Source: http://www.google.com/patents/US7894817?dq=4484186
Timestamp: 2015-03-27 11:22:51
Document Index: 138976937

Matched Legal Cases: ['art 1101', 'art 1102', 'art 1103', 'art 1104', 'art 1103', 'art 1201', 'art 1202', 'art 1203', 'art 1204', 'art 1203', 'art 1301', 'art 1302', 'art 1303', 'art 1304', 'art 1305', 'art 1306', 'arts 1303']

Patent US7894817 - Communication system using multiple wireless resources during a soft handoff - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsIn a wireless communications system operating according to CDMA or the like, when one terminal simultaneously performs communication using multiple wireless resources (e.g., multiple carriers), there was a problem that when it was attempted to guarantee network mobility by the same soft handoff system...http://www.google.com/patents/US7894817?utm_source=gb-gplus-sharePatent US7894817 - Communication system using multiple wireless resources during a soft handoffAdvanced Patent SearchPublication numberUS7894817 B2Publication typeGrantApplication numberUS 11/822,228Publication dateFeb 22, 2011Filing dateJul 3, 2007Priority dateAug 31, 2006Fee statusPaidAlso published asCN101137228A, CN101137228B, US8831609, US20080057970, US20110142007Publication number11822228, 822228, US 7894817 B2, US 7894817B2, US-B2-7894817, US7894817 B2, US7894817B2InventorsMay Takada, Yosuke Takahashi, Shiro Mazawa, Rintaro KatayamaOriginal AssigneeHitachi, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (15), Non-Patent Citations (2), Classifications (17), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetCommunication system using multiple wireless resources during a soft handoff
US 7894817 B2Abstract
The present application claims priority from Japanese application JP 2006-234897 filed on Aug. 31, 2006, the content of which is hereby incorporated by reference into this application.
The present invention is suitable for wireless communications systems terminals and base stations that support terminal mobility such as mobile phones and wireless LAN, and particularly, for those using MC-CDMA (multi carrier code division multiple access).
Wireless communications systems such as mobile phones aim to enable communication �anytime and anywhere� without interruption, and have developed to support the expansion of communication areas and handoff technology between base stations.
In order to obtain higher data throughput, whereas communication with the base station was previously made through only one carrier frequency, it is now being considered to increase the communications throughput N times by permitting communication via multiple carriers for 1 user simultaneously. For instance, 1xEVDO method of 3GPP2 (3GPP2 C.S0024-A_v2.0 (8.7.6.1.6.3, Active Set Maintenance)) is a communication standard for the Code-Division Multiple Access system that uses one carrier. If you try to enhance the communication capability for each terminal N times by using N carriers with the conventional soft handoff method, the efficiency and the stability will become problems. In the following, these problems are described in detail.
FIG. 1 shows how communication is performed during soft handoff while simultaneously communicating via three carriers in a first network configuration;
A first embodiment of the present invention will now be described referring to FIG. 5. In this embodiment, a first example of a network configuration is shown in FIG. 3. In this embodiment, the salient points are that soft handoff termination is periodically determined, and stability is maintained while redundant soft handoff is avoided. To ensure above points, soft handoff is terminated on the basis of the following sequences.
FIG. 9 shows a flow chart when applying the first embodiment in the aforesaid second network configuration. In this embodiment, as in the first embodiment, a soft handoff termination judgment is made periodically, and a prolonged soft handoff state is avoided while maintaining stability.
A third embodiment will now be described referring to FIG. 7. In this embodiment, when a RouteUpdate message for soft handoff termination is received from the terminal for one carrier among multiple carriers (equivalent to sequence 405), the same soft handoff termination judgment is made as in the case of the first embodiment (701). For example, as shown by 500 of FIG. 5, when there is a soft handoff state for all the carriers f1-f3 and an instruction to terminate soft handoff for f1 is notified from the terminal side, it is instructed to terminate soft handoff also for the carriers f2, f3 which are still in the soft handoff state.
FIG. 10 is a flow chart showing a case where, in the aforesaid second network configuration, a software handoff termination decision preparation is made in the same way as in the third embodiment. As in FIG. 9, an ANC-A1001 of AP-A is the main element which judges the feasibility of soft handoff termination for all the carriers of the terminal based on a notification of soft handoff termination for any one carrier received from the terminal (1002). A handoff request message which requires taking over data flow control to this terminal is transmitted to an ANC-B1003 in AP-and PCF/PDSN (1004). When an ACK1005 which notifies acceptance of the handoff request from ANC-B is returned, ANC-A instructs ANTS-A to disconnect communication with the terminal for all carriers. The operations of ANTS-A and AT which received the communication disconnection instruction are identical to those of the third embodiment.
In the first embodiment, soft handoff termination to avoid soft handoff using multiple carriers was described, but even if there is a termination from the soft handoff state, a new RouteUpdate message is issued by the terminal immediately due to the received strength, and there may be a return to the soft handoff state with multiple carriers which would offset the effect of the invention. Therefore, some modification is required also of the part shown by 500 of FIG. 5. The following two methods constitute the fifth embodiment of this patent.
The composition of ANC in the first network example will now be described using FIG. 11. The ANC has a network interface part 1101 for performing transmission and reception of control messages or communication data exchanged with PCF/PDSN, network interface part 1102 for performing transmission and reception of communication data exchanged with each ANTS, a control part 1103, and a data processing part 1104 which performs processing of communication data. The control part 1103 performs management of the Active Set and performs updating of Active Set information of the terminal which corresponds to reception of a control message during soft handoff start and termination. Transmission/reception control of control messages required for soft handoff start and termination control is also performed, including the soft handoff termination judgment described in FIG. 6. Transmission control for distributing terminal communication data to ANTS is also performed during, before and after soft handoff.
The construction of an ANTS in the first network configuration example will now be described referring to FIG. 12. ANTS has a network interface part 1201 for sending and receiving control messages and communication data to and from ANC, a wireless part 1202 for sending and receiving control messages and communication data to and from AT, a control part 1203, and a data processing part 1204 which performs processing of communication data. The control part 1203 has a message interface for communicating the possible terminal reception rate for each carrier which is required for the soft handoff termination judgment described based on FIG. 6, to ANC.
AP in the second example of a network configuration has the function of the ANC of FIG. 11 and ANTS of FIG. 12 in one case. Specifically, as shown in FIG. 13, it has a network interface part 1301 for sending/receiving control messages and communication data to and from CR, wireless part 1302 for sending/receiving control messages and communication data to and from AT, ANC control part 1303 which has the same functions as the ANC control part and data processing part of FIG. 11, ANC data processing part 1304, ANTS control part 1305 which has the same functions as the ANTS control part and data processing part of FIG. 12, and ANTS data processing part 1306. The operating functions of each of the parts 1303-1306 are essentially identical to those of the corresponding parts in FIGS. 11 and 12. However, if this AP is the origin of the hand off, the ANC performs control for forwarding communication data addressed to a terminal to the ANC of the target AP via CR. When this AP is the handoff target, control which receives forwarding of communication data addressed to the terminal from the ANC of the AP which is the origin of the hand off via CR, is performed. The ANC control part also performs processing of control messages for handoff between AP.
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