Communication apparatus and method for mobile terminal communication through a sensor network

A communication method for a gateway in a sensor network, the method comprising:

• receiving an upstream packet of a mobile terminal through an upstream agent, and the upstream agent is selected via an agent request message, wherein:
• the agent request message is continuously broadcast, and specifies request information at predetermined time intervals during a first period,
• an agent reply message is transmitted containing a reply value corresponding to the request information from at least one of a plurality of sensor nodes that has received the agent request message;
• and
• the upstream agent selected is a sensor node that has transmitted a best value among the reply values of the agent reply messages received during the first period,
• the agent request message includes a first field specifying the request information and a second field specifying a current best value among the reply values of the agent reply messages received during the first period, and
• the broadcasting comprises specifying the best value among the reply values of the agent reply messages in the second field of the agent request message to be broadcast in a second period immediately after the first period, and broadcasting the agent request message;
• registering the upstream agent, a downstream agent, and the address of the mobile terminal corresponding to the sequence number of the upstream packet in a management table;
• receiving a downstream packet responsive to the upstream packet from an upper server;
• and
• transmitting the downstream packet to the mobile terminal through a downstream agent corresponding to the sequence number of the upstream packet.

A communication apparatus for a mobile terminal in a sensor network, the apparatus comprising:

• a transmitter that continuously broadcasts an agent request message specifying request information to a plurality of sensor nodes of the sensor network at predetermined time intervals;
• a receiver that receives an agent reply message responsive to the agent request message from at least one of the sensor nodes that has received the agent request message during respective time periods;
• and
• an agent selector that selects an upstream agent and a downstream agent based on a reply value corresponding to the request information contained in the agent reply message during a predetermined period, and the upstream agent is selected via the agent request message, wherein:
• the agent request message is continuously broadcast, and specifies the request information at the predetermined time intervals during a first period,
• an agent reply message is transmitted containing the reply value corresponding to the request information from the at least one of the plurality of sensor nodes that has received the agent request message;
• and
• the upstream agent selected is a sensor node that has transmitted a best value among the reply values of the agent reply messages received during the first period,
• the agent request message includes the first field specifying the request information and a second field specifying a current best value among the reply values of the agent reply messages received during the first period, and
• the broadcasting comprises specifying the best value among the reply values of the agent reply messages in the second field of the agent request message to be broadcast in a second period immediately after the first period, and broadcasting the agent request message.

A communication apparatus for a gateway in a sensor network, the apparatus comprising:

• a management table;
• a receiver that receives an upstream packet of a mobile terminal from an upstream agent selected by the mobile terminal, and the upstream agent is selected via an agent request message, wherein:
• the agent request message is continuously broadcast, and specifies request information at the predetermined time intervals during a first period,
• an agent reply message is transmitted containing the reply value corresponding to the request information from at least one of a plurality of sensor nodes that has received the agent request message;
• and
• the upstream agent selected is a sensor node that has transmitted a best value among the reply values of the agent reply messages received during the first period,
• the agent request message includes the first field specifying the request information and a second field specifying a current best value among the reply values of the agent reply messages received during the first period, and
• the broadcasting comprises specifying the best value among the reply values of the agent reply messages in the second field of the agent request message to be broadcast in a second period immediately after the first period, and broadcasting the agent request message;
• an agent selector that selects a downstream agent using a list of neighboring sensor nodes delivered as a piggyback on the upstream packet of the mobile terminal and state information of the neighboring sensor nodes in the list;
• an information manager that registers the upstream agent, the downstream agent, and the address of the mobile terminal corresponding to the sequence number of the upstream packet in the management table;
• and
• a transmitter that transmits a downstream packet responsive to the upstream packet to the mobile terminal through the downstream agent.