Device-triggered handover with long connected-discontinuous receive cycle in connected mode

Abstract

Wireless communication device (106, 106A, 106B) comprising the following: one or more antennas (335) configured to transmit and receive wireless communications over a wireless network (100); and Processing hardware configured to interact with the one or more antennas (335) and to cause the wireless communication device (106, 106A, 106B) to: to measure a currently serving base station (102) and one or more neighboring base stations (103, 105) after the wireless communication device (106, 106A, 106B) has entered a duty cycle of an attached discontinuous operating mode, C-DRX; to select a best neighboring base station from the one or more neighboring base stations (103, 105) as a new serving base station in response to measurements taken by the currently serving base station (102) and the one or more neighboring base stations (103, 105), wherein the selection of the best neighboring base station is performed by the wireless communication device (106, 106A, 106B) instead of the wireless communication device (106, 106A, 106B) transmitting a measurement report message to the currently serving base station (102), wherein the best neighboring base station is selected as the new serving base station, at least partially based on a measured radio quality of the currently serving base station (102) that is within a predetermined proximity to a specified radio link failure threshold; and to transmit a Radio Resource Control (RRC) link recovery message to the newly serving base station so that the newly serving base station initiates a handover operation to the newly serving base station.

Description

AREA OF INVENTION

[0001] The present invention relates to wireless communication devices and methods for reducing handover error rates between wireless devices in a wireless communication network. STATE OF THE ART

[0002] The use of wireless communication systems is increasing rapidly. In recent years, wireless devices such as smartphones and tablet computers have become increasingly sophisticated. Besides supporting telephone calls, many mobile devices now offer access to the internet, email, text messaging, and navigation using the Global Positioning System (GPS), and are also capable of running sophisticated applications that utilize these features. Generally speaking, wireless communication technologies, such as cellular communication technologies, are essentially designed to provide mobile communication capabilities to wireless devices, which are typically powered by a portable power source, such as a battery.Batteries have a finite charge, and one approach to extending the battery life of wireless devices is to reduce the power consumption required for wireless communication. To this end, some wireless communication technologies implement features designed to conserve power while maintaining a high-quality user experience. Generally speaking, circuit sections in a wireless device can be switched off when not in use to save power and extend battery life.

[0003] A significant power consumer in wireless devices is the transmitter and receiver circuitry (hereafter referred to as the "wireless circuit" or "transceiver circuit") that enables wireless communication. One example of a power-saving technique designed to conserve power in the transceiver circuitry is known as discontinuous receive (or DRX). In devices using DRX, sections of the wireless circuitry can be switched off when there is no information (such as packets) to receive or transmit. The wireless circuitry can be switched on periodically to determine whether information is being received and then switched off again if the check reveals that no information is arriving. A device using DRX can determine from the header in a transmitted packet whether the information contained therein is intended for that device.If the information is not relevant to this device, the circuitry can be switched off, at least for part of the remaining packet, and then switched back on before the next header. Polling is another usable technique where a device can periodically send a polling signal to an access point or base station to determine if any information is awaiting reception. If no information is awaiting reception, parts of the wireless circuitry can be switched off until the next polling signal is to be transmitted. In addition to determining whether information is waiting to be received by the mobile device, a neighbor search can be performed while the wireless circuitry is switched on in DRX mode.Neighbor cell searches can be performed to enable cell re-selection and handover of the mobile device from one cell to another. DRX (Direct Radio Query) has been implemented in various radio standards, such as UMTS (Universal Mobile Telecommunications System), LTE (Long-term Evolution), WiMAX, etc., which shuts down most of the terminal equipment (UE) circuitry when there are no packets to receive or transmit, and only wakes up at predetermined times or intervals to monitor the network. DRX can be activated in different network connection states, including connected and idle modes. In connected DRX (C-DRX) mode, the UE listens to downlink (DL) packets according to a specific pattern defined by the base station (BS).In idle DRX (I-DRX) mode, the UE listens to the call from the BS to determine if re-entry into the network and acquisition of the uplink (UL) schedule are necessary. Because DRX allows the UE to power down its transceiver circuitry for short intervals when there is no data to receive or transmit, and to initiate "wake and sleep" cycles to determine whether data is to be sent or received, operating in C-DRX mode helps reduce battery consumption. To save more power on the UE side, it is desirable to configure a long C-DRX cycle in connected LTE mode, especially when only non-real-time sensitive background data is present. For example, a network (NW)-configured C-DRX cycle currently lasts 320 ms (milliseconds), and it may be desirable to extend this cycle, for example, to 640 ms.However, 3GPP special simulations show that a UE in connected mode with a C-DRX cycle of 640 ms (or longer) experiences higher handover (HO) error rates. These increased HO error rates can be explained by the fact that when the UE wakes up and enters power-on mode during the longer C-DRX cycle, the currently serving cell (base station) may be too weak because the UE has moved into range of a distant cell during the off-time of the now longer C-DRX cycle. For example, the network may have difficulty decoding a measurement report message from the UE indicating that neighboring base stations (cells) are performing better than the currently serving base station, or a downlink signal from a serving base station may be too weak to be decoded by the UE.In the latter case, the UE may be unable to decode the Physical Downlink Control Channel (PDCCH) and / or the Physical Downlink Shared Channel (PDSCH). This means the UE might not receive a HO command before the radio link failure is declared. These problems can lead to higher HO failure rates and higher radio link failure rates, prompting the UE to send an additional Radio Resource Control (RRC) reconnection message to a nearby base station that is better positioned to re-establish an RRC connection than the current base station.

[0004] The prior art document US 2009 / 0238098 A1 describes discontinuous reception (DRX) for user devices in the E-UTRA infrastructure. The prior art document EP 2 359 629 B1 describes declaring a radio link failure based on a target-specific threshold.

[0005] The prior art documents US 2013 / 0260810 A1 and US 2013 / 0260811 A1 each describe the handling of connections between nodes in a wireless communication system. The prior art document WO 2017 / 028808 A1 describes a method for reselecting cells in connected mode for user devices configured with an extended DRX cycle in LTE systems. SUMMARY OF THE INVENTION

[0006] The present invention is defined in independent claims 1, 6, 7, and 12. Advantageous embodiments are specified in the dependent claims. Some of the embodiments described herein relate to a terminal device (DTD) and an associated power-saving method in a radio receiver implemented in a wireless communication device. A connection to a radio network (RW) comprising a base station can be established wirelessly. Communication can take place in an attached discontinuous receive mode (C-DRX).According to various implementations, the UE can trigger a handover (HO) procedure by initiating an RRC link restoration to a neighboring base station when it is determined that the neighboring base station is better positioned (or determined to be a better) supply cell than a base station currently operating as a supply cell. Conversely, the HO may not be initiated by the network side in response to a measurement report sent to the current supply cell by the UE. This allows for a longer C-DRX cycle to conserve more UE power during non-real-time sensitive background data transmissions, while avoiding higher HO error rates and additional radio resource control (RRC) signaling resulting from radio link failures.As explained in more detail below, the UE is generally said to "trigger a HO procedure" when it re-establishes (or initiates the re-establishment of) a connection with a neighboring base station that is different from the currently serving base station, in order to initiate an HO from the network side. In other words, the current HO can be initiated by the network, but the HO is initiated in response to the UE triggering the HO procedure by re-establishing a connection with a neighboring base station that is different from the currently serving base station, as distinct from the HO that is initiated in response to a test report sent by the UE to the currently serving base station.

[0007] In some embodiments, when the UE enters the ON time of a C-DRX cycle, the UE can measure the currently serving cell (base station) and neighboring cells (base stations). The measurements can include various radio quality measurements to evaluate which base station would best support the UE's communication. If the measurement for the current serving cell is within a specified range (for example, within a specified number N of decibels or dBs) of the radio link error limit, and a better neighboring cell is present, and both the measurement with respect to the serving cell (or serving cell measurement) and the measurement with respect to the neighboring cell (or neighboring cell measurement) are within the HO limit—i.e.,If the criteria for initiating a Home Office (HO) are met, then instead of sending a measurement report message to the current supply cell, the UE can select the best adjacent (or neighboring) cell (base station) as the new supply cell and send an RRC reconnection message to this new supply cell. The new supply cell can then retrieve the UE context information from the old supply cell, whose cell ID may be included in the RRC reconnection message, and re-establish the RRC connection with the UE on the new supply cell.This eliminates the need for additional (extra) RRC signaling, including the need for the UE to transmit a measurement report and reconfigure the RRC connection for a HO, which would most likely fail, and also allows for the configuration of a longer C-DRX cycle in the network to save more UE power in connected mode.

[0008] In further accordance with the above, a first base station within communication range of a wireless communication device—but not currently active as a support cell for the wireless communication device—can receive an RRC (Reconnection Recovery Call) message from the wireless communication device, which is transmitted by the wireless communication device to initiate a handover procedure. In response to receiving the RRC message, the first base station can initiate a handover from a second base station—currently active as a support cell for the wireless communication device—to the first base station. The RRC message can include information relating to the second base station.Based on the information contained in the RRC reconnection message, the first base station can retrieve device context information from the second base station as part of initiating the handover procedure. The first base station can then establish an RRC connection with the wireless communication device according to the device context information.

[0009] This summary provides a brief overview of some of the items described in this document. It should therefore be noted that the features described above are only examples and should not be interpreted as limiting the scope or basic principle of the item described herein in any way. Other features, aspects, and advantages of the item described herein will become apparent from the detailed description, figures, and claims below. BRIEF DESCRIPTION OF THE DRAWINGS In Fig. Figure 1 shows an exemplary (and simplified) wireless communication system; In Fig. Figure 2 shows an exemplary base station communicating with an exemplary wireless terminal (DTN) device; In Fig. Figure 3 shows an exemplary block diagram of a UE according to some embodiments; In Fig. Figure 4 shows an exemplary block diagram of a base station according to some embodiments; Fig. Figure 5 is a timing diagram illustrating an example of the general operation of a C-DRX-capable wireless communication device over a period of time according to some embodiments; and Fig. Figure 6 is a flowchart illustrating an example of a method for a wireless terminal device that triggers a handover procedure in a radio network in C-DRX mode, according to some embodiments.

[0010] Although the features described here are open to different modifications and alternative forms, specific embodiments are illustrated in the drawings and described in detail here. It should be noted, however, that the drawings and the accompanying detailed description are not suitable for limiting the specific disclosed form. DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES (Ecronyms)

[0011] This application uses various acronyms. The following are definitions of the most frequently used acronyms found in this application: BLER: Block Error Rate (identical to packet error rate) BER: Bit Error Rate BS: Base station C-DRX: Connected Discontinuous Reception CRC: Cyclic Redundancy Check DL: Downlink DRX: Discontinuous Reception GSM: Global System for Mobile Communication LTE: Long Term Evolution PDCCH: Physical Downlink Control System PDSCH: Physical Downlink Shared Channel PER: Packet Error Rate PUCCH: Physical Uplink Control Channel PUSCH: Physical Uplink Shared Channel SFN: System Frame Number SINR: Signal-to-Interference-and-Noise Ratio (Signal-to-noise ratio) SIR: Signal-to-Interference Ratio (Signal-to-noise ratio) SNR: Signal-to-Noise Ratio SPS: Semi Persistent Scheduling TX: Transmission UE: User Equipment (end device) UL: Uplink UMTS: Universal Mobile Telecommunications System VoLTE: Voice over LTE (Voice over LTE) terms

[0012] The following is a glossary of terms that may appear in this application. Storage medium – One of several types of non-volatile storage devices. The term “storage medium” also extends to an installation medium, e.g., a CD-ROM, floppy disk, or tape device; a computer system memory or random access memory, such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory, magnetic media, e.g., a hard disk or optical storage; registers or similar types of memory elements, etc. The storage medium may include other types of non-volatile memory as well as combinations thereof. Furthermore, the storage medium may be located in a first computer system, in which the programs are executed, or in a second, separate computer system connected to the first computer system via a network, such as the internet. In the latter case, the second computer system can transmit program instructions to the first computer system for execution.The term "storage medium" can encompass two or more storage media that may be located in different places, e.g., in different computer systems connected via a network. Carrier medium - A storage medium as described above, as well as a physical transmission medium, such as a bus, a network and / or another physical transmission medium that carries signals, for example electrical, electromagnetic or digital signals. Programmable hardware element – ​​This encompasses various hardware devices comprising multiple programmable function blocks interconnected via a programmable link. Examples include FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), FPOAs (Field Programmable Object Arrays), and CPLDs (Complex PLDs). The programmable function blocks can range from fine-grained (combinatorial logic or lookup tables) to coarse-grained (arithmetic logic units or processor cores). A programmable hardware element can also be referred to as "reconfigurable logic." Computer system (or computer) – Any of different types of computing or processing systems, including a personal computer system (PC), a mainframe computer system, a workstation, a network application, an Internet application, a personal digital assistant (PDA), a TV system, a grid computing system, or other devices or combinations of devices. In general, the term "computer system" can be defined so broadly as to include any device (or combination of devices) that has at least one processor that executes instructions from a storage medium. Terminal Equipment (TE) (or “terminal device”) – Any of various types of computer system equipment that is mobile or portable and capable of wireless communication. Examples of TEs include mobile phones or smartphones (e.g., iPhone™, Android™-based phones), portable gaming devices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™, iPhone™), laptops, body-worn devices (e.g., smartwatches, smart glasses), PDAs, portable internet devices, music players, data storage devices, or other portable devices and equipment, etc. More generally, the term “TE” or “TE” can be defined broadly to include any electronic, computer, and / or telecommunications device (or a combination of devices) that is easily portable by a user and capable of wireless communication. Base station (BS) – The term “base station” has the full breadth of its usual meaning and includes at least one wireless communications station installed in a fixed location and used to communicate as part of a wireless telephone or radio system. Processor element – ​​refers to different elements or combinations of elements. Processor elements include, for example, circuits such as an ASIC (Application Specific Integrated Circuit), sections or circuits of individual processor cores, entire processor cores, individual processors, programmable hardware devices such as a Field Programmable Gate Array (FPGA), and / or larger sections of systems comprising multiple processors. Automatic – Describes an action or operation performed by a computer system (e.g., by software running the computer system) or a device (e.g., a circuit, programmable hardware elements, ASICs, etc.) without user input directly defining or executing the action or operation. The term "automatic" thus contrasts with an operation that is manually performed or defined by the user, where the user provides input for the immediate execution of the operation. An automatic procedure may be triggered by user input, but the subsequent actions performed "automatically" are not defined by the user; that is, they are not performed "manually" with the user specifying each action to be carried out. For example, if a user selects individual fields and provides input of specific information (e.g.,When a user fills out an electronic form (by typing information, checking boxes, selecting options, etc.), they are filling it out manually, even if the computer system needs to update the form in response to user actions. The form can then be filled out automatically by the computer system if the computer system (e.g., software running on the computer system) analyzes the form's fields and fills it out without user input specifying the answers in the fields. As stated above, the user can request automatic form filling but is not involved in the actual process of filling out the form (e.g., the user does not manually specify the answers in the fields; rather, they are filled in automatically). This specification provides several examples of operations that are performed automatically in response to user actions. Figures 1 and 2 - Exemplary communication systems

[0013] In Fig. Figure 1 shows an exemplary (and simplified) wireless communication system. It should be noted that the system is... Fig. Figure 1 is only one example of a possible system, and embodiments can be implemented in any of the different systems as needed. As shown, the exemplary wireless communication system comprises a base station 102, which communicates with one or more user devices 106A to 106N via a transmission medium. Each of the user devices can be referred to here as an "end device" (UE) or end device. Thus, the user devices 106A to 106N are referred to as UEs or UE devices. When referring generally to an individual UE, user devices are also referred to here as UE 106 or simply UE.

[0014] Base Station 102 can be a Base Transceiver Station (BTS) or a radio cell and can include hardware that enables wireless communication with UEs 106A to 106N. Base Station 102 can also be equipped to communicate with a Network 100 (for example, a cellular service provider's core network, a telecommunications network such as a public switched telephone network (PSTN), and / or the Internet, among other possibilities). In this way, Base Station 102 can enable communication between user devices and / or between user devices and Network 100. The communication area (coverage area) of the Base Station can be referred to as a "cell." Furthermore, the Base Station serving the coverage area referred to as a "cell" is also referred to here as a "coverage cell."In other words, base station 102 can be referred to as a "service cell" to describe the fact that base station 102 facilitates communication between user devices and / or between the user devices and network 100. As also used here, from the perspective of the user devices (UEs), a base station can sometimes be considered a representative of the network (NW) insofar as uplink and downlink communications of the UE are concerned. Consequently, a UE communicating with one or more base stations in the network (NW) can also be considered the UE communicating with the NW.

[0015] As also in Fig. As shown in Figure 1, the exemplary (and simplified) wireless communication system can also include additional base stations, for example, base stations 103 and 105 (of course, other embodiments may include more or fewer base stations), which, as shown, can communicate with one or more of the other base stations. For example, base station 102 can communicate with base station 105 and base station 103. Similar to base station 102, base stations 103 and 105 can also enable communication between different user devices and / or between different user devices and network 100, as shown. The different base stations can be considered as serving different cells, while the different cells may have overlapping coverage areas.A mobile communication device (MCD) that moves into and out of different service areas may require the transfer of its communication capability from one currently serving base station to another. For example, MCD 106A might be served by base station 102, but then move into a service area (cell) primarily served by base station 105. In this case, MCD 106A's communication is transferred from base station 102 to base station 105 via a handover (HO) procedure. Following the HO procedure, MCD 106A's communication is then enabled by base station 105. Various implementation examples are described below, where the MCD can trigger such an HO procedure, which in turn leads to an HO performed by the network.

[0016] The base station 102 and the user devices can be configured to communicate over the transmission medium using various radio access technologies (RATs), also known as wireless communication technologies or telecommunications standards, such as GSM, UMTS (WCDMA), LTE, LTE-Advanced (LTE-A), 3GPP2 CDMA2000 (e.g. 1xRTT, 1xEV-DO, HRPD, eHRPD), WiFi, WiMAX, etc.

[0017] The UE 106 can be capable of communicating using multiple wireless communication standards. For example, the UE 106 could be configured to communicate using one or both of a 3GPP cellular communication standard (such as LTE) or a 3GPP2 cellular communication standard (such as a cellular communication standard in the DMA2000 family of cellular communication standards). Consequently, in some embodiments, the UE 106 can be configured to communicate with the base station 102 using a first cellular communication standard (such as LTE) and could also be configured to communicate with other base stations using a second cellular communication standard (such as one or more CDMA2000 cellular communication standards).The Base Station 102 and other similar base stations operating on the same or a different cellular communication standard can thus be deployed as one or more cell networks capable of providing a continuous or near-continuous, overlapping service for the UE 106 and similar devices over a large geographical area by means of one or more cellular communication standards.

[0018] The UE 106 could also be configured to communicate using WLAN, Bluetooth, one or more global navigation satellite systems (GNSS, e.g., GPS or GLONASS), one and / or more mobile TV broadcasting standards (e.g., ATSC-M / H or DVB-H), etc. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0019] In Fig. Figure 2 shows an example of an end device 106 (e.g., one of devices 106-1 to 106-N) communicating with a base station 102. The UE 106 can be a device with wireless network connectivity, such as a mobile phone, a portable device, a computer, or a tablet, or virtually any type of wireless device. The UE 106 can contain processing hardware, which may include a processor configured to execute program instructions stored in memory. The UE 106 can perform any of the procedure examples described herein by executing such stored instructions.Alternatively or additionally, the UE 106 can include a programmable hardware element, such as an FPGA (Field-Programmable Gate Array), configured to perform one of the procedure examples of the UE-triggered handover described herein, or any section of one of the procedure examples of the UE-triggered handover described herein. The UE 106 can be configured to communicate using one of several wireless communication protocols. For example, the UE 106 can be configured to communicate using two or more of CDMA2000, LTE, LTE-A, WLAN, or GNSS. Other combinations of wireless communication standards are also possible.

[0020] The UE 106 can include one or more antennas for communication over a radio network using one or more wireless communication protocols. In some embodiments, the UE 106 can share one or more parts of a receive and / or transmit chain between multiple wireless communication standards. The shared radio can include a single antenna or multiple antennas (for example, for MIMO) for wireless communication. Alternatively, the UE 106 can include separate transmit and / or receive chains (for example, with separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As another alternative, the UE 106 can include one or more radios shared between multiple wireless communication protocols and one or more radios used exclusively by a single wireless communication protocol.For example, the UE 106 can include a shared radio for communication using LTE or CDMA2000 1xRTT and separate radios for communication using Wi-Fi and Bluetooth. Other configurations are also possible. Figure 3 - exemplary block diagram of a teaching unit

[0021] In Fig. Figure 3 shows an exemplary block diagram of a UE 106. As shown, the UE 106 can comprise a system-on-a-chip (SOC) 300, which may contain sections for different purposes. As shown, the SOC 300 may, for example, include one or more processors 302, which can execute program instructions for the UE 106, and display circuits 304, which can perform graphics processing and output display signals to the display 340. The different components, or any number of the components, in the UE 106, excluding the antenna 335, may be collectively referred to as "processing hardware".The processor(s) 302 can also be coupled to the memory management unit (MMU) 340, which can be configured to receive addresses from the processor(s) 302 and translate these addresses to locations in memory (for example, memory 306, ROM 350, NAND flash memory 310) and / or to other circuits or devices, such as the display circuit 304, the radio 330, the interface 320, and / or the display 340. The MMU 340 can be configured to perform memory protection, page table mapping, or setup. In some embodiments, the MMU 340 can be included as part of the processor(s) 302.

[0022] As shown, the SOC 300 can be coupled to various circuits of the UE 106. For example, the UE 106 can include different memory types (e.g., including a NAND flash 310), a connection interface 320 (e.g., for coupling to the computer system), the display 340, and a wireless communication circuit (e.g., for LTE, LTA-A, CDMA2000, Bluetooth, Wi-Fi, GPS, etc.). The UE device 106 can include at least one antenna and possibly several antennas to perform wireless communication with base stations and / or other devices. For example, the UE device 106 can use the antenna 335 to perform wireless communication. As mentioned above, the UE can be configured to communicate wirelessly using multiple wireless communication standards in some embodiments.

[0023] As explained in more detail below, the UE 106 can include hardware and software components for implementing a method for performing handover (HO) operations while operating in C-DRX mode. The processor 302 of the UE device 106 can be configured to implement some or all of the methods described herein, for example, by executing program instructions stored on a memory medium (for example, on a non-volatile, computer-readable memory medium). In other embodiments, the processor 302 can be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). Furthermore, the processor 302 can be coupled to and / or interact with other components, as described in Fig. 3 shown to enable the performance of HO operations, as further described in the chapter “Handover (HO) procedure during extended C-DRX cycles”. Figure 4 - Exemplary block diagram of a base station

[0024] In Fig. Figure 4 shows an exemplary block diagram of a base station 102. It should be noted that the base station of Fig. Figure 4 represents only one example of a possible base station. As shown, the base station 102 can contain processor(s) that execute program instructions for the base station 102. The processor(s) 102 can also be coupled to a memory management unit (MMU) 440, which can be configured to receive addresses from the processor(s) 102 and translate these addresses to locations in memory (e.g., memory 460 and ROM 450) or to other circuits or devices. Again, the hardware components within the base station 102—excluding the antenna 434—or a subset of the various hardware components within the base station 102 can be collectively referred to as "processing hardware."

[0025] The base station 102 can include at least one network interface 470. The network interface 470 can be configured to connect to a telephone network and provide access to the telephone network to a plurality of devices, for example, UE devices 106, as described above. Fig. 1 and Fig. 2 described. The network interface 470 (or an additional network interface) can also be configured, or alternatively configured, to connect to a cellular network, for example, a cellular service provider's core network. The core network can provide mobility-related services and / or other services to a plurality of devices, for example, UE devices 106. In some cases, the network interface 470 can connect to a telephone network via the core network, and / or the core network can provide a telephone network (e.g., alongside other UE devices served by the cellular service provider).

[0026] The base station 102 can have at least one antenna 434 and possibly several antennas. The at least one antenna 434 can be configured to operate as a wireless transceiver and can further be configured to communicate with UE devices 106 via the radio 430. The antenna 434 communicates with the radio 430 via the communication chain 432. The communication chain 432 can be a receive chain, a transmit chain, or both. The radio 430 can be configured to communicate using various wireless telecommunications standards, including—but not limited to—LTE, LTE-A, WCDMA, CDMA200, etc.The 404 processor of base station 102 can be configured to implement some or all of the procedures for performing the HO operations described here, for example, by executing program instructions stored on a storage medium (for example, a non-volatile, computer-readable storage medium). Alternatively, the 404 processor can be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or as a combination thereof. DRX

[0027] The parameters for DRX cycles can be configured by the BS (e.g., BS 102) using various timers. The DRX inactivity timer specifies the number of consecutive subframes that must be waited for before DRX activation. Short and long DRX cycles are defined to allow the BS to adjust the DRX cycles based on application categories and their associated characteristics. A DRX short-cycle timer can be defined to determine the transition to the long DRX cycle. If no packets are received for an extended period after a successful packet reception, the BS can initiate the release of the RRC connection, and the UE can enter the RRC IDLE state, during which the inactive DRX can be activated.The power-on timer can be used to determine the number of frames the UE will read the DL control channel in each DRX cycle before entering power-saving mode. Examples of acceptable values ​​are 1, 2, 3, 4, 5, 6, 8, 10, 20, 30, 40, 50, 60, 80, 100, and 200. During inactive DRX mode, the UE can monitor one paging opportunity (PO) per DRX cycle, which is a subframe.

[0028] In Fig. Section 5 illustrates different aspects of general C-DRX operations. As shown in Section 602, the UE 106 can operate in an active state and perform one or more uplink and / or downlink (UL / DL) transmissions (e.g., transmitting uplink data and / or receiving downlink data). An inactivity timer can be initiated at Section 504. The inactivity timer can be initiated at the end of the active transmissions in Section 502. Note that the inactivity timer may have been initiated one or more times during the active transmissions in Section 502, but each time it may have been reset due to ongoing activity (transmissions) until no further activity is observed at Section 504, at which point it can run until its expiration date in Section 508.The inactivity timer can be of any length as required; some examples of possible inactivity timer lengths could include 100 ms, 80 ms, 50 ms, 40 ms or any other value as specified, for example, by the 3GPP 36.331 specification.

[0029] In 506, between the initiation (at 504) and expiration (at 508) of the inactivity timer, the UE 106 may not perform any uplink or downlink transmissions, but could continue operating in the active state and monitor one or more communication channels (e.g., a PDCCH) for downlink assignments. At 508, the inactivity timer could expire. At this point, the UE 106 may enter a low-power (DRX) state because a sufficient period of data communication inactivity has been observed (e.g., as indicated by the expiration of the inactivity timer). During the period in the low-power state, the UE 106 may power down and / or reduce power to one or more components, such as baseband logic components and / or radio components.

[0030] At 510, the UE 106 can "wake up" and return to active state. The UE 106 can wake up at a time specified by a schedule, which is communicated to it, for example, by a base station (e.g., an eNode-B in LTE). At the specified time (or after a specified interval), the base station can notify the UE 106 of a downlink assignment if downlink data is pending, allowing the UE 106 to check for downlink assignments during this time (e.g., monitor a communication channel such as PDCCH). During this time, one or more other functions can also be performed if desired. This period can also be referred to as the "power-on time" in C-DRX operation. According to some embodiments, the duty cycle can last for a fixed time, for example 5 ms or 10 ms or another duration, such as that specified in 3GPP 36.331 is set; alternatively, the power-on duration can last until certain functions have been performed and end when no further specified functions need to be performed. At 512, the power-on duration can end, and if no downlink mappings have been received during the power-on duration, the UE 106 can return to "sleep mode" and enter a low-power state. Any number of consecutive sleep (DRX) and wake (power-on duration) cycles can be performed as needed.

[0031] Note that the UE 106 can also be configured to switch between C-DRX cycles of different lengths. For example, as shown, the UE 106 can perform up to a specified number (such as 2, 4, 8, 16, etc.) of "short C-DRX" cycles 514 (which can last 20 ms, 40 ms, 80 ms, or any other duration). If no uplink or downlink transmissions are performed by the end of the predetermined number of cycles, the UE 106 can perform one or more "long C-DRX" cycles 516 (which can last 80 ms, 160 ms, 320 ms, or any other duration, such as that specified by 3GPP 36.331). These cycles can establish a longer period of operation in the low-power state before waking up for duty-time operations in the active state. It should be noted that, for energy conservation purposes, it may be desirable to extend the long C-DRX cycle.The current maximum value for a long-C-DRX cycle might be set to 320 ms, for example, but it may be advantageous to extend the length of this cycle to 640 ms, for instance, to potentially lengthen the inactivity period and thus reduce the power consumption of the UE 106. The long-C-DRX cycles can continue until further active communication occurs (which could be initiated, for example, by the UE 106 or the network), or until one or more other conditions arise that could cause the UE 106 to exit the long-C-DRX cycles.

[0032] If active communications are initiated again at a subsequent time, the UE 106 can perform similar steps (for example, monitoring activity / inactivity via an inactivity timer and initiating one or more C-DRX cycles when sufficient inactivity is detected between active communications) if this appears necessary, for example, depending on the communication activity. Handover (HO) procedure during extended C-DRX cycles

[0033] Communication, for example between a UE (such as the UE 106 in Fig. 1) and a BS (e.g. BS 102 in Fig. 1) can take place in C-DRX mode. For example, referring to Fig. 1. The UE 106B can communicate within a cell served by base station 102, which can therefore be referred to as the service cell, or in other words, considered the service base station for the UE 106B. Base stations 103 and 105 can also be adjacent base stations to the UE 106B, and as the UE 106B moves, it can move out of the (primary) service area of ​​base station 102 and into the (primary) service area of ​​base station 103. While moving, the UE can trigger a handover (HO) procedure to initiate an HO from the network side after the UE has determined that an adjacent base station (e.g., BS 103 or BS 105) is a better service cell than a base station operating as the current service cell (e.g., BS 102). In such a case, the UE (e.g.UE 106B) initiates the re-establishment of an RRC link to a better-serving neighboring base station with a HO that is initiated in response to the initiation of the re-establishment of an RRC link to the better-serving base station. In other words, the HO cannot be initiated in response to a measurement report transmitted by the UE to the currently serving base station, but can instead be initiated in response to the UE initiating the re-establishment of an RRC link to a better-serving base station. This allows for a longer C-DRX cycle, which reduces the power consumed by the UE during transmissions of non-real-time sensitive background data, while avoiding higher HO error rates and additional radio resource control (RRC) signaling resulting from a radio link failure.

[0034] In some embodiments, when the UE enters the on-time (or ON-time) of a C-DRX cycle, it can perform various measurements in conjunction with the currently serving base station and one or more neighboring base stations. Specifically, the UE can measure the radio quality of the currently serving base station and one or more neighboring base stations. For example, the UE can measure the radio quality indicators of neighboring cells (neighboring base stations), such as RSSI (Received Signal Strength Indicator), RSCP (Reference Signal Code Power), and RSRQ (Reference Signal Received Quality), and can also measure the radio quality indicators of its serving cell (serving base station), such as RSSI, RSCP, and RSRQ. The UE can also measure other indicators if applicable and / or available.

[0035] If the measurement for the current service cell is within a defined range, for example, within a specified number N decibels (dBs) of the radio link fault threshold, and a better neighboring cell is available, and if the measurements of the service cell and the neighboring cell both meet predefined criteria that are considered an indication that a homeover (HO) should be performed (in other words, both measurements meet an HO threshold), then the service unit (UE) can select the best neighboring cell (base station) as the new service cell and trigger an HO procedure so that an HO is initiated from the network side to the new service cell. The HO can then be initiated in response to this triggering mechanism and not in response to the UE transmitting a measurement report message to the current service cell.

[0036] In a group of embodiments, the UE can trigger a HO procedure by initiating a restoration of an RRC connection with a new supply cell in response to the measurements, provided that at least one of the following conditions is met: • First condition: The measured radio quality of the serving base station is close to a specified radio link error threshold. For example, the measured radio quality of the serving base station, e.g., RSCP, might be -100 dBm, and the specified radio link error threshold might be set to -102 dBm. In this case, the radio quality of the currently serving base station is 2 dBm higher than the radio link error threshold. If the specified value N, for which the currently serving base station can be considered "close to the radio link error threshold," is "3," then in this case, the radio quality of the currently serving base station is considered close to the radio link error threshold, and the first condition is met. • Second condition: The measured radio quality of one of the neighboring base stations is better than the measured radio quality of the currently serving base station. • Third condition: The difference between the radio quality measurement of the currently serving base station and the radio quality measurement of one of the neighboring base stations satisfies a HO threshold requirement. The HO threshold refers to any condition that is interpreted as a starting signal or indication to perform an HO. For example, the HO threshold may be set at 4 dBm, meaning that an HO must take place if the radio quality of a neighboring cell is at least 4 dB better than the radio quality of the currently serving cell. If the RSCP measurement of the currently serving cell (base station) is -100 dBm and the RSCP measurement of the neighboring cell (base station) is -80 dBm, the difference between the radio quality measurements is 20 dB, which is higher than the 4 dBm threshold, and therefore the HO threshold is met.

[0037] The UE can initiate the HO procedure by sending a Radio Resource Control (RRC) link re-establishment message to the newly selected supply cell. The RRC message can contain the cell ID of the currently supplying cell (base station). The newly supplying cell can then retrieve the UE context information from the currently supplying cell, whose cell ID is included in the RRC link re-establishment message, and re-establish the RRC link with the UE on the newly supplying cell, thereby making the newly supplying cell the currently supplying cell. This eliminates the need for additional (extra) RRC signaling, including UE transmission of a measurement report and RRC link reconfiguration for an HO that would most likely fail, and also allows for the configuration of a longer C-DRX cycle in the NW to save more UE power in connected mode. Exemplary procedure of UE-triggered handover

[0038] In Fig. Figure 6 is a flowchart illustrating an example of a method for a wireless communication device (or UE or UE device) that triggers a handover procedure to initiate a handover from the network side in a radio network in C-DRX mode according to some embodiments. As shown in Fig.As shown in Figure 6, the wireless communication device can measure the radio quality of a currently serving base station and one or more neighboring base stations (602) during a C-DRX cycle. The wireless communication device can then select one of the neighboring base stations from among the one or more neighboring base stations as the new serving base station, based on the radio quality measurements of the currently serving base station and the neighboring base stations (604).The wireless communication device can, for example, select the neighboring station if the measured radio quality of the currently serving base station is sufficiently close to a limit for radio link errors, the measured radio quality of the neighboring station is better than the measured radio quality of the currently serving base station, and the difference between the measured radio quality of the currently serving base station and the measured radio quality of the neighboring station is greater than a specified HO limit.

[0039] The wireless communication device can then initiate a handover (HO) procedure from the currently serving base station to the newly serving base station in response to the selection of the newly serving base station (606). The wireless communication device can initiate the HO procedure by transmitting a radio resource control (RRC) link recovery message to the newly serving base station (608). The RRC link recovery message can contain information regarding the currently serving base station to enable the initiation of the HO from the network side. In some embodiments, the wireless communication device can select the best adjacent base station and initiate the HO procedure instead of transmitting a measurement report message to the currently serving base station.

[0040] The procedure may further include the newly providing base station (cell), in response to the RRC connection recovery message transmitted from the wireless communication device to the newly providing base station, retrieving device context information from the currently providing base station during the initiation of the HO procedure (610). The newly providing base station can then establish an RRC connection with the wireless communication device according to the device context information (612). Various implementation examples

[0041] The embodiments of the present invention can be implemented in a variety of different forms. For example, some embodiments can be implemented as computer-aided methods, computer-readable storage media, or computer systems. Other embodiments can be implemented using one or more customer-specific hardware devices, such as ASICs. In other embodiments, one or more programmable hardware elements, such as FPGAS, can be used.

[0042] In some embodiments, a non-volatile, computer-readable storage medium can be configured to store program instructions and / or data, wherein the program instructions, when executed by a computer system, cause the computer system to perform a procedure, e.g., one of the procedures in the embodiments described herein, or a combination of the embodiments described herein, or a subset of one of the embodiments described herein, or a combination of such subsets.

[0043] In some embodiments, a device (e.g., a wireless communication device or a UE device) can be configured to include a processor (or a group of processors) and a storage medium, wherein the storage medium stores program instructions, the processor is configured to read and execute the program instructions from the storage medium, and the program instructions are executable to implement one of the various method embodiments described herein (or any combination of the method examples described herein, or a subset of any of the method examples described herein, or a combination of such subsets). The device can be implemented in any of the various forms.

[0044] Even though the exemplary embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to the person skilled in the art after having full knowledge of the preceding disclosure.

Claims

[1] Wireless communication device (106, 106A, 106B) comprising the following: one or more antennas (335) configured to transmit and receive wireless communications over a wireless network (100); and Processing hardware configured to interact with the one or more antennas (335) and to cause the wireless communication device (106, 106A, 106B) to: to measure a currently serving base station (102) and one or more neighboring base stations (103, 105) after the wireless communication device (106, 106A, 106B) has entered a duty cycle of an attached discontinuous operating mode, C-DRX; to select a best neighboring base station from the one or more neighboring base stations (103, 105) as a new serving base station in response to measurements taken by the currently serving base station (102) and the one or more neighboring base stations (103, 105), wherein the selection of the best neighboring base station is performed by the wireless communication device (106, 106A, 106B) instead of the wireless communication device (106, 106A, 106B) transmitting a measurement report message to the currently serving base station (102), wherein the best neighboring base station is selected as the new serving base station, at least partially based on a measured radio quality of the currently serving base station (102) that is within a predetermined proximity to a specified radio link failure threshold; and to transmit a Radio Resource Control (RRC) link recovery message to the newly serving base station so that the newly serving base station initiates a handover operation to the newly serving base station. [2] Wireless communication device (106, 106A, 106B) according to claim 1, wherein the RRC connection recovery message includes information that identifies the currently serving base station (102). [3] Wireless communication device (106, 106A, 106B) according to any one of claims 1 to 2, wherein the processing hardware is configured to further cause the wireless communication device (106, 106A, 106B) to select the best adjacent base station as the new serving base station in response to at least one of the following: a measured radio quality of at least one of the one or more neighboring base stations (103, 105) that is better than the measured radio quality of the currently serving base station (102); or a difference between the measured radio quality of the currently serving base station (102) and the measured radio quality of at least one of the one or more neighboring base stations (103, 105) that meets a handover threshold. [4] Wireless communication device (106, 106A, 106B) according to any one of claims 1 to 3, wherein the processing hardware is configured to further cause the wireless communication device (106, 106A, 106B) to select the best adjacent base station as the new serving base station instead of sending a measurement report message to the currently serving base station (102). [5] Wireless communication device (106, 106A, 106B) according to any one of claims 1 to 4, wherein the newly supplying base station is configured to: to retrieve device context information from the currently serving base station (102); and to restore the RRC connection with the wireless communication device (106, 106A, 106B) according to the device context information. [6] Wireless communication system comprising the following: a plurality of wireless communication devices (106, 106A, 106B) as listed in claims 1 to 5, wherein the plurality of wireless communication devices (106, 106A, 106B) are configured to communicate with each other via one or more of the following: the currently serving base station (102); or one or more adjacent base station(s) (103, 105). [7] Method for reducing handover error rates between wireless devices in a wireless communication network during connected discontinuous, C-DRX, operating mode, the method comprising: Measuring the radio quality of a currently serving base station (102) and one or more neighboring base stations (103, 105) by a wireless communication device (106, 106A, 106B) during a switching-on time of a C-DRX operating mode; Selecting a best neighboring base station from the one or more neighboring base stations (103, 105) by the wireless communication device (106, 106A, 106B) as a new serving base station in response to measuring the radio quality of the currently serving base station (102) and the one or more neighboring base stations (103, 105), and selecting the best neighboring base station by the wireless communication device (106, 106A, 106B) instead of transmitting a measurement report message to the currently serving base station (102) by the wireless communication device (106, 106A, 106B), wherein the best neighboring base station is selected as the new serving base station, at least partially based on a measured radio quality of the currently serving base station (102) that is within a predetermined proximity to a specified radio link failure threshold; and Transmitting a Radio Resource Control (RRC) link recovery message to the newly serving base station through the wireless communication device (106, 106A, 106B) so that the newly serving base station initiates a handover operation to the newly serving base station. [8] Method according to claim 7, wherein the RRC connection restoration message includes information regarding the currently serving base station (102). [9] Method according to any one of claims 7 to 8, wherein selecting the best adjacent base station comprises selecting the best adjacent base station in response to at least one of the following: the radio quality of at least one of the one or more neighboring base stations (103, 105) is better than the radio quality of the currently serving base station (102); or A difference between the radio quality of the currently serving base station (102) and the radio quality of at least one of the one or more neighboring base stations (103, 105) has a value that meets a handover threshold requirement. [10] Method according to any one of claims 7 to 9, further comprising: Establishing an RRC connection with the wireless communication device (106, 106A, 106B) by the newly supplied base station in response to the handover procedure initiated by the wireless communication device (106, 106A, 106B). [11] Method according to claim 10, further comprising: Retrieval of device context information by the newly serving base station from the currently serving base station (102) in response to an RRC reconnection message transmitted by the wireless communication device (106, 106A, 106B) to the newly serving base station as part of the handover procedure; wherein the establishment of the RRC connection with the wireless communication device (106, 106A, 106B) by the newly serving base station includes establishing the RRC connection according to the device context information. [12] Non-volatile memory element in which program instructions are stored which can be executed by a processor circuit to carry out the method as set out in any one of claims 7 to 11.

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