Method and apparatus for low-overhead system information acquisition for wireless communication

Abstract

A method for low overhead system information acquisition (LOSIA) is disclosed. The LOSIA method includes several techniques for transmitting common channels in next generation radio access technologies (xRATs). Instead of transmitting system information in a periodic, static, cell-specific, broadband manner, the transmission is triggered by the user equipment in an "on-demand" manner. The LOSIA method allows the network to control overhead, bandwidth, and periodicity, among other features. The LOSIA method employs several different techniques to trigger information, upon which the network can act, such as by sending different payloads depending on the trigger received.

Description

[0001] This application is a divisional application of the invention patent application with application date of December 24, 2015, application number 201580079954.9, and invention name “Low-overhead system information acquisition for wireless communications”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 174,140, ​​filed on June 11, 2015, the entire disclosure of which is incorporated herein by reference. Technical Field

[0004] The present application relates to providing system information (SI) to a user equipment (UE) implementing wireless communication technology. Background Art

[0005] In the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) fourth generation mobile communication standard, base stations (so-called enhanced Node Bs or eNodeBs (eNBs)) schedule transmissions of common channels in the physical layer (PHY) via a cell-specific periodic broadband physical downlink control channel (PDCCH). In addition, reference signals that user equipment (UE) can use to demodulate the PDCCH are also sent in a cell-specific periodic broadband manner.

[0006] Previous research on the enhanced LTE Advanced (LTE-A) communication standard focused on lean reference signal design. For example, in LTE Release 11, a separate new carrier type (NCT) for the primary cell (PCell) was proposed, but it was not adopted. In the subsequent Release 12, small cell enhancements were introduced, which allow small cell eNBs to turn their transceiver circuits on and off depending on the traffic load. However, these enhancements only apply to secondary cells (SCells), and UEs are not allowed to reside on these cells operating in small cell on / off mode. In fact, there are no lean carrier waveforms in LTE-A. Instead, for LTE-A, overhead is controlled by switching between transmission and non-transmission of legacy waveforms (i.e., those waveforms that have been standardized since LTE Release 8).

[0007] For example, the PCell may slowly reduce its transmit power to simulate the impact of mobility at the UE, thereby triggering a handover to a neighboring cell. Once all UEs are switched out of the corresponding PCell, the eNB may shut down its radio front end to produce the desired energy savings and interference reduction, i.e., spectral efficiency enhancement. In addition, the eNB shutting down the PCell may use the X2 Application Protocol (X2AP) used on the X2 interface connecting the eNBs to communicate the reason for shutting down the PCell to other eNBs. This ensures that ping-pong effects are avoided, for example, an event in which a neighboring eNB attempts to switch the UE back to the PCell to be shut down. This allows the eNB to turn cells on and off, and subsequently turn their RF circuits on and off. Nevertheless, when the PCell is active (i.e., not in energy saving mode), for reasons of backward compatibility, properly operating eNBs send a wideband, periodic, cell-specific waveform of Release 8.

[0008] For SCells, LTE Release 12 provides a more dynamic solution that uses the carrier aggregation (CA) process of Release 10 to activate (or deactivate) SCells based on the short-term traffic load in the eNB's media access control (MAC) layer buffer. For deactivated SCells, the eNB only sends discovery reference signals (DRS). In addition, the eNB can use the radio resource control (RRC) protocol to control the transmission bandwidth and periodicity of DRS. However, similar to the previous example, when the SCell is activated, appropriate eNB operation dictates the transmission of a wideband, periodic, cell-specific waveform of Release 8 for backward compatibility.

[0009] Therefore, a method by which a user equipment can obtain system information in a manner that overcomes the shortcomings of the prior art is desired. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The foregoing aspects of this document and many of the attendant advantages will become more readily appreciated as the present invention is better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts throughout the various drawings unless otherwise specified.

[0011] Figure 1 is a simplified block diagram of a Low Overhead System Information Acquisition (LOSIA) method according to some embodiments;

[0012] Figure 2 According to some embodiments, Figure 1 Illustration of the LOSIA method for triggering “on-demand” system information transmission;

[0013] Figures 3A-3C According to some embodiments, Figure 1 A first embodiment of the LOSIA method;

[0014] Figure 4A-4B According to some embodiments, Figure 1 A diagram of a second embodiment of the LOSIA method;

[0015] Figure 5A and Figure 5B According to some embodiments, Figure 1 A diagram of a third embodiment of the LOSIA method;

[0016] Fig. 6A and 6B According to some embodiments, Figure 1 A diagram of a fourth embodiment of the LOSIA method;

[0017] Figure 7 According to some embodiments, Figure 1 An example system information transmission window used in a sixth embodiment of the LOSIA method;

[0018] Figure 8 According to some embodiments, Figure 1 A seventh embodiment of the LOSIA method uses an example of load-dependent transmission;

[0019] Fig. 9 According to some embodiments, Figure 1 An example of a millimeter wave communication system adopted by a ninth embodiment of the LOSIA method; and

[0020] Fig.10 According to some embodiments, it is possible to achieve Figure 1 Simplified block diagram of a UE of the LOSIA method. DETAILED DESCRIPTION

[0021] According to the embodiments described herein, a method for low overhead system information acquisition (LOSIA) is disclosed. The LOSIA method includes several techniques for transmitting common channels in next generation radio access technologies (xRATs). Instead of transmitting system information in a periodic, static, cell-specific, broadband manner, the transmission is triggered by the user equipment in an "on-demand" manner. The LOSIA method allows the network to control overhead, bandwidth, and periodicity, among other features. The LOSIA method employs several different techniques to trigger information, upon which the network can act, for example, by sending different payloads depending on the received trigger.

[0022] Reference is made to the accompanying drawings in the following detailed description, which illustrate by way of illustration specific embodiments in which the subject matter described herein may be practiced. However, it should be understood that other embodiments will become apparent to those of ordinary skill in the art upon reading this disclosure. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the disclosure. Therefore, the detailed description below should not be construed as being restrictive, as the scope of the subject matter is defined by the claims.

[0023] For the next generation of wireless communication standards, a flexible physical layer (PHY) air interface is envisioned, where common channels are transmitted with flexible bandwidth, low overhead and dynamic periodicity. In addition, for the next generation of minimalist and flexible radio access technologies (RATs), it should be possible to achieve low-overhead primary cell (PCell) deployment by avoiding wideband, periodic transmissions to the greatest extent possible. Such enhancements are not only desirable from the perspective of energy saving and spectral efficiency, but also to enable new features that are currently prohibited by the wideband, periodic nature of the Long Term Evolution Advanced (LTE-A) waveform, such as flexible bandwidth or flexible duplex deployment. As will be described in more detail below, the LOSIA method takes advantage of these next generation enhancements to wireless communication standards.

[0024] Figure 1 is a simplified block diagram of a Low Overhead System Information Acquisition (LOSIA) method 100 according to some embodiments. The LOSIA method 100 works by allowing a user equipment (UE) to send a random access preamble signature that prompts a base station or enhanced Node B (eNodeB / eNB) to transmit system information "on demand" rather than in a periodic, static, cell-specific, wideband manner (as is done in LTE and LTE-A).

[0025] Nomenclature

[0026] The LOSIA method 100 as described herein operates in a wireless network. In other embodiments, the LOSIA method operates in a wireless cellular network. In other embodiments, the LOSIA method operates in a novel fifth generation radio access technology (5G RAT). For ease of explanation, throughout this disclosure, channels, signals, and information elements prefixed with "x" represent corresponding counterparts in LTE modified for 5G RAT (which itself will be referred to as xRAT herein). Thus, for example, the physical downlink shared channel referred to as PDSCH is referred to as xPDSCH for xRAT. Similarly, the demodulation reference signal (DMRS) is referred to as xDMRS in this article, the master information block (MIB) is referred to as xMIB, and so on. No assumptions are made about the design of the channels, signals, and information elements prefixed with "x"; this analogy should be understood conceptually. SS, DRS, TRS, CSI-RS, CSI-IM, and DMRS represent synchronization signals, discovery reference signals, tracking reference signals, channel state information reference signals, and channel state information interference measurement resources, respectively. For LTE, cell-specific reference signal (CRS) and TRS are used interchangeably.

[0027] According to the LOSIA method 100, the UE receives a minimum set of system information 60, 70 from the eNB, as shown below. Figure 2 This system information allows the UE to send a trigger, such as an enhanced physical random access channel (xPRACH) 80. Upon receiving the xPRACH trigger, the eNB sends additional system information 90. The xPRACH can trigger different types of this additional system information.

[0028] In LOSIA method 100, several schemes with varying degrees of overhead are proposed, as described in more detail below. In some embodiments, each scheme within LOSIA method 100 may differ in robustness, complexity, latency, and capacity compared to another scheme.

[0029] In the current LTE-Advanced (LTE-A) communication standard, system information transmission is periodic and broadband, and is transmitted independently of the system load. In the LOSIA method 100, in some embodiments, by allowing user equipment to trigger the transmission of system information, energy saving and interference reduction are achieved, thereby achieving spectrum efficiency improvement. In addition, as described in detail herein, the advantages of the LOSIA method 100 vary depending on certain applications and deployments (e.g., millimeter wave spectrum, device-to-device (D2D) communication, or machine type communication (MTC)). Therefore, the LOSIA method 100 meets the vision of flexible next generation radio access technology (xRAT) by specifying a means to transmit common channels in an efficient and flexible manner as proposed herein.

[0030] Overview of LOSIA Method 100

[0031] The design of LTE common channels relies on cell-specific, periodic, broadband, carrier aggregation (CA), and load-agnostic mechanisms. This contradicts the flexible PHY air interface design paradigm of fifth-generation networks. When the UE already knows the radio access network (RAN) from the xSS / xDRS transmissions from the eNB, the LOSIA method 100 proposes a technique for "on-demand" transmission of all system information (SI) other than those that enable xPRACH transmissions based on triggers sent by the user equipment (i.e., xPRACH). In addition to obtaining the system information that is the subject of the LOSIA method 100, the xPRACH channel is also used by the UE for uplink synchronization to make scheduling requests, make RRC connection setup requests, and perform other tasks. Therefore, the LOSIA method 100 also enhances its use for triggering system information transmission.

[0032] Figure 2 Depicted are steps performed by the LOSIA method 100 according to some embodiments, where the system information transmission is triggered "on demand". As indicated, the steps are described as five steps performed by the eNB or UE, represented as 50, 60, 70, 80 and 90. However, it should be understood that these steps can include multiple steps or operations respectively. The left side of each step indicates the channel (also called signal or waveform) used to perform the LOSIA method 100, which are provided as examples only. The fourth step (step 80) is different from the other steps because steps 50, 60, 70 and 90 are wireless downlink transmissions from the eNB, while step 80 is an uplink transmission from the UE to the eNB.

[0033] Continuing with LTE as an example, a UE performs a cell search operation when it first attempts to connect to a radio access network (RAN). During the cell search, the UE obtains the minimum system information (SI) required to access the network. The UE then performs a so-called random access procedure by sending a preamble sequence (also called a "signature") to establish a radio link with the eNB. In addition to acquiring the necessary uplink timing information before UL and DL transmissions can occur, the UE also obtains a unique identifier during the random access procedure.

[0034] In addition, the following LTE physical layer channels are described, which occupy the transmission band of the air interface between the eNB and the UE. The Physical Broadcast Channel (PBCH) includes a portion of the SI used by the UE to access the network, namely the Master Information Block (IB). The Physical Hybrid Automatic Request (HARQ) Indicator Channel (PHICH) is used for retransmission messages. Before receiving the Physical Downlink Control Channel (PDCCH), the UE obtains the PHICH configuration (see Figure 2 , reference numeral 60). Next, the PDCCH is obtained before receiving the physical downlink shared channel (PDSCH) from the eNB for scheduling grants that enable the UE to transmit to the eNB using the physical uplink shared channel (PUSCH). PDSCH and PUSCH are the main transport channels for data transmission between the UE and the eNB. The physical random access channel (PRACH) is used for random access by the UE. The transport channels in the MAC layer are mapped to the above-mentioned physical channels. Physical channels that do not correspond to transport channels are used for downlink control information (DCI), etc., which provides the UE with information for decoding DL and / or UL transmissions. The primary and secondary synchronization signals (PSS / SSS) are continuously sent on the air interface and are therefore always available to the UE, for example to perform cell search or radio resource management (RRM).

[0035] refer to Figure 2 , step 50 is the initial cell search, in which the UE first obtains coarse time and frequency synchronization from the PSS / SSS. The PSS / SSS transmission from the eNB also indicates the cyclic prefix (CP) length, duplex mode, and physical cell ID (PCI) of the cell. The duplex mode indicates whether the eNB uses time domain duplexing (TDD) or frequency domain duplexing (FDD), and the PCI is the physical layer identifier associated with that cell of the eNB. Coarse time / frequency synchronization allows the UE to synchronize its clock with the clock of the eNB. These downlink transactions 50 enable the UE to synchronize with the network and decode subsequent downlink transmissions on the physical downlink channel.

[0036] The most necessary system information is sent on the PBCH, including the DL cell bandwidth, the cell's PHICH configuration, and the system frame number (SFN). Figure 2 In the example, these items are displayed in step 60 as part of the xMIB.

[0037] Once the PSS / SSS is correctly detected, the UE is able to decode the PBCH. The UE can then get the minimum system information from the PBCH. In LTE, there are two ways to pass system information to the UE. First, there is a limited amount of system information called the Master Information Block (MIB), which is transmitted over the PBCH. In step 60, the LTE payload for the PBCH is shown. The UE decodes the PBCH to obtain the system bandwidth (BW), PHICH configuration, system frame number (SFN), and the number of cell-specific reference signal (CRS) ports. These payloads are only examples and do not exclude new payload partitions for the enhanced Master Information Block (MIB) (labeled as xMIB).

[0038] Secondly, a more complete set of system information divided into system information blocks (SIBs) is transmitted using PDSCH, where the association with PDCCH is made through SI-RNTI (System Information - Radio Network Temporary Identifier). More precisely, the UE monitors the common search space to find PDCCH whose cyclic redundancy check (CRC) bits are scrambled by the SI-RNTI. In step 70, the LTE payload for PDSCH scheduled by PDCCH is shown. One or more system information blocks (xSIBs) provide xPRACH configuration.

[0039] The downlink control information (DCI) transmitted on the PDCCH schedules the PDSCH transmission that conveys these SIBs. In LTE, for example, the UE obtains SIB1 and SIB2 to transmit PRACH because they contain the PRACH configuration, random access channel (RACH) configuration, etc. and the downlink reference signal transmit power, which the UE uses for path loss compensation when sending the PRACH sequence. It should be noted that other partitioning of other payloads and system information into SIBs is not excluded and is collectively referred to here as xSIB1.

[0040] Steps 50, 60 and 70 are transmitted by the eNB over the wireless medium (air interface) using continuous and periodic signals / channels. After receiving the xPRACH configuration from the eNB in ​​step 70, the UE has enough information to know which sequence to use in which time / frequency resources to trigger the network to transmit further system information (SI).

[0041] Unlike steps 50, 60, and 70, in some embodiments, step 80 has an uplink transmission from the UE to the eNB. In step 80, the UE uses a random access preamble signature to trigger "on-demand" SI acquisition, i.e., the transmission of additional system information in addition to the system information already received in steps 60 and 70. The xPRACH channel is used for many different things. Therefore, in some embodiments, after obtaining all the necessary system information for transmitting the xPRACH, the UE can modulate the xPRACH transmission with a dedicated sequence (or signature) to indicate that it is requesting additional SI to be transmitted from the eNB. This triggers the eNB to send SI in step 90, and in some embodiments may require a contention-based random access process.

[0042] In the case of LTE, steps 80 and 90 are swapped. The eNB performs downlink transmissions continuously and periodically (although the period of each step may not be the same) in accordance with steps 50, 60, 70 and 90. After these steps, the UE may send PRACH 80 to connect to the network, i.e., request RRC connection setup. Here, in contrast, the UE sends xPRACH (operation 80) to trigger the "on-demand" transmission of step 90, i.e., the transmission of additional system information from the network to the UE. Therefore, continuous and periodic transmission of all SI (as in LTE) is not necessary, which enables the claimed energy saving and spectrum efficiency improvements. More precisely, in some embodiments, the UE may send xPRACH, not in an attempt to request RRC connection setup, but to trigger the transmission of additional SI. Therefore, in the LOSIA method 100, the downlink transmission of step 90 is no longer continuous and periodic, but is performed "on demand". According to several different implementations of the random access preamble sequence (signature) of the UL step 80, further enhancements can be achieved as described below.

[0043] Detailed Description

[0044] Example 1: Return Figure 1 In one embodiment of the LOSIA method 100, a single sequence of random access preambles is reserved per cell or cell group by specification or configuration. When the eNB receiver detects this dedicated sequence from any UE in its cell, the eNB then sends system information in the downlink. After transmitting the random access preamble sequence using the xPRACH channel to trigger the downlink transmission of system information, the UE monitors the eNB's SI transmission and acquires the rest of the system information upon successful decoding.

[0045] Therefore, in Figure 2In step 70, the eNB indicates a dedicated sequence for SI acquisition in the xPRACH configuration. Any UE in the cell or cell group can therefore send the sequence on the xPRACH channel, as shown in step 80. Then in step 90, the eNB triggers the transmission of SI by the UE.

[0046] In some embodiments, the transmission of system information by the eNB triggered by the UE through its xPRACH transmission mentioned above is cell-specific or cell-group-specific. In the former, the payload is common to all UEs in a single cell; in the latter, the payload is common to all UEs in multiple cells. Figure 3A and 3B shows a possible uplink transmission, while Figure 3C The downlink transmission of this embodiment is shown.

[0047] exist Figure 3A , cellular neighborhood 150A is comprised of four units 40A, 40B, 40C, and 40D (collectively, “cell(s) 40”), each of which is provided by a single respective eNB 30A, 30B, 30C, and 30D (collectively, “eNB(s) 30”) and one or more UEs 20 (in the illustrations herein, a mobile phone is depicted; however, a UE may include a mobile phone, smart phone, personal digital assistant, laptop, notebook, tablet, pad, or any other technology operable in a cellular neighborhood). The eNB 30A of cell 40A configures xPRACH sequence A for triggering SI transmission for any or all UEs 20 in cell 40A; similarly, the eNB 30B of cell 40B configures xPRACH sequence B for triggering SI transmission for cell 40B, the eNB 30C of cell 40C configures xPRACH sequence C for triggering SI transmission for cell 40C, and the eNB 30D configures xPRACH sequence D for triggering SI transmission for cell 40D. Any of the UEs 20 in a given cell may send a cell-specific sequence (i.e., a random access preamble signature for SI acquisition, such as Figure 2 Only one UE 20 in each cell 40 sends the appropriate sequence, and the eNB 30 will then send downlink SI information.

[0048] exist Figure 3B In the example, the cellular neighborhood 150B is actually connected to Figure 3A30D, but now the cells 40A-40D with corresponding eNBs 30A-30D form a cell group 40E. In this case, each eNB 30 in the cellular neighborhood configures the same xPRACH sequence, sequence E, to trigger SI transmissions for the corresponding cell 40. (It does not matter which eNB in ​​the cell group receives the sequence, as long as 1) one of the eNBs in the cell group sends the SI information, and 2) the requesting UE is able to receive the transmission). Figure 3B These eNBs 30 are coordinated as a single cell group, enabling the same sequence to be used throughout the cell group. It is sufficient that one UE 20 sends a sequence specified for the entire cell group 40E and one eNB from the cell group sends SI information.

[0049] Figure 3C It is shown that the eNB 30 sends the same system information to all UEs 20 within a cell 40, whether coordinated by cell or cell group.

[0050] Example 2: Return to Figure 1 In one embodiment of the LOSIA method 100, the UE randomly selects a random access sequence from a set of predefined sequences known to both the UE and the eNB. When the eNB receiver detects this randomly selected sequence from any UE in its cell, the eNB then sends system information in the downlink, but this time, the information will be specific to the requesting UE, as described below. The set of known sequences to be selected by the UE may be specific to the LOSIA method 100, or alternatively, may be the same set of sequences used for other random access procedures, such as those used to obtain uplink synchronization or send a scheduling request (SR). Once the randomly selected sequence has been sent, the UE monitors the eNB's SI transmissions to obtain the rest of the system information.

[0051] refer to Figure 2 In step 90, SI information may be sent in a "UE-specific" manner, a feature that is exploited in the second embodiment. This feature may be desirable in a cellular environment where UEs with different capabilities are clustered. For example, one UE may be a cheap phone with limited capabilities, while another UE may be a feature-rich smartphone. This embodiment enables the eNB to adjust the type of system information sent to each UE.

[0052] Figure 4A and 4B A second embodiment is shown. Figure 4AIn FIG. 4 , a cell 40 includes an eNB 30 and several UEs 20. Each UE randomly selects from a lookup table 44 of predefined sequences (denoted as sequences F, G, H, ..., Z), wherein the number of predefined sequences in the lookup table 44 is configurable or fixed. Figure 4A In the present invention, each UE 20 randomly selects a different sequence to send via the xPRACH channel to the eNB 30. By receiving a unique randomly selected sequence from each UE 20, the eNB 30 is able to uniquely identify each UE.

[0053] Figure 4B The flowchart includes operations performed in the second embodiment. The UE 20 randomly selects from available predefined sequences known to both the UE and the eNB 30 (such as from the lookup table 44) (block 202). The selected sequence is used as a random access preamble signature (see Figure 2 , step 80) is sent from the UE 20 to the eNB 30 (block 204). The eNB 30 detects the transmitted sequence (block 206). If more than one UE 20 transmits the same sequence (block 208), the eNB 30 will perform contention resolution before further transmissions occur (block 210). Since the UE has randomly selected the initial sequence from a set of predefined sequences, if multiple UEs select the same sequence at the same time, this intermediate contention resolution step resolves the conflict before the eNB 30 can send the UE-specific SI.

[0054] Upon successful detection of the UE's xPRACH transmission (and / or contention resolution), the eNB 30 sends a random access response (RAR) to the UE 20 in a predefined RAR time window instead of the system information itself (box 212). The RAR message contains at least: 1) an identification of the detected preamble, 2) a timing alignment instruction for subsequent synchronous uplink transmission, and 3) an UL grant for the UE to send the next message in the uplink (box 214). In addition, the RAR assigns a unique identifier to the UE 20, such as a cell radio network temporary identifier (C-RNTI) (box 216). The C-RNTI is dedicated to each UE 20 that has initiated communication with the eNB 30 and will replace the randomly selected sequence as an identifier, for example, as long as the UE is connected to the cellular network, it is a unique tag associated with the UE. After successfully decoding the RAR from the eNB 30, the UE 20 uses the UL grant in the RAR to instruct the eNB to send the rest of the system information (box 218). After successfully decoding the UE's instruction, the eNB 30 sends UE-specific SI to the UE 20 (block 220).

[0055] Recall that the UE retrieves SI from xPDCCH and xPDSCH channels ( Figure 2 In some embodiments, the UE 20 retrieves the UE-specific SI by monitoring a common or UE-specific search space for an xPDCCH with a CRC scrambled by a C-RNTI (step 220). Since the UE is not assigned a unique identifier C-RNTI, in some embodiments, the random access RNTI (RA-RNTI) is not used to scramble the CRC of the xPDCCH that schedules the RAR (step 212) until after contention is resolved.

[0056] As in the first embodiment, when the eNB receiver transmits common system information triggered by xPRACH using a dedicated sequence for SI acquisition, a unique identifier can be used to schedule SI transmission in the downlink. Using LTE as an example, Figure 5A and Figure 5B As shown, the UE transmits a random access preamble sequence using the xPRACH channel (block 252). The eNB scrambles the CRC of the xPDCCH that schedules the SI transmission using a unique SI radio network temporary identifier (SI-RNTI) (block 254). After sending the xPRACH, the UE monitors the common search space (block 256) to find an xPDCCH with a CRC scrambled by the SI-RNTI (block 258). If one is detected, the UE uses the downlink control information (DCI) contained in the xPDCCH to decode the SI in the xPDSCH (block 260).

[0057] exist Figure 5B In the example, the eNB 30 uses xPDCCH to send system information (such as Figure 2 Step 90) and scrambles the CRC of the xPDCCH using the SI-RNTI. For the xPDCCH that uses the SI-RNTI to scramble the CRC, UE 20A monitors a common and / or UE-specific search space. Therefore, although the SI is broadcast to all UEs in the cell 40 (or cell group (as the case may be)), only UE 20A receives the system information (successful reception is indicated by a thick arrow). This is an improvement of Example 1 over the existing method, in which each UE that wants to receive SI can do so by monitoring the SI-RNTI in a predefined periodic time / frequency resource.

[0058] If, as in the case of the second embodiment, the SI transmission triggered by the xPRACH is UE-specific, the UE instead monitors a common or UE-specific search space for an xPDCCH with a CRC scrambled by the C-RNTI. Since the UE is not assigned a unique identifier before contention resolution, the random access RNTI (RA-RNTI) is used to scramble the CRC of the xPDCCH that schedules the RAR. This is an improvement of embodiment 2 over prior art methods, in which each UE that wants to receive SI can do so by monitoring the SI-RNTI in predefined periodic time / frequency resources, and where the SI is never UE-specific (hence the common SI-RNTI identifier in prior art methods).

[0059] Example 3: Return Figure 1 In one embodiment of the LOSIA method 100, different sequences are dedicated to triggering different types of SI transmissions from the eNB, either by specification or by broadcasting such information in xSIB1. Fig. 6A and 6B This embodiment is shown. Fig. 6A An example of a flexible xRAT design is depicted, with different partitions for different services and applications. For example, services can be divided into mission-critical MTC (machine type communication), massive MTC, and mobile broadband. Mission-critical MTC can include UEs in cars communicating with each other, UEs operating power grids for communities, etc., where very high reliability and low latency (delay) are expected. Massive MTC can include what is known in the industry as the Internet of Things (IoT), such as each appliance in a home having the characteristics of a UE (e.g., coffee maker, toaster, refrigerator). Since these are not critical services, they are characterized by "best effort" reliability and can operate successfully even with large delays. Mobile broadband, which includes making and receiving voice calls, watching and downloading videos, etc., is another service or application category.

[0060] For example, short TTI (Transmission Time Interval) partitions may be reserved for mission-critical MTC (Machine Type Communication) services, long TTI partitions may be reserved for large MTC services, and normal TTI partitions may be reserved for mobile broadband services. Figure 2 , coarse time and frequency synchronization (step 50) and bandwidth (step 60) are provided by the eNB to any UE that wants to connect to the network. By dividing the spectrum into different parts and dedicating these parts to different UE services and application categories, each UE knows which part or partition of the time / frequency domain to access to receive system information. Fig. 6AThe partitioning shown in is just one example of how the time / frequency domain may be allocated, other UE service or application classes may also be defined.

[0061] Different sequences can be linked to these different partitions, either by specification or by broadcasting such information in xSIB1, which sequences are dedicated to triggering SI transmission from the eNB. Thus, the UE can trigger SI acquisition (i.e., transmission of SI information by the eNB) for a given partition (in other words, service or application) by adopting the relevant sequence sent in its xPRACH transmission as a trigger. In this embodiment, the SI transmission by the eNB is not UE-specific, but service-specific or RAT-specific.

[0062] Figure 6B The operation of the LOSIA method 100 according to some embodiments is shown. In one embodiment, the eNB provides a sequence ( Figure 2 In another embodiment, these sequences for different services or applications are predefined and thus known to each UE. Therefore, the UE selects an appropriate sequence for the service and application it provides (block 302) and transmits the sequence using the xPRACH channel (block 304). The eNB detects the UE's xPRACH transmission (block 306).

[0063] The eNB then determines which service class of UE sent the xPRACH transmission. If a mission-critical MTC UE sent the sequence (block 308), appropriate mission-critical MTC system information is broadcast (block 310). If a large MTC UE sent the sequence (block 312), large MTC system information is broadcast by the eNB (block 314). If a mobile broadband UE sent the sequence, mobile broadband system information is broadcast (block 316). Since a mobile broadband UE may be rich in multiple services, its SI information is more extensive than the SI information for a large MTC UE, which may only perform one or two operations (e.g., if the UE is used for a toaster, indicating that toasting is complete).

[0064] In another example, different sequences reserved to trigger SI transmission from the eNB may be linked to different air interfaces. For example, one xPRACH sequence may be linked to device-to-device (D2D) communication, while another xPRACH sequence may be linked to relay communication.

[0065] Implementation 4: Return Figure 1In one embodiment of the LOSIA method 100, the dedicated xPRACH sequence(s) may be transmitted less frequently than the xPRACH sequence used for uplink synchronization. In particular, the xPRACH transmission instances for SI transmission triggering may be predefined or configured by higher layers via MIB, SIB, or dedicated RRC signaling.

[0066] In one example, the xPRACH transmission instance for triggering SI transmission is defined as an uplink subframe that satisfies the following equation:

[0067]

[0068] where n f and n s are the radio frame number and time slot number respectively. OFFSET，PRACH is the xPRACH subframe offset, PRACH PERIODICITY is the transmission period of xPRACH.

[0069] In one example, N OFFSET，PRACH and PRACH PERIODICITY By parameter I PRACH The definitions are shown in Table 1. Note that I PRACH 、N OFFSET，PRACH and PRACH PERIODICITY Other values ​​of can be extended from the examples shown in Table 1.

[0070] Table 1. xPRACH periodicity and subframe offset configuration

[0071]

[0072] According to Table 1, xPRACH configuration index I is allocated PRACH UEs with 0-4 will have PRACH PERIODICITY The periodicity is 5ms, and N OFFSET，PRACH For I PRACH The subframe offset is (0-4), and the xPRACH configuration index I is allocated PRACH 5-14 UEs will have a periodicity of 10ms and I PRACH -5 (0-9) subframe offset and so on.

[0073] This embodiment enables the eNB to "listen" to xPRACH transmissions from the UE on specific time and frequency resources, rather than having to monitor all the time. Using equation (1) and Table 1, each cell (eNB) can be assigned a different subframe for monitoring xPRACH transmissions.

[0074] Example 5: Return to Figure 1In one embodiment of the LOSIA method 100, dedicated time / frequency resources are reserved for xPRACH transmissions that trigger SI acquisition. In one example, dedicated frequency resources are allocated for xPRACH to trigger SI transmission. When the UE transmits an xPRACH signal in the dedicated frequency resource, the eNB will transmit SI upon successful detection of the xPRACH signal.

[0075] In another example, dedicated time resources are allocated to xPRACH to trigger SI transmission. For example, xPRACH for triggering SI transmission can be transmitted in subframes 0, 2, 4, 6, 8 within a single frame, while xPRACH for uplink synchronization can be transmitted in subframes 1, 3, 5, 7, 9 within a single frame.

[0076] In another example, a combination of time division multiplexing (TDM) (by allocating different time resources), frequency division multiplexing (FDM) (by allocating different frequency resources) and / or code division multiplexing (CDM) (by allocating different xPRACH sequences) can be used to distinguish between xPRACH transmissions for uplink synchronization and xPRACH transmissions for triggered SI transmissions.

[0077] Recall that in addition to obtaining system information, the xPRACH channel is also used by the UE for uplink synchronization, to make scheduling requests, to make RRC connection setup requests, and to perform other tasks. In the case where the UE sends xPRACH to trigger common or service / RAT-specific SI acquisition (i.e., not UE-specific SI acquisition), the communication for SI acquisition is broadcast or multicast in nature. (For the case where the eNB allocates a C-RNTI to the UE (e.g., Example 2), the SI acquisition process is unicast in nature.) In other words, the eNB may not estimate the timing advance from the xPRACH transmission and may not respond to the xPRACH with a timing advance allocation or uplink grant. This significantly reduces the complexity of the eNB receiver and scheduler because the eNB only detects the sequence sent on the xPRACH to trigger SI transmission.

[0078] For the case where multiple UEs transmit the same sequence in the same time-frequency resources, e.g. because there is a single dedicated sequence (see embodiment 1) or because the UEs request SI for the same service / RAT (see embodiment 3), the detection performance at the eNB is improved due to macro-diversity. An example of macro-diversity is when the transmission from one UE is blocked (e.g. by a building), the eNB still receives the transmission from another UE, leading to the transmission of the triggered SI.

[0079] Furthermore, in the case where the eNB is receiving transmissions of a single sequence from multiple UEs, e.g. Figure 3BIn Embodiment 1, another efficiency gain is obtained by forming a single frequency network (SFN) with multiple UEs transmitting the same PRACH sequence from dispersed locations, which results in SFN gain. In some embodiments, LOSIA method 100 employs both macrodiversity and SFN to improve detection performance.

[0080] Similarly, since the UE does not send xPRACH to connect to a cell (but to obtain SI), multiple eNBs can detect the xPRACH transmission and can jointly send SI in a SFN manner, assuming that the backhaul and coordination capabilities of the network controlling these eNBs allow such processing.

[0081] Recall the first embodiment ( Figure 3A and 3B ), multiple UEs can send the same sequence to each cell or cell group. A cell group can be composed of a single macro eNB and multiple small cell eNBs, and smaller cells help improve coverage or increase capacity. From the UE's perspective, multiple eNBs can look like a single cell. In another example, the network can dynamically decide which eNB among multiple eNBs receiving xPRACH can send SI. Since the UE does not reside in a given cell of a given eNB, this causes a "cell-less" RRC_IDLE state. As an example, the LOSIA method 100 can define the eNB that receives xPRACH with the strongest receive power as the eNB that sends SI.

[0082] It should be noted that after sending xPRACH, the UE expects to receive SI within a defined time window. The location of this SI transmission window can be predefined or configured by higher layers via MIB, SIB1 / 2 or dedicated RRC signaling. Figure 7 The SI transmission window in response to an xPRACH transmission by a UE according to some embodiments is illustrated. In one example, similar to the random access response (RAR) window defined in LTE, the UE may start monitoring for SI transmission three subframes after the xPRACH transmission. Figure 7 In the example, the xPRACH uplink transmission occurs in the third subframe, while the eNB sends the xPDCCH and xPDSCH channels in the eleventh subframe. Therefore, there is a delay of eight subframes (window size) between the request and reception. In some embodiments, the window size is configured in the SI-ResponseWindowSize (SI-Response Window Size) Information Element (IE), where a range of 0-10 subframes is indicated.

[0083] As described above, independent xPRACH sequences can be used to trigger SI transmission for different applications, partitions or services. In order to further distinguish the SI transmission for these applications, partitions or services, different radio network temporary identifiers (RNTIs) can be considered. For example, SI-D2D-RNTI and SI-MTC-RNTI can be defined for SI transmission of D2D and MTC applications respectively. In this case, a D2D-capable UE will decode the xPDCCH and the corresponding xPDSCH with a CRC scrambled by the SI-D2D-RNTI for D2D SI transmission, thereby scrambling and initializing the xPDSCH by the SI-D2D-RNTI.

[0084] As part of its Radio Resource Management (RRM) procedures, the UE continuously and periodically performs RRM measurements. If the RRM procedures indicate that the UE is moving out of the coverage of one cell / transmission point and into the coverage of another cell / transmission point (e.g., the relative strength of Reference Signal Received Power (RSRP) becomes favorable for the other cell / transmission point), the UE performs Figure 2 The steps outlined in are used to obtain the xPRACH configuration of the new stronger cell and subsequently obtain the SI of the new cell.

[0085] Additional variants depending on system load

[0086] Example 6: Return to Figure 1 In one embodiment of the LOSIA method 100, the system information acquisition scheme operates in one of two modes to account for differences in network / traffic loads. A flag updated by the eNB and available to all UEs is used to distinguish between the two operating modes.

[0087] In conventional LTE / LTE-A wireless communication systems, system information is always broadcast periodically. This is very effective when the load in the network is high, because the UE in RRC-IDLE mode can autonomously receive SI without network intervention. Only when moving from one tracking area to another does the UE send PRACH to inform the network of its new tracking area. However, in the case of low load, especially low mobility, the periodic and continuous transmission of SI is inefficient.

[0088] For example, at night, the UE may not be moving between cells and may have no data to send or receive. The UE only obtains SI at a very long periodicity (e.g., every three hours) according to a defined timer. Therefore, the continuous periodic transmission of SI by the eNB every tens or hundreds of milliseconds results in a huge energy consumption at the eNB transmitter, during which no (or few) UEs are receiving transmissions. Therefore, the LOSIA method 100 enables the network to configure the eNB to send SI in different ways according to the system load.

[0089] In some embodiments, the LOSIA method 100 solves energy consumption issues, such as Figure 8 As shown in the flowchart 350 of . The illustration is divided into two parts, wherein the crescent shape indicates typical nighttime, i.e., low network / traffic load behavior (fewer UE connections to the network); and the sun shape indicates typical daytime behavior, i.e., medium to high network / traffic load (more UE connections to the network). Therefore, in Embodiment 6, the LOSIA method 100 contemplates two behavior modes, such as daytime (high load) mode and nighttime (low load) mode. However, operations associated with the nighttime mode may occur during the daytime, and operations associated with the daytime mode may occur at night.

[0090] Flowchart 350 begins with the broadcast of xMIB / xSIB1 transmission by the eNB, which enables the UE to access the network (e.g. Figure 2 The flag is queried to determine whether the eNB is operating in day mode or night mode (block 354). In some embodiments, the eNB broadcasts the flag (e.g., in xMIB or xSIB1) to indicate the current mode of SI transmission.

[0091] During high load times, the flag is set to FALSE (block 354) and conventional LTE procedures are applied, i.e., all xSIBs are sent periodically and continuously, and the UE is able to autonomously receive xSIB2 (block 362) and / or RRC_IDLE mode SI (block 364). When the load in the cell decreases and continuous and periodic transmission of all SI becomes inefficient, the network sets the broadcasted flag to TRUE (block 354).

[0092] During low load time, the flag is set to TRUE (block 354) and the procedure according to embodiments herein is applied, ie, xSIB is sent (block 358) based on a trigger from the UE (block 356).

[0093] In some embodiments, a change in the flag value may not trigger all UEs to reacquire all SI. Instead, those UEs that gain new access to the network or those UEs that update their SI can simply check the xMIB / xSIB1 for the value of the flag. In addition, in some embodiments, when changing the flag broadcasted in the xMIB / xSIB1, the eNB does not immediately stop the transmission of all SI, but allows a grace period during which the UE currently decoding the SI has enough time to complete the final SI acquisition. Similarly, when switching from low load to high load and changing the broadcasted flag accordingly, the network can continue to send the triggered SI within a certain grace period as described above, or the network can cause the triggered SI transmission to occur at the same time / frequency resource as the periodic continuous SI transmission, so that the change is transparent to the UE. The grace period is for the fact that the eNB does not receive feedback from the UE once the UE completes SI acquisition.

[0094] Similar problems occur when SI is not transmitted continuously and periodically. Taking LTE as an example, for the case where SI is sent continuously and periodically (daytime mode), the UE can use incremental redundancy (IR) to combine multiple SI transmissions within the same SI window, and since SI is transmitted periodically, it can repeatedly attempt to decode SI until it is successfully decoded. In some embodiments, the LOSIA method 100 uses a timer that is activated at the UE when the xPRACH that triggers SI acquisition is transmitted and is activated at the eNB when the above xPRACH is successfully received. Note that the above timer can be different for the eNB and the UE. Before the timer expires, the eNB sends a copy of the same SI message to allow the above process using IR at the UE.

[0095] For example, the first triggered xSIB may contain a schedule to instruct the UE how to combine SI transmissions for IR, for example, the concept of SI window may be applied in a similar manner to the LTE specification. After the timer at the eNB expires, if the network is in night mode and no other xPRACH is received to trigger SI transmission, the eNB stops sending SI. If the timer expires but the UE has not successfully decoded the SI, the UE repeats the process by sending another xPRACH to trigger another burst of SI transmission from the eNB.

[0096] For the case where the eNB switches from low load to high load mode, the UE can send another xPRACH if the UE has not successfully decoded the SI. This causes the UE to perform unnecessary xPRACH transmissions because the SI information has become continuous and periodic from the eNB. Alternatively, the UE can check the flag in xMIB / xSIB1 before sending another xPRACH to trigger SI acquisition.

[0097] For the case where the eNB switches from high load mode to low load mode, if the UE has not successfully acquired all SI, the UE may first check the flag in xMIB / xSIB1 before continuing with SI acquisition (in the case where the eNB has stopped periodic and continuous SI transmission). Alternatively, if the mode is switched from high load to low load during the SI acquisition process at the UE, the UE may simply assume that the eNB is still in a high load situation, and it is left to the specific implementation of the UE when the UE checks the flag that triggers SI transmission via xPRACH.

[0098] Example 7: Return to Figure 1 In one embodiment of the LOSIA method 100, in order to improve the robustness and latency of SI acquisition, all SI for RRC connection setup are sent continuously and periodically, while any of the aforementioned examples and embodiments apply only to SI required for RRC_IDLE mode.

[0099] UEs essentially operate in one of three modes. They are either turned off (in which case the network cannot access the UE), or are actively being used (connected mode), or are connected to the network but not being used (idle mode). When in idle mode, the network may still be able to access the UE, such as when the UE receives a voice call, text message, etc.

[0100] Since some SI (i.e., SI for RRC connection setup) is sent continuously and periodically, energy savings cannot be achieved. At the same time, in some embodiments, most SI is only applied to RRC_IDLE mode, and they are transmitted on demand. Since RRC_IDLE mode is generally more tolerant to delays, most energy savings can be retained without sacrificing robustness or delay for the delay-sensitive RRC connection setup process.

[0101] Additional variants depending on factors other than system load

[0102] Example 8: Return to Figure 1 In one embodiment of the LOSIA method 100, as xMIB / xSIB1( Figure 8 ) is not set based on load but depends on other considerations.

[0103] For example, in mmWave deployments, the communication link between the eNB and the UE may suffer from severe path loss. This path loss is typically overcome by employing analog (or RF or passband) beamforming at both the transmitter (Tx) and / or receiver (Rx) so that an equivalent channel comprising the physical propagation channel and the Tx and Rx RF beamforming has acceptable coupling loss between the transmitter and the receiver. However, such analog beamforming is typically UE-specific and requires extensive training. It may therefore be beneficial to limit the amount of cell-specific transmissions (which may be omnidirectional) and transmit as much information as possible over a dedicated unicast channel, which may benefit from the analog beamforming described above.

[0104] Fig. 9 One such example of a millimeter wave communication system is shown. Using LTE as an example, PSS, SSS, PBCH, and PDCCH and PDSCH associated with xSIB1 are broadcast by the eNB (steps 410, 420, and 430). In order to overcome severe path loss, SFN, time domain repetition, or beam scanning techniques can be used. However, this will result in a reduction in spectral efficiency because resources are reused in frequency, time, and space, respectively. After successfully decoding the xPRACH by the eNB's millimeter wave receiver (step 440), the eNB millimeter wave transmitter can use the best (UE-specific) analog beamformer to send the remaining SI, which increases spectral efficiency.

[0105] Operating Environment

[0106] As used herein, the term "circuitry" may refer to, may be part of, or may include an ASIC, an electronic circuit, a (shared, dedicated, or group) processor and / or (shared, dedicated, or group) memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other appropriate hardware components that provide the described functionality. In some embodiments, the circuit may be implemented in one or more software or firmware modules, or the functionality associated with the circuit may be implemented by one or more software or firmware modules. In some embodiments, the circuit may include logic that is capable of operating at least in part as hardware.

[0107] The embodiments described herein may be implemented as a system using any suitably configured hardware and / or software. Fig.10 Example components of a user equipment (UE) device 800 of one embodiment are shown. In some embodiments, the UE device 800 may include at least application circuitry 802, baseband circuitry 804, radio frequency (RF) circuitry 806, front end module (FEM) circuitry 808, and one or more antennas 810 coupled together as shown.

[0108] The application circuitry 802 may include one or more application processors. For example, the application circuitry 802 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 special-purpose processors (e.g., graphics processors, application processors, etc.). The processor may be coupled to and / or may include a storage medium 812 or other type of memory / storage device, and may be configured to execute instructions stored in the memory / storage device to enable various applications and / or operating systems to run on the system.

[0109] The baseband circuit 804 may include circuits, such as but not limited to: one or more single-core or multi-core processors. The baseband circuit 804 may include one or more baseband processors and / or control logic to process baseband signals received from the receive signal path of the RF circuit 806 and generate baseband signals for the transmit signal path of the RF circuit 806. The baseband processing circuit 804 may be connected to the application circuit 802 interface for generating and processing baseband signals and for controlling the operation of the RF circuit 806. For example, in some embodiments, the baseband circuit 804 may include a second generation (2G) baseband processor 804A, a third generation (3G) baseband processor 804B, a fourth generation (4G) baseband processor 804C, a fifth generation (5G) baseband processor 804D, and / or (one or more) other baseband processors 804E for other existing generations, generations under development, or generations to be developed in the future (e.g., the sixth generation (6G), etc.). The baseband circuitry 804 (e.g., one or more of the baseband processors 804A-E) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 806. The radio control functions may include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, etc. In some embodiments, the modulation / demodulation circuitry of the baseband circuitry 804 may include fast Fourier transform (FFT), precoding, and / or constellation mapping / demapping functions. In some embodiments, the encoding / decoding circuitry of the baseband circuitry 804 may include convolution, tail-biting convolution, turbo, Viterbi, and / or low-density parity check (LDPC) encoder / decoder functions. The embodiments of the modulation / demodulation and encoder / decoder functions are not limited to these examples, and may include other suitable functions in other embodiments.

[0110] In some embodiments, the baseband circuit 804 may include elements of a protocol stack, for example, elements of an EUTRAN protocol, for example, including: 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) 804G of the baseband circuit 804 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP, and / or RRC layers. In some embodiments, the baseband circuit may include one or more audio digital signal processors (DSPs) 804F. (One or more) audio DSPs 804F may include elements for compression / decompression and echo cancellation, and may include other appropriate processing elements in other embodiments. In some embodiments, the components of the baseband circuit may be appropriately combined in a single chip, a single chipset, or appropriately arranged on the same circuit board. In some embodiments, some or all of the constituent components of the baseband circuit 804 and the application circuit 802 may be implemented together, for example, on a system on a chip (SOC).

[0111] In some embodiments, the baseband circuit 804 may provide communications compatible with one or more radio technologies. For example, in some embodiments, the baseband circuit 804 may support communications with EUTRAN and / or other wireless metropolitan area networks (WMANs), wireless local area networks (WLANs), or wireless personal area networks (WPANs). Embodiments in which the baseband circuit 804 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuits.

[0112] The RF circuit 806 may enable communication with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuit 806 may include switches, filters, amplifiers, etc. to assist in communication with the wireless network. The RF circuit 806 may include a receive signal path, which may include circuitry that down-converts RF signals received from the FEM circuit 808 and provides a baseband signal to the baseband circuit 804. The RF circuit 806 may also include a transmit signal path, which may include circuitry that up-converts baseband signals provided by the baseband circuit 804 and provides an RF output signal to the FEM circuit 808 for transmission.

[0113] In some embodiments, the RF circuit 806 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuit 806 may include a mixer circuit 806A, an amplifier circuit 806B, and a filter circuit 806C. The transmit signal path of the RF circuit 806 may include a filter circuit 806C and a mixer circuit 806A. The RF circuit 806 may also include a synthesizer circuit 806D, which is used to synthesize frequencies for use by the mixer circuit 806A of the receive signal path and the transmit signal path. In some embodiments, the mixer circuit 806A of the receive signal path may be configured to down-convert the RF signal received from the FEM circuit 808 based on the synthesized frequency provided by the synthesizer circuit 806D. The amplifier circuit 806B may be configured to amplify the down-converted signal, and the filter circuit 806C may be a low pass filter (LPF) or a band pass filter (BPF) configured to remove unwanted signals from the down-converted signal to generate an output baseband signal. The output baseband signal may be provided to the baseband circuit 804 for further processing. In some embodiments, the output baseband signal may be a zero-frequency baseband signal, but this is not required.In some embodiments, mixer circuit 806A of the receive signal path may include a passive mixer, although the scope of the embodiments is not limited in this respect.

[0114] In some embodiments, mixer circuit 806A of the transmit signal path may be configured to up-convert an input baseband signal based on a synthesized frequency provided by synthesizer circuit 806D to generate an RF output signal for FEM circuit 808. The baseband signal may be provided by baseband circuit 804 and may be filtered by filter circuit 806C. Filter circuit 806C may include a low pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[0115] In some embodiments, the mixer circuit 806A of the receive signal path and the mixer circuit 806A of the transmit signal path may include two or more mixers and may be arranged for quadrature down-conversion and / or up-conversion, respectively. In some embodiments, the mixer circuit 806A of the receive signal path and the mixer circuit 806A of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuit 806A of the receive signal path and the mixer circuit 806A of the transmit signal path may be arranged for direct down-conversion and / or direct up-conversion, respectively. In some embodiments, the mixer circuit 806A of the receive signal path and the mixer circuit 806A of the transmit signal path may be configured for superheterodyne operation.

[0116] In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, but the scope of the embodiments is not limited in this respect. In some alternative embodiments, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative embodiments, the RF circuit 806 may include an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) circuit, and the baseband circuit 804 may include a digital baseband interface for communicating with the RF circuit 806.

[0117] In some dual-mode embodiments, separate radio IC circuits may be provided to process signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0118] In some embodiments, synthesizer circuit 806D 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 806D may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase-locked loop with a frequency divider.

[0119] Synthesizer circuit 806D may be configured to synthesize an output frequency based on the frequency input and the divider control input for use by mixer circuit 806A of RF circuit 806. In some embodiments, synthesizer circuit 806D may be a fractional-N / N+1 synthesizer.

[0120] In some embodiments, the frequency input may be provided by a voltage controlled oscillator (VCO), but this is not required. The divider control input may be provided by baseband circuitry 804 or application processor 802, depending on the desired output frequency. In some embodiments, the divider control input (e.g., N) may be determined from a lookup table based on the channel indicated by application processor 802.

[0121] The synthesizer circuit 806D of the RF circuit 806 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) 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 element may be configured to decompose the VCO cycle into at most 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.

[0122] In some embodiments, the synthesizer circuit 806D 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 can be used in conjunction with a quadrature generator and divider circuit to generate multiple signals with multiple different phases at the carrier frequency. In some embodiments, the output frequency can be the LO frequency (f LO ). In some embodiments, the RF circuit 806 may include IQ and / or polarity converters.

[0123] The FEM circuitry 808 may include a receive signal path, which may include circuitry configured to operate on RF signals received from one or more antennas 810, amplify the received signals, and provide an amplified version of the received signals to the RF circuitry 806 for further processing. The FEM circuitry 808 may also include a transmit signal path, which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 806 for transmission by one or more of the one or more antennas 810.

[0124] In some embodiments, the FEM circuit 808 may include a TX / RX switch to switch between transmit mode and receive mode operation. The FEM circuit may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuit may include a low noise amplifier (LNA) to amplify the received RF signal and provide the amplified received RF signal as an output (e.g., to the RF circuit 806). The transmit signal path of the FEM circuit 808 may include a power amplifier (PA) to amplify the input RF signal (e.g., provided by the RF circuit 806), and may include one or more filters to generate an RF signal for subsequent transmission (e.g., through one or more antennas 810).

[0125] In some embodiments, UE device 800 may include additional elements, such as memory / storage, displays, cameras, sensors, and / or input / output (I / O) interfaces.

[0126] In summary, the LOSIA method 100 may be implemented by a user equipment (UE) occupying a radio access network (RAN) in a first example, the UE initiating a cell search of the RAN to decode a limited set of system information (SI), sending a preamble / sequence to a RAN base station transceiver, wherein the preamble / sequence indicates a request for additional SI, and monitoring the transmission of the additional SI in the RAN.

[0127] Further to the first example or any other example discussed herein, in the second example, the UE may also decode additional SI, where the UE is thereafter able to communicate with the RAN base station.

[0128] Further to the second example or any other example discussed herein, in a third example, the additional SI is common to all UEs operating in the RAN.

[0129] Further to the second example or any other examples discussed herein, in a fourth example, the additional SI is UE-specific relative to other UEs operating in the RAN.

[0130] For the first, second, third or fourth example or any other example discussed herein, further, in the fifth example, the UE also sends the preamble / sequence by randomly selecting the preamble / sequence from a set of predefined preambles / sequences.

[0131] Further to the fifth example or any other example discussed herein, in a sixth example, the transmission of the preamble / sequence triggers additional SI associated with the identifier.

[0132] Further to the sixth example or any other example discussed herein, in the seventh example, the identifier is selected from a group consisting of: a common radio network temporary identifier (RNTI), a UE-specific RNTI, a UE-specific RNTI that changes after contention resolution, a service / application-specific RNTI, and a radio access technology (RAT)-specific RNTI.

[0133] Further to the first, second, third, fourth or fifth examples or any other examples discussed herein, in an eighth example, the preamble / sequence indicates a request to send additional system information for a predetermined service or application.

[0134] Further to the eighth example or any other example discussed herein, in a ninth example, the UE identifies an association of a preamble / sequence from a broadcasted SI transmission.

[0135] Further to the first example or any other examples discussed herein, in a tenth example, the UE sends a preamble / sequence in dedicated frequency resources.

[0136] Further to the first example or any other example discussed herein, in an eleventh example, the UE sends a preamble / sequence in a dedicated time resource.

[0137] Further to the first example or any other examples discussed herein, in the twelfth example, additional SI is received from multiple base station transceivers.

[0138] Further to the second example or any other examples discussed herein, in a thirteenth example, additional SI is received within a predetermined time window.

[0139] Further to the first example or any other examples discussed herein, in a fourteenth example, the UE checks a broadcasted flag, wherein the flag indicates whether transmission of additional SI is periodic or triggered.

[0140] For the first example or any other example discussed herein, further, in the fifteenth example, the UE starts a timer when transmitting a preamble code / sequence, and retransmits the preamble code / sequence if the additional SI has not been decoded by the UE when the timer expires.

[0141] In a sixteenth example, the LOSIA method 100 can also be implemented by a base station (BS) occupying the radio access network in the first example, wherein the BS sends a limited set of SI in a periodic manner; and sends additional SI upon receiving one or more preamble codes / sequences, wherein the additional SI is not transmitted continuously and periodically.

[0142] Further to the sixteenth example or any other examples discussed herein, in the seventeenth example, the BS broadcasts a flag, where the flag indicates whether additional SI is continuously and periodically transmitted.

[0143] Further to the sixteenth or seventeenth examples or any other examples discussed herein, in the eighteenth example, the additional SI is common to all UEs operating in the RAN.

[0144] Further to the sixteenth or seventeenth examples or any other examples discussed herein, in the nineteenth example, the additional SI is UE-specific relative to other UEs operating in the RAN.

[0145] Further to the sixteenth example or any other examples discussed herein, in the twentieth example, transmission of additional SI is associated with an identifier.

[0146] For the twentieth instance or any other example discussed herein, further, in the twenty-first instance, the identifier is selected from a group consisting of: a common radio network temporary identifier (RNTI), a UE-specific RNTI, a UE-specific RNTI that changes after contention resolution, a service / application-specific RNTI, and a radio access technology (RAT)-specific RNTI.

[0147] For the sixteenth example or any other example discussed herein, further, in the twenty-second example, the BS receives a second preamble / sequence from a second UE, wherein the second preamble / sequence is the same as the preamble / sequence, and performs a contention resolution process to distinguish the UE from the second UE.

[0148] The LOSIA method 100 may also be implemented in an article of manufacture including a computer-readable medium including instructions that cause an electronic device to implement a device as described in any of the foregoing examples when the instructions are executed by one or more processors of the electronic device.

[0149] In the twenty-fourth example, the LOSIA method 100 can also be implemented in a UE device, which includes: a radio frequency circuit coupled to one or more antennas, the antennas being used to receive signals transmitted through a cellular network; and one or more processors for executing instructions, which, once executed by the one or more processors, cause the UE to: decode a limited set of system information (SI), the set including: coarse time and frequency synchronization, cyclic prefix length, duplex mode, and a physical cell identifier of a cell in the cellular network; send a preamble code / sequence to the cell using the radio frequency circuit and one or more antennas, wherein the preamble code / sequence indicates a request for additional SI; monitor the cellular network for additional SI; and decode the additional SI.

[0150] For the twenty-fourth example or any other example discussed herein, further, in the twenty-fifth example, the instructions of the device may also start a timer when sending the preamble code / sequence, and retransmit the preamble code / sequence if the additional SI has not been decoded by the UE when the timer expires.

[0151] Although the foregoing examples are illustrative of the principles of one or more specific applications, it is obvious to those skilled in the art that a large number of modifications can be made to the form, usage and details of the implementation without inventive work and without departing from the principles and concepts described herein. It is intended that the appended claims cover all such modifications and variations that fall within the true spirit and scope of the present disclosure.

Claims

1. An apparatus for a user equipment UE, comprising a processor, wherein the processor is configured to enable the UE: Decoding a set of system information SI, the set of SI comprising a system information block type 1 SIB1, the SIB1 indicating a physical random access channel PRACH resource configuration for triggering system information on demand, wherein the SIB1 comprises a flag, the flag indicating that additional SI is not broadcast; sending a preamble / sequence to a RAN base station transceiver according to the PRACH resource configuration, wherein the preamble / sequence, when sent according to the PRACH resource configuration, indicates a request for the additional SI; and The transmission of the additional SI is monitored.

2. The apparatus according to claim 1, wherein the processor is further configured to cause the UE to: The transmission of the additional SI is monitored within a window, where the location and size of the window are configured by higher layers.

3. The apparatus of claim 2, wherein the position and size of the window are configured by an SI information element, the SI information element specifying a number of subframes used for the window.

4. The apparatus of claim 1, wherein the flag indicates whether additional SI is periodic or triggered.

5. The apparatus of claim 1, wherein the additional SI is common to all UEs operating in the RAN.

6. The apparatus of claim 1, wherein the additional SI is specific to the UE relative to other UEs operating in the RAN.

7. The apparatus of claim 1 , wherein the preamble / sequence triggers additional SI associated with an identifier, and the identifier comprises a common radio network temporary identifier (RNTI), a UE-specific RNTI, a UE-specific RNTI that changes after contention resolution, a service / application-specific RNTI, or a radio access technology-specific RNTI.

8. An apparatus for a base station BS, comprising a processor, wherein the processor is configured to cause the base station to: Sending a set of system information SI, the set of SI including system information block type 1 SIB1, the SIB1 indicating a physical random access channel PRACH resource configuration for triggering system information on demand, wherein the SIB1 includes a flag indicating that additional SI is not broadcast; as well as receiving a preamble / sequence according to the PRACH resource configuration, the preamble / sequence indicating a request for the additional SI; as well as The additional SI is sent to a user equipment UE identified by the preamble / sequence.

9. The apparatus according to claim 8, wherein the processor is further configured to cause the base station to: The additional SI is sent within a window, where the location and size of the window is configured by higher layers.

10. The apparatus of claim 9, wherein the position and size of the window are configured by an SI information element, the SI information element specifying a number of subframes for the window.

11. The apparatus of claim 8, wherein the flag indicates whether additional SI is periodic or triggered.

12. The apparatus of claim 8, wherein the additional SI is common to all UEs operating in the RAN.

13. The apparatus of claim 8, wherein the additional SI is specific to the UE relative to other UEs operating in the RAN.

14. The apparatus of claim 8, wherein the preamble / sequence triggers additional SI associated with an identifier, and the identifier comprises: A common radio network temporary identifier RNTI, a UE-specific RNTI, a UE-specific RNTI that changes after contention resolution, a service / application-specific RNTI, or a radio access technology-specific RNTI.

15. A method comprising: Receive and decode a set of system information SI, the set of SI including system information block type 1 SIB1, the SIB1 indicating a physical random access channel PRACH resource configuration for triggering system information on demand, wherein the SIB1 includes a flag indicating that additional SI is not broadcast; sending a preamble / sequence to a RAN base station transceiver according to the PRACH resource configuration, wherein the preamble / sequence when sent according to the PRACH resource configuration indicates a request for the additional SI; as well as The transmission of the additional SI is monitored.

16. The method according to claim 15, further comprising: The transmission of the additional SI is monitored within a window, where the location and size of the window are configured by higher layers.

17. The method of claim 16, wherein the position and size of the window are configured by an SI information element, the SI information element specifying a number of subframes for the window.

18. The method of claim 15, wherein the flag indicates whether additional SI is periodic or triggered.

19. The method of claim 15, wherein the additional SI is common to all UEs operating in the RAN.

20. The method of claim 15, wherein the additional SI is specific to the UE relative to other UEs operating in the RAN.

21. A non-transitory computer readable storage medium storing instructions which, when executed, are used to implement the method according to any one of claims 15 to 20.

22. A computer program product comprising program code portions for performing the method according to any one of claims 15 to 20 when the program code portions are run on one or more computing devices.

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