Source: http://www.google.com/patents/US7047003?dq=6,044,471
Timestamp: 2016-06-29 06:10:42
Document Index: 509137459

Matched Legal Cases: ['art 34', 'art 35', 'art 33', 'art 33', 'art 36', 'art 33', 'art 33', 'art 33', 'art 34', 'art 35', 'art 33', 'art 33', 'art 36']

Patent US7047003 - Mobile communication system, mobile unit and network host processor - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA mobile unit that provides an improved handover function in a mobile communication system having a soft handover function defined by 3GPP (3rd Generation Partnership Project). The mobile unit sets a flutter-preventing threshold relative to an event 1C at a first value when the communication level of...http://www.google.com/patents/US7047003?utm_source=gb-gplus-sharePatent US7047003 - Mobile communication system, mobile unit and network host processorAdvanced Patent SearchPublication numberUS7047003 B2Publication typeGrantApplication numberUS 10/515,627PCT numberPCT/JP2003/008246Publication dateMay 16, 2006Filing dateJun 27, 2003Priority dateJun 27, 2003Fee statusLapsedAlso published asCN1679367A, US20050186957, WO2005002268A1Publication number10515627, 515627, PCT/2003/8246, PCT/JP/2003/008246, PCT/JP/2003/08246, PCT/JP/3/008246, PCT/JP/3/08246, PCT/JP2003/008246, PCT/JP2003/08246, PCT/JP2003008246, PCT/JP200308246, PCT/JP3/008246, PCT/JP3/08246, PCT/JP3008246, PCT/JP308246, US 7047003 B2, US 7047003B2, US-B2-7047003, US7047003 B2, US7047003B2InventorsTakumi Sako, Yoshihiro YamabeOriginal AssigneeMitsubishi Denki Kabushiki KaishaExport CitationBiBTeX, EndNote, RefManPatent Citations (8), Referenced by (12), Classifications (15), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetMobile communication system, mobile unit and network host processor
US 7047003 B2Abstract
A mobile unit that provides an improved handover function in a mobile communication system having a soft handover function defined by 3GPP (3rd Generation Partnership Project). The mobile unit sets a flutter-preventing threshold relative to an event 1C at a first value when the communication level of a monitor set cell does not fall within an emergency range, and at a second value lower than the first value when the communication level of the monitor set cell falls within the emergency range.
The present invention relates to a mobile communication system, and more particularly, to a mobile communication system having a soft handover function defined by 3GPP (3rd Generation Partnership Project). The present invention also relates to a mobile unit and a network host processor constituting the mobile communication system.
A mobile communication system is provided with a handover function such that a call is not interrupted even when a user is talking while moving. The third generation mobile telephone system is called W-CDMA (Wideband Code Division Multiple Access) system. With this system, a mobile unit is capable of communicating with a plurality of base stations (called “cells”) simultaneously if the base stations use the same frequency. Accordingly, in the case of a call while moving, the mobile unit maintains communication with a first base station with which the mobile unit is currently communicating while starting communicating with a second base station, and thereafter, communication with the first base station is interrupted in the case where the communication level with respect to the first base station is lowered. Such handover is called soft handover (SHO) or diversity handover (DHO). The state in which a mobile unit is communicating with a plurality of base stations is called a soft handover state or diversity handover state.
It is an object of the present invention to solve the above problem and to achieve an improved handover function.
FIG. 1 is a block diagram showing the construction of a mobile communication system according to a prerequisite technique of the present invention;
First, a mobile communication system according to a prerequisite technique of the present invention will be discussed prior to discussing preferred embodiments of a mobile communication system according to the present invention.
FIG. 4 is an explanatory view showing the event 1C. Here, the maximum RL number is 3 by way of example. In the case where the cells 11 a to 11 c are active set cells, the event 1C occurs when the communication level between the monitor set cell 11 d and the mobile unit 12 is equal to or higher than the sum total of the communication level between the worst active set cell 11 c and the mobile unit 12 and the flutter-preventing threshold H1c. The reason why FIG. 4 depicts the value “H1c/2” not “H1C” is because H1c/2 is defined in each of the positive direction and negative direction with respect to a reference value (communication level of cell 11 c) so that flutters within the range of H1c are allowed as a whole.
MNew is the measurement result of the cell entering the reporting range/not included in the active set.
First, in step S100, the mobile unit 12 judges whether or not the monitor set cell 11 d satisfies the judgment expression relative to the event 1C given by the above expression (3). When the judgment result in step S100 is “YES”, the process goes to step S101, where the mobile unit 12 judges whether or not a timer for judging whether or not a predetermined time period has passed is activated. The predetermined time period is previously determined as a time-to-trigger value (β).
When the judgment result in step S101 is “YES”, the process goes to step S102, where the mobile unit 12 judges whether or not the predetermined time period has expired. When the judgment result in step S102 is “YES”, i.e., when the judgment expression relative to the event 1C is kept satisfied over the predetermined time period or longer, the process goes to step S103, where the mobile unit 12 reports the occurrence of the event 1C to the network host processor 10. Thereafter, the judgment process for the event 1C is finished.
When the judgment result in step S100 is “NO”, the process goes to step S104, where the mobile unit 12 stops the timer if activated. Thereafter, the judgment process for the event 1C is finished.
When the judgment result in step S101 is “NO”, the process goes to step S105, where the mobile unit 12 activates the timer. Thereafter, the judgment process for the event 1C is finished.
When the judgment result in step S102 is “NO”, the mobile unit 12 finishes the judgment process for the event 1C.
First, in step S21, the ER judgment part 34 judges whether or not the communication level of the monitor set cell 11 d falls within the emergency range ER. When the judgment result in step S21 is “YES”, i.e., when the communication level of the monitor set cell 11 d falls within the emergency range ER, the flutter-preventing threshold a relative to the event 1C is determined in step S22. In other words, “H1c” is changed to “α” in the above-mentioned expression (3). In the example shown in FIG. 10, the flutter-preventing threshold α is determined since the communication level of the monitor set cell 11 d falls within the emergency range ER. On the other hand, when the judgment result in step S21 is “NO”, i.e., when the communication level of the monitor set cell 11 d does not fall within the emergency range ER, the flutter-preventing threshold H1c relative to the event 1C is determined in step S23.
Next, in step S24, the event 1C judgment part 35 judges whether or not the monitor set cell 11 d satisfies the judgment expression relative to the event 1C. When the judgment result in step S24 is “YES”, the process goes to step S25, where the event 1C processing part 33 judges whether or not the timer 37 for judging whether or not a predetermined time period has passed is activated. This predetermined time period is previously determined as a time-to-trigger value (β).
When the judgment result in step S25 is “YES”, the process goes to step S26, where the event 1C processing part 33 judges whether or not the predetermined time period has expired. When the judgment result in step S26 is “YES”, i.e., when the judgment expression relative to the event 1C is kept satisfied over the predetermined time period or longer, the process goes to step S27, where the event sending part 36 reports the occurrence of the event 1C to the network host processor 10 through the active set cells 11 a to 11 c. Thereafter, the judgment process for the event 1C is finished.
When the judgment result in step S24 is “NO”, the process goes to step S28, where the event 1C processing part 33 stops the timer 37 if activated. Thereafter, the judgment process for the event 1C is finished.
When the judgment result in step S25 is “NO”, the process goes to step S29, where the event 1C processing part 33 activates the timer 37. Thereafter, the judgment process for the event 1C is finished.
When the judgment result in step S26 is “NO”, the event 1C processing part 33 finishes the judgment process for the event 1C.
First, in step S21, the ER judgment part 34 judges whether or not the communication level of the monitor set cell 11 d falls within the emergency range ER. When the judgment result in step S21 is “YES”, the time-to-trigger value is set at the second value (zero) in step S31. In the example shown in FIG. 13, the time-to-trigger value is set at the second value (zero), since the communication level of the monitor set cell 11 d falls within the emergency range ER. As a result, the event 1C occurs just after the communication level of the monitor set cell 11 d become equal to or higher than the sum total of the communication level of the worst active set cell 11 c and the flutter-preventing threshold H1c (strictly saying, H1c/2). On the other hand, when the judgment result in step S21 is “NO”, the time-to-trigger value is set at the first value (β) in step S32.
Next, in step S24, the event 1C judgment part 35 judges whether or not the monitor set cell 11 d satisfies the judgment expression relative to the event 1C. When the judgment result in step S24 is “YES”, the process goes to step S25, where the event 1C processing part 33 judges whether or not the timer 37 for judging whether or not a predetermined time period has passed is activated. In the example shown in FIG. 13, the predetermined time period is determined as the second time-to-trigger value (zero).
When the judgment result in step S25 is “YES”, the process goes to step S26, where the event 1C processing part 33 judges whether or not the predetermined time period has expired. When the judgment result in step S26 is “YES”, the process goes to step S27, where the event sending part 36 reports the occurrence of the event 1C to the network host processor 10 through the active set cells 11 a to 11 c. Thereafter, the judgment process for the event 1C is finished.
The process to be followed when the judgment result in each of steps S24 to S26 is “NO” is similar to that described in the first preferred embodiment, explanation of which is thus omitted here.
First, in step S41, the network host processor 10 having received the report on the event 1A judges whether or not the mobile unit 12 is in communication with the maximum RL number. When the judgment result in step S41 is “NO”, the process goes to step S45, where the network host processor 10 performs a normal operation (RL addition operation). That is, the monitor set cell 11 d is added as an active set cell.
On the other hand, when the judgment result in step S41 is “YES”, the process goes to step S42, where the network host processor 10 judges whether or not the communication level of the monitor set cell 11 d is higher than that of the worst active set cell 11 c. However, comparison may be made with other active set cells 11 a and 11 b, instead of the worst active set cell 11 c. Further, the flutter-preventing threshold H1a may be determined to judge whether or not the communication level of the monitor set cell 11 d exceeds the reporting range R1a by not less than the flutter-preventing threshold H1a.
When the judgment result in step S42 is “NO”, the process goes to step S44, where the network host processor 10 finishes the process for the event 1A.
On the other hand, when the judgment result in step S42 is “YES”, the process goes to step S43, where the network host processor 10 causes the mobile unit 12 to replace the monitor set cell 11 d and the worst active set cell 11 c with each other without waiting for a report on the event 1C from the mobile unit 12.
First in step S51, the network host processor 10 having received the report on the event 1D judges whether or not the cell having the highest communication level is the monitor set cell 11 d. When the judgment result in step S51 is “NO”, the process goes to step S52, where the network host processor 10 performs an equal operation as in the case of the conventional event 1D.
On the other hand, when the judgment result in step S51 is “YES”, the process goes to step S53, where the network host processor 10 causes the mobile unit 12 to replace the monitor set cell 11 d and the worst active set cell 11 c with each other without waiting for the report on the event 1C from the mobile unit 12.
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