For the purposes of the present document, the terms and definitions given in TR 21.905 apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.

For the purposes of the present document, the abbreviations given in TR 21.905 apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.

The study is targeting MTC devices and services that are expected to be widely used in GSM networks, and which could benefit from power saving studies. Smart gas meter is one important example for this kind of MTC device. To facilitate the study and to make the candidate GERAN enhancements general enough and future proof, general use cases are summarized.

For this use case, the MTC device is triggered to send a report to the network entity, e.g. metering devices (sensors) that are monitored and controlled by entities outside or inside the operator's network wherein a device normally only sends a report when triggered to do so by the network. Such use case requires MTC device that can be reached (triggered) as a result of network paging. After sending a report a device will remain reachable at least during a time interval determined by the Ready timer (i.e. during the first part of this interval when non-DRX timer is running it continuously monitors AGCH/PCH blocks. After the non-DRX timer expires it then monitors its nominal paging block according to legacy DRX operation for the remainder of this interval). After expiration of the Ready timer, reachability will be supported based on monitoring the nominal PCH block within the context of a power savings state. MTC devices that support this use case will make use of a power saving mechanism that introduces limitations on device reachability (e.g. either eDRX or PSM). In addition, these devices will go into a power saving state between each triggered report where the longer the device remains in the power saving state the larger the power savings.

For this use case, the MTC device will autonomously detect the need to send a report, e.g. in a periodic manner or the report is sent in specified time period. The network may want to dynamically adjust the periodicity based on the actual network traffic load at a specific time. Reachability will be possible using either paging or reporting events as opportunities to send messages to these types of devices (determined based on use case attribute settings). After sending a report a device will remain reachable at least during a time interval determined by the Ready timer (i.e. during the first part of this interval it continuously monitors AGCH/PCH blocks according to the Non-DRX timer and it then monitors its nominal paging block according to legacy DRX operation for the remainder of this interval). After expiration of the Ready timer, reachability will not be possible until the next reporting event. The class of devices operate according to this use case would benefit from being able to go into a power saving state between each report transmission - the longer time between the mobile originated reports the larger the power savings. For both use cases the reachability of devices will therefore be possible during actual reporting events (i.e. while transmitting a report) and while the Ready timer is running. The option of using an Active timer (started immediately following expiration of the Ready timer) for a period of additional reachability is not seen to be needed.