公开(公告)号：US09961179B2

公开(公告)日：2018-05-01

申请号：US15320330

申请日：2014-07-28

Applicant: MOTOROLA SOLUTIONS, INC

Inventor： Dong Zhao ,  Yi Tang ,  Fan Yang

IPC: H04M1/725 ,  H04W4/90 ,  H04W8/14 ,  H04W4/02 ,  H04L12/26 ,  H04W4/22 ,  H04W84/18

CPC classification number: H04W76/25 ,  H04L43/10 ,  H04M1/72516 ,  H04W4/025 ,  H04W4/90 ,  H04W8/14 ,  H04W8/26 ,  H04W76/23 ,  H04W84/18

Abstract: At least one embodiment takes the form of a process carried out by a given mobile radio in a group of mobile radios. The process includes broadcasting heartbeat messages in accordance with a group-wide symmetric-timing protocol and maintaining an in-range list of mobile radios. The in-range list is maintained at least in part by (i) adding mobile radios that are not already on the in-range list to the in-range list upon detecting transmissions from such mobile radios; (ii) maintaining, for each mobile radio on the in-range list, a respective keepalive timer in accordance with the group-wide symmetric-timing protocol; and (iii) removing mobile radios from the in-range list upon expiration of the respective keepalive timers. The process further includes presenting an alert via a user interface when a count of mobile radios on the in-range list falls below a notification threshold.