TECHNICAL FIELD

The present disclosure relates generally to narrowband communications in an Internet of Things network.

BACKGROUND

To support machine type communication, which is the radio infrastructure, to realize the Internet of Things, two work items named Release 13 Long Term Evolution (LTE) Machine-type communication (MTC) and Narrowband Internet of Things (NB-IoT) have been introduced within 3rd Generation Partnership Project (3GPP). For both Release 13 LTE MTC and NB-IoT, the main solution to reach user equipment (UE) that is in a bad or extreme coverage area is to repeat transmissions over data and control channels.

SUMMARY

Repeat transmissions to reach UEs in bad or extreme coverage could take up to hundreds or even thousands of milliseconds. In the case of Release 13 LTE MTC, the available bandwidth is 6 physical resource blocks (PRB) and for the extreme coverage case, the whole bandwidth is assigned to one UE and one channel, which, might cause delay in transmission of other UEs. However, the enhanced Node B (eNB) can schedule up to 16 different MTC carriers at the same time within the whole bandwidth of the system, in this case 20 MHz, as described in RAN1 Chairman's Notes, 3GPP TSG RAN WG1 Metting #84, St. Julian's, Malta, Feb. 15-19, 2016.

Compared to this, NB-IoT can only have 180 kHz bandwidth within one carrier, which equals to 1 PRB in LTE terms, it may not be possible to schedule extra carriers especially in the case where the deployment of NB-IoT is in the LTE guard-band or stand-alone case. Based on this fact, it is agreed that for NB-IoT downlink, control and data channels, e.g., Narrowband physical downlink control channel (NB-PDCCH) and Narrowband physical downlink shared channel (NB-PDSCH), are only multiplexed in time division multiplexing (TDM) fashion as described in R1-161546, “RAN1 Agreements for Rel-13 eMTC Sorted and Edited by Topic,” RAN1 #84, February 2016.

Further, if a UE is in bad coverage, then it could delay transmissions to other UEs in good coverage. For example, to reach the UE in bad coverage, it could take hundreds or thousands of repeated transmissions of one message (whether through the control channel or the shared channel) before the UE receives the message and acknowledges it. During the time these repeated transmissions are being made, messages intended for UEs in good coverage and messages communicated by UEs in good coverage may be blocked and/or delayed. As an example, a UE in good coverage may need to wait hundreds of milliseconds to be able to transmit its data or signaling when repeated transmissions are being made to a UE in bad coverage on the same network. Therefore, there exists a problem with scheduling transmissions to different UEs with different coverage levels (e.g., a different number of repeated transmissions needed to reach the UEs) for NB-IoT in terms of delays in the transmission.

This disclosure contemplates a network node and/or UE that includes various components and/or that perform certain processes to address some or all of the issues described above. The network node may divide a transmission time of a narrowband physical downlink control channel (NB-PDCCH) or a narrowband physical downlink shared channel (NB-PDSCH) into a repetition period and a non-blocking period. The repetition period may be used for transmission to a UE in bad or low coverage, while the non-blocking period may be used for transmission to a UE in better coverage. For example, the repetition period may be used to transmit messages to a UE that needs hundreds or thousands of repetitions in order to be reached while the non-blocking period may be used to transmit messages to a UE that does not need as many repetitions (if any at all) in order to be reached. By separating transmission periods to UEs in low or bad coverage from transmission periods to UEs in better coverage, it is possible to reduce delays and/or avoid blocking of transmissions to UEs in better coverage caused by repeated transmissions to UEs in low or bad coverage. In this manner, the system may avoid stalling or delaying transmissions to UEs in better coverage.

According to one embodiment, a method in a network node includes communicating, over a narrowband Internet of Things downlink, a first message to a first wireless device during repetition periods of at least a first time frame and a second time frame of a plurality of time frames of a transmission time of a narrowband physical downlink control channel (NB-PDCCH) or a narrowband physical downlink shared channel (NB-PDSCH). Each timeframe of the plurality of time frames includes a repetition period and a gap. The method also includes communicating a second message to a second wireless device during a gap of the first time frame. By performing this method, delays in communicating the second message and/or blocking of the second message caused by repeated transmissions of the first message may be avoided and/or reduced.

According to another embodiment, a network node includes a memory and processing circuitry. The processing circuitry communicates a first message to a first wireless device during repetition periods of at least a first time frame and a second time frame of a plurality of time frames of a transmission time of a narrowband physical downlink control channel (NB-PDCCH) or a narrowband physical downlink shared channel (NB-PDSCH). Each time frame of the plurality of time frames includes a repetition period and a gap. The processing circuitry is also configured to communicate a second message to a second wireless device during a gap of the first time frame. In this manner, the network node reduces delays in communicating the second message and/or avoids blocking the second message caused by repeated transmissions of the first message.

According to yet another embodiment, a wireless device includes a memory and processing circuitry. The processing circuitry is configured to receive a configuration indicating a subframe in which a communication over a narrowband physical downlink control channel (NB-PDCCH) is scheduled to be communicated. The processing circuitry is further configured to receive the communication over the NB-PDCCH in the subframe indicated by the configuration and to decode the communication. In this manner, the wireless device may avoid blocking or delaying of messages intended for the wireless device and/or of transmissions made by the wireless device.

According to another embodiment, a method in a wireless device includes receiving, over a narrowband Internet of Things downlink, a configuration indicating a subframe in which a communication over a narrowband physical downlink control channel (NB-PDCCH) is scheduled to be communicated. The method also includes receiving the communication over the NB-PDCCH in the subframe indicated by the configuration and decoding the communication. By performing this method, the wireless device may avoid blocking or delaying of messages intended for the wireless device and/or of transmissions made by the wireless device.

Certain embodiments may provide one or more technical advantages. For example, one embodiment avoids blocking of UEs with no or few repetitions in downlink transmission of NB-IoT while there are a large number of repetitions of the data and control channels caused by UEs in bad or extreme coverage. Another embodiment avoids blocking of control signals by aligning scheduled transmission times in a grid with the possible starting subframe structure for NB-PDCCH search space design. Yet another technical advantage of an embodiment maintains usage efficiency of downlink resources. Certain embodiments may include none, some, or all of the above technical advantages. One or more other technical advantages may be readily apparent to one skilled in the art from the figures, descriptions, and claims included herein.

