In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.
For example, one parameter in providing good performance and capacity for a given communications protocol in a communications network is the availability of accurate system time information.
For example, accurate system time information may be required in radio-based communications networks in order to facilitate good sleep opportunities for both wireless devices and network nodes, saving significant power on both sides, without introducing any ambiguities in the communication links between the wireless devices and the network nodes. In general terms, time information is to the wireless device provided by the network node in the serving cell of the wireless device. By maintain per cell time information the need to synchronize cells is removed, simplifying deployment of radio-based communications networks.
Time information is provided in system broadcasts and the frequency and granularity of the information is a trade-off between sleep efficiency of the wireless devices, the maximum sleep time of the wireless devices, and system overhead. For example, in telecommunications networks based on the long term evolution (LTE) standards the system frame number is provided in the master information block (MIB) which is transmitted once every 10 ms. The time granularity is 10.24 seconds, or 1024 frames, limited by the number of bits used in the MIB to signal the frame number.
It has been considered to extend the time information in communications networks to enable longer sleep-times for the wireless device, for example by reserving additional bits for signaling or to introduce new messages for providing a secondary timing, differentiating between cycles of the existing timing.
However, in some communications networks, such as in some multi-layer multi technology environments, the ability of network energy saving by network node dormancy and overhead saving is reduced by the need to provide frequent time-information to enable efficient sleep of the wireless devices. The network node still frequently needs to provide time information in order for the wireless device to quickly (re-)acquire timing information.
Hence, there is still a need for an improved provision of time information to a wireless device.