Hyper system frame number determination

A communication method that avoids SFN hopping, the method comprising:

• receiving, by a core network device, a second hyper system frame number (HSFN) and a time at which the second HSFN is enabled that are sent by an access network device, where the second HSFN is determined at a time when the access network device enables enhanced discontinuous reception (eDRX);
• and
• determining, by the core network device based on the second HSFN and a third HSFN, a time at which a paging message is sent to the access network device, where the third HSFN is determined based on the time at which the access network device enables the eDRX and a preconfigured time, wherein the determining, by the core network device based on the second HSFN and a third HSFN, of the time at which the paging message is sent to the access network device comprises
• determining a difference between the third HSFN and the second HSFN;
• determining the time at which the paging message is sent as a first time if the difference between the third HSFN and the second HSFN is 0, wherein the first time is a time at which the paging message is sent, and the time at which the paging message is sent is determined by the core network device based on the third HSFN;
• or
• if the difference between the third HSFN and the second HSFN is p, and p is a positive integer greater than 0, advancing, by the core network device, the first time at which the paging message is sent by p hyper frames;
• or
• if the difference between the third HSFN and the second HSFN is q, and q is an integer less than 0, delaying, by the core network device, the first time at which the paging message is sent by |q| hyper frames, wherein |q| is an absolute value of q and wherein a second SFN is continuously used, and SFN hopping is not required.

An access network device that avoids SFN hopping, the method comprising:

• a first determining unit, configured to determine a first hyper system frame number (HSFN) and a first system frame number (SFN), wherein the first HSFN and the first SFN are determined by the access network device based on a time at which enhanced discontinuous reception (eDRX) is enabled and a preconfigured time at which the HSFN counts from 0, wherein the HSFN is computed by the access network device and a core network device independently;
• and
• a second determining unit, configured to determine an HSFN adjustment value based on the first SFN and a second SFN, wherein the second SFN is an SFN used at the time at which the access network device enables the eDRX by
• determining the HSFN adjustment value as 0 if determining that an absolute value of a difference between the first SFN and the second SFN is less than or equal to a preset threshold;
• determining the HSFN adjustment value as m if determining that the difference between the first SFN and the second SFN is greater than the preset threshold, wherein m is an integer greater than 0;
• or
• determining the HSFN adjustment value as n if determining that the difference between the second SFN and the first SFN is greater than the preset threshold, wherein n is an integer less than 0;
• and adjust the first HSFN to obtain a second HSFN based on the HSFN adjustment value, the adjusting performed by determining a sum of the HSFN adjustment value and the first HSFN as the second HSFN, and update the second HSFN based on the second SFN, wherein when the second SFN is 1023, 1 is added to the second HSFN, and when the value of the second HSFN reaches 1023, the second HSFN starts from 0 again, and wherein the second SFN is continuously used, and SFN hopping is not required.