.

Example 37 includes the apparatus of Example 36, wherein the apparatus is further configured to sense the PUSCH channel as idle when the sensed energy during CCA or ECCA is below a predetermined threshold.

Example 38 includes the apparatus of Example 36, wherein the apparatus is further configured to: perform ECCA by spanning a plurality of sensing granularity slits, wherein the number of the plurality of sensing granularity slits spanned by the ECCA is determined by a contention window (CW); determine the number of the plurality of sensing granularity slits by generating a random number, wherein the random number ranges from 1 to the number of the plurality of sensing granularity slits spanned by the ECCA determined by the CW as a back-shift counter; and reduce the number of the plurality of sensing granularity slits spanned by the ECCA whenever the PUSCH channel is sensed as idle.

Example 39 includes the apparatus of Example 38, wherein the apparatus is further configured to: decrement the ECCA counter by one (1) each time the PUSCH channel is sensed as idle; process a reserved signal for alignment with a symbol boundary for transmission; or process a reserved signal for starting the next symbol for transmission.

Example 40 includes the apparatus of Example 39, wherein the apparatus is further configured to sense whether a current transmission attempt is unsuccessful, wherein the UE continues to perform ECCA using a current count of the ECCA counter in a subsequent subframe without generating a new random number.

Example 41 includes the apparatus of Example 40, wherein the apparatus is further configured to: sense whether the current transmission attempt is unsuccessful, wherein the UE performs a pre-conversation listening process consisting of CCA and ECCA by regenerating a new backshift counter in the next transmission attempt (e.g., a subsequent subframe); and perform the pre-conversation listening process starting from symbol 0 for a specified number of symbols M, wherein the PUSCH transmission starts from symbol M+1 and ends at symbol 14 within the subframe, wherein M is a positive integer, wherein a channel sounding reference signal (SRS) is sent on symbol 14, wherein truncation of symbol 14 is eliminated.

Example 42 includes the apparatus of Example 41, wherein the apparatus is further configured to reserve an idle one of the PUSCH channels for transmitting the PUSCH transmission.

Example 43 includes the apparatus of Example 42, wherein the unique UE identity is one of a cell radio network temporary identifier (C-RTI) or a radio network temporary identifier (RNTI).

Example 44 includes the apparatus of Example 32, wherein transmitting the PUSCH transmission is performed when the UL packet arrives at a medium access control (MAC) buffer of the UE.

Example 45 includes the apparatus of Example 32, wherein the PUSCH transmission consists of a plurality of symbols corresponding to subcarriers in a resource block, wherein the circuit is further configured to use at least one of the plurality of symbols to sense whether the PUSCH channel is idle, while using a remaining number of the plurality of symbols for the PUSCH transmission.

Example 46 includes the apparatus of Example 32, wherein the apparatus is further configured to use a modulation and coding scheme (MCS) for UL transmission, wherein the MCS can be predefined by a lowest MCS.

Example 47 includes the apparatus of Example 32, wherein the apparatus is further configured to sense whether the PUSCH channel is idle using preamble signaling.

Example 48 includes the apparatus of Example 32, wherein the apparatus is further configured to sense whether the PUSCH channel is idle using an additional preamble signal, wherein the additional preamble signal includes a radio network temporary identifier (RNTI) and/or a DMRS signal for demodulation, wherein the DMRS signal is removed during the PUSCH transmission pulse.

Example 49 includes the apparatus of Example 48, wherein the apparatus is further configured to transmit the PUSCH transmission in a hybrid automatic repeat request (HARQ) operation.

Example 50 includes the apparatus of Example 49, wherein the apparatus is further configured to process the PUSCH transmission for retransmission when the UE receives a negative acknowledgement (NACK) in the physical HARQ indicator channel (PHICH).

Example 51 includes the apparatus of Example 32, wherein the retransmission of the PUSCH transmission is based on the UL grant or based on a new data indicator (NDI) toggled in the UL grant.

Example 52 includes the apparatus of Example 32, wherein the apparatus is further configured to transmit a PUSCH transmission in a configured time or frequency region.

Example 53 includes the apparatus of Example 32, wherein the apparatus is further configured to adaptively partition the UE into different contention zones having different contention windows relative to alternative UEs, wherein each of the contention zones is dynamically or semi-statically modified according to a latency constraint.

Example 54 includes the apparatus of Example 32, wherein the apparatus comprises at least one of an antenna, a touch-sensitive display, a speaker, a microphone, a graphics processor, an application processor, a baseband processor, an internal memory, a non-volatile memory port, and combinations thereof.

Example 55 includes an apparatus of an anchor enhanced Node B (eNB) operable to achieve contention-free uplink (UL) synchronization with a user equipment (UE), the apparatus being configured to: process a physical uplink shared channel (PUSCH) transmission received from the UE after sensing an idle PUSCH channel for a predetermined time period; receive a unique UE identifier in the PUSCH transmission; and determine the identity of the UE for contention-free UL synchronization via the unique UE identifier in the PUSCH transmission.

Example 56 includes the apparatus of Example 55, wherein the apparatus is further configured to perform blind UE detection based on a demodulation reference signal (DMRS).

Example 57 includes the apparatus of Example 55, wherein the apparatus is further configured to generate a demodulation reference signal (DMRS) sequence by using a constant envelope zero autocorrelation waveform (CAZAC) sequence, wherein the CAZAC sequence is a Zadoff-Chu (ZC) sequence.

Example 58 includes the apparatus of Example 55, wherein the apparatus is further configured to process a PUSCH transmission received from the UE in one of the idle PUSCH channels without UL synchronization scheduling.

Example 59 includes the apparatus of Example 55, wherein the apparatus is further configured to process a reservation signal received from the UE, the reservation signal being used to reserve an idle one of the plurality of PUSCH channels for receiving the PUSCH transmission.

Example 60 includes the apparatus of Example 55, wherein the apparatus is further configured to process a PUSCH transmission received from the UE when the UL packet arrives at a medium access control (MAC) buffer of the UE.

Example 61 includes the apparatus of Example 55, wherein the apparatus is further configured to: use a modulation and coding scheme (MCS) for UL transmission, wherein the MCS can be predefined by a minimum MCS; process a PUSCH transmission received in a hybrid automatic repeat request (HARQ) operation; and process a negative acknowledgement (NACK) in a physical HARQ indicator channel for transmission to a UE to trigger the UE to retransmit the PUSCH transmission.

Example 62 includes the apparatus of Example 55, wherein the apparatus is further configured to: process an UL grant or a new data indicator (NDI) switched in an UL grant for transmission to the UE for retransmission of a PUSCH transmission; process a PUSCH transmission received in a configured time or frequency region; and upon determining a cell conflict between the UE and an alternative UE, dynamically or semi-statically modify or allocate a contention window by creating a new contention area with a different contention window or reducing a currently used contention area for successful reception of the PUSCH transmission.

Example 63 includes an apparatus of a user equipment (UE) for implementing low-latency synchronization with an enhanced Node B (eNB) under the control of one or more processors and memories, the apparatus being configured to: sense whether any physical uplink shared channel (PUSCH) is idle for a predetermined time period; provide a unique UE identifier in a PUSCH transmission; and transmit the PUSCH transmission in one of the idle PUSCH channels for contention-free communication with the eNB for uplink synchronization.

Example 64 includes the apparatus of Example 63, wherein the apparatus is further configured to: transmit a PUSCH transmission to the eNB in one of the idle PUSCH channels without uplink synchronization scheduling; sense the PUSCH channel as idle when the sensed energy is below a predetermined threshold; perform a clear channel assessment (CCA) or an extended clear channel assessment (ECCA) for multiple sensing granularity gaps known to the UE, or perform the CCA or ECCA by signaling to the eNB; or sense whether any of the PUSCH channels is idle during the CCA and extended CCA (ECCA), wherein the duration of the CCA or ECCA is based on the minimum sensing granularity.

Example 65 includes the apparatus of Example 63 or 64, wherein the apparatus is further configured to sense the PUSCH channel as idle when the sensed energy during the duration of the CCA or ECCA is below a predetermined threshold.

In Example 66, the subject matter of Example 63 or any example described herein may further include: the apparatus being further configured to: perform ECCA by spanning a plurality of sensing granularity slits, wherein the number of the plurality of sensing granularity slits spanned by the ECCA is determined by a contention window (CW); determine the number of the plurality of sensing granularity slits by generating a random number ranging from 1 to the number of the plurality of sensing granularity slits spanned by the ECCA determined by the CW as a back-shift counter; or reduce the number of the plurality of sensing granularity slits spanned by the ECCA whenever the PUSCH channel is sensed as idle.

In Example 67, the subject matter of Example 63 or any example described herein may also include: the apparatus is further configured to: decrement the ECCA counter by one (1) each time the PUSCH channel is sensed as idle; process a reserved signal for alignment with a symbol boundary for transmission; or process a reserved signal for starting the next symbol for transmission.

In Example 68, the subject matter of Example 63 or any example described herein may also include: the apparatus is further configured to: sense whether the current transmission attempt is unsuccessful, wherein the UE continues to perform ECCA in a subsequent subframe using the current count of the ECCA counter without generating a new random number; sense whether the current transmission attempt is unsuccessful, wherein the UE performs a pre-conversation listening process consisting of CCA and ECCA by regenerating a new backshift counter in the next transmission attempt (e.g., a subsequent subframe); or perform a pre-conversation listening process starting from symbol 0 for a specified number of symbols M, wherein the PUSCH transmission starts from symbol M+1 and ends at symbol 14 within the subframe, wherein M is a positive integer, wherein a channel sounding reference signal (SRS) is sent on symbol 14, wherein truncation of symbol 14 is eliminated.

In Example 69, the subject matter of Example 63 or any example described herein may further include: the apparatus is further configured to reserve one of the PUSCH channels that is idle for transmitting the PUSCH transmission. The unique UE identity is one of a cell radio network temporary identifier (C-RNTI) or a radio network temporary identifier (RNTI), wherein transmitting the PUSCH transmission is performed when an UL packet arrives at a medium access control (MAC) buffer of the UE, wherein the PUSCH transmission consists of a plurality of symbols corresponding to subcarriers in a resource block, wherein the circuit is further configured to use at least one of the plurality of symbols to sense whether the PUSCH channel is idle, while using a remaining number of the plurality of symbols for the PUSCH transmission.

In Example 70, the subject matter of Example 63 or any example described herein may also include, wherein the apparatus is further configured to: use a modulation and coding scheme (MCS) for UL transmission, wherein the MCS can be predefined by a minimum MCS; use preamble signaling to sense whether the PUSCH channel is idle; wherein an additional preamble signal is used to sense whether the PUSCH channel is idle, wherein the additional preamble signal includes a radio network temporary identifier (RNTI) and/or a DMRS signal for demodulation, wherein the DMRS signal is removed during the PUSCH transmission pulse; or transmit the PUSCH transmission in a hybrid automatic repeat request (HARQ) operation.

In Example 71, the subject matter of Example 63 or any example described herein may further include: the apparatus is further configured to: process a PUSCH transmission for retransmission when the UE receives a negative acknowledgement (NACK) in a physical HARQ indicator channel (PHICH); the retransmission of the PUSCH transmission is based on an UL grant or based on a new data indicator (NDI) switched in the UL grant; transmit the PUSCH transmission in a configured time or frequency region; adaptively divide the UE into different contention zones with different contention windows relative to an alternative UE, wherein each of the contention zones is dynamically or semi-statically modified according to a delay constraint, wherein the apparatus comprises at least one of: an antenna, a touch-sensitive display, a speaker, a microphone, a graphics processor, an application processor, a baseband processor, an internal memory, a non-volatile memory port, and combinations thereof.

Example 72 includes an apparatus of an anchor enhanced Node B (eNB) operable to achieve contention-free uplink (UL) synchronization with a user equipment (UE), the apparatus being configured to: process a physical uplink shared channel (PUSCH) transmission received from the UE after sensing an idle PUSCH channel for a predetermined time period; receive a unique UE identifier in the PUSCH transmission; and determine the identity of the UE for contention-free UL synchronization via the unique UE identifier in the PUSCH transmission.

Example 73 includes the apparatus of Example 72, wherein the apparatus is further configured to perform blind UE detection based on a demodulation reference signal (DMRS).

Example 74 includes the apparatus of any of Examples 72 or 73, wherein the apparatus is further configured to generate a demodulation reference signal (DMRS) sequence by using a constant envelope zero autocorrelation waveform (CAZAC) sequence, wherein the CAZAC sequence is a Zadoff-Chu (ZC) sequence.

In Example 75, the subject matter of Example 72 or any example described herein may also include: the apparatus being further configured to: process a PUSCH transmission received from the UE in one of the idle PUSCH channels without UL synchronization scheduling; or process a reservation signal received from the UE, the reservation signal being used to reserve one of the multiple PUSCH channels that is idle for receiving the PUSCH transmission.

In Example 76, the subject matter of Example 72 or any example described herein may further include the apparatus being further configured to process a PUSCH transmission received from the UE when the UL packet arrives at a medium access control (MAC) buffer of the UE.

In Example 77, the subject matter of Example 72 or the subject matter of any example described herein may also include: the apparatus is further configured to: use a modulation and coding scheme (MCS) for UL transmission, wherein the MCS can be predefined by a minimum MCS; process a PUSCH transmission received in a hybrid automatic repeat request (HARQ) operation; or process a negative acknowledgement (NACK) in a physical HARQ indicator channel for transmission to the UE to trigger the UE to retransmit the PUSCH transmission; process an UL grant or a new data indicator (NDI) switched in the UL grant for transmission to the UE to retransmit the PUSCH transmission; process a PUSCH transmission received in a configured time or frequency region; or upon determining a cell conflict between the UE and an alternative UE, dynamically or semi-statically modify or allocate a contention window by creating a new contention area with a different contention window or reducing the contention area currently used for successful reception of the PUSCH transmission.

Example 78 includes an apparatus for achieving low latency synchronization with an enhanced Node B (eNB), the apparatus comprising: means for sensing whether any physical uplink shared channel (PUSCH) is idle for uplink (UL) synchronization with the eNB for a predetermined time period; means for providing a unique UE identification in a PUSCH transmission; and means for transmitting the PUSCH transmission in one of the idle PUSCH channels for contention-free communication with the eNB for uplink synchronization.

Example 79 includes a device for achieving low-latency synchronization with a user equipment (UE), the device comprising: a device for receiving an uplink shared channel (PUSCH) transmission for UL synchronization from the UE after the UE senses whether a PUSCH is idle for an anchor eNB for a predetermined time period; a device for receiving a unique UE identifier in the PUSCH transmission; and a device for determining the identity of the UE through the unique UE identifier in the PUSCH transmission for contention-free UL synchronization.

Example 79 includes an apparatus of an anchor enhanced Node B (eNB) operable to perform contention-free uplink (UL) synchronization with a user equipment (UE), the apparatus being configured to: process a physical uplink shared channel (PUSCH) transmission received from the UE after sensing an idle PUSCH channel for a predetermined time period; process a unique UE identifier in the PUSCH transmission received by the eNB; determine the identity of the UE for contention-free UL synchronization through the unique UE identifier in the PUSCH transmission; and perform blind UE detection based on a demodulation reference signal (DMRS).

The term "processor" as used herein may include general-purpose processors, special-purpose processors (eg, VLSI, FPGA, or other types of special-purpose processors), and baseband processors used in a transceiver to transmit, receive, and process wireless communications.

It should be understood that many of the functional units described in this specification have been labeled as modules in order to more specifically emphasize their implementation independence. For example, modules can be implemented as hardware circuits (including custom very large scale integration (VLSI) circuits or gate arrays), off-the-shelf semiconductors (e.g., logic chips, transistors, or other discrete components). Modules can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, etc.

Modules can also be implemented in software so as to be executed by various types of processors. For example, an identified module of executable code can include one or more physical or logical blocks of computer instructions, which can be organized, for example, as objects, procedures, or functions. However, the executable files of the identified module do not have to be physically together, but can include different instructions stored in different locations that, when logically combined together, comprise the module and achieve the stated purpose of the module.

In fact, the module of executable code can be a single instruction or many instructions, and can even be distributed on several different code segments, between different programs and across several memory devices.Similarly, operational data can be identified and illustrated in this article within the module, and can be implemented and organized in the data structure of any suitable type in any suitable form.Operational data can be collected as a single data set, or can be distributed in different locations (comprising different storage devices), and at least partially only exist in a system or network as an electronic signal.Module can be passive or active, including an agent that can be operated to perform desired function.

Reference throughout this specification to "an example" or "exemplary" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present technology. Thus, the appearances of the phrase "in an example" or the word "exemplary" in various places in this specification are not necessarily all referring to the same embodiment.

For convenience, multiple items, structural elements, constituent elements and/or materials used herein may be presented in a public list. However, these lists should be interpreted as each member in the list being identified as an independent and unique member. Therefore, each member of such a list should not be interpreted as a de facto equivalent of any other member in the same list simply based on the fact that they are presented in a public group and there is no contrary indication. In addition, various embodiments and examples of the present technology may be mentioned together with alternatives to its various components. It should be understood that such embodiments, examples and alternatives should not be interpreted as de facto equivalents of each other, but are considered to be separate and autonomous representations of the present technology.

In addition, the described features, structures or characteristics can be combined in one or more embodiments in any suitable manner. In the following description, many specific details (e.g., examples of layouts, distances, network examples, etc.) are provided to provide a thorough understanding of the technical embodiments. However, it will be appreciated by those skilled in the art that the technology can be practiced without one or more of these specific details, or implemented with other methods, components, layouts, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid blurring aspects of the technology.

While the above examples illustrate the principles of the present technology in one or more specific applications, it will be apparent to those skilled in the art that various modifications in form, use, and details of the implementations can be made without the exercise of creative ability without departing from the principles and concepts of the present technology. Therefore, the present technology is not intended to be limited except as set forth in the claims below.

Claims (33)

1. A user equipment (UE), the UE being configured, under the control of one or more processors and a memory, to achieve low-latency synchronization with a base station, the UE being configured to: For a predetermined time period, sense whether any Physical Uplink Shared Channel (PUSCH) is idle; Provides a unique UE identifier in PUSCH transmission; and In the absence of uplink authorization from the base station, the PUSCH transmission is carried out in one of the idle PUSCH channels for contention-free communication with the base station for uplink synchronization. 2. The UE according to claim 1, wherein the UE is further configured to transmit the PUSCH transmission to the base station in one of the idle PUSCH channels in the absence of uplink synchronization scheduling. 3. The UE according to claim 1 or 2, wherein the UE is further configured to sense the PUSCH channel as idle when the sensed energy is below a predetermined threshold. 4. The UE according to claim 1, wherein the UE is further configured to perform free channel assessment (CCA) or extended free channel assessment (ECCA) for a plurality of sensing granularity slits known to the UE, or to perform the CCA or the ECCA by signaling to the base station. 5. The UE according to claim 1 or 4, wherein the UE is further configured to sense whether either of the PUSCH channels is idle during Idle Channel Assessment (CCA) and Extended CCA (ECCA), wherein the duration of the CCA or ECCA is based on the minimum sensing granularity. 6. The UE of claim 5, wherein the UE is further configured to sense the PUSCH channel as idle when the energy sensed during the duration of the CCA or the ECCA is below a predetermined threshold. 7. The UE according to claim 5, wherein the UE is further configured to: The ECCA is performed by crossing multiple sensing granularity slits, wherein the number of the multiple sensing granularity slits crossed by the ECCA is determined by the contention window (CW). The number of the plurality of sensing granular slits is determined by generating random numbers ranging from 1 to the number of the plurality of sensing granular slits spanned by the ECCA, determined by the CW as a shift counter; and Whenever the PUSCH channel is sensed to be idle, the number of the plurality of sensing granular slits that the ECCA crosses is reduced. 8. The UE according to claim 1 or 7, wherein the UE is further configured to: Whenever the PUSCH channel is sensed to be idle, the ECCA counter is decremented by one (1); Process reserved signals for alignment with symbol boundaries for transmission; and The reserved signal used to begin the next symbol is processed for transmission. 9. The UE of claim 8, wherein the UE is further configured to sense whether the current transmission attempt is unsuccessful, wherein the UE continues to perform the ECCA in subsequent subframes using the current count of the ECCA counter without generating a new random number. 10. The UE according to claim 9, wherein the UE is further configured to: Sensing whether the current transmission attempt has failed, wherein the UE performs a pre-dialogue listening process consisting of the CCA and the ECCA by regenerating a new shift counter in the next transmission attempt; and For a specified number of symbols M, the pre-dialogue listening process is performed starting from symbol 0, wherein the PUSCH transmission begins at symbol M+1 and ends at symbol 14 within the subframe, where M is a positive integer, wherein a channel sounding reference signal (SRS) is transmitted on symbol 14, wherein truncation of symbol 14 is eliminated. 11. The UE of claim 1, wherein the UE is further configured to reserve one of the idle PUSCH channels for transmitting the PUSCH transmission. 12. The UE according to claim 1 or 11, wherein the unique UE identifier is one of a Cell Radio Network Temporary Identifier (C-RNTI) or a Radio Network Temporary Identifier (RNTI). 13. The UE of claim 1, wherein the transmission of the PUSCH is performed when the UL packet arrives at the UE's Media Access Control (MAC) buffer. 14. The UE according to claim 1 or 13, wherein the PUSCH transmission consists of a plurality of symbols corresponding to subcarriers in a resource block, wherein the UE is further configured to use at least one of the plurality of symbols to sense whether the PUSCH channel is idle, while using the remaining number of symbols of the plurality of symbols for the PUSCH transmission. 15. The UE of claim 1, wherein the UE is further configured to use a modulation and coding scheme (MCS) for UL transmission, wherein the MCS can be predefined by a minimum MCS. 16. The UE according to claim 1 or 15, wherein the UE is further configured to use preamble signaling to sense whether the PUSCH channel is idle. 17. The UE of claim 1, wherein the UE is further configured to use an additional preamble signal to sense whether the PUSCH channel is idle, wherein the additional preamble signal includes a Radio Network Temporary Identifier (RNTI) and/or a DMRS signal for demodulation, wherein the DMRS signal is removed during the PUSCH transmission pulse. 18. The UE according to claim 1 or 17, wherein the UE is further configured to transmit the PUSCH transmission in a Hybrid Automatic Repeat Request (HARQ) operation. 19. The UE of claim 18, wherein the UE is further configured to process the PUSCH transmission for retransmission when the UE receives a negative acknowledgment (NACK) in the Physical HARQ Indicator Channel (PHICH). 20. The UE of claim 19, wherein the retransmission of the PUSCH transmission is based on a UL grant or on a New Data Indicator (NDI) switched in the UL grant. 21. The UE of claim 1, wherein the UE is further configured to transmit the PUSCH transmission in a configured time or frequency region. 22. The UE according to claim 1 or 21, wherein the UE is further configured to adaptively divide the UE relative to an alternative UE into different contention regions with different contention windows, wherein each of the contention regions is dynamically or semi-statically modified according to latency requirements. 23. The UE of claim 1, wherein the UE comprises at least one of the following: an antenna, a touch-sensitive display, a speaker, a microphone, a graphics processor, an application processor, a baseband processor, internal memory, a non-volatile memory port, and combinations thereof. 24. A base station, operable under the control of one or more processors and memories to perform contention-free uplink (UL) synchronization with a user equipment (UE), the base station being configured to: After sensing an idle Physical Uplink Shared Channel (PUSCH) for a predetermined time period, the PUSCH transmission received from the UE is processed without sending an uplink grant to the UE. Processing the unique UE identifier in the PUSCH transmission received by the base station; and The identity of the UE is determined by the unique UE identifier in the PUSCH transmission for use in contention-free UL synchronization. 25. The base station of claim 24, wherein the base station is further configured to perform blind UE detection based on a demodulation reference signal (DMRS). 26. The base station according to claim 24 or 25, wherein the base station is further configured to generate a demodulation reference signal (DMRS) sequence by using a constant envelope zero autocorrelation waveform (CAZAC) sequence, wherein the CAZAC sequence is a Zadoff-Chu (ZC) sequence. 27. The base station of claim 24, wherein the base station is further configured to process the PUSCH transmission received from the UE in one of the idle PUSCH channels without UL synchronization scheduling. 28. The base station according to claim 24 or 27, wherein the base station is further configured to process a reserved signal received from the UE, the reserved signal being used to reserve one of a plurality of idle PUSCH channels for receiving the PUSCH transmission. 29. The base station of claim 24, wherein the base station is further configured to process the PUSCH transmission received from the UE when a UL packet arrives at the UE's Media Access Control (MAC) buffer. 30. The base station according to claim 24 or 29, wherein the base station is further configured to: The modulation and coding scheme (MCS) is used for UL transmission, wherein the MCS can be predefined by a minimum MCS; Processing PUSCH transmissions received during Hybrid Automatic Repeat Request (HARQ) operations; and The negative acknowledgment (NACK) in the physical HARQ indicator channel is processed and transmitted to the UE to trigger the UE to retransmit the PUSCH transmission. 31. The base station according to claim 24 or 29, wherein the base station is further configured to: A new data indicator (NDI) for processing UL authorization or switching within said UL authorization is transmitted to the UE to retransmit the PUSCH transmission; Process the PUSCH transmissions received in the configured time or frequency region; and When a cell conflict is determined between the UE and the replacement UE, the contention window is dynamically or semi-statically modified or allocated by creating a new contention area with a different contention window or reducing the currently used contention area for successful reception of the PUSCH transmission. 32. An apparatus for achieving low-latency synchronization with a base station, the apparatus comprising: The apparatus is used to sense, for a predetermined time period, whether any uplink shared channel (PUSCH) is idle for uplink (UL) synchronization with the base station; A means for providing a unique UE identifier in PUSCH transmission; and An apparatus for transmitting a PUSCH transmission in one of the idle PUSCH channels in the absence of a UL authorization received from the base station, for contention-free communication with the base station for uplink synchronization. 33. An apparatus for achieving low-latency synchronization with a user equipment (UE), the apparatus comprising: The apparatus is used to process PUSCH transmissions received from the UE after sensing an idle Physical Uplink Shared Channel (PUSCH) channel for a predetermined time period. A means for processing a unique UE identifier in the PUSCH transmission received by a base station; A means for using the following operations: determining the identity of a UE for contention-free UL synchronization by means of the unique UE identifier in the PUSCH transmission without transmitting uplink (UL) authorization to the UE; and Apparatus for performing blind UE detection based on demodulation reference signal (DMRS).