Paging is a technique which is widely used in most wireless telecommunications and, generally speaking, paging and notification is the first step being involved in a mobile-terminated voice call setup between a Node B and a User Equipment (UE) in the context of a third generation (3G) of cellular communication standard, as defined by the 3GPP (3rd Generation Partnership Project).
Taking the 3GPP standard as an example, there are two types of paging—PagingType1 and PagingType2—which are used in different situations. The first type is used when the UE is in a idle mode—for saving battery life—to establish an Radio Resource Control RRC (ie layer 2 of the OSI model) connection to deliver a call.
In an Idle mode, the UE regularly monitors—in the so-called Discontinous Reception DRX cycle—whether it is receiving a call. Each time the UE is active in the DRX cycle, a Paging Information Channel (PICH) is monitored. In case the information received on the PICH is positive, i.e., indicates an incoming call for the UE, this is followed by a monitoring of a Secondary Common Control Physical Channel (SCCPCH) carrying a Paging Channel PCH. This paging procedure is used to signal to UE that there is an incoming call. A multipath detection may need to be performed each time the user equipment becomes active in the DRX cycle.
The paging procedure allows signaling from a network to a UE or to a plurality of UEs. More particularly, the PICH channel allows the notification of a short paging indicator (PI) to a UE and the latter, once notified, has to decode the corresponding Paging Channel (PCH) corresponding to the PI previously received.
The following patents are examples of processes in the art.
US2009129343 describes an incoming data detection method for handling unsuccessful reception of PCH messages. In this case it is proposed that the mobile terminal will have to make a cell re-selection decision itself if the PICH indicates a system information and the terminal fails to receive the PCH, ie CRC-NG.
U.S. Pat. No. 5,930,706 method and apparatus for detecting data contained in transmitted messages (e.g. page messages) at a selected early point in the receiving and decoding process. By forming, at that point, a received data vector (RDV) from the data corresponding to a received message, and by comparing the RDV with one or more test data vectors (TDVs) representing selected relevant or irrelevant data contained in transmitted message, the receiver can determine whether the received message contains relevant data which should be fully decoded or irrelevant data which does not need to be decoded.
Clearly, the decoding of the PI signal is particularly critical for the reasons below:
Firstly, the PI is the first signal generated by the Node B in relation to a mobile-terminated call setup with a UE and its decoding within the PICH channel has to be achieved by the UE with minimum knowledge of the channel and also without taking advantage of the error correction mechanism existing in the channel decoder.
Secondly, the need to minimize battery consumption prevents the possibility of providing the UE with a significant duration for activating its RF circuits for the purpose of sensing the PI signal and thus detecting the latter in the best conditions
Thirdly, the PI is transmitted by the base station with a predefined transmission power which is accurately set by the operators so as to achieve a limited amount of interference possibly affecting neighboring cells.
When a UE is not capable of decoding the Paging Indicator, the base station might have to regenerate it to get the appropriate response from the UE.
Generally speaking, the network operators typically set the power level of the transmission of the PCH channel so as to lead to a failure rate in between 0 and 30% in accordance with the radio conditions.
It results from the observations above that the PI detection is a highly critical operation which affects not only power consumption of the UE (RF circuits using a significant amount of current) but also the efficiency of the RF receiver, as perceived by the operators and the customers. The paging signal typically lasts only a few micro seconds and if the UE does not detect such signal, the base station would then need to retransmit the same paging signal.
Therefore, there is a desire for enhanced processes and receivers which improve the handling of the PI received from the base station.