TECHNICAL FIELD

Various examples of the invention relate to coverage enhancement using multiple repetitions of messages communicated on a wireless link. Various examples of the invention further relate to cell re-selection.

BACKGROUND

Mobile communication by means of cellular networks is an integral part of modern life. Examples of cellular networks include the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE; sometimes also referred to as 4G) and 3GPP New Radio (NR; sometimes also referred to as 5G) technology. Here, multiple nodes are connected to form the network. The network may include a plurality of cells. Each cell may be associated with one or more base stations (BSs). Communication devices (UEs) may connect to the network through different cells. UE mobility is supported.

A set of features where a comparably large coverage is achieved is referred to as Coverage Enhancement (CE). CE is envisioned to be applied for Machine Type Communication (MTC) and the Narrowband IoT (NB-IOT), sometimes also referred to as NB-LTE. For example, such techniques may be based on the 3GPP LTE technology to some extent and may reuse some of the LTE concepts.

A key feature of the CE is to implement multiple transmission repetitions of messages; thereby multiple repetitions of encoded data are facilitated. Here, each repetition may include the same redundancy version of the message. The repetitions may be “blind”, i.e., may not in response to a respective retransmission request that may be defined with respect to a Hybrid Acknowledgment Repeat Request protocol (HARQ protocol). Rather, repetitions according to CE may be preemptive. Examples are provided by the 3GPP Technical Report (TR) 45.820 version 13.0.0 (2015-08), section 6.2.1.3. By employing an appropriate CE policy, a likelihood of successful transmission can be increased even in scenarios of poor conditions of communicating on a corresponding wireless link. Robustness against channel fading is increased. Thereby, the coverage of networks can be significantly enhanced—even for low transmission powers as envisioned for the MTC and MB-IOT domain.

However, CE may face certain restrictions and drawbacks. For example, due to the multiple transmission repetitions, increased system load can result. In particular, due to the multiple transmission repetitions, an increased amount of resources in time and frequency domain (time-frequency resources) is required to transmit a message. Typically, the amount of time-frequency resources required scales linearly with the repetition level of the employed CE policy. Thus, larger/smaller repetition levels result in larger/smaller system load.

Furthermore, the latency of communicating messages may increase. In particular, the time duration required to successfully deliver the message may also scale linearly with the repetition level of the CE policy.

Such restrictions and drawbacks may have significant impacts on the reliability of communication, in particular in mobility scenarios where the UE moves from cell to cell of the network. This applies, in particular, to CE-associated access barring, see, e.g., 3GPP RP-170732, “Even further enhanced MTC for LTE”, 3GPP TSG RAN Meeting #75, Dubrovnik, Croatia, Mar. 6-9, 2017 where the UE is to refrain from connection attempts to a cell which implements such access restrictions. US 2010 0159928 A1 discloses techniques associated with access restrictions.

SUMMARY

Therefore, a need exists for advanced techniques of restricting access to cells. In particular, a need exists for techniques which mitigate or overcome at least some of the above-identified restrictions and drawbacks.

This need is met by the features of the independent claims. The features of the dependent claims define embodiments.

A method of operating a communication device includes receiving at least one downlink control message from a base station of a source cell of a network. The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network. The method further includes selecting a target cell from the plurality of candidate cells based on the at least one downlink control message. The method further includes communicating between the communication device and a base station of the target cell.

A computer program product includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method of operating a communication device. The method includes receiving at least one downlink control message from a base station of a source cell of a network. The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network. The method further includes selecting a target cell from the plurality of candidate cells based on the at least one downlink control message. The method further includes communicating between the communication device and a base station of the target cell.

A computer program includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method of operating a communication device. The method includes receiving at least one downlink control message from a base station of a source cell of a network. The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network. The method further includes selecting a target cell from the plurality of candidate cells based on the at least one downlink control message. The method further includes communicating between the communication device and a base station of the target cell.

A communication device includes control circuitry. The control circuitry is configured to perform: receiving at least one downlink control message from a base station of a source cell of a network. The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network. The method further includes selecting a target cell from the plurality of candidate cells based on the at least one downlink control message. The method further includes communicating between the communication device and a base station of the target cell.

A method includes transmitting at least one downlink control message from a base station of a source cell of a network to a communication device. The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network.

A computer program product includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method. The method includes transmitting at least one downlink control message from a base station of a source cell of a network to a communication device.

The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network.

A computer program includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method. The method includes transmitting at least one downlink control message from a base station of a source cell of a network to a communication device. The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network.

A base station includes control circuitry configured to perform: transmitting at least one downlink control message from a base station of a source cell of a network to a communication device. The at least one downlink control message is indicative of access restrictions of a plurality of candidate cells of the network.

A method of operating a communication device includes receiving at least one downlink control message from a base station of a source cell of a network, the at least one downlink control message being indicative of access restrictions of a plurality of candidate cells of the network. The method further includes selecting a target cell from the plurality of candidate cells based on the at least one downlink control message.

The method further includes camping on the target cell.

A computer program product includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method of operating a communication device. The method includes receiving at least one downlink control message from a base station of a source cell of a network, the at least one downlink control message being indicative of access restrictions of a plurality of candidate cells of the network. The method further includes selecting a target cell from the plurality of candidate cells based on the at least one downlink control message. The method further includes camping on the target cell.

A computer program includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method of operating a communication device. The method includes receiving at least one downlink control message from a base station of a source cell of a network, the at least one downlink control message being indicative of access restrictions of a plurality of candidate cells of the network. The method further includes selecting a target cell from the plurality of candidate cells based on the at least one downlink control message. The method further includes camping on the target cell.

A method of operating a communication device includes, in connected mode, receiving at least one downlink control message from a base station of a source cell of a network. The the at least one downlink control is indicative of access restrictions of at least one candidate cell of the network which is different from the source cell.

A computer program product includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method of operating a communication device. The method includes, in connected mode, receiving at least one downlink control message from a base station of a source cell of a network. The at least one downlink control is indicative of access restrictions of at least one candidate cell of the network which is different from the source cell.

A computer program includes program code that may be executed by at least one processor. Executing the program code may cause the at least one processor to perform a method of operating a communication device. The method includes, in connected mode, receiving at least one downlink control message from a base station of a source cell of a network. The the at least one downlink control is indicative of access restrictions of at least one candidate cell of the network which is different from the source cell.

It is to be understood that the features mentioned above and those yet to be explained below may be used not only in the respective combinations indicated, but also in other combinations or in isolation without departing from the scope of the invention. For illustration, it would be possible that techniques of signalling access restrictions of one or more cells in connected mode—e.g., using RRC control signalling—are combined with techniques of regulated repetition levels for CE.

