Title of Invention	A METHOD OF NETWORK SEARCH OPTIMIZATION FOR MULTI BAND SUPPORTED MOBILES
Abstract	The present invention in general relates to communication systems which use radio frequency (RF) signals and, in particular, to systems for multi-mode, multi-band Code Division Multiple Access (CDMA) and Global System for Mobile (GSM) communication system. The invention particularly relates to battery life saving in multi-band, multi-mode supported mobiles by optimizing the network search for the different bands by considering their possibility of occurrence. The invention explains a method of network search optimization for multi band supported mobiles comprising the steps of: maintaining a quad band supported geographical area list have the PLMN IDs by the mobile station; searching for all possible bands by the mobile station when the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band; updating the said list whenever the user equipment finds service on non RBAND while doing search for the possible bands periodically; searching for all the bands which user equipment is capable of when the user equipment camps on any one PLMN of the geographical regions; and wherein in other cases the search is restricted to the RBAND of previously camped PLMN and periodically searches for the service on other bands that user equipment is capable of.

Title of Invention

A METHOD OF NETWORK SEARCH OPTIMIZATION FOR MULTI BAND SUPPORTED MOBILES

Abstract

The present invention in general relates to communication systems which use radio frequency (RF) signals and, in particular, to systems for multi-mode, multi-band Code Division Multiple Access (CDMA) and Global System for Mobile (GSM) communication system. The invention particularly relates to battery life saving in multi-band, multi-mode supported mobiles by optimizing the network search for the different bands by considering their possibility of occurrence. The invention explains a method of network search optimization for multi band supported mobiles comprising the steps of: maintaining a quad band supported geographical area list have the PLMN IDs by the mobile station; searching for all possible bands by the mobile station when the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band; updating the said list whenever the user equipment finds service on non RBAND while doing search for the possible bands periodically; searching for all the bands which user equipment is capable of when the user equipment camps on any one PLMN of the geographical regions; and wherein in other cases the search is restricted to the RBAND of previously camped PLMN and periodically searches for the service on other bands that user equipment is capable of.

Full Text	FIELD OF THE INVENTION The present invention in general relates to communication systems which use radio frequency (RF) signals and, in particular, to systems for multi-mode, multi-band Code Division Multiple Access (CDMA) and Global System for Mobile (GSM) communication system. The invention particularly relates to battery life saving in multi-band, multi-mode supported mobiles by optimizing the network search for the different bands by considering their possibility of occurrence. DESCRIPTION OF RELATED ART The GSM communication standard is a worldwide mode of digital cellular communication operating over different frequency bands. GSM-850 operates in 850 MHz frequency band and is used in some parts of USA. GSM-900 is currently used in Europe and Asia. DCS is another digital cellular standard based on GSM technology, operating in the 1800 MHz frequency band and also currently used in Europe and Asia. The United States uses PCS, another digital cellular standard similar to DCS, but operating in the 1900 MHz band. GSM is currently used in approximately 154 countries, including the geographic areas of North Africa, India, China, Europe, the Middle East, and Taiwan. CDMA, another mode of digital cellular communication operating in either the 900 or 1900 MHz band is one of the most widely used modes of cellular communication in the United States and Korea. WCDMA 2100 bands are used in some countries of Europe. CDMA is also being used in China, India, and Taiwan. With improved voice and data communications and political climates continuing to expand the world market, a "world telephone" capable of operating in many different countries would be of interest to international business travelers. Multi-mode, multi-band cellular telephones with shared functionality and an optimized architecture capable of operating under all of these standards afford consumers widespread applicability and allow manufacturers to benefit from the cost-efficiency of a common design. However, multi-mode, multi-band cellular telephones such as combined CDMA/GSM telephones present a number of design challenges. When multi-band supported UE is powered ON or trying to recover from lack of coverage or while doing background scanning it will search in all the bands until it finds service. But all the bands are not expected to co-exist in a given geographical area. When UE is searching for service it may search in all the bands with equal priority. This will lead to excessive battery drain, though practically all the bands may not co-exist in most of the places. So, there is a need for the UE to identify the bands which have high probability of existence in a given geographical area and spend more time in searching for those bands. This method should also take care of situations where the service exists in other bands also. If the UE searches in both bands (PCS (GSM 850, 1900 and UMTS 2100 MHz) & DCS (GSM900 & 1800 MHz)), the battery will drain fast. If the UE searches only in one pair of Bands based on country, user may miss the service in regions of overlapping bands (for ex: DCS band & PCS bands exist in some states in US). So no Generic method solves this problem. SUMMARY OF THE INVENTION The present invention deals with optimization of battery consumption while searching for service when UE is in NO SERVICE or Emergency Service or while doing background scanning. Searching for the possible bands can be optimized by having the prior knowledge about the geographical regions where there will be over lapping bands and in other regions only one set of band can exist (for ex: DCS 1800 in Europe and PCS 1900 in USA). Accordingly, this invention explains a method of network search optimization for multi band supported mobiles comprising the steps of: (a) maintaining a quad band supported geographical area list have the PLMN IDs by the mobile station; (b) searching for all possible bands by the mobile station when the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band; (c) updating the said list whenever the user equipment finds service on non RBAND while doing search for the possible bands periodically; (d) searching for all the bands which user equipment is capable of when the user equipment camps on any one PLMN of the geographical regions; and where in other cases the search is restricted to the RBAND of previously camped PLMN and periodically searches for the service on other bands that user equipment is capable of. The said geographical region list have the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band and for the said PLMN IDs, the mobile station is expected to search for all the possible bands. The periodicity of searching for the possible bands is implementation dependent based on trade off between battery life and camping time. The list of PLMNs which is surrounded with quad band supported region is stored in the SIM where mobile station compares the previously camped PLMN ID with the said PLMN list. When mobile station compares the previously camped PLMN ID with the said PLMN list and if any match is found then user equipment searches all the bands which user equipment is capable of. Quad band supported geographical area list is updated by OTA message if there is any change in network planning. After switching on the mobile, user equipment searches for bands supported by RPLMN. If user equipment is not able to acquire service for RPLMN bands, then all the bands that user equipment is capable of are searched. If user equipment is able to acquire service for RPLMN bands the user equipment starts processing the corresponding signals of the selected band. A background search is initialized to search for the previously camped PLMN. In the background search the user equipment checks whether the RPLMN belongs to any of the PLMN's which is present in the quad band supported geographical area list. In the background search if the camped PLMN belongs to the list, user equipment searches in all the supported bands. In the background search if the camped PLMN is not present user equipment searches for the RBAND and for every nth trial user equipment searches for all supported bands. During loss of coverage or emergency if RPLMN of the user equipment belongs to quad band supported geographical area list, then user equipment triggers for normal search for all the bands which user equipment is capable of until it regains the service. During loss of coverage or emergency if RPLMN of the user equipment does not belongs to quad band supported geographical area list then user equipment triggers for the normal service on the band set on which it has previously camped on and repeat the said procedure for n iteration. If user equipment is not able to get the service in n iteration, the user equipment triggers for the service on other set of supported bands which enables the user equipment to scan for other bands. In another approach the geographical area list is stored in the non-volatile memory of the mobile station based on the information received from a operator. The user equipment uses the stored information for latching on to the network where the non-volatile items are initialized during the manufacturing of the user based on the network planning. If the user equipment is able to find any new PLMN, the list is updated accordingly. These and other objects, features and advantages of the present invention will become more readily apparent from the detailed description taken in conjunction with the drawings and the claims. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Figure 1 shows the frequency band overlapping. Figure 2 shows the list of PLMNs where the quad band supported region exists. DETAILED DESCRIPTION OF THE INVENTION The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. The MS will maintain a list called Quad Band Supported Geographical Area, Gq (FIGURE 1). This Geographical region list will have the PLMN IDs which has over lapping bands or neighbors surround the PLMN supporting other band and for those PLMNs, MS is expected to search for all the possible bands. This list can be updated whenever UE finds service on non RBAND while doing search for both the bands periodically. This periodicity can be implementation dependent based on trade off between battery life and camping time. Geographical List of PLMNs where quad band supported region exists (FIGURE 2). The region consisting of PLMN IDs not present in the list Geographical are assumed to be supporting single band region. When UE camps on any one PLMN of the Gq (geographical regions) it will search for all the bands which UE is capable of. And in other cases the search will be restricted to the RBAND of previously camped PLMN and periodically it will search for the service on other bands that UE is capable of. Approach 1: The Geographical information is stored in the Non Volatile (NV) memory of the Mobile Station based on the information received from the operator. UE will use this data base information for latching on to the network. This NV items will be initialized during the manufacturing of the UE based on the network planning. If UE is able to find any new PLMN in due course of time, this list can be updated accordingly. Approach 2: There will be a list of PLMNs which is surrounded with Quad Band Supported region (Gq) in the SIM. MS will compare the previously camped PLMN ID with the Gq list. If it matches with any of the Gq list then UE will search all the bands which UE is capable of. The Gq list can be updated by OTA message if there is any change in NW planning. By this approach the PLMNs of Gq can be updated by the operator as and when there is change in network planning (supporting non conventional bands of that country). Behavior of the UE under different scenarios are explained below Figure 3 is the flow chart showing the various steps undergone by UE during power ON. During power ON, UE will search for bands corresponding to the bands supported by the RPLMN. The steps involved are; i) After switching on the mobile, UE will search for bands supported by RPLMN. ii) If UE is not able to acquire service for RPLMN bands, then all the bands that UE is capable of will be searched, iii) If it gets the service, it starts processing the corresponding signals of the selected band Steps undergone by UE on powering ON. i) During Power ON user equipment will trigger for the service on the RPLMN. ii) If UE is not able to camp on the RPLMN/RBAND combination then UE will check if the RPLMN of the UE belongs to Gq. Then trigger for the normal service for all the supported bands until it gets the service. iii) If the RPLMN of the UE doesn't belongs to Gq, then UE will trigger for the normal service on the band set on which it has previously camped on and repeat this procedure for n iteration. iv) If UE is not able to get the service in n iteration, it will trigger for the services on other set of supported bands. This will enable the UE to scan for other bands also as it may get service on other bands. This scenario will occur when UE loss the coverage and trying to regain the services. Figure 4 is the flow chart showing the various steps undergone by UE during back ground scanning. The steps are: i) The background search is initialized to search for the previously camped PLMN. ii) The system checks whether the RPLMN belongs to any of the PLMN's which is present in the Gq list, iii) If the camped PLMN belongs to the list, UE will search in all the supported bands, iv) If it is not present UE will search for the RBAND and for every nth trial UE will search for all supported bands. Steps undergone by UE during background scanning: Background scan will be triggered when the mobile is in national or international roaming. During the background scan UE will try to search if there is any HPLMN of ' the High priority PLMN available so that it can camp on those. Searching will be triggered on the RBAND or the all supported band depending on the PLMN on which it has camped on. If the camped PLMN belongs to Gq then UE will search for all the supported band and provide the set of available PLMNs. If UE is able to get HPLMN or Higher priority PLMN than what it is camped on it will try to register on it. Figure 5 is the flowchart showing the various steps undergone by UE during loss of coverage or emergency: i) If RPLMN (i.e. previously camped PLMN) of the UE belongs to Gq, then UE will trigger for normal search for all the bands which UE is capable of until it regains the service, ii) If the RPLMN of the UE doesn't belongs to Gq, then UE will trigger for the normal service on the band set on which it has previously camped on and repeat this procedure for n iteration, iii) If UE is not able to get the service in n iteration, it will trigger for the service on other set of supported bands. This will enable the UE to scan for other bands also as it may get service on other bands. This scenario will occur when UE loss the coverage and trying to regain the service. Steps undergone by UE during loss of coverage or emergency: If mobile loss the coverage or goes to emergency due to moving to week signal area, recovering back to service depends on the RPLMN/RBAND. This scenario is similar to power on case checking if the PLMN belonging to Gq or not. If it not belonging to the Gq then UE will trigger for search on the all possible supported band. If last camped PLMN doesn't belong Gq then UE will trigger for the service on the RBAND only. It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a microchip, microprocessor, handheld communication device, computer, rendering device or a multi function device. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. GLOSSARY OF TERMS AND DEFINITIONS THEREOF WE CLAIM 1. A method of network search optimization for multi band supported mobiles comprising the steps of: (a) maintaining a quad band supported geographical area list have the PLMN IDs by the mobile station; (b) searching for all possible bands by the mobile station when the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band; (c) updating the said list whenever the user equipment finds service on non RBAND while doing search for the possible bands periodically; (d) searching for all the bands which user equipment is capable of when the user equipment camps on any one PLMN of the geographical regions; and where in other cases the search is restricted to the RBAND of previously camped PLMN and periodically searches for the service on other bands that user equipment is capable of. 2. A method as claimed in claim 1 wherein the said geographical region list have the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band and for the said PLMN IDs, the mobile station is expected to search for all the possible bands. 3. A method as claimed in claim 1 wherein the periodicity of searching for the possible bands is implementation dependent based on trade off between battery life and camping time. 4. A method as claimed in claim 1 wherein the list of PLMNs which is surrounded with quad band supported region is stored in the SIM where mbbile station compares the previously camped PLMN ID with the said PLMN list. 5. A method as claimed in claim 1 wherein when mobile station compares the previously camped PLMN ID with the said PLMN list and if any match is found then user equipment searches all the bands which user equipment is capable of. 6. A method as claimed in claim 1 wherein quad band supported geographical area list is updated by OTA message if there is any change in network planning. 7. A method as claimed in claim 1 wherein after switching on the mobile, user equipment searches for bands supported by RPLMN. 8. A method as claimed in claim 7 wherein if user equipment is not able to acquire service for RPLMN bands, then all the bands that user equipment is capable of are searched. 9. A method as claimed in claim 7 wherein if user equipment is able to acquire service for RPLMN bands the user equipment starts processing the corresponding signals of the selected band. 10. A method as claimed in claim 1 wherein a background search is initialized to search for the previously camped PLMN. 11. A method as claimed in claim 10 wherein in the background search the user equipment checks whether the RPLMN belongs to any of the PLMN's which is present in the quad band supported geographical area list. 12. A method as claimed in claim 10 wherein in the background search if the camped PLMN belongs to the list, user equipment searches in all the supported bands. 13. A method as claimed in claim 10 wherein in the background search if the camped PLMN is not present user equipment searches for the RBAND and for every nth trial user equipment searches for all supported bands. 14. A method as claimed in claim 1 wherein during loss of coverage or emergency if RPLMN of the user equipment belongs to quad band supported geographical area list, then user equipment triggers for normal search for all the bands which user equipment is capable of until it regains the service. 15. A method as claimed in claim 14 wherein during loss of coverage or emergency if RPLMN of the user equipment does not belongs to quad band supported geographical area list then user equipment triggers for the normal service on the band set on which it has previously camped on and repeat the said procedure for n iterations. 16. A method as claimed in claim 14 wherein if user equipment is not able to get the service in n iteration, the user equipment triggers for the service on other set of supported bands which enables the user equipment to scan for other bands. 17. A method as claimed in claim 1 wherein the geographical area list is stored in the non-volatile memory of the mobile station based on the information received from an operator. 18. A method as claimed in claim 17 wherein the user equipment uses the stored information for latching on to the network where the non-volatile items are initialized during the manufacturing of the user based on the network planning. 19. A method as claimed in claim 17 wherein if the user equipment is able to find any new PLMN, the list is updated accordingly. 20. A method of network search optimization for multi band supported mobiles substantially described particularly with reference to the accompanying

Full Text

FIELD OF THE INVENTION
The present invention in general relates to communication systems which use radio frequency (RF) signals and, in particular, to systems for multi-mode, multi-band Code Division Multiple Access (CDMA) and Global System for Mobile (GSM) communication system. The invention particularly relates to battery life saving in multi-band, multi-mode supported mobiles by optimizing the network search for the different bands by considering their possibility of occurrence.
DESCRIPTION OF RELATED ART
The GSM communication standard is a worldwide mode of digital cellular communication operating over different frequency bands. GSM-850 operates in 850 MHz frequency band and is used in some parts of USA. GSM-900 is currently used in Europe and Asia. DCS is another digital cellular standard based on GSM technology, operating in the 1800 MHz frequency band and also currently used in Europe and Asia. The United States uses PCS, another digital cellular standard similar to DCS, but operating in the 1900 MHz band. GSM is currently used in approximately 154 countries, including the geographic areas of North Africa, India, China, Europe, the Middle East, and Taiwan.
CDMA, another mode of digital cellular communication operating in either the 900 or 1900 MHz band is one of the most widely used modes of cellular communication in the United States and Korea. WCDMA 2100 bands are used in some countries of Europe. CDMA is also being used in China, India, and Taiwan.
With improved voice and data communications and political climates continuing to expand the world market, a "world telephone" capable of operating in many different countries would be of interest to international business travelers. Multi-mode, multi-band cellular telephones with shared functionality and an optimized architecture capable of operating under all of these standards afford consumers widespread applicability and allow manufacturers to benefit from the

cost-efficiency of a common design.
However, multi-mode, multi-band cellular telephones such as combined CDMA/GSM telephones present a number of design challenges. When multi-band supported UE is powered ON or trying to recover from lack of coverage or while doing background scanning it will search in all the bands until it finds service. But all the bands are not expected to co-exist in a given geographical area. When UE is searching for service it may search in all the bands with equal priority. This will lead to excessive battery drain, though practically all the bands may not co-exist in most of the places.
So, there is a need for the UE to identify the bands which have high probability of existence in a given geographical area and spend more time in searching for those bands. This method should also take care of situations where the service exists in other bands also.
If the UE searches in both bands (PCS (GSM 850, 1900 and UMTS 2100 MHz) & DCS (GSM900 & 1800 MHz)), the battery will drain fast. If the UE searches only in one pair of Bands based on country, user may miss the service in regions of overlapping bands (for ex: DCS band & PCS bands exist in some states in US). So no Generic method solves this problem.
SUMMARY OF THE INVENTION
The present invention deals with optimization of battery consumption while searching for service when UE is in NO SERVICE or Emergency Service or while doing background scanning. Searching for the possible bands can be optimized by having the prior knowledge about the geographical regions where there will be over lapping bands and in other regions only one set of band can exist (for ex: DCS 1800 in Europe and PCS 1900 in USA).

Accordingly, this invention explains a method of network search optimization for multi band supported mobiles comprising the steps of:
(a) maintaining a quad band supported geographical area list have the PLMN IDs by the mobile station;
(b) searching for all possible bands by the mobile station when the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band;
(c) updating the said list whenever the user equipment finds service on non RBAND while doing search for the possible bands periodically;
(d) searching for all the bands which user equipment is capable of when the user equipment camps on any one PLMN of the geographical regions; and
where in other cases the search is restricted to the RBAND of previously camped PLMN and periodically searches for the service on other bands that user equipment is capable of.
The said geographical region list have the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band and for the said PLMN IDs, the mobile station is expected to search for all the possible bands. The periodicity of searching for the possible bands is implementation dependent based on trade off between battery life and camping time. The list of PLMNs which is surrounded with quad band supported region is stored in the SIM where mobile station compares the previously camped PLMN ID with the said PLMN list. When mobile station compares the previously camped PLMN ID with the said PLMN list and if any match is found then user equipment searches all the bands which user equipment is capable of. Quad band supported geographical area list is updated by OTA message if there is any change in network planning. After switching on the mobile, user equipment searches for bands supported by RPLMN. If user equipment is not able to acquire service for RPLMN bands, then all the bands that user equipment is capable of are searched. If user equipment is able to acquire service for RPLMN bands the user equipment starts processing the corresponding signals of the selected band.
A background search is initialized to search for the previously camped PLMN. In

the background search the user equipment checks whether the RPLMN belongs to any of the PLMN's which is present in the quad band supported geographical area list. In the background search if the camped PLMN belongs to the list, user equipment searches in all the supported bands. In the background search if the camped PLMN is not present user equipment searches for the RBAND and for every nth trial user equipment searches for all supported bands.
During loss of coverage or emergency if RPLMN of the user equipment belongs to quad band supported geographical area list, then user equipment triggers for normal search for all the bands which user equipment is capable of until it regains the service. During loss of coverage or emergency if RPLMN of the user equipment does not belongs to quad band supported geographical area list then user equipment triggers for the normal service on the band set on which it has previously camped on and repeat the said procedure for n iteration. If user equipment is not able to get the service in n iteration, the user equipment triggers for the service on other set of supported bands which enables the user equipment to scan for other bands.
In another approach the geographical area list is stored in the non-volatile memory of the mobile station based on the information received from a operator. The user equipment uses the stored information for latching on to the network where the non-volatile items are initialized during the manufacturing of the user based on the network planning. If the user equipment is able to find any new PLMN, the list is updated accordingly.
These and other objects, features and advantages of the present invention will become more readily apparent from the detailed description taken in conjunction with the drawings and the claims.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1 shows the frequency band overlapping.

Figure 2 shows the list of PLMNs where the quad band supported region exists.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail.
The MS will maintain a list called Quad Band Supported Geographical Area, Gq (FIGURE 1). This Geographical region list will have the PLMN IDs which has over lapping bands or neighbors surround the PLMN supporting other band and for those PLMNs, MS is expected to search for all the possible bands. This list can be updated whenever UE finds service on non RBAND while doing search for both the bands periodically. This periodicity can be implementation dependent based on trade off between battery life and camping time.
Geographical List of PLMNs where quad band supported region exists (FIGURE 2). The region consisting of PLMN IDs not present in the list Geographical are assumed to be supporting single band region.
When UE camps on any one PLMN of the Gq (geographical regions) it will search for all the bands which UE is capable of. And in other cases the search will be restricted to the RBAND of previously camped PLMN and periodically it will search for the service on other bands that UE is capable of.

Approach 1:
The Geographical information is stored in the Non Volatile (NV) memory of the Mobile Station based on the information received from the operator. UE will use this data base information for latching on to the network. This NV items will be initialized during the manufacturing of the UE based on the network planning. If UE is able to find any new PLMN in due course of time, this list can be updated accordingly.
Approach 2:
There will be a list of PLMNs which is surrounded with Quad Band Supported region (Gq) in the SIM. MS will compare the previously camped PLMN ID with the Gq list. If it matches with any of the Gq list then UE will search all the bands which UE is capable of. The Gq list can be updated by OTA message if there is any change in NW planning. By this approach the PLMNs of Gq can be updated by the operator as and when there is change in network planning (supporting non conventional bands of that country).
Behavior of the UE under different scenarios are explained below
Figure 3 is the flow chart showing the various steps undergone by UE during power ON. During power ON, UE will search for bands corresponding to the bands supported by the RPLMN. The steps involved are;
i) After switching on the mobile, UE will search for bands supported by
RPLMN. ii) If UE is not able to acquire service for RPLMN bands, then all the bands
that UE is capable of will be searched, iii) If it gets the service, it starts processing the corresponding signals of the
selected band

Steps undergone by UE on powering ON.
i) During Power ON user equipment will trigger for the service on the RPLMN.
ii) If UE is not able to camp on the RPLMN/RBAND combination then UE will check if the RPLMN of the UE belongs to Gq. Then trigger for the normal service for all the supported bands until it gets the service.
iii) If the RPLMN of the UE doesn't belongs to Gq, then UE will trigger for the normal service on the band set on which it has previously camped on and repeat this procedure for n iteration.
iv) If UE is not able to get the service in n iteration, it will trigger for the services on other set of supported bands. This will enable the UE to scan for other bands also as it may get service on other bands. This scenario will occur when UE loss the coverage and trying to regain the services.
Figure 4 is the flow chart showing the various steps undergone by UE during back ground scanning.
The steps are:
i) The background search is initialized to search for the previously camped
PLMN. ii) The system checks whether the RPLMN belongs to any of the PLMN's
which is present in the Gq list, iii) If the camped PLMN belongs to the list, UE will search in all the
supported bands, iv) If it is not present UE will search for the RBAND and for every nth trial
UE will search for all supported bands.
Steps undergone by UE during background scanning:
Background scan will be triggered when the mobile is in national or international roaming. During the background scan UE will try to search if there is any HPLMN of

' the High priority PLMN available so that it can camp on those. Searching will be triggered on the RBAND or the all supported band depending on the PLMN on which it has camped on. If the camped PLMN belongs to Gq then UE will search for all the supported band and provide the set of available PLMNs. If UE is able to get HPLMN or Higher priority PLMN than what it is camped on it will try to register on it.
Figure 5 is the flowchart showing the various steps undergone by UE during loss of coverage or emergency:
i) If RPLMN (i.e. previously camped PLMN) of the UE belongs to Gq, then
UE will trigger for normal search for all the bands which UE is capable of
until it regains the service, ii) If the RPLMN of the UE doesn't belongs to Gq, then UE will trigger for the
normal service on the band set on which it has previously camped on
and repeat this procedure for n iteration, iii) If UE is not able to get the service in n iteration, it will trigger for the
service on other set of supported bands. This will enable the UE to scan
for other bands also as it may get service on other bands. This scenario
will occur when UE loss the coverage and trying to regain the service.
Steps undergone by UE during loss of coverage or emergency: If mobile loss the coverage or goes to emergency due to moving to week signal area, recovering back to service depends on the RPLMN/RBAND. This scenario is similar to power on case checking if the PLMN belonging to Gq or not. If it not belonging to the Gq then UE will trigger for search on the all possible supported band. If last camped PLMN doesn't belong Gq then UE will trigger for the service on the RBAND only.
It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is

therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a microchip, microprocessor, handheld communication device, computer, rendering device or a multi function device.
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

GLOSSARY OF TERMS AND DEFINITIONS THEREOF

WE CLAIM
1. A method of network search optimization for multi band supported mobiles
comprising the steps of:
(a) maintaining a quad band supported geographical area list have the PLMN IDs by the mobile station;
(b) searching for all possible bands by the mobile station when the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band;
(c) updating the said list whenever the user equipment finds service on non RBAND while doing search for the possible bands periodically;
(d) searching for all the bands which user equipment is capable of when the user equipment camps on any one PLMN of the geographical regions; and
where in other cases the search is restricted to the RBAND of previously camped PLMN and periodically searches for the service on other bands that user equipment is capable of.
2. A method as claimed in claim 1 wherein the said geographical region list have the PLMN IDs which has over lapping bands surrounding the PLMN supporting other band and for the said PLMN IDs, the mobile station is expected to search for all the possible bands.
3. A method as claimed in claim 1 wherein the periodicity of searching for the possible bands is implementation dependent based on trade off between battery life and camping time.
4. A method as claimed in claim 1 wherein the list of PLMNs which is surrounded with quad band supported region is stored in the SIM where mbbile station compares the previously camped PLMN ID with the said PLMN list.
5. A method as claimed in claim 1 wherein when mobile station compares the previously camped PLMN ID with the said PLMN list and if any match is found

then user equipment searches all the bands which user equipment is capable of.
6. A method as claimed in claim 1 wherein quad band supported geographical area list is updated by OTA message if there is any change in network planning.
7. A method as claimed in claim 1 wherein after switching on the mobile, user equipment searches for bands supported by RPLMN.
8. A method as claimed in claim 7 wherein if user equipment is not able to acquire service for RPLMN bands, then all the bands that user equipment is capable of are searched.
9. A method as claimed in claim 7 wherein if user equipment is able to acquire service for RPLMN bands the user equipment starts processing the corresponding signals of the selected band.
10. A method as claimed in claim 1 wherein a background search is initialized to search for the previously camped PLMN.
11. A method as claimed in claim 10 wherein in the background search the user equipment checks whether the RPLMN belongs to any of the PLMN's which is present in the quad band supported geographical area list.
12. A method as claimed in claim 10 wherein in the background search if the camped PLMN belongs to the list, user equipment searches in all the supported bands.
13. A method as claimed in claim 10 wherein in the background search if the camped PLMN is not present user equipment searches for the RBAND and for every nth trial user equipment searches for all supported bands.
14. A method as claimed in claim 1 wherein during loss of coverage or emergency if

RPLMN of the user equipment belongs to quad band supported geographical area list, then user equipment triggers for normal search for all the bands which user equipment is capable of until it regains the service.
15. A method as claimed in claim 14 wherein during loss of coverage or emergency
if RPLMN of the user equipment does not belongs to quad band supported
geographical area list then user equipment triggers for the normal service on the
band set on which it has previously camped on and repeat the said procedure
for n iterations.
16. A method as claimed in claim 14 wherein if user equipment is not able to get the
service in n iteration, the user equipment triggers for the service on other set of
supported bands which enables the user equipment to scan for other bands.
17. A method as claimed in claim 1 wherein the geographical area list is stored in
the non-volatile memory of the mobile station based on the information received
from an operator.
18. A method as claimed in claim 17 wherein the user equipment uses the stored
information for latching on to the network where the non-volatile items are
initialized during the manufacturing of the user based on the network planning.
19. A method as claimed in claim 17 wherein if the user equipment is able to find
any new PLMN, the list is updated accordingly.
20. A method of network search optimization for multi band supported mobiles
substantially described particularly with reference to the accompanying

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=PhA5rf6fqjfQ0pLYF9miRg==&loc=egcICQiyoj82NGgGrC5ChA==

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Patent Number

268891

Indian Patent Application Number

1745/CHE/2005

PG Journal Number

39/2015

Publication Date

25-Sep-2015

Grant Date

22-Sep-2015

Date of Filing

28-Nov-2005

Name of Patentee

SAMSUNG R&D INSTITUTE INDIA-BANGALORE PRIVATE LIMITED

Applicant Address

#2870 ORION BUILDING BAGMANE CONSTELLATION BUSINESS PARK OUTER RING ROAD DODDANEKUNDI CIRCLE MARATHAHALLI POST BANGALORE 560037

Inventors:

#	Inventor's Name	Inventor's Address
1	SESHAGIRI R	EMPLOYED AT SAMSUNG ELECTRONICS CO LTD INDIA SOFTWARE OPERATIONS (SISO) J.P TECHNO PARK 3/1 MILLERS ROAD BANGALORE 560 052 KARNATAKA
2	A N V B RAJU	EMPLOYED AT SAMSUNG ELECTRONICS CO LTD INDIA SOFTWARE OPERATIONS (SISO) J.P TECHNO PARK 3/1 MILLERS ROAD BANGALORE
3	PRAKASH RAO	EMPLOYED AT SAMSUNG ELECTRONICS CO LTD INDIA SOFTWARE OPERATIONS (SISO) J.P TECHNO PARK 3/1 MILLERS ROAD BANGALORE 560 052 KARNATAKA
4	LAKSHMI NARAYANA KAVURI	EMPLOYED AT SAMSUNG ELECTRONICS CO LTD INDIA SOFTWARE OPERATIONS (SISO) J.P TECHNO PARK 3/1 MILLERS ROAD BANGALORE 560 052 KARNATAKA

PCT International Classification Number

H04Q7/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA