WO2000018167A1 - A method relating to a radio communications system - Google Patents
A method relating to a radio communications system Download PDFInfo
- Publication number
- WO2000018167A1 WO2000018167A1 PCT/SE1999/001422 SE9901422W WO0018167A1 WO 2000018167 A1 WO2000018167 A1 WO 2000018167A1 SE 9901422 W SE9901422 W SE 9901422W WO 0018167 A1 WO0018167 A1 WO 0018167A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- rlt
- radio
- connection
- quality
- level
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W76/00—Connection management
- H04W76/30—Connection release
- H04W76/34—Selective release of ongoing connections
- H04W76/36—Selective release of ongoing connections for reassigning the resources associated with the released connections
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
Definitions
- the present invention relates to a method of handling radio channels that have been allocated to a radio base station for communication with radio terminals .
- WO 96/00482 describes handling of radio channels in a mobile communications system where a number of radio connections use a small number of radio channels. It is possible that a connection will obtain access to the radio channel only when there is a need to transmit information over said channel.
- WO 96/00482 addresses the problem of the small delay that may arise before a channel is found available for the connection when information shall be transmitted over said connection. This may mean that the first word in a sequence speech message will not reach the receiver.
- the problem is solved according to WO 96/00482, by allowing a connection to retain access to the channel for a short period of time after the latest information transmission. It is said that this is an advantage, because one information transfer is often followed by another.
- the length of time over which the radio channel is retained for the latest connection is determined by a number of parameters. One of these parameters determines the magnitude of the load on remaining radio channels, in other words the urgency of the need to use the radio channel concerned for some other connection.
- the present invention relates to a radio communications system where a connection is allocated a dedicated radio channel, i.e. the connection obtains exclusive access to the radio channel for the geographical area in which the mobile is situated.
- the present invention addresses a problem where a radio based station bars new radio connections, because no free radio channels are available.
- the block is manifested, inter al ia , by the in-ability of a mobile station that moves into the area covered by the radio base station during an ongoing connection to handover to the radio base station. This means that the quality of the radio connection will be impaired and there is also the risk that the connection will be terminated.
- the mobile station may also interfere with other connections .
- one object of the present invention is to release occupied radio channels for use with new radio connections .
- the radio channel is released from the connection after a short time period when only a few free channels are available in the radio base station. On the other hand, if there is a good supply of free channels, the radio channel is not released until a longer period of time has lapsed.
- the radio quality is measured over one time period and compared with a given quality level.
- the radio channel is released, if the radio quality falls beneath said given level over this time period.
- the level is normally set to a value which is so low that the large part of the information sent over the connection will be lost.
- the present invention has the advantage of flexibly adapting the risk .of premature release of an ongoing connection against the need of free radio channels in the radio base station.
- it is possible to adapt the level at which the channel shall be released to the need of using the channel for a new connection at that moment in time.
- the channels can be utilised more effectively, i.e. can accommodate more traffic, when the load on the radio base station is high.
- the traffic load is low, on the other hand, there is less risk of losing a call connection as a result of premature release of the channel.
- Fig. 1 illustrates a cellular radio communications system, or specifically the mobile communications system GSM.
- Fig. 2 is a diagrammatic illustration of the value of a given counter relative to a given level .
- Fig. 3 is a flowchart illustrating a method of changing a level that determines whether or not a radio channel shall be released from a given connection.
- Fig. 1 illustrates parts of a cellular radio communications system, more specifically a GSM system.
- the Figure shows a number of radio terminals or mobile stations MS1-MS3 dispersed over a geographical area, and a number of base transceiver stations BTS1, BTS2.
- Each base transceiver station BTS1-BTS2 is connected to a base station controller BSC.
- a number of base transceiver stations BTS1-BTS2 are connected to the base station controller.
- the base station controller BSC is connected to a mobile switching centre MSC, not shown.
- Telecommunications connections can be setup between a mobile station MS1-MS3 and the mobile communications system via a radio connection between the mobile station MS1-MS3 and a base transceiver station BTS1, BTS2.
- the base transceiver station BTS1, BTS2 that serves, e.g., a given mobile station MSI will depend on where the mobile station MSI is situated geographically. In the illustrated case, the mobile station MSI is situated within the area covered by the first base transceiver station BTS1, that is to say it is situated within a first cell Cl served by the first base transceiver station BTS1.
- the base transceiver station BTSl governs an array of radio channels that can be used for communication with mobile stations MS1-MS3 that are situated within the own cell Cl .
- a dedicated radio channel For the connection established with the mobile station MSI, there is allocated a dedicated radio channel, i.e. a radio channel Jtehat is used solely for the connection with the mobile station MSI.
- the dedicated radio channel is comprised of a physical uplink channel and a physical downlink channel.
- a physical channel is comprised of a specific timeslot on a specific carrier frequency.
- a physical channel can also be divided into different logic channels. Unless otherwise mentioned, a channel or radio channel shall be understood in the following as meaning a physical duplex radio channel.
- BTS2 There are times when the number of radio channels available in a base transceiver station BTSl, BTS2 is insufficient to serve all mobile stations that request such service within the cell Cl, C2 of the base transceiver station BTSl, BTS2.
- a connection is usually terminated by sending a release signal in one of the terminal points of the connection, in conjunction with a person wishing to terminate a call.
- the radio connection is terminated subsequent to the transmission of release signals and subsequent to obtaining a response to the transmitted release signal.
- the radio channel used for this particular connection is then free to be used for a new connection.
- the quality of the radio connection may be so poor that information transmitted over the channel does not reach the receiver end. Connection quality is measured over a time period and compared with a given quality level. If the quality is below this level, the connection is terminated and the radio channel can be reused for another connection.
- the parameter that sets this level in the GSM system is designated Radio Link Time-Out.
- the quality is measured in each respective uplink and downlink. There is a respective level in the uplink and the downlink against which the quality is compared; the comparison level in uplink is designated Radio Link Time-Out Uplink. If the quality is found to be below the comparison level, the connection is terminated and the radio channel released for reuse.
- Radio connection reports are regularly sent over said connection in both uplink and downlink. Each report has a well-defined format.
- the quality of the radio connection is measured in accordance with an earlier known method, by stepping a counter up one step or increment from a starting value in the event the absence of a measurement report from the receiver.
- Fig. 2 is a diagrammatic illustration that shows how the uplink counter is reset over a time period on the basis of a starting value in relation to the level RLT_UL .
- the X-axis of the diagram shows the number of measurement reports received, which also corresponds to time that has lapsed.
- the Y-axis shows the counter value. If three reports have been lost in succession and the counter thus counts-up three increments from the starting value, the counter will be stepped down two increments should a measurement report be received correctly.
- Fig. 2 the correct measurement report received is followed by 15 sequentially excluded measurement reports.
- the counter has been stepped-up by 16 increments from the starting value, after the fifteenth measurement report in the succession of excluded reports.
- an increase of 16 increments represents the level RLT_UL at which the uplink radio connection is so poor as to terminate the radio connection.
- the quality in downlink is measured separately in the same way as in 1 » the uplink, although the downlink level is set independently of the uplink level RLT_UL . Accordingly, separate counters are included in the uplink and downlink respectively, for registering the quality of the radio connectio .
- the level RLT_UL is set to a fixed value, by an operator of the mobile communications system.
- the level RLT_UL that represents how poor a radio connection shall be in order to release the channel is changed in accordance with the number of free channels available in the base transceiver station BTSl.
- the level RLT_UL can be set in increments or steps between an upper limit value RLT_UL_max and a lower limit value RLT_UL_min. If only a few free channels are available, it is thereby possible to release a channel from a given radio connection subsequent to the counter having stepped up solely 10 increments, which in the illustrated case corresponds to the lower limit value RLT_UL_min for the level RLT_UL .
- a given radio channel may continue to be dedicated to a given connection until the counter value has been increased by 22 increments, which in the illustrated case corresponds to the upper limit value RLT_UL_max for the level RLT_UL.
- Fig. 3 is a flowchart illustrating how the uplink level RLT UL and the downlink level RLT_DL are changed in respect of time, depending on the number of free channels in the base transceiver station BTSl.
- Step S2 a check is made to establish whether or not the number of free channels in the base transceiver station 1 exceeds a given limit.
- Step S3 is carried out if the answer is No, i.e. only a few free channels are available .
- step S3 a check is made to establish whether or not the uplink level RLT_UL is set to the lower limit value RLT_UL_min.
- step S5 is carried out if the answer is Yes, the level RLT_UL is set to the lower limit value.
- a step S4 is carried out before step S5 if, on the other hand, the answer is No.
- step S4 the uplink level RLT__UL is decreased preferably by one increment.
- the counter therewith needs to be increased by one increment fewer, prior to releasing the channel from the connection.
- step S5 a check is made to establish whether or not the downlink level RLT_DL is set to the lower limit value RLT_DL_min .
- a new step SI and its following steps are carried out if the answer is Yes, the level RLT_DL is set to the lower limit value RLT_DL_min.
- step S6 is carried out before step SI and its following steps .
- step S6 the downlink level RLT_DL is decreased by one increment .
- step S7 the check carried out in accordance with step S2 above reveal that the number of free channels exceeds a given limit and the answer to the question is therefore Yes there is a sufficient number of free channels in the base transceiver station 1, a following step S7 is carried oiife .
- step S7 a check is made to establish whether or not the uplink level RLT_UL is set to a highest permitted limit value
- a step S9 is carried out if the answer is Yes, i.e. that the level RLT_UL is set to the upper limit value
- step S8 is carried out before step S9.
- the uplink level RLT_UL is increased by one increment .
- step S9 a check is made to establish whether or not the downlink level RLT_DL is set to the upper limit value RLT_DL_max .
- Step SI and its following steps are repeated if the answer is Yes, i.e. that the level RLT_DL is set to the upper limit value RLT_DL_max.
- step SI is repeated if the answer is No there is carried out a step S10 in which the uplink level RLT_DL is increased through one increment, whereafter step SI is repeated.
- a measurement report is sent every 480 ms in uplink and in downlink over a logic channel designated Slow Associated Control Channel, referred to by the acronym SACCH.
- the measurement report has a strict structure and its information is coded so that said information can be established upon receipt, even though some data may have been distorted in the radio transmission. The information cannot be recovered, however, if an excessively large part of the data has been distorted. The measurement report is then considered to be lost and the counter counts-up one increment.
- uplink and downlink are inflicted simultaneously with poor radio quality, for instance when the mobile station accompanies its user into a garage and becomes situated in radio shadow.
- the radio channel continues to dedicate the connection until the counter of the mobile station MSI has also reached the downlink level RLT_DL, wherewith any attempt to transmit further in uplink on the part of the mobile station MSI can be excluded.
- the time before the channel can be released from the time at which the mobile entered radio shadow will be:
- the base station controller In the GSM system, it is the base station controller that controls the radio connection. It is thus the base station controller BSC that handles the control of radio channels and allocates radio channels to different users.
- the uplink measurement reports are received by the base transceiver station 1 and forwarded to the base station controller BSC.
- the counter which counts the number of lost measurement reports ⁇ * implemented in the base station controller.
- the base station controller BSC also checks the counter value relative to the level RLT__UL in uplink and releases the radio channel, depending on the result of this comparison.
- the mobile station MSI includes a counter for establishing the quality of the downlink connection, and the counter value is compared with the level RLT__DL in the mobile station MSI. If the downlink quality falls below the level RLT_DL, the mobile station MSI initiates the release of the connection.
- the base station controller BSC also includes a counter corresponding to the counter in the mobile station MSI which is compared with the level RLT_DL in downlink with regard to the possible release of the channel.
- This counter is used when a channel release message is sent in downlink, for instance as in the above radio shadow example.
- the counter is stepped-up from a starting value after the channel release message has been sent in downlink.
- Upper and lower limit values RLT_DL_max, RLT_UL_max, RLT_DL_min, RLT_UL_min are set to a value by the operator of the mobile communications system in the same way as the level RLT_DL, RLT_UL while earlier set to a given value.
- the downlink level RLT_DL is calculated in the base station controller on the basis of these limit values in accordance with the method illustrated in Fig. 3, and is sent downlink to the mobile station MSI.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU56667/99A AU5666799A (en) | 1998-09-22 | 1999-08-20 | A method relating to a radio communications system |
EP99943602A EP1116405A1 (en) | 1998-09-22 | 1999-08-20 | A method relating to a radio communications system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9803214-7 | 1998-09-22 | ||
SE9803214A SE512791C2 (en) | 1998-09-22 | 1998-09-22 | Method for managing radio channels depending on the traffic load in a radio communication system |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000018167A1 true WO2000018167A1 (en) | 2000-03-30 |
Family
ID=20412678
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE1999/001422 WO2000018167A1 (en) | 1998-09-22 | 1999-08-20 | A method relating to a radio communications system |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1116405A1 (en) |
AU (1) | AU5666799A (en) |
SE (1) | SE512791C2 (en) |
WO (1) | WO2000018167A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002009452A2 (en) * | 2000-07-20 | 2002-01-31 | Koninklijke Philips Electronics N.V. | Idle handoff method for mobile communication devices taking into account critical system jobs |
GB2404310A (en) * | 2003-06-05 | 2005-01-26 | Nec Corp | Managing radio resources in a mobile communication system |
CN101119534B (en) * | 2006-08-04 | 2010-05-12 | 中兴通讯股份有限公司 | Multi-user channel resource abnormity detecting method |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5159702A (en) * | 1988-06-21 | 1992-10-27 | Fujitsu Limited | Multichannel access radio data communication system which holds a channel to reduce burden of reallocation |
WO1996000482A2 (en) * | 1994-06-27 | 1996-01-04 | Nokia Telecommunications Oy | Method for allocating radio channels |
US5535429A (en) * | 1993-01-27 | 1996-07-09 | Telefonaktiebolaget Lm Ericsson | Method of disconnecting an established communication connection in a mobile radio system |
-
1998
- 1998-09-22 SE SE9803214A patent/SE512791C2/en not_active IP Right Cessation
-
1999
- 1999-08-20 AU AU56667/99A patent/AU5666799A/en not_active Abandoned
- 1999-08-20 WO PCT/SE1999/001422 patent/WO2000018167A1/en not_active Application Discontinuation
- 1999-08-20 EP EP99943602A patent/EP1116405A1/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5159702A (en) * | 1988-06-21 | 1992-10-27 | Fujitsu Limited | Multichannel access radio data communication system which holds a channel to reduce burden of reallocation |
US5535429A (en) * | 1993-01-27 | 1996-07-09 | Telefonaktiebolaget Lm Ericsson | Method of disconnecting an established communication connection in a mobile radio system |
WO1996000482A2 (en) * | 1994-06-27 | 1996-01-04 | Nokia Telecommunications Oy | Method for allocating radio channels |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002009452A2 (en) * | 2000-07-20 | 2002-01-31 | Koninklijke Philips Electronics N.V. | Idle handoff method for mobile communication devices taking into account critical system jobs |
WO2002009452A3 (en) * | 2000-07-20 | 2002-07-11 | Koninkl Philips Electronics Nv | Idle handoff method for mobile communication devices taking into account critical system jobs |
GB2404310A (en) * | 2003-06-05 | 2005-01-26 | Nec Corp | Managing radio resources in a mobile communication system |
GB2404310B (en) * | 2003-06-05 | 2006-01-18 | Nec Corp | Mobile communication system and method, and base station controller and computer program for use therein |
CN101119534B (en) * | 2006-08-04 | 2010-05-12 | 中兴通讯股份有限公司 | Multi-user channel resource abnormity detecting method |
Also Published As
Publication number | Publication date |
---|---|
AU5666799A (en) | 2000-04-10 |
SE512791C2 (en) | 2000-05-15 |
SE9803214L (en) | 2000-03-23 |
EP1116405A1 (en) | 2001-07-18 |
SE9803214D0 (en) | 1998-09-22 |
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