	US 7,499,440 B2
	Communication system, network router and network connection method
Kazuya Nakajima, Isesaki (Japan); Masaki Yoshizawa, Honjo (Japan); Masaru Tabata, Gunma (Japan); and Wataru Iwazaki, Gunma (Japan)
Assigned to Sanden Corporation, Gunma (Japan)
Filed on Mar. 23, 2006, as Appl. No. 11/387,058.
Claims priority of application No. 2005-087619 (JP), filed on Mar. 25, 2005; and application No. 2006-069177 (JP), filed on Mar. 14, 2006.
Prior Publication US 2006/0227738 A1, Oct. 12, 2006
Int. Cl. H04Q 7/00 (2006.01); H04J 3/24 (2006.01); H04L 12/66 (2006.01); H04L 12/28 (2006.01); H04L 12/54 (2006.01)

U.S. Cl. 370—338 [370/328; 370/349; 370/352; 370/402]

12 Claims

1. A communication system connecting a LAN and a radio communication terminal through a radio packet communication network by a network connection service dynamically giving an IP address within a first address space at the time the network is connected;

wherein a network router is provided at a boundary point between the radio packet communication network and the LAN;

wherein the radio communication terminal comprises a communication device connecting to the radio packet communication network, high-level equipment performing a communication by using the communication device, and a connection adapter interposed between the communication device and the high-level equipment and performing a relay of the communication;

wherein the high-level equipment is allotted in advance with an IP address for a network connection service fixedly giving an IP address within a second address space as its own IP address, and moreover, an IP address within a third address space is fixedly set as an IP address of a terminal of a LAN side; and

wherein the connection adapter comprises a communication control unit which mutually converts the IP address within the first address space stored in a header of an IP packet to be transmitted and received and the IP address within the second or third address space therebetween.