Method and apparatus for paging group handling

(54) Title: METHOD AND APPARATUS FOR HANDLING PAGER GROUPS (30) Unionist Priority: 31/01/2007 us 60 / 887,440 (73) Holder (s): interdigital Technology Corporation (72) Inventor (s): jin wang , peter s. wang, stephen e. terry (74) Attorney (s): Advocacia Pietro Ariboni S / C (86) International Request: pct us2oosooi267de 31/01/2008 (87) International Publication: wo 2008 / 094630de 07/08/2008 (57) Summary: Method and pager group manipulation apparatus. A method and apparatus for manipulating pager groups includes the grouping of wireless transmit and receive units (WTRUs) in a pager group. The pager group is assigned a pager occasion and the existence of content is indicated for WTRUs.

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Method and apparatus for manipulating pager groups.

FIELD OF THE INVENTION

This application relates to wireless communications.

BACKGROUND

One of the efforts for the long-term evolution program (LTE) of the third generation partnership project (3GPP) is to bring new technology, new architecture and new methods to the new LTE settings and configurations. The LTE program is designed to provide greater spectrum efficiency, reduced latency and better use of radio resources, in order to provide faster user experiences and richer applications and services with less associated cost.

Regarding the reception of pager in idle mode by mobile terminals, the LTE system can use the signaling control of lower link layer 1 (L1) and layer 2 (L2) to signal pager indicators for groups of transmission and reception units (WTRUs) with the same pager group identity. This may not be practical, however, in implementing certain aspects of pager group manipulation with respect to idle pager bases (such as total system paging capacity, system pager load distribution and flexibility in assigning to pagers). WTRUs of different discontinuous reception cycle (DRX) lengths in a single WTRU pager group).

It would therefore be beneficial to provide a method and apparatus for manipulating pager groups.

SUMMARY OF THE INVENTION

A method and apparatus for manipulating pager groups are described. The method includes grouping wireless transmit and receive units (WTRUs) into a pager group. The pager group is assigned a pager occasion and the existence of content is indicated for WTRUs.

BRIEF DESCRIPTION OF THE FIGURES

A more detailed understanding can be obtained from the description below, provided as an example and to be understood together with the attached Figures, in which:

- Figure 1 shows an example of a wireless communication system that includes a series of WTRUs and a base station;

Figure 2 is a functional block diagram of a WTRU and the base station of Figure 1;

Figure 3 is a flow chart of a method of manipulating pager groups;

Figure 4 shows an example of a basic pager occasion;

Figure 5 shows an example of bitmap representation of pager groups; and

Figure 6 is a diagram of an example LTE pager message.

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DETAILED DESCRIPTION

When indicated below, the terminology “wireless transmission and reception unit (WTRU)” includes, but is not limited to, user equipment (UE), mobile station (STA), fixed or mobile subscriber unit, pager, cell phone, personal digital assistant (PDA), computer or any other type of user device capable of operating in a wireless environment. When indicated below, the terminology “base station” includes, but is not limited to, a Node B, location controller, access point (AP) or any other type of interface device capable of operating in a wireless environment.

10 'Figure 1 shows a wireless communication system 100 that includes a series of WTRUs 110 and a base station 120. As shown in Figure 1, WTRUs 110 are separated, for example, into three pager groups called “ A ”that includes 110 WTRUs ^“ B ”that includes 110 WTRUs₂ and “C that includes 110 WTRUs₃. WTRUs 110 are in communication with base station 120. It should be noted that, although an example configuration of WTRUs 110 and base station 120 is illustrated in Figure 1, any combination of wired and wireless devices can be included in the wireless communication system 100.

Figure 2 is a functional block diagram 200 of a WTRU 110 and base station 120 of the wireless communication system 100 of Figure 1.

As shown in Figure 2, WTRU 110 is in communication with base station 120 and both are configured to perform a method of manipulating pager groups.

In addition to the components that can be found in a typical WTRU, the WTRU 110 includes a processor 115, a receiver 116, a transmitter 117 and an antenna 118. Processor 115 is configured to perform a pager group manipulation procedure. Receiver 116 and transmitter 117 are in communication with processor 115. Antenna 118 is in communication with receiver 116 and transmitter 117 to facilitate wireless data transmission and reception.

In addition to the components that can be found in a typical base station, base station 120 includes a processor 125, a receiver 126, a transmitter 127 and an antenna 128. Processor 125 is configured to perform a pager group manipulation procedure. Receiver 126 and transmitter 127 are in communication with processor 125. Antenna 128 is in communication with receiver 126 and transmitter 127 to facilitate wireless data transmission and reception.

The arrival of content received on a WTRU 110 is a random event. This should be considered in the light of the maintenance needs of the

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WTRU in idle mode for the maximum practicable time for energy saving. WTRU 110 should “wake up regularly to check for content. It may be desirable, therefore, to address an appropriate number of pager groups of WTRUs 110, while allowing different WTRUs 110 in a pager group to have different lengths of DRX cycles. In one example, a minimum pager occasion time unit is an LTE frame.

Consequently, Figure 3 is a flow chart of a method 300 of manipulating pager groups. In step 310, the WTRUs are grouped into pager groups. Again with reference to Figure 1, for example, the

10 'WTRUs 110i are placed in pager group A, WTRUs 110i₂ are placed in pager group B and WTRUs 110₃ are placed in pager group C.

In an LTE network, a pager group that has a pager group identity (PG ID) can be defined in a number of ways. WTRUs can be grouped numerically, for example, by the WTRU entity, such as the international mobile subscriber identity (IMSI) or the temporary mobile subscriber entity (TMSI). Due to the temporary nature of TMSI, however, IMSI can be a more stable identity to be used in LTE for pager handling in idle mode. Alternatively, the pager group can be logically grouped by network operators for the purpose of distinguishing or classifying services, differentiating network service handling and paying customer prioritization.

When the grouping is numeric, the following examples of methods can be used: ID PG = (IMSI mod cycle length DRX) or ID PG = (IMSI div cycle length DRX) + (IMSI mod cycle length DRX). The resulting pager group, ID PG, becomes the basic pager occasion payoff table number when all pager occasions for a specific WTRU are determined and a group of WTRUs with a similar numerical property to their IMSIs (or TMSI) with respect to the shortest DRX cycle length is defined by the LTE system. A WTRU 110 can derive its own PG ID by IMSI to which it is assigned with one of the equations above. If the WTRU 110 is assigned an IMSI of

18922, for example, and the network's DRX cycle length (as published in a system information transmission) is 32, the PG ID for that WTRU would be 10 (ten) according to the first equation (ie 18922 mod 32 = 10).

When grouping is logical, network operators may wish to group WTRUs 110 into sets of WTRUs based on certain properties or those requiring differential treatment. In this case, WTRUs are assigned to different local pager groups by the service provider / network in a specific service category, within a network source or using other properties. Examples of groupings may depend on the mobile network code

4/12 (MNC) of the WTRU IMSI, mobile country code (MCC) or certain attributes of the WTRU IMSI mobile station identification number (MSIN). Network operators can use some of the following possible combinations to define the pager occasion group identity:

- PG ID = e-UTRAN prefix || MNC || e-UTRAN suffix;

- PG ID = e-UTRAN prefix || MCC || e-UTRAN suffix; and

- PG ID = e-UTRAN prefix || (MSIN logical partition) || e-UTRAN suffix;

where the e-UTRAN prefix and e-UTRAN suffix can be any value, except one that is used for another PG ID in subsequent operations. Alternatively, a PG ID with other desired properties can be assigned.

Since WTRUs in idle mode periodically wake up to check if the E-UTRAN network has sent or is sending a specific pager indication to it and to its group of WTRUs, pager occasions are assigned to pager groups (step 320). A pager occasion, which can occur at the beginning of an LTE frame, defines a specific time when a WTRU must wake up to check if it is receiving pager messages. The LTE system distributes three paging occasions in the time domain, so that the pager load at any time is equalized and the WTRU that received pager messages receives the pager messages with minimal delay in relation to its rest and activity cycle (i.e., DRX cycle).

In step 330, WTRUs in a pager group can be assigned different DRX cycle lengths. Consequently, for a specific pager group, with respect to the PG ID, the system will need to determine a base pager occasion compensation that would be equivalent to a frame number.

Continuous and subsequent paging occasions are built on base paging occasion compensation. This base pager occasion compensation can be called PO-GP.

In the distribution of full pager occasions for different WTRUs that have different DRX cycle lengths, the PO-GP indicates, at the beginning of the system frame, a numerical scale that is used as the compensation frame number. This may be the shortest DRX cycle length by the LTE system due to the assignment of variable DRX cycle lengths that a WTRU can have, regardless of the pager group to which it belongs. A specific WTRU 110 may have the shortest or longest DRX cycle. Figure 4 shows an example of a 400 base pager occasion. Figure 4 shows a group of WTRUs 110 in a PG ID “A” which also includes PO GP “1”. These WTRUs have different lengths of DRX cycles that are displayed as 8 or 16. Consequently, WTRUs can expect their corresponding pager occasions on the

5/12 system frames (SFNs). A WTRU with cycle length DRX = 8, for example, would expect its pager at SFN 1, 9, 17, 25, 33 and the like, while a WTRU with cycle length DRX = 16 may expect its pager at 1, 17 , 33 and the like. A selection between DRX cycle lengths can include performance considerations against energy savings. The WTRU with a DRX cycle length of 8, for example, can consume more energy, but it can have more possibility of receiving a pager, which results in faster call reception, and the like.

Similar to the PG ID, the PO-PG can be determined numerically or logically. PO-PG can be determined numerically, for example, 'according to the equation; PO-PG = PG ID mod DRX cycle length, where the DRX cycle length is the minimum DRX cycle length defined by the system.

PG-OP can also be organized logically, especially for logically formed pager groups. In this case, the PG ID is converted to PO-GP by means of a mapping table if there is no short formula for numerical translation of PG ID into PO-GP where, for example, PG IDs are not sequenced consecutively. The mapping table can also be used to achieve the desired PO-GP distribution or retain the allocation flexibility, such that, for example, the new allocation can be easily arranged. Table 1 below shows an example of a table mapping a PG ID to a PO-GP.

Table 1

<td>PG ID (WTRU Group ID Allocated)</td><td>PO-GP (Base Pager Occasion Clearing Group)</td>

<td>PG ID A</td><td> 0</td>

<td>PG B ID</td><td> 1</td>

<td>PGC ID</td><td> 2</td>

<td>PG D ID</td><td> 2</td>

<td>PG ID E</td><td> 3</td>

<td></td><td></td>

<td>PG ID Nid pq max</td><td>φ</td>

It should be noted that N |_{0 PG} Max is the maximum number of pager groups that the LTE system will be able to accommodate, φ is an absolute value less than or equal to the shortest DRX cycle length minus one (φ &lt;shortest DRX cycle length - 1). Several pager groups can be assigned to the same PO-GP.

From the system's point of view, the PO-GP needs to be distributed to all occasions of frames covered in the shortest DRX cycle, from

6/12 in order to homogenize the pager load, as well as maintain the pager performance. In addition, more than one pager group can be assigned to the same PO-GP, in order to maintain the flexibility of DRX cycle length and to maximize the paging capacity of the system.

In a LTE system and WTRU, the general continuous paging occasions (ie, the “PO-FN” pager occasion frame numbers) with any DRX cycle lengths are calculated using PO-FN = PO-GP + n * DRX cycle length, where n = 0,1,2, ..., in such a way that the resulting PO-FN does not exceed the maximum number of frames in the system and the DRX cycle length is assigned by WTRU. In this way, the pager status for any specific WTRU 110 (step 340) is indicated.

On each pager occasion, PO-FN, a WTRU 110 in a DRX cycle in idle mode, as well as WTRUs 110 in their pager occasion group or other groups with the same PO-GP, agree to read the pager indication (step 350) based on the PO-GP it is in and the DRX cycle length to which it is assigned. Since more than one group of WTRUs 110 may be in the process of checking the pager indicator to find the pager status towards their group at the same time, the system may need to accommodate more pager groups in the limited space of the pager indicator and , at the same time, efficiently organize the space for indicating the situation of different pager groups.

One way to accommodate needs is to use a bitmap method to indicate the pager position of the pager groups belonging to a pager occasion (PO-GP). A bit in the map or pager status bit would indicate whether a specific pager group is receiving content (such as bit value "1") or not (such as bit value "0"). Figure 5 shows an example of bitmap representation of pager groups 500. As shown in Figure 5, the pager group ID “A” includes a PO-GP of 1, the pager group ID “B includes a PO-GP of 4 and the pager group ID“ C ”includes a PO-GP of 1. Each WTRU in a pager group reads the pager status bit in the bitmap during the pager occasion of the group and according to the DRTR cycle length of the WTRU, as indicated by the arrows shown in Figure 5, in order to determine whether or not there is content for the WTRU.

The bitmap construction is essentially a line of up to N bits where bit 0 represents the pager group with the lowest PG ID, bit 1 represents the group with the next PG ID value, and so on. Table 2 below shows an example of a bitmap for a PO-GP.

Table 2

<td>BitO</td><td>Bit 1</td><td>Bit 2</td><td></td><td>Bit n</td>

<td>PG ID a1</td><td>PG ID a2</td><td>PG ID a3</td><td></td><td>PG ID an</td>

7/12 where ID G a1 &lt;PG ID a2 &lt;PG ID a3 &lt;... &lt;PG ID an. There will be N (ie N = shorter cycle length

DRX - 1) bitmaps in the system, with one for each PO-GP position. The EUTRAN system transmits this PG / PO-GP ID mapping when transmitting system information. Table 3 below shows a PG ID mapping bitmap at the time of paging.

Table 3

<td></td><td>PO-GP 0</td><td>PO-GP 1</td><td>PO-GP 2</td><td></td><td>PO-GP N</td>

<td>Bit 0</td><td>PG ID a</td><td>PG ID x1</td><td>PG ID y1</td><td></td><td>PG ID z1</td>

<td>Bit 1</td><td>PG ID b</td><td>PG ID x2</td><td>PG ID y2</td><td></td><td>PG ID z2</td>

<td></td><td></td><td></td><td></td><td></td><td></td>

<td>Bit K</td><td>PG S ID</td><td>PG ID xn</td><td>PG ID yn</td><td></td><td></td>

If the E-UTRAN system has adopted the approach described in Table 1 above and published Table 1, however, WTRU 110 can calculate the bit position of its pager group based on the rule specified in Table 2 above.

As previously described, a WTRU 110 in idle mode wakes up at the pager occasions indicated by the PO-FN and checks the pager indicator. Based on the assigned PG ID and bit position in the bitmap, WTRU 110 checks whether its pager group (s) have active content, which can include whether the bit position J in the pager group bitmap is set or not.

If the bit position is set (that is, content is indicated), the WTRU 110 reads the physical LTE channel (PDSCH) (step 360), described by the radio bearer allocation (RB) part of the pager indicator, wherein an upper layer pager message will list the exact IMSI / TMSI of each of the WTRUs 110 receiving the pager message. If the WTRU 110 finds an exact match of your IMSI / TMSI, it indicates that there is a page for the WTRU 110.

In addition, the bitmap is defined by the E-UTRAN and is transmitted to each of the PO-GPs in the system information when the PO-GP receives this information in relation to PG IDs. Only one bitmap for each POGP needs to be transmitted. Consequently, although WTRUs in any specific group can have variable DRX cycles, they can use the same bitmap for all PG-FNs.

In one example, you can use a pager message

LTE when a WTRU receives signaling from a defined page and the exact WTRU is addressed directly to reset the pager. Figure 6 is an example of a diagram of

8/12 is an example of an LTE 600 pager message.

As shown in Figure 6, a WTRU in table 9 receives a pager indicator (obtained), which contains a “Pager Situation Bit Map” and “RB allocation information (LTE resource block)” so that the

WTRU receives the actual pager message (such as the LTE pager message) from another channel that carries the actual pager message. This provides time and physical channel information. If the bitmap status bit for your pager group is not set, the WTRU may not read the actual pager message in order to conserve energy.

10 'The LTE 600 pager message contains the pager records (ie the actual WTRU IMSIs) for each WTRU that actually received pager content. A WTRU checks the bitmap to look at its set PG ID bit and uses the RB allocation information to read the LTE 600 pager message. A WTRU determines that it receives pager messages by confirming that its

IMSI is found in the pager registers.

The number of IMSIs that can be addressed in an LTE pager message represents the maximum LTE paging capability and should be designed to take peak pager loads into account. If the defined IMSI conduction capacity is not large enough, certain

110 WTRUs can be left out of pager confirmation and may not receive incoming calls on time.

In addition, the LTE pager message record should contain as many WTRU IMSIs that received pager content as possible. If the allocated RB space is limited, extensions can be made to include all pager / IMSI records. The extension can be performed in the RB allocation part of the pager indicator, where a pointer can indicate another RB allocation or assist in the extension of LTE pager messages. Alternatively, the extended space can be resolved in the PCH domain, where additional space can be temporarily provided for the LTE pager message extension.

Additionally, to accommodate as many IMSIs in the message as possible, signal compression can be applied. Duplicate MCCs and MNCs do not need to be included in the message, which results in a direct list of IMSI MSINs in most cases, in order to save message space. IMSI formatting can start with the MCC and then move to the MNC and, finally, the MSIN. The MCC is the frontal index and then the MNC. If the next MCC or MNC is not different from the previous one, they do not need to be included. A WTRU search for an IMSI match can also use this formatting rule, disregarding MCCs and non-matching MNCs and going directly

9/12 for the MCC and coincident MNC to increase the efficiency of the pairing process.

Although the characteristics and elements are described above in specific combinations, each characteristic or element can be used alone, without the other characteristics and elements or in various combinations with or without other characteristics and elements. The methods or flowcharts provided herein may be implemented in a computer program, software or firmware embedded in a computer-readable storage medium for execution by a general purpose computer or processor. Examples of means of

10 'computer-readable storage includes read-only memory (ROM), random access memory (RAM), registry, cache memory, semiconductor memory devices, magnetic media such as internal hard drives and removable disks, magneto-optical media and optical media such as CD-ROM discs and digital versatile discs (DVDs).

Suitable processors include, for example, a general purpose processor, special purpose processor, conventional processor, digital signal processor (DSP), a series of microprocessors, one or more microprocessors in association with a DSP core, controller, microcontroller, Application Specific Integrated Circuits (ASICs),

Field Programmable Portal Sets (FPGAs), any other type of integrated circuit (IC) and / or state machine.

A processor in association with software can be used to implement a radio frequency transceiver for use in a wireless transmission and reception unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC) ) or any host computer. The WTRU can be used in conjunction with modules, implemented in hardware and / or software, such as a camera, video camera module, videophone, headset, vibrating device, speaker, microphone, television transceiver, headset handsfree headset, keyboard, Bluetooth® module, frequency modulated radio (FM) unit, liquid crystal display (LCD) unit, organic light-emitting diode (OLED) unit, digital music device, media player, video game module, Internet browser and / or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.

Achievements

1. Method of manipulating pager groups.

2. Method according to realization 1, which additionally comprises the grouping of wireless transmission and reception units (WTRUs) in at least one pager group.

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3. Method according to any of the previous achievements, which additionally includes the assignment of pager occasions to at least one pager group.

4. Method according to any of the previous achievements, which additionally includes the indication of the existence of content for the WTRUs.

5. Method according to any of the previous realizations, which additionally includes the assignment of lengths of discontinuous reception cycle (DRX) to WTRUs within at least one pager group.

6. Method according to any of the previous projects, in which the DRX cycle lengths of WTRUs are not identical.

7. Method according to any of the previous achievements, in which at least one pager group is determined numerically.

8. Method according to any of the previous achievements, in which at least one pager group is determined based on a WTRU identity.

9. Method according to any of the previous achievements, in which at least one pager group is determined based on the WTRU's international mobile subscriber identity (IMSI).

10. Method according to any of the previous achievements, in which at least one pager group is determined logically.

11. Method according to any of the previous achievements, in which a pager group is based on a WTRU service category.

12. Method according to any of the previous achievements, in which a pager group is based on a network source of the WTRU.

13. Method according to any of the previous accomplishments, which additionally comprises the distribution of the pager occasions for the WTRUs in the time domain.

14. Method according to any of the previous accomplishments, which additionally includes the determination of an occasion compensation of base pager.

15. Method according to any of the previous achievements, in which the base pager occasion compensation is determined numerically.

16. Method according to any of the previous achievements, in which the base pager occasion compensation is determined logically.

17. Method according to any of the previous achievements, which additionally comprises the mapping of a pager group to a base pager compensation location.

18. Method according to any of the previous achievements, in which the existence of content is indicated by a value of a bit in a bitmap in a long-term evolution indicator (LTE).

19. Method according to any of the previous accomplishments, in which the existence of

11/12 content is indicated by a long-term evolution (LTE) pager message.

20. Method according to any of the previous embodiments, in which the LTE pager message includes an international mobile subscriber identity (IMSI) of a WTRU for which content exists.

21. Base station configured to perform a method according to any of the previous accomplishments.

22. Base station according to embodiment 21, which additionally comprises a receiver.

23. Base station according to any of the embodiments 21 or 22, which additionally comprises 10 'a transmitter.

24. Base station according to any of the embodiments 21 to 23, which additionally comprises a processor in communication with the receiver and the transmitter.

25. Base station according to any of the realizations 21 to 24, in which a processor is configured to group wireless transmission and reception units (WTRUs) in at least one pager group, assign pager occasions to at least one pager group and indicate the existence of a page for WTRUs.

26. Base station according to any of the embodiments 21 to 25, in which a processor is additionally configured to assign lengths of discontinuous reception cycles (DRX) to WTRUs within at least one pager group.

27. Base station according to any of the embodiments 21 to 26, in which a processor is additionally configured to determine a base pager occasion compensation.

28. Base station according to any of the embodiments 21 to 27, in which a processor is additionally configured for a pager group for a base pager compensation location.

29. Base station according to any of the realizations 21 to 28 in which a processor is additionally configured to indicate the existence of content in a value of a bit in a bitmap in a long term evolution indicator (LTE).

30. Base station according to any of the realizations 21 to 29, in which a processor is additionally configured to indicate the existence of content through a long-term evolution (LTE) pager message.

31. Wireless transmission and reception unit (WTRU) configured to perform a method according to any of the realizations 1 to 20.

32. WTRU as per embodiment 31, which further comprises a receiver.

33. WTRU according to any of the embodiments 31 or 32, which additionally comprises a transmitter.

34. WTRU according to any of the embodiments 31 to 33, which additionally comprises a processor in communication with the receiver and the transmitter.

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35. WTRU according to any of the achievements 31 to 34, in which a processor is configured to wake up during a paging occasion, determine whether or not there is content for the WTRU and read a long-term evolution (LTE) physical channel (PDSCH) by means of determining whether or not the content exists.

36. WTRU according to any of the embodiments 31 to 35, in which a processor is additionally configured to receive an LTE pager message and determine whether or not there is content for the WTRU.

37. WTRU according to any of the embodiments 31 to 36, in which a processor is additionally configured to read a value of a bit in a bitmap in an 'LTE indicator to determine if a page exists for the WTRU.

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