Title of Invention	A METHOD FOR OVERLAYING ONE WIRELESS NETWORK SYSTEM OVER ANOTHER WIRELESS NET WORK SYSTEM OVER ANOTHER WIRELESS NETWORK SYSTEM
Abstract	The present invention relates to a method for overlaying incompatible 3G NETWORK on the existing widely deployed 2G NETWORK, where the following are carried out: a) Usage of Registration Zones of the existing 2G network to identify whether MS is in preferred (3G) RAT's area; b) Once MS finds that it is in a 2G registration zone where there is a deployment of preferred (3G) RAT NETWORK, then MS can trigger RF power measurements of preferred (3G) RAT. c) If RF channel power of preferred (3G) RAT is above some threshold consistently for some time, then MS can switch to preferred (3G) RAT NETWORK. No need to perform periodic measurements for preferred NETWORK when MS is camped on non-preferred NETWORK and this results in: A. Saving in sleep time and hence tremendous battery power saving; B. Savings in processing power. Usage of registration zone avoids Frequent Transition IDLE handoff between CDMA20001X and WCDMA NETWORK and provides Very cost effective solution for initial phase of the deployment (during trials, etc) as no complex NETWORK modifications are needed in this procedure.

Title of Invention

A METHOD FOR OVERLAYING ONE WIRELESS NETWORK SYSTEM OVER ANOTHER WIRELESS NET WORK SYSTEM OVER ANOTHER WIRELESS NETWORK SYSTEM

Abstract

The present invention relates to a method for overlaying incompatible 3G NETWORK on the existing widely deployed 2G NETWORK, where the following are carried out: a) Usage of Registration Zones of the existing 2G network to identify whether MS is in preferred (3G) RAT's area; b) Once MS finds that it is in a 2G registration zone where there is a deployment of preferred (3G) RAT NETWORK, then MS can trigger RF power measurements of preferred (3G) RAT. c) If RF channel power of preferred (3G) RAT is above some threshold consistently for some time, then MS can switch to preferred (3G) RAT NETWORK. No need to perform periodic measurements for preferred NETWORK when MS is camped on non-preferred NETWORK and this results in: A. Saving in sleep time and hence tremendous battery power saving; B. Savings in processing power. Usage of registration zone avoids Frequent Transition IDLE handoff between CDMA20001X and WCDMA NETWORK and provides Very cost effective solution for initial phase of the deployment (during trials, etc) as no complex NETWORK modifications are needed in this procedure.

Full Text	FIELD OF TECHNOLOGY The present invention relates to wireless communication systems including Cellular/Mobile/Wireless communications. More particularly this invention relates to a method for overlaying one wireless network system over another wireless network system. Also here it is assumed that the inter-operability specifications of these two systems are not yet standardized. This invention deals with dual-mode MS IDLE mode procedures for network selection when one wireless system is overlaid on another wireless system. These wireless network systems can be of any generation like 3G (WCDMA, CDMA20001x EVDV, etc) or 2G (CDMA20001x, GSM, etc). Here MS refers to Dual mode MS which supports operation in both 3G and 2G network systems and the preferred RAT is 3G. DESCRIPTION OF RELATED ART In the present scenario, there are several competing standards existing in mobile communications and each one is widely deployed in different countries. The most widely utilized standards are 3G and 2G standards. With the emergence of 3G standards, mobile/cellular operators have many choices to evolve their networks to 3G. But, "statutory bodies for standards" are yet to come up with inter-working specifications for competing 3G standards (and 2G standards). Also, since each 3G standard has its own evaluation path and been specified to keep it backward compatible with it's respective 2G standard, the evaluation from any 2G network to any other 3G network is not smooth. Also different operators/countries have adopted different 2G standards widely. In these circumstances and in the absence of inter-working specifications between competing 3G (and 2G) standards, operators/vendors need to come up with their own methods of deploying 3G network of their choice on the widely deployed 2G standard. i) One evolution path for the operators is: 1. To deploy the 3G network (for which there is no inter-working specification with the existing 2G network) in some areas where there is demand for 3G services; 2. To target at the initial stages, only to switch between two different RATs when MS is in IDLE mode; 3. To avoid supporting call handoffs from 2G network to 3G network or vice-versa, but the 2G calls can still be continued across boundaries without any problem as this is widely deployed; 4. To cut 3G calls when the MS is moving from 3G coverage area to 2G coverage area. ii) Issues to be considered in this evolution path: In this evolution path the issues are: • To decide as to whether MS is in the preferred RAT region in the absence of any directives from network; • To decide as to when and how MS takes decision to switch from non-preferred RAT to preferred RAT; • To decide how to carry out network planning in the absence of inter-working between networks with different RATs, so that MS knows which region it is. iii) Steps of operation (in IDLE mode) for this simple solution: 1. When MS is in non-preferred RAT (2G) network, MS keeps measuring preferred RAT's (3G) RF channel power periodically; 2. If RF channel power of preferred RAT is acceptable, then MS can simply tune to the preferred RAT network; 3. Once it tunes to preferred RAT, then MS can simply monitor preferred RAT's RF channel power; 4. Whenever RF channel power of preferred RAT is below some threshold, then MS can switch back to non-preferred RAT network. LIMITATIONS The simple method described above has the following limitations: 1. Except for the extensive RF measurements, there is no way for MS to recognize that it is in preferred mode network; 2. For measurements to be done periodically, the period is to be calculated; 3. If period is less, then RF measurements on preferred RAT is too often and this has following disadvantages: A. Processing power consumption is very high in tuning to new RAT and processing for RF measurements; B. Reduction in IDLE mode sleep time (when MS is operating in slotted mode) thereby considerably increasing battery power consumption. 4. If period is too high, then measurements on preferred RAT is seldom resulting in the following disadvantages: A. Camping on the non-preferred RAT for too long even though preferred RAT is available B. Still MS loses valuable sleep time whenever preferred RAT RF measurement is triggered Note: Sleep is an MS procedure in which MS operates in low power mode by shutting down some of the unused circuits to save battery power, OBJECTS OF THE INVENTION It is the primary object of the invention to invent a unique method of overlaying for over-laying a 3G wireless network system over a 2G wireless network system in which the second network system is incompatible with the first network system. It is another object of the invention to provide an efficient method of tracking of RAT zones by utilizing the concept of registration zones. It is another object of the invention to invent a method by which the present difficulty of frequent measurement of RAT is obviated and which leads to less power consumption by MS and reduces the need of availability of IDLE mode. SUMMARY OF THE INVENTION The present invention overcomes the limitations to overlay incompatible 3G network on the existing widely deployed 2G network, by the following steps: 1. Usage of Registration Zones of the existing 2G network to identify if the MS is in preferred (3G) RAT's area; 2. Once MS finds that it is in a registration zone where there is a deployment of preferred (3G) RAT network, then MS triggers RF power measurements of preferred (3G) RAT; 3. If RF channel power of preferred (3G) RAT is above some threshold consistently for some time, then MS can switch to preferred (3G) RAT network. Accordingly, the present invention comprises a method for over-laying a 3G wireless network system over a 2G wireless network system wherein, the following steps are carried out: a) using information regarding the Registration Zones of the existing 2G network, it is identified as to whether the Mobile Station is in preferred (3G) Radio Access Technology's (RAT's) area; b) Mobile Station triggers Radio Frequency power measurements of preferred (3G) Radio Access Technology (RAT) when Mobile Station determines that it is entering or is in 2G Registration Zone (REG ZONE) where there is 3G Network deployment and then, if Radio Frequency channel power of preferred (3G) Radio Access Technology (RAT) is consistently above certain threshold value. Mobile Station enters from non-preferred Radio Access Technology (RAT) NETWORK to preferred Radio Access Technology (RAT) NETWORK. The other objects, features and advantages of the present invention will be apparent from the accompanying drawings and the detailed description as follows. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Figure 1 illustrates existing network deployment with 2G RAT with an example of CDMA2000 1XasRAT. Figure 2 shows the flow chart for the steps of operation for NW (re-) selection by Dual mode MS in IDLE mode. Figure 3 illustrates a typical network planning for overlaying 3G network on existing 2G network as per the present invention; wherein: GREEN = 3G + 2G coverage area with 2G registration zone identified by (REG_Z0NE1,SID1,NID1) YELLOW = 3G + 2G coverage area with 2G registration zone identified by (REG_Z0NE2, SID1,NID1) PINK = 3G + 2G coverage area with 2G registration zone identified by (REG_Z0NE1, SID1,NID2) Here 2G is network is shown as CDMA2000. Colored cells are the ones which have 3G network overlaid on existing 2G network. Figures 4a and 4b: illustrate, respectively, simple procedure and the proposed procedure of the invention. DETAILED DESCRIPTION OF THE INVENTION A preferred embodiment of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. The following deschption 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. Whenever an operator wants to overlay an incompatible 3G standard in the area where there is widely deployed 2G network in a phased manner, in the initial phases of the deployment, operator chooses to have only a minimum set of functionality. For example, MS to move from non-preferred RAT to preferred RAT and vice-versa only in IDLE mode. The following conditions are considered: 1. 2G system is widely deployed in the entire coverage area; 2. MS has the capability to support both (2G and 3G) RATs (in terms of frequency bands and Radio Access Technology); 3. In the later phase of the deployment only, all advanced features like handoff of a (voice/data) call between 2G and 3G RATs are to be considered; 4. Operators/vendors have MORE flexibility to have the modifications in MS side than on network side to implement changes required for this kind of implementation; 5. Preferred system is 3G RAT/network and non-preferred system is 2G RAT/network. A method is proposed here based on Registration Zones of the existing 2G networks for various decisions to be made in MS. Procedures in brief 1.1: Network Planning: 1. Operators define the registration zones of 2G network where they want to overlay 3G network; 2. Operators have to plan their overlay such that the 3G network will be deployed/overlaid to fully cover the identified registration zones of the existing 2G network: A. If the existing 2G network deployment is such that new 3G network cannot be deployed to cover any of the registration zones of the existing 2G network, then it will not be so difficult for the operators to change some of the 2G network parameters to define new 2G registration zones. 3. The 2G registration zones are unique in that, by knowing the 2G registration zone, MS can recognize whether that particular area is covered by 3G network or not. The Mobile Power limits for CDMA2000 (3G) and CDMAone (2G) are as follows: Table 1- Test Parameters for Testing Occupied Bandwidth at IVIaximum R Output Power The following is the detailed procedure: 1.2: MS Procedures: 1. When MS is powered on, it will enter into System determination module; 2. MS's system determination module will look for the preferred RAT; 3. If MS finds preferred system: A. It will camp on the preferred system. 4. If MS doesn't find the preferred system: A. It will exit from searching for the preferred RAT, and search for 2G (non- preferred) RAT; B. Once it finds 2G network, MS will camp onto the 2G system. 1.2.1: If MS camps on to the 30 system: 1. MS keeps performing usual RF/channel measurements on the 30 system; 2. MS utilizes the services of 30 network; 3. If MS sees that RF/channel power of 30 system to be at unacceptable level consistently for some time, then MS switches back to 20 system; 1.2.2: If MS camps on to the 2G system: 1. MS keeps performing usual RF channel (pilot channel in CDMA2000) power measurements in the 20 system; 2. Whenever MS sees that there is a need to perform IDLE handoff within the 20 system, then MS performs the IDLE handoff; 3. While performing IDLE handoff, if MS enters into a new registration zone and if there is a need to perform registration on 2G system, tlien MS checks if that particular registration zone has 3G system coverage or not; 4. If it finds, there is a 3G system coverage in that registration coverage area: A. MS performs measurements on 30 system, and if power is acceptable, then it switches to 3G system; B. Then it performs the same tasks (mentioned in section 1.2.1) that MS generally does when it is camped onto 3G system. 5. If it doesn't find the 3G system in the registration area where there is supposed to be 3G coverage: A. Then, MS will come back and camp onto the 2G system; B. Now MS can turn on periodic measurements for the 3G RAT also as it is very likely to acquire 3G system in this 2G REG ZONE; C. At the time of these periodic measurements, if MS finds 3G system, then MS will acquire 3G system and does the same tasks as it does when it is camped onto 3G system; D. It is recommended that 3G system should fully cover the 2G registration zone so that the situation of MS not finding 3G system in the 2G registration zone where there is supposed to be 3G coverage does not arise. 6. MS can obtain the information regarding the 2G registration zones which have support for 3G from the parameters that are configured in non-volatile memory or SIM card of MS (see section 1.3). 1.3: MS configuration: 1. It is recommended that operators do not change the network planning too often which changes the pattern of 2G registration zones and their support for 3G coverage; 2. if network planning changes too frequently which affects 2G registration zone areas, then operators need to configure MSs to reflect the new 2G registration zones and their support for 3G coverage. For example, simple configuration table on MS side may look like this: Whenever this table is changed due to network re-planning, this table can be updated in MS by operator/vendor specific OTA or SMS procedures. Operation of the Invention An example of CDMA20001X as 2G NETWORK and WCDMA as 3G NETWORK is considered. Here it is assumed that CDMA20001X is deployed in the entire area (entire country or entire Operators coverage area as shown in Figure 1). CDMA20001X NETWORK has System ID (SID), Network ID (NID) and Registration zone (REG_ZONE) to uniquely define a registration zone. BTS informs SID, NID and REG_ZONE parameters to MS by System Parameters Message (SPM). MS can store more than one registration zone (TOTAL_ZONES) depending on the instruction from BTS. MS is considered to be registered in the zones that are present in its Registration zone list. Also MS maintains the timers (ZONE_TIMER) for each registration zone except for the registration zone that it has recently received in SPM. Once timer expires for a particular registration zone, it will be removed from registration zone list. Whenever MS does IDLE handoff, it will check if it is entering into a new registration zone and if it needs to do registration. When the size of registration zone list is made to ONE, then MS is forced to register whenever it enters into new registration zone. The mobile station shall perform zone-based registration if all the following conditions are met: A. TOTAL_ZONESs is not equal to zero; B. The stored configuration parameters are current; C. REG_ENABLEDs is equal to YES; and D. There is no entry of ZONE_LISTs whose SID, NID and REG_ZONE fields match the stored SIDs, NIDs and REG^ZONEs. Now, for overlaying WCDMA network on the existing widely deployed CDMA20001X network: 1. The registration zones (REG_ZONE, NID and SID) in which operator would like to (fully) overlay WCDMA network are defined. 2. The WCDMA network is overlaid on the identified CDMA20001x registration zones such that WCDMA network fully covers the CDMA2000 1X registration zones (as shown in Figure 3) 3. The MS CDMA20001X network parameters are configured such that MS recognizes the registration zones in which there is a WCDMA coverage Now when MS is powered on, and if the preferred mode is WCDMA, the MS tries to acquire WCDMA network. If MS is able to acquire WCDMA network, it follows the sequence of operations mentioned in section 1.2.1. If MS is not able to acquire WCDMA network, then the following procedure (see Figure 4b for flow chart description of this procedure) is applicable: 1. MS will acquire CDMA20001X network. 2. Whenever MS does IDLE handoff (HO) to a new registration zone and if it needs to perform registration, MS checks if there is coverage for WCDMA network. A. The IDLE HO can be made to new registration zones (may be in which there is WCDMA coverage) little harder by making expected pilot strength little more than that is usually needed. This avoids lot of Frequent Transition handoffs between WCDMA and CDMA20001X networks. 3. If MS finds there is WCDMA coverage, then MS can acquire WCDMA network and perform registration in WCDMA network to announce its presence. A. Here an optional power-down registration is done to CDMA20001X NETWORK to inform the NETWORK that MS is exiting out of it's region and no need to page to that MS from CDMA20001X NETWORK. 4. Whenever MS finds WCDMA NETWORK signal strength is at unacceptable levels, then MS can acquire CDMA20001X NETWORK and perform registration in CDMA20001X NETWORK. Note: At the time of IDLE HO, if MS finds (by virtue of REG^ZONE info) that the target cell has WCDMA coverage but still the WCDMA signal strength is not good, then MS can trigger for continuous 3G signal measuremets as it is very likely to find 3G system in the target cell. Effects/Advantage(s) of the Invention a) Advantages: 1. As the novel procedure of utilization of registration zones is incorporated here there is no need to make the continuous RF measurement for 3G system when MS is camped on non-preferred network. This results in the following advantages: A. Saving in sleep time and hence tremendous battery power saving; B. Savings in processing power. 2. Usage of registration zone avoids Frequent Transition IDLE handoff between 2G and 3G networks. That is providing some histerysis to move from 2G network to 3G network; 3. Very cost effective solution for initial phase of the deployment (during trials, etc.) as no complex/costly network modifications are needed in this procedure. b) Effects: 1. Definition of NETWORK planning parameters if there is a need to redefine the registration zones; 2. Configuration of MSs whenever there is a change in overlay network plan which impact the 2G registration zone and 3G system coverage relationship. 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 computer, printer 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 THEIR DEFINITIONS 2G Second Generation 3G Third Generation MS Mobile Station BTS Base Terminal Station NW Network CDMA20001X Code Division Multiple Access 20001X WCDMA Wideband Code Division Multiple Access RAT Radio Access Technology IDLE mode Mode of MS when there is no dedicated connection between MS and network HO Handoff SID System Identification (used in CDMA20001X network) NID Network Identification (used in CDMA20001X network) REG_ZONE Registration zone (used in CDMA20001X network) TOTAL_ZONES Total number of zones ZONE_LISTS List of zones RF Radio Frequency SIM Subscriber Identification Module SMS Short Messaging Service OTA Over The Air provisioning WE CLAIM 1. A method for over-laying a 3G wireless network system over a 2G wireless network system wherein, the following steps are carried out: a) using information regarding the Registration Zones of the existing 2G network, it is identified as to whether the Mobile Station is in preferred (3G) Radio Access Technology's (RAT's) area; b) Mobile Station triggers Radio Frequency power measurements of preferred (3G) Radio Access Technology (RAT) when Mobile Station determines that it is entering or is in 2G Registration Zone (REG ZONE) where there is 3G Network deployment and then, if Radio Frequency channel power of preferred (3G) Radio Access Technology (RAT) is consistently above certain threshold value. Mobile Station enters from non-preferred Radio Access Technology (RAT) NETWORK to preferred Radio Access Technology (RAT) NETWORK. 2. A method for over-laying a 3G wireless network system over a 2G wireless network system as claimed in claim 1 wherein, tracking of Radio Access Technology (RAT) zones is carried out by utilising the concept of register zones and wherein, when 2G IDLE Handoff is needed and 2G Registration Zone is being crossed, the new Registration zone is checked for support for 3G Network, Radio Frequency measurements are carried out and thereby frequent Transition IDLE handoff between the two networks is avoided. 3. A method for over-laying a 3G wireless network system over a 2G wireless network system as claimed in claim 1 wherein, frequent measurement of Radio Access Technlogy is obviated for less power consumption by MS and reduced wake-up time in IDLE mode, in that, when MS decides to do IDLE Handoff and needs to enter into new registration zone of 2G system, then only if that particular registration zone has 3G system coverage, MS performs RF power measurements on 3G system, and if power is acceptable, then it switches to 3G system. 4. A method for over-laying a 3G wireless network system over a 2G wireless network system substantially as herein described particularly with reference to the accompanying drawings, namely figures 2, 3 and 4b.

Full Text

FIELD OF TECHNOLOGY
The present invention relates to wireless communication systems including Cellular/Mobile/Wireless communications. More particularly this invention relates to a method for overlaying one wireless network system over another wireless network system. Also here it is assumed that the inter-operability specifications of these two systems are not yet standardized.
This invention deals with dual-mode MS IDLE mode procedures for network selection when one wireless system is overlaid on another wireless system. These wireless network systems can be of any generation like 3G (WCDMA, CDMA20001x EVDV, etc) or 2G (CDMA20001x, GSM, etc).
Here MS refers to Dual mode MS which supports operation in both 3G and 2G network systems and the preferred RAT is 3G.
DESCRIPTION OF RELATED ART
In the present scenario, there are several competing standards existing in mobile communications and each one is widely deployed in different countries. The most widely utilized standards are 3G and 2G standards. With the emergence of 3G standards, mobile/cellular operators have many choices to evolve their networks to 3G. But, "statutory bodies for standards" are yet to come up with inter-working specifications for competing 3G standards (and 2G standards).
Also, since each 3G standard has its own evaluation path and been specified to keep it backward compatible with it's respective 2G standard, the evaluation from any 2G network to any other 3G network is not smooth. Also different operators/countries have adopted different 2G standards widely. In these circumstances and in the absence of inter-working specifications between competing 3G (and 2G) standards, operators/vendors need to come up with their own methods of deploying 3G network of their choice on the widely deployed 2G standard. i) One evolution path for the operators is:
1. To deploy the 3G network (for which there is no inter-working specification

with the existing 2G network) in some areas where there is demand for 3G services;
2. To target at the initial stages, only to switch between two different RATs when MS is in IDLE mode;
3. To avoid supporting call handoffs from 2G network to 3G network or vice-versa, but the 2G calls can still be continued across boundaries without any problem as this is widely deployed;
4. To cut 3G calls when the MS is moving from 3G coverage area to 2G coverage area.
ii) Issues to be considered in this evolution path:
In this evolution path the issues are:
• To decide as to whether MS is in the preferred RAT region in the absence of any directives from network;
• To decide as to when and how MS takes decision to switch from non-preferred RAT to preferred RAT;
• To decide how to carry out network planning in the absence of inter-working between networks with different RATs, so that MS knows which region it is.
iii) Steps of operation (in IDLE mode) for this simple solution:
1. When MS is in non-preferred RAT (2G) network, MS keeps measuring preferred RAT's (3G) RF channel power periodically;
2. If RF channel power of preferred RAT is acceptable, then MS can simply tune to the preferred RAT network;
3. Once it tunes to preferred RAT, then MS can simply monitor preferred RAT's RF channel power;
4. Whenever RF channel power of preferred RAT is below some threshold, then MS can switch back to non-preferred RAT network.
LIMITATIONS
The simple method described above has the following limitations:

1. Except for the extensive RF measurements, there is no way for MS to recognize that it is in preferred mode network;
2. For measurements to be done periodically, the period is to be calculated;
3. If period is less, then RF measurements on preferred RAT is too often and this has following disadvantages:
A. Processing power consumption is very high in tuning to new RAT and
processing for RF measurements;
B. Reduction in IDLE mode sleep time (when MS is operating in slotted
mode) thereby considerably increasing battery power consumption.
4. If period is too high, then measurements on preferred RAT is seldom resulting
in the following disadvantages:
A. Camping on the non-preferred RAT for too long even though preferred
RAT is available
B. Still MS loses valuable sleep time whenever preferred RAT RF
measurement is triggered
Note: Sleep is an MS procedure in which MS operates in low power mode by shutting down some of the unused circuits to save battery power,
OBJECTS OF THE INVENTION
It is the primary object of the invention to invent a unique method of overlaying for over-laying a 3G wireless network system over a 2G wireless network system in which the second network system is incompatible with the first network system.
It is another object of the invention to provide an efficient method of tracking of RAT zones by utilizing the concept of registration zones.
It is another object of the invention to invent a method by which the present difficulty of frequent measurement of RAT is obviated and which leads to less power consumption by MS and reduces the need of availability of IDLE mode.

SUMMARY OF THE INVENTION
The present invention overcomes the limitations to overlay incompatible 3G network on the existing widely deployed 2G network, by the following steps:
1. Usage of Registration Zones of the existing 2G network to identify if the MS is in preferred (3G) RAT's area;
2. Once MS finds that it is in a registration zone where there is a deployment of preferred (3G) RAT network, then MS triggers RF power measurements of preferred (3G) RAT;
3. If RF channel power of preferred (3G) RAT is above some threshold consistently for some time, then MS can switch to preferred (3G) RAT network.
Accordingly, the present invention comprises a method for over-laying a 3G wireless network system over a 2G wireless network system wherein, the following steps are carried out:
a) using information regarding the Registration Zones of the existing 2G network, it is identified as to whether the Mobile Station is in preferred (3G) Radio Access Technology's (RAT's) area;
b) Mobile Station triggers Radio Frequency power measurements of preferred (3G) Radio Access Technology (RAT) when Mobile Station determines that it is entering or is in 2G Registration Zone (REG ZONE) where there is 3G Network deployment and then, if Radio Frequency channel power of preferred (3G) Radio Access Technology (RAT) is consistently above certain threshold value. Mobile Station enters from non-preferred Radio Access Technology (RAT) NETWORK to preferred Radio Access Technology (RAT) NETWORK.
The other objects, features and advantages of the present invention will be apparent from the accompanying drawings and the detailed description as follows.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1 illustrates existing network deployment with 2G RAT with an example of

CDMA2000 1XasRAT.
Figure 2 shows the flow chart for the steps of operation for NW (re-) selection by Dual mode MS in IDLE mode.
Figure 3 illustrates a typical network planning for overlaying 3G network on existing
2G network as per the present invention; wherein:
GREEN = 3G + 2G coverage area with 2G registration zone identified by (REG_Z0NE1,SID1,NID1)
YELLOW = 3G + 2G coverage area with 2G registration zone identified by (REG_Z0NE2, SID1,NID1)
PINK = 3G + 2G coverage area with 2G registration zone identified by (REG_Z0NE1, SID1,NID2)
Here 2G is network is shown as CDMA2000. Colored cells are the ones which have 3G network overlaid on existing 2G network.
Figures 4a and 4b: illustrate, respectively, simple procedure and the proposed procedure of the invention.
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. The following deschption 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.
Whenever an operator wants to overlay an incompatible 3G standard in the area where there is widely deployed 2G network in a phased manner, in the initial phases of the deployment, operator chooses to have only a minimum set of functionality. For example, MS to move from non-preferred RAT to preferred RAT and vice-versa only in IDLE mode.
The following conditions are considered:
1. 2G system is widely deployed in the entire coverage area;
2. MS has the capability to support both (2G and 3G) RATs (in terms of frequency bands and Radio Access Technology);
3. In the later phase of the deployment only, all advanced features like handoff of a (voice/data) call between 2G and 3G RATs are to be considered;
4. Operators/vendors have MORE flexibility to have the modifications in MS side than on network side to implement changes required for this kind of implementation;
5. Preferred system is 3G RAT/network and non-preferred system is 2G RAT/network.
A method is proposed here based on Registration Zones of the existing 2G networks for various decisions to be made in MS.
Procedures in brief
1.1: Network Planning:
1. Operators define the registration zones of 2G network where they want to overlay 3G network;
2. Operators have to plan their overlay such that the 3G network will be deployed/overlaid to fully cover the identified registration zones of the existing 2G network:

A. If the existing 2G network deployment is such that new 3G network cannot be deployed to cover any of the registration zones of the existing 2G network, then it will not be so difficult for the operators to change some of the 2G network parameters to define new 2G registration zones.
3. The 2G registration zones are unique in that, by knowing the 2G registration zone, MS can recognize whether that particular area is covered by 3G network or not.
The Mobile Power limits for CDMA2000 (3G) and CDMAone (2G) are as follows:
Table 1- Test Parameters for Testing Occupied Bandwidth at IVIaximum R
Output Power

The following is the detailed procedure:
1.2: MS Procedures:
1. When MS is powered on, it will enter into System determination module;
2. MS's system determination module will look for the preferred RAT;
3. If MS finds preferred system:
A. It will camp on the preferred system.
4. If MS doesn't find the preferred system:
A. It will exit from searching for the preferred RAT, and search for 2G (non-
preferred) RAT;
B. Once it finds 2G network, MS will camp onto the 2G system.
1.2.1: If MS camps on to the 30 system:
1. MS keeps performing usual RF/channel measurements on the 30 system;
2. MS utilizes the services of 30 network;
3. If MS sees that RF/channel power of 30 system to be at unacceptable level consistently for some time, then MS switches back to 20 system;
1.2.2: If MS camps on to the 2G system:
1. MS keeps performing usual RF channel (pilot channel in CDMA2000) power
measurements in the 20 system;
2. Whenever MS sees that there is a need to perform IDLE handoff within the 20 system, then MS performs the IDLE handoff;
3. While performing IDLE handoff, if MS enters into a new registration zone and

if there is a need to perform registration on 2G system, tlien MS checks if that particular registration zone has 3G system coverage or not;
4. If it finds, there is a 3G system coverage in that registration coverage area:
A. MS performs measurements on 30 system, and if power is acceptable,
then it switches to 3G system;
B. Then it performs the same tasks (mentioned in section 1.2.1) that MS
generally does when it is camped onto 3G system.
5. If it doesn't find the 3G system in the registration area where there is
supposed to be 3G coverage:
A. Then, MS will come back and camp onto the 2G system;
B. Now MS can turn on periodic measurements for the 3G RAT also as it is
very likely to acquire 3G system in this 2G REG ZONE;
C. At the time of these periodic measurements, if MS finds 3G system, then
MS will acquire 3G system and does the same tasks as it does when it is
camped onto 3G system;
D. It is recommended that 3G system should fully cover the 2G registration
zone so that the situation of MS not finding 3G system in the 2G
registration zone where there is supposed to be 3G coverage does not
arise.
6. MS can obtain the information regarding the 2G registration zones which
have support for 3G from the parameters that are configured in non-volatile
memory or SIM card of MS (see section 1.3).
1.3: MS configuration:
1. It is recommended that operators do not change the network planning too often which changes the pattern of 2G registration zones and their support for 3G coverage;
2. if network planning changes too frequently which affects 2G registration zone areas, then operators need to configure MSs to reflect the new 2G registration zones and their support for 3G coverage.
For example, simple configuration table on MS side may look like this:

Whenever this table is changed due to network re-planning, this table can be updated in MS by operator/vendor specific OTA or SMS procedures.
Operation of the Invention
An example of CDMA20001X as 2G NETWORK and WCDMA as 3G NETWORK is considered. Here it is assumed that CDMA20001X is deployed in the entire area (entire country or entire Operators coverage area as shown in Figure 1).
CDMA20001X NETWORK has System ID (SID), Network ID (NID) and Registration zone (REG_ZONE) to uniquely define a registration zone.
BTS informs SID, NID and REG_ZONE parameters to MS by System Parameters Message (SPM). MS can store more than one registration zone (TOTAL_ZONES) depending on the instruction from BTS. MS is considered to be registered in the zones that are present in its Registration zone list. Also MS maintains the timers (ZONE_TIMER) for each registration zone except for the registration zone that it has recently received in SPM. Once timer expires for a particular registration zone, it will be removed from registration zone list.
Whenever MS does IDLE handoff, it will check if it is entering into a new registration zone and if it needs to do registration. When the size of registration zone list is made to ONE, then MS is forced to register whenever it enters into new registration zone.
The mobile station shall perform zone-based registration if all the following conditions are met:

A. TOTAL_ZONESs is not equal to zero;
B. The stored configuration parameters are current;
C. REG_ENABLEDs is equal to YES; and
D. There is no entry of ZONE_LISTs whose SID, NID and REG_ZONE fields
match the stored SIDs, NIDs and REG^ZONEs.
Now, for overlaying WCDMA network on the existing widely deployed CDMA20001X network:
1. The registration zones (REG_ZONE, NID and SID) in which operator would like to (fully) overlay WCDMA network are defined.
2. The WCDMA network is overlaid on the identified CDMA20001x registration zones such that WCDMA network fully covers the CDMA2000 1X registration zones (as shown in Figure 3)
3. The MS CDMA20001X network parameters are configured such that MS recognizes the registration zones in which there is a WCDMA coverage
Now when MS is powered on, and if the preferred mode is WCDMA, the MS tries to acquire WCDMA network.
If MS is able to acquire WCDMA network, it follows the sequence of operations mentioned in section 1.2.1.
If MS is not able to acquire WCDMA network, then the following procedure (see Figure 4b for flow chart description of this procedure) is applicable:
1. MS will acquire CDMA20001X network.
2. Whenever MS does IDLE handoff (HO) to a new registration zone and if it needs to perform registration, MS checks if there is coverage for WCDMA network.
A. The IDLE HO can be made to new registration zones (may be in which there is WCDMA coverage) little harder by making expected pilot strength little more than that is usually needed. This avoids lot of Frequent Transition handoffs between WCDMA and CDMA20001X networks.
3. If MS finds there is WCDMA coverage, then MS can acquire WCDMA
network and perform registration in WCDMA network to announce its

presence.
A. Here an optional power-down registration is done to CDMA20001X NETWORK to inform the NETWORK that MS is exiting out of it's region and no need to page to that MS from CDMA20001X NETWORK. 4. Whenever MS finds WCDMA NETWORK signal strength is at unacceptable
levels, then MS can acquire CDMA20001X NETWORK and perform
registration in CDMA20001X NETWORK.
Note: At the time of IDLE HO, if MS finds (by virtue of REG^ZONE info) that the target cell has WCDMA coverage but still the WCDMA signal strength is not good, then MS can trigger for continuous 3G signal measuremets as it is very likely to find 3G system in the target cell.
Effects/Advantage(s) of the Invention
a) Advantages:
1. As the novel procedure of utilization of registration zones is incorporated here
there is no need to make the continuous RF measurement for 3G system
when MS is camped on non-preferred network. This results in the following
advantages:
A. Saving in sleep time and hence tremendous battery power saving;
B. Savings in processing power.
2. Usage of registration zone avoids Frequent Transition IDLE handoff between 2G and 3G networks. That is providing some histerysis to move from 2G network to 3G network;
3. Very cost effective solution for initial phase of the deployment (during trials, etc.) as no complex/costly network modifications are needed in this procedure.
b) Effects:
1. Definition of NETWORK planning parameters if there is a need to redefine the registration zones;
2. Configuration of MSs whenever there is a change in overlay network plan which impact the 2G registration zone and 3G system coverage relationship.

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 computer, printer 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 THEIR DEFINITIONS
2G Second Generation
3G Third Generation
MS Mobile Station
BTS Base Terminal Station
NW Network
CDMA20001X Code Division Multiple Access 20001X
WCDMA Wideband Code Division Multiple Access
RAT Radio Access Technology
IDLE mode Mode of MS when there is no dedicated connection between
MS and network
HO Handoff
SID System Identification (used in CDMA20001X network)
NID Network Identification (used in CDMA20001X network)
REG_ZONE Registration zone (used in CDMA20001X network)
TOTAL_ZONES Total number of zones
ZONE_LISTS List of zones
RF Radio Frequency
SIM Subscriber Identification Module
SMS Short Messaging Service
OTA Over The Air provisioning

WE CLAIM
1. A method for over-laying a 3G wireless network system over a 2G wireless
network system wherein, the following steps are carried out:
a) using information regarding the Registration Zones of the existing 2G network, it is identified as to whether the Mobile Station is in preferred (3G) Radio Access Technology's (RAT's) area;
b) Mobile Station triggers Radio Frequency power measurements of preferred (3G) Radio Access Technology (RAT) when Mobile Station determines that it is entering or is in 2G Registration Zone (REG ZONE) where there is 3G Network deployment and then, if Radio Frequency channel power of preferred (3G) Radio Access Technology (RAT) is consistently above certain threshold value. Mobile Station enters from non-preferred Radio Access Technology (RAT) NETWORK to preferred Radio Access Technology (RAT) NETWORK.

2. A method for over-laying a 3G wireless network system over a 2G wireless network system as claimed in claim 1 wherein, tracking of Radio Access Technology (RAT) zones is carried out by utilising the concept of register zones and wherein, when 2G IDLE Handoff is needed and 2G Registration Zone is being crossed, the new Registration zone is checked for support for 3G Network, Radio Frequency measurements are carried out and thereby frequent Transition IDLE handoff between the two networks is avoided.
3. A method for over-laying a 3G wireless network system over a 2G wireless network system as claimed in claim 1 wherein, frequent measurement of Radio Access Technlogy is obviated for less power consumption by MS and reduced wake-up time in IDLE mode, in that, when MS decides to do IDLE Handoff and needs to enter into new registration zone of 2G system, then only if that particular registration zone has 3G system coverage, MS performs RF power measurements on 3G system, and if power is acceptable, then it switches to 3G system.

4. A method for over-laying a 3G wireless network system over a 2G wireless network system substantially as herein described particularly with reference to the accompanying drawings, namely figures 2, 3 and 4b.

Documents:

1044-che-2003-abstract.pdf

1044-che-2003-claims filed.pdf

1044-che-2003-claims granted.pdf

1044-che-2003-correspondnece-others.pdf

1044-che-2003-correspondnece-po.pdf

1044-che-2003-description(complete) filed.pdf

1044-che-2003-description(complete) granted.pdf

1044-che-2003-drawings.pdf

1044-che-2003-form 1.pdf

1044-che-2003-form 19.pdf

1044-che-2003-form 26.pdf

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Patent Number

203516

Indian Patent Application Number

1044/CHE/2003

PG Journal Number

13/2007

Publication Date

30-Mar-2007

Grant Date

27-Nov-2006

Date of Filing

23-Dec-2003

Name of Patentee

M/S. SAMSUNG ELECTRONICS CO. LTD

Applicant Address

BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, CV RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093

Inventors:

#	Inventor's Name	Inventor's Address
1	TIRUMALA SREE HARI VARA PRASAD	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, CV RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093
2	VADLAPUDI	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, CV RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093

PCT International Classification Number

H04Q 7/20

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA