The assignee for this patent, patent number 8620300, is Telefonaktiebolaget L M Ericsson (publ) (
Reporters obtained the following quote from the background information supplied by the inventors: "There is currently work ongoing within the third Generation Partnership Program (3GPP) to introduce a new Radio Access Technology (RAT). The new RAT is called E-UTRAN (Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network), and also known as Long Teem Evolution (LTE). One item to be specified is the interworking between E-UTRAN and the other existing RATs, such as Global System for Mobile Communication/Enhanced Data rates for GSM Evolution (GSM/EDGE) Radio Access Network (GERAN) and Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN).
"In order to inform mobile stations in a cellular radio system about neighbouring E-UTRAN cells, the procedure is to broadcast information about the neighbouring (allowed) E-UTRAN frequencies and an optional 'black list' of not allowed neighbouring E-UTRAN cells for each of the E-UTRAN frequencies. The E-UTRAN cells are then identified through their Physical Layer Cell Identities (PCID), which is an identity that is locally unique per E-UTRAN frequency. Efficient coding of sets of PCIDs is currently being discussed within 3GPP for the case where a group of PCIDs needs to be blacklisted, e.g. at country borders. The reason is that the information about what E-UTRAN cells that are blacklisted or which are not blacklisted needs to be sent on the broadcast channels. The broadcast channels typically have a very limited capacity and hence there is a need to limit the use of the resources of the broadcast channels as far as possible. Further the
"In comparison, the information about neighbouring GERAN and UTRAN cells is sent as lists of allowed neighbouring GERAN and UTRAN cells. Cells are divided into different areas, within GERAN and UTRAN into Location Areas/Routing Areas and within E-UTRAN into Tracking Areas. Each cell thus belongs to a Location Area/Routing Area (GERAN and UTRAN) or a Tracking Area (E-UTRAN).
"When a mobile station (in GERAN mode) performs measurements for cells that belong to non-GERAN access technologies, such as UTRAN and E-UTRAN (LTE) the mobile station is unaware of the Location Area/Routing Area/Tracking Area they belong to. Also in some scenarios a mobile station is not allowed to enter a specific Location/Routing/Tracking Area. This becomes apparent when the mobile station tries to perform cell reselection to a cell in that area. For the GERAN to UTRAN case today the mobile station is then not allowed to try cell reselection to any UTRAN cell on the same frequency for a certain time, a back off time. The reason is that the mobile station is not aware of what Location/Routing Areas the other UTRAN cells belong to.
"Thus, when the mobile station is in an area with different Location/Routing/Tracking Areas, where some are allowed and some are not, the mobile station will in some scenarios not be able to perform cell reselection to any of the allowed cells due to that cell reselection was attempted for a not allowed cell/area the first time. This can be either in idle mode or in packet transfer mode where the mobile station controls the cell reselection/handover (in NC0 and NC1 modes).
"In case the mobile station is in dedicated mode or packet transfer mode, the mobile station would in the corresponding scenarios be performing unnecessary measurements, and transmit unnecessary measurement reports, of cells that belong to not allowed Location/Routing/Tracking Areas. The list of not allowed areas is kept in the mobile station based on previous rejected accesses in those areas.
"Hence, there exist a need for a method and a mobile station that eliminates or reduces the problems encountered when performing cell reselection."
In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "It is an object of the present invention to overcome or at least reduce some of the problems as described above.
"These objects and others are obtained by the method and system as set out in the appended claims. Thus, in accordance with embodiments of the present invention, cell identities, in particular the EUTRAN Physical Layer Cell Identities (PCIDs), are grouped in accordance with the area, in particular the Tracking Area, to which they belong to in a message transmitted from a radio base station to a mobile station. In one embodiment the grouped cell identity information is transmitted as a broadcast message.
"A multi RAT, e.g. GERAN/E-UTRAN, capable mobile station receiving such a broadcast message where the PCIDs are grouped together in tracking area groups is then enabled to determine the neighbouring cells, such as E-UTRAN cells that belong to the same area, such as a Tracking Area. As a result when cell reselection to a cell is rejected due to that the area is not allowed, the mobile station can then be allowed to directly initiate cell reselection to cells that are not part of the same group of cells of that area. This in turn results in that no waiting time is needed to initiate a cell reselection towards those cells.
"In accordance with one embodiment a method of performing cell reselection in a mobile station is provided. The method comprises receiving a message including the cell identities grouped in accordance with the area to which they belong. The mobile station then performs cell reselection, and attempts to select a cell belonging to another group if the mobile station is rejected in a selected cell after a reduced back off time.
"Mobile stations in dedicated/packet transfer/dual transfer modes can use the information about the groups of cells that belong to the same area/Tracking Area in order to avoid unnecessary measurements/measurement reports for all cells that belong to an area/Tracking Area that is not allowed.
"In accordance with in one embodiment a mechanism to inform mobile stations in dedicated/packet transfer/dual transfer modes about specific rules that apply towards some neighbouring E-UTRAN cells in those modes is provided. For example the mobile stations can be informed that handover is not supported even though cell reselection is supported in idle mode towards the same cells. Such information can be transmitted to mobile stations either by including information about the meaning of different PCID groups, e.g. about black listing, in the broadcasted system information and/or by letting the network inform mobile stations about additional PCIDs not to be included in measurements/measurement reports when in dedicated mode/packet transfer mode/dual transfer mode.
"Embodiments of the invention also extend to a radio base station and a mobile station configured in accordance with the above."
For more information, see this patent: Bergqvist, Jens; Schliwa-Bertling, Paul. Method of Transmitting Cell Identity Information. U.S. Patent Number 8620300, filed
Keywords for this news article include: Telecommunications, Telefonaktiebolaget L M Ericsson.
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