Motorola Solutions, Inc.

Yu-Yang Zheng

Quan-Wen Du

Yueh Ching Chung

Yong Huang

In a direct mode two-way radio frequency communications system having a plurality of direct mode traffic channels, a first direct mode subscriber unit (DMSU) monitors a preconfigured direct mode control channel (DMCC), the DMCC being a channel that is monitored by all DMSUs that are idle in the system, and which is time divided into slots including traffic channel status slots (TCSSs), each TCSS associated with another physical direct mode traffic channel (DMTC) in the communication system. Responsive to detecting a request to initiate a new call, the DMSU selects a first DMTC on which to transmit the call, transmits during the next TCSS of the DMCC associated with the selected DMTC a header indicating the first DMSU's intention to transmit a new call on the selected DMTC, and subsequently switches to the selected DMTC and transmits the new call.

Method and device for reusing channel frequencies in direct mode

A radio receives a call including a call include bitmask (CIB). The radio retrieves a call include list (CIL) that, for each bit position in the CIB, maps the bit position to one of a radio identifier, a talk group identifier, and a sub-CIL. The radio determines that one bit position in the CIB is set to a value indicating that a radio associated with a radio identifier mapped to the bit position in the CIB via the CIL or to a talk group identifier mapped to the bit position in the CIB via the CIL are to be included in the call. The radio matches its identifier to the radio identifier mapped to the bit position or matches a talk group to which it subscribes to the talk group identifier mapped to the at least one bit position and unmutes the call.

Growing community of inventors

Sichuan, China

Yu-Yang Zheng