Power Saving Method for Monitoring Data Channel

A power saving method for monitoring data channel is proposed. The network node may indicate that the UE can enter a power saving mode by transmitting a DCI to the UE. The DCI may indicate a power saving duration and an additional monitoring duration. The power saving duration may indicate the length of the power saving mode and the starting point and the end point of the power saving mode. The additional monitoring duration may indicate that the UE needs to perform monitoring for a period of time before the power saving mode based on the first power saving duration indicated in the DCI.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless communication, and, more particularly, to power saving method for monitoring data channel.

BACKGROUND

The wireless communications network has grown exponentially over the years. A long-term evolution (LTE) system offers high peak data rates, low latency, improved system capacity, and low operating cost resulting from simplified network architecture. LTE systems, also known as the 4G system, also provide seamless integration to older wireless network, such as GSM, CDMA and universal mobile telecommunication system (UMTS). In LTE systems, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNodeBs or eNBs) communicating with a plurality of mobile stations, referred to as user equipments (UEs). The 3rdgeneration partner project (3GPP) network normally includes a hybrid of 2G/3G/4G systems. The next generation mobile network (NGMN) board, has decided to focus the future NGMN activities on defining the end-to-end requirements for 5G new radio (NR) systems.

In conventional technology, when the network node may indicate that the UE can enter a power saving mode by transmitting a DCI to the UE. However, if the data scheduled by the DCI is not decoded by the UE successfully, the UE may still enter the power saving mode based on the DCI directly.

A solution is sought

SUMMARY

A power saving method for monitoring data channel is proposed. The network node may indicate that the UE can enter a power saving mode by transmitting a DCI to the UE. The DCI may indicate a power saving duration and an additional monitoring duration. The power saving duration may indicate the length of the power saving mode and the starting point and the end point of the power saving mode. The additional monitoring duration may indicate that the UE needs to perform monitoring for a period of time before the power saving mode based on the first power saving duration indicated in the DCI.

In one embodiment, a UE receives a first downlink control information (DCI) from a network node, wherein the first DCI indicates a first power saving duration and a first additional monitoring duration. The UE determines whether data in the first DCI is decoded successfully by the UE. In an event that the data scheduled by the first DCI is not decoded successfully, the UE performs monitoring for a period of time based on the first additional monitoring duration before a power saving mode based on the first power saving duration.

DETAILED DESCRIPTION

FIG. 1is a simplified block diagram of a network node and a user equipment (UE) that carry out certain embodiments of the present invention. The network node101may be a base station (BS) or a gNB, but the present invention should not be limited thereto. The UE102may be a smart phone, a wearable device, an Internet of Things (IoT) device, and a tablet, etc. Alternatively, UE110may be a Notebook (NB) or Personal Computer (PC) inserted or installed with a data card which includes a modem and RF transceiver(s) to provide the functionality of wireless communication.

Network node101has an antenna array111having multiple antenna elements that transmits and receives radio signals, one or more RF transceiver modules112, coupled with the antenna array, receives RF signals from antenna111, converts them to baseband signal, and sends them to processor113. RF transceiver112also converts received baseband signals from processor113, converts them to RF signals, and sends out to antenna111. Processor113processes the received baseband signals and invokes different functional modules and circuits120to perform features in network node101. Memory114stores program instructions and data115to control the operations of network node101. Network node101also includes multiple function modules that carry out different tasks in accordance with embodiments of the current invention.

Similarly, UE102has an antenna131, which transmits and receives radio signals. A RF transceiver132, coupled with the antenna, receives RF signals from antenna131, converts them to baseband signals and sends them to processor133. RF transceiver132also converts received baseband signals from processor133, converts them to RF signals, and sends out to antenna131. Processor133processes the received baseband signals and invokes different functional modules and circuits140to perform features in UE102. Memory134stores program instructions and data135to control the operations of UE102. UE102also includes multiple function modules and circuits that carry out different tasks in accordance with embodiments of the current invention.

The functional modules and circuits120and140can be implemented and configured by hardware, firmware, software, and any combination thereof. The function modules and circuits120and140, when executed by the processors113and133(e.g., via executing program codes115and135), allow network node101and UE102to perform embodiments of the present invention.

In the example ofFIG. 1, the network node101may comprise an allocation circuit121and a downlink control information (DCI) delivery circuit122. Allocation circuit121may determine to transmit normal DCI to the UE102or transmit specific DCI to the UE102. DCI delivery circuit122may transmit the normal DCI or the specific DCI to the UE102. In accordance with one novel aspect, compared with normal DCI, the specific DCI is regarded as a DCI which indicates PDCCH monitoring adaptation and the DCI is associated with an additional monitoring duration.

Similarly, the UE102may comprise a determination circuit141, a monitoring circuit142and a mode selection circuit143. Determination circuit141may determine whether data in the DCI is decoded successfully. Monitoring circuit142may monitor the data channel, e.g. Physical Downlink Control Channel (PDCCH). Mode selection circuit143may determine to enter a power saving mode based on a DCI.

In accordance with one novel aspect, the network node101may indicate that the UE102can enter a power saving mode by transmitting a specific DCI to the UE102. In accordance with one novel aspect, the specific DCI may indicate a power saving duration and an additional monitoring duration. The power saving duration may indicate the length of the power saving mode and the starting point and the end point of the power saving mode. The starting point of the power saving mode is the slot the UE102receive the specific DCI. In embodiment, the power saving duration may be a continuous time duration. In another embodiment, the power saving duration may comprise several periodical time durations. The additional monitoring duration may indicate that the UE102needs to perform monitoring for a period of time before the power saving mode based on the power saving duration indicated in the specific DCI.

In accordance with one novel aspect, when the UE102receives the specific DCI from the network node101, the UE102may determine whether the specific DCI is decoded successfully, e.g. whether the Hybrid Automatic Repeat Request (HARQ) processing outcome is valid. In an embodiment, for downlink transmission, when the HARQ processing outcome is valid, the UE102may transmit a HARQ ACK to the network node101. That is to say, when the UE102transmits a HARQ ACK to the network node101, the UE102may determine the specific DCI is decoded successfully.

In an event that the data scheduled by the specific DCI is not decoded successfully (e.g. HARQ processing outcome is not valid), the UE102may need to perform monitoring the data channel (e.g. PDCCH) for a period of time based on the additional monitoring duration indicated in the specific DCI. During the additional monitoring duration, the UE102may determine whether a new indication (e.g. a new DCI) is scheduled by the network node101. If the UE102receives a new indication from the network node101during the additional monitoring duration, the UE102may perform following operations based on information of the new indication. If the UE102does not receive a new indication from the network node101during the additional monitoring duration, the UE102may enter the power saving mode based on the power saving duration indicated in the specific DCI. In accordance with another novel aspect, when the HARQ processing outcome is unknown or uncertain (e.g. for uplink transmission), the UE102may also need to perform monitoring the data channel (e.g. PDCCH) for a period of time based on the additional monitoring duration indicated in the specific DCI.

In accordance with one novel aspect, the additional monitoring duration may be counted by a timer. When the timer has been expired and the UE102does not receive a new indication from the network node101, the UE102may enter the power saving mode based on the power saving duration indicated in the specific DCI.

In an event that the data scheduled by the specific DCI is decoded successfully (e.g. HARQ processing outcome is valid), the UE102may enter the power saving mode based on the power saving duration indicated in the specific DCI.

FIG. 2Aillustrates an example of a power saving duration and an additional monitoring duration. As shown inFIG. 2A, if the data scheduled by the specific DCI (i.e. the DCI indicates PDCCH monitoring adaptation) is decoded successfully (e.g. HARQ processing outcome is valid), the UE102may enter the power saving mode based on the power saving duration indicated in the specific DCI. If the specific DCI is not decoded successfully (e.g. HARQ processing outcome is not valid), before the UE102enters the power saving mode based on the power saving duration indicated in the specific DCI, the UE102may need to perform monitoring the data channel (e.g. PDCCH) for a period of time based on the additional monitoring duration indicated in the specific DCI.FIG. 2Billustrates another example of a power saving duration and an additional monitoring duration. As shown inFIG. 2B, UE enters the power saving mode first. If the specific DCI is not decoded successfully (e.g. HARQ processing outcome is not valid), the UE102may need to perform monitoring the data channel (e.g. PDCCH) for a period of time based on the additional monitoring duration indicated in the specific DCI. Then, the UE102may enter the power saving mode based on the power saving duration indicated in the specific DCI.

In accordance with one novel aspect, the UE102may receive two specific DCIs (e.g. a first specific DCI and a second specific DCI) with different types respectively. In an example, the first specific DCI is for uplink transmission (e.g. a UL grant) and the second specific DCI is for downlink transmission (e.g. a DL grant). In another example, the first specific DCI is for downlink transmission (e.g. a DL grant) and the second specific DCI is for uplink transmission (e.g. a UL grant). The first specific DCI may indicate a first power saving duration and a first additional monitoring duration and the second specific DCI may indicate a second power saving duration and a second additional monitoring duration. The first additional monitoring duration and the second additional monitoring duration are configured based on the same configuration rules. For downlink transmission, the additional monitoring duration (e.g. the first additional monitoring duration and the second additional monitoring duration) may be configured to be the sum of drx-HARQ-RTT-TimerDL duration and drx-RetransmissionTimerDL duration. The UE102may be not required to perform monitoring during the portion of time corresponding to drx-HARQ-RTT-TimerDL duration. For uplink transmission, the additional monitoring duration (e.g. the first additional monitoring duration and the second additional monitoring duration) may be configured to be the sum of drx-HARQ-RTT-TimerUL duration and drx-RetransmissionTimerUL duration. The UE102may be not required to perform monitoring during the portion of time corresponding to drx-HARQ-RTT-TimerUL duration.

In accordance with an embodiment, when the UE102receives two specific DCIs (e.g. a first specific DCI and a second specific DCI) with different types respectively, the UE102may determine a duration of the power saving mode based on the overlapped time duration of the first power saving duration and the second power saving duration.FIG. 3illustrates an example of two specific DCIs with different types. The UE102receives a first specific DCI. The first specific DCI may indicate a first power saving duration from PSDstart, 1to PSDend, 1. Then, the UE102receives a second specific DCI before entering the power saving mode based on the first power saving duration. The second specific DCI may indicate a second power saving duration from PSDstart, 2to PSDend, 2. Therefore, the UE102may determine a duration of the power saving mode based on the overlapped time duration of the first power saving duration and the second power saving duration. That is to say, the duration of the power saving mode is from PSDstart, 2to PSDend, 1.

In accordance with another embodiment, when the UE102may receive two specific DCIs (e.g. a first specific DCI (i.e. an early specific DCI) and a second specific DCI (i.e. a late specific DCI)) with different types respectively, the UE102may determine a duration of the power saving mode based on the second power saving duration indicated by the latest specific DCI (i.e. second specific DCI).FIG. 4illustrates another example of two specific DCIs with different types. The UE102receives a first specific DCI (i.e. early specific DCI). The first specific DCI may indicate a first power saving duration from PSDstart, 1to PSDend, 1. Then, the UE102receives a second specific DCI (i.e. a late specific DCI) before entering the power saving mode based on the first power saving duration. The second specific DCI may indicate a second power saving duration from PSDstart, 2to PSDend, 2. Therefore, the UE102may determine a duration of the power saving mode based on the second power saving duration indicated by the latest specific DCI (i.e. second specific DCI). That is to say, the duration of the power saving mode is from PSDstart, 2to PSDend, 2.

In accordance with one novel aspect, the UE102may stay in the power saving mode until receiving an indication for leaving the power saving mode from the network node101or the UE may leave the power saving mode after the end of the power saving duration indicated by the specific DCI. In accordance with one novel aspect, if the connected Discontinuous Reception (c-DRX) is configured by the network node101, the UE102can be configured to return data channel monitoring mode at every long cycle start.

In accordance with one novel aspect, the UE102may maintain the power saving mode for a period of time based on an additional power-saving duration before leaving the power saving mode. In accordance with one novel aspect, the additional power-saving duration may be longer than the additional monitoring duration. In an embodiment, the additional power-saving duration is obtained based on the additional monitoring duration. For example, the length of the additional power-saving duration may be the length of the additional monitoring duration plus a time unit, wherein the time unit may be symbol, slot, and so on. In another embodiment, the additional power-saving duration is indicated in a DCI.FIG. 5illustrates an example of an additional monitoring duration and an additional power-saving duration. The network node101may transmit a specific DCI for entering power saving mode to the UE102and transmit a specific DCI for leaving power saving mode to the UE102. The length of the additional power-saving duration indicated in the specific DCI for leaving power saving mode may be longer than the additional monitoring duration indicated in the specific DCI for entering power saving mode.

FIG. 6is a flow chart of a power saving method for monitoring data channel in accordance with one novel aspect. In step601, the UE102receives a first downlink control information (DCI) from the network node101, wherein the first DCI indicates a first power saving duration and a first additional monitoring duration. In step602, the UE102determines whether data in the first DCI is decoded successfully.

In step603, if the data scheduled by the first DCI is not determined to be decoded successfully, the UE102performs monitoring for a period of time based on the first additional monitoring duration before a power saving mode based on the first power saving duration. In step604, if the data scheduled by the first DCI is decoded successfully, the UE102enters the power saving mode based on the first power saving duration.

In accordance with one novel aspect, in the power saving method, the UE102may receive a second DCI from the network node101before entering the power saving mode based on the first power saving duration, wherein the second DCI indicates a second power saving duration and a second additional monitoring duration.