Tunnels are established between nodes along a packet transfer route in a communication network so that a packet is transferred from a first relay node to a second relay node via one or more intermediate relay nodes using the established tunnels. An intermediate relay node receives, from an adjacent downstream relay node, a reply message storing relay-node addresses identifying the downstream relay node and at least one intermediate relay node between the downstream relay node and the first relay node. The intermediate relay node establishes a tunnel to the downstream relay node in association with the relay-node address of the downstream relay node, updates the reply message by removing the relay-node address of the down stream relay node from the reply message, and transfers the updated reply message to an adjacent upstream relay node along the packet transfer route.

Tunnels are established between nodes along a packet transfer route in a communication network so that a packet is transferred from a first relay node to a second relay node via one or more intermediate relay nodes using the established tunnels. An intermediate relay node receives, from an adjacent downstream relay node, a reply message storing relay-node addresses identifying the downstream relay node and at least one intermediate relay node between the downstream relay node and the first relay node. The intermediate relay node establishes a tunnel to the downstream relay node in association with the relay-node address of the downstream relay node, updates the reply message by removing the relay-node address of the down stream relay node from the reply message, and transfers the updated reply message to an adjacent upstream relay node along the packet transfer route.

A repeater receives a first group message directed to a talk group. The repeater assigns a first unique message identifier including a generated first sequence number to the first group message. The repeater broadcasts the first group message with the first unique message identifier and the unique talk group address to the talk group. The repeater later receives a second group message directed to the talk group, generates a second sequence number from the generated first sequence number, assigns a second unique message identifier including the second sequence number to the second group message and broadcasts the second group message to the talk group. The first sequence number and the second sequence number may be used by a receiving radio of the talk group to determine if the radio failed to receive one or more group messages or if a received group messages is a duplicate message.

A repeater receives a first group message directed to a talk group. The repeater assigns a first unique message identifier including a generated first sequence number to the first group message. The repeater broadcasts the first group message with the first unique message identifier and the unique talk group address to the talk group. The repeater later receives a second group message directed to the talk group, generates a second sequence number from the generated first sequence number, assigns a second unique message identifier including the second sequence number to the second group message and broadcasts the second group message to the talk group. The first sequence number and the second sequence number may be used by a receiving radio of the talk group to determine if the radio failed to receive one or more group messages or if a received group messages is a duplicate message.

A communication network includes relaying apparatuses, each including redundant-route ports providing communication routes between the relaying apparatuses. The relaying apparatus determines whether a first frame received via a usual port is highly important. The first frame being highly important is transmitted via the respective redundant-route ports; the first frame being not highly important is transmitted via one redundant-route port. The relaying apparatus receives a second frame being highly important via the respective redundant-route ports; the second frame has a transmission destination corresponding to an apparatus connected with the relaying apparatus via the usual port. The relaying apparatus makes determination whether or not all the second frames received via the respective redundant-route ports accord with each other. With affirmative determination, one of the second frames is transferred to the transmission destination. With negative determination, all the second frames are cancelled.

A communication network includes relaying apparatuses, each including redundant-route ports providing communication routes between the relaying apparatuses. The relaying apparatus determines whether a first frame received via a usual port is highly important. The first frame being highly important is transmitted via the respective redundant-route ports; the first frame being not highly important is transmitted via one redundant-route port. The relaying apparatus receives a second frame being highly important via the respective redundant-route ports; the second frame has a transmission destination corresponding to an apparatus connected with the relaying apparatus via the usual port. The relaying apparatus makes determination whether or not all the second frames received via the respective redundant-route ports accord with each other. With affirmative determination, one of the second frames is transferred to the transmission destination. With negative determination, all the second frames are cancelled.

When a first condition is satisfied, a controlling unit selects a first mode in which communication between a C-BBU and a mobile communication terminal is intermediated. When a second condition is satisfied, the controlling unit selects a second mode in which communication between another wireless communication apparatus and the mobile communication terminal is intermediated. In the first mode, an RRH unit receives a wireless signal from the mobile communication terminal, converts the wireless signal into a baseband signal, and transmits the baseband signal to the C-BBU, and receives a baseband signal from the C-BBU, converts the baseband signal into a wireless signal, and transmits the wireless signal to the mobile communication terminal. In the second mode, a repeater unit transfers a signal output from said another wireless communication apparatus to the mobile communication terminal, and transfers a signal output from the mobile communication terminal to said another wireless communication apparatus.

When a first condition is satisfied, a controlling unit selects a first mode in which communication between a C-BBU and a mobile communication terminal is intermediated. When a second condition is satisfied, the controlling unit selects a second mode in which communication between another wireless communication apparatus and the mobile communication terminal is intermediated. In the first mode, an RRH unit receives a wireless signal from the mobile communication terminal, converts the wireless signal into a baseband signal, and transmits the baseband signal to the C-BBU, and receives a baseband signal from the C-BBU, converts the baseband signal into a wireless signal, and transmits the wireless signal to the mobile communication terminal. In the second mode, a repeater unit transfers a signal output from said another wireless communication apparatus to the mobile communication terminal, and transfers a signal output from the mobile communication terminal to said another wireless communication apparatus.

A vehicle communication system for use in a vehicle having a vehicle bus. The vehicle communication system includes a display unit, a processing unit, and a relay device. The display unit provides a display screen and a receiver for receiving messages from the processing unit to be displayed on the display screen. Further, the processing unit, having means for voice recognition and dictation, includes a transmitter for sending messages to the receiver and a plurality of controls for selecting and inputting the desired message. The relay device is in electrical communication with the vehicle bus for receiving information as to the brakes, turn signals, and transmission of the vehicle, wherein the relay device powers the display unit when the transmission of the vehicle is started and displays a predetermined message on the display screen when the brakes and turn signals are engaged. The processing unit can further be operated via a remote device.

A repeater receiving an original frame from a connected Electronic Control Unit (ECU) by a normal port divides data stored in a data area of the received frame, and each of a plurality of divided data pieces is stored in the data area in each of a plurality of division frames to be sent out to a destination. Each of the plurality of division frames of the original frame is distributed to one of two ring ports according to a determination of the repeater, and each of the division frames is sent out therefrom to the destination. In such manner, the frame transmission time required for a transmission of the frame is reduced.