# US 8,787,173 B2 · Base station, mobile station, communication system, and reordering method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,173 B2 - Document ID: US8787173B2 - Status: Granted - Kind: B2 - Application number: 13/464,361 - Filed: 2012-05-04 - Published: 2012-08-30 - Granted: 2014-07-22 - Earliest claimed: 2007-03-22 - Assignees: Fujitsu Limited - Applicants: Yoshiaki Ohta - Inventors: Yoshiaki Ohta - Web page: https://patentgrep.com/patent/US8787173B2 ## CPC - H04W 36/02: Buffering or recovering information during reselection {; Modification of the traffic flow during hand-off} - H04W 36/0005: {Control or signalling for completing the hand-off} - H04W 36/0033: {with transfer of context information} - H04W 36/0064: {of control information between different access points} - H04W 36/0235: {by transmitting sequence numbers, e.g. SN status transfer} - H04W 36/0077: {of access information of target access point} - H04W 36/08: Reselecting an access point - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A communication system wherein a base station sends packets having sequence numbers attached, to a mobile station, the mobile station rearranges the packets by sequence number, and hard handover is performed. A handover source base station having a controller decides whether the handover source base station forwards packets which were not sent to the mobile station, out of packets received from a host station, to a handover target base station, controls forwarding of the packets to the handover target base station and sends forwarding execution information from the handover source base station to the mobile station to notify whether the forwarding of the packets has been executed, the mobile station including a receiver that receives the forwarding execution information from the handover source base station; and a controller that executes reordering of the received packets based on the forwarding execution information at the handover. ## Claims ### Claim 1 A communication system in which a base station sends packets to which numbers indicating sequence are attached, to a mobile station, the mobile station rearranges the packets in order of the sequence number, and hard handover is performed, comprising: a handover source base station having a controller that decides whether the handover source base station forwards packets which have not been sent to the mobile station, out of packets received from a host station, to a handover target base station or not, controls forwarding of the packets from the handover source base station to the handover target base station at the handover based on the decision, and sends forwarding execution information from the handover source base station to the mobile station to notify whether the forwarding of the packets from the handover source base station to the handover target base station has been executed or not, wherein the mobile station including: a receiver that receives the forwarding execution information from the handover source base station; and a controller that executes reordering of the packets received from the handover target base station based on the forwarding execution information at the handover. ### Claim 2 (depends on 1) The communication system according to claim 1, wherein the controller in the handover source base station sends the forwarding execution information to the mobile station, the forwarding execution information being used by the mobile station for determining whether the mobile station should execute reordering of the packets received from the handover target base station. ### Claim 3 (depends on 1) The communication system according to claim 1, wherein in a case where the handover source base station is to forward the packets which have not been sent to the mobile station, to the handover target base station at the handover, the controller in the handover source base station forwards the packets to the handover target base station at the handover and sends the forwarding execution information which notifies that the forwarding of the packets from the handover source base station to the handover target base station has been executed, to the mobile station, and in a case where the handover source base station is not to forward the packets to the handover target base station at the handover, the controller in the handover source base station sends the forwarding execution information which notifies that the forwarding of the packets from the handover source base station to the handover target base station has been not executed, to the mobile station at the handover. ### Claim 4 (depends on 1) The communication system according to claim 1, wherein the controller in the handover source base station decides whether the handover source base station forwards the packets which have not been sent to the mobile station, to the handover target base station at the handover or not, in conformity with the type of communication call. ### Claim 5 (depends on 4) The communication system according to claim 4, wherein the controller in the mobile station controls the reordering of the packets received from the handover target base station based on the forwarding execution information which is set in conformity with the type of the communication call. ### Claim 6 (depends on 1) The communication system according to claim 1, wherein the handover target base station includes a storage unit that stores both packets received from the host station and the packets received from the handover source base station at the handover and a sender that sends the packets stored in the storage unit to the mobile station. ### Claim 7 (depends on 6) The communication system according to claim 6, wherein the handover target base station has a sending controller that sends the packets received from the handover source base station at the handover preferentially and sends the packets received from the host station subsequently. ### Claim 8 (depends on 1) The communication system according to claim 1, wherein the controller in the mobile station determines at the handover whether the mobile station executes reordering of the packets received from the handover target base station or not, based the forwarding execution information. ### Claim 9 (depends on 1) The communication system according to claim 1, wherein the mobile station has a storage unit that stores the packets received from the handover target base station and the controller in the mobile station controls reordering of the packets stored in the storage unit. ### Claim 10 (depends on 1) The communication system according to claim 1, wherein the controller in the mobile station ends reordering processing when packets having continuous numbers are not received even if reordering processing of the received packets is executed for a predetermined time. ### Claim 11 A communication system in which a base station sends packets to which numbers indicating order are attached, to a mobile station, the mobile station performs delivery of the packets in order, and handover is performed, comprising: a handover source base station provided with a controller that sends configuration information indicating whether forwarding of packets has been executed or not, to the mobile station, wherein the mobile station includes: a receiver that receives the configuration information indicating whether the forwarding of packets has been executed or not, from the handover source base station; and a controller that controls delivery of the packets received from a handover target base station at the handover, in order based on the configuration information indicating whether the forwarding of packets has been executed or not, and wherein the controller in the handover source base station decides whether the handover source base station forwards packets which have not been sent to the mobile station, out of packets received from a host station, to the handover target base station or not, controls the forwarding of the packets from the handover source base station to the handover target base station at the handover based on the decision, and controls of sending the configuration information indicating whether forwarding of packets has been executed or not, from the handover source base station to the mobile station.