WO2015140635A2

WO2015140635A2 - Method of establishing small data transmission connection

Info

Publication number: WO2015140635A2
Application number: PCT/IB2015/000542
Authority: WO
Inventors: Yonggang Wang; Hua Chao
Original assignee: Alcatel Lucent
Priority date: 2014-03-21
Filing date: 2015-03-20
Publication date: 2015-09-24
Also published as: TW201540113A; WO2015140635A3; CN104936207A

Abstract

The invention relates to a method, implemented in a core network node of a mobile communication network, of assisting an access network node in establishing small data transmission connection, the method comprises the core network node counting first information about traffic pattern within a first time window; and sending the first information to the access network node to indicate to the access network node to configure wireless access network parameter, wherein the first time window is longer than a time duration of the last connection. The present invention further relates to a method of establishing small data transmission connection in an access network node of a mobile communication network, the method comprises receiving first information about traffic pattern from a corresponding core network node, the first information being counted by the core network node within a first time window, wherein the first time window is longer than a time duration of the last connection.

Description

Method of Establishing Small

Data Transmission Connection

Field of the invention

The present invention relates to the communication technology, and particularly to a method of assisting access network node in establishing small data transmission connection in a core network node of a wireless communication system and a method of establishing small data transmission connection in an access network node of a wireless communication system.

Background of the invention

SA2 is working on the work item MTCe (Machine-Type and other mobile data application Communications Enhancements) and has discussed and documented some potential solutions for several key issues in the TR 23.887 "Machine-Type and other Mobile Data Application Communications Enhancements".

Within the solution 5.1.2.3.1 SA2 specified in TR 23.887, a new core network assistance information procedure over S IAP enables the base station to optimize the setting of these parameters in order to reduce the frequency of idle/active transitions, minimize network signaling and save user equipment battery consumption.

In the last meeting, RAN2 discussed the details of core network assisted base station parameters tuning and concluded as the following in "R2-141014 LS on core network assisted base station parameters tuning":

1) RAN2 agreed that information about the traffic patterns (e.g. CDF of packet inter-arrival times, details for RAN3) could be provided from the core network to random access network, if it is reliable and if it actually represents the expected user equipment activity pattern. 2) RAN2 would also like to note that the possibility to provide assistance information about the user equipment inactivity periods was discussed in general, i.e. not only for E-UTRAN but also for UTRAN.

RAN2 invites RAN3 to define the corresponding signaling and indicates whether this should be done only for E-UTRAN or for UTRAN as well.

In the following sections, the details of CDF of packet inter-arrival times are investigated which would be provided as this core network assistance procedure over S1AR

In order to minimize user equipment state transitions, solutions can be defined to keep the user equipment in connected mode while reducing the signaling overhead (e.g. modifying the value of the parameters for measurement reporting and handover behavior) and power consumption (e.g. adjusting the DRX cycle) resulting from connected mode.

For this solution, the base station may employ user inactivity timer to a very longer value. The purpose is to reduce the signaling overhead of frequent RRC connection establishments. The main benefits of the solution are: it doesn't have specification change to the protocol, and greatly reduces the signaling overhead.

However, there are several challenges for this solution, here the inventors of the present invention list them and point out the possible solvents:

Table 1 : Challenges and Solvents

Challenges Solvents

1 keeping user equipment in to optimize the connected mode will consume DRX parameter considerable amount of user

equipment power, because user

equipment will often send small

amounts of data, for example, maintenance of user equipment timing

advance, periodic channel sounding,

and measurement reports.

2 whether the control channel is to optimize the sufficient to support a large number of inactivity timer user equipments with small data

transmissions? The long connected

may be inefficient due to the very

long packet inter- arrival time.

3 for fast moving user equipments, to evaluate per the handover signaling would increase user equipment even more than the signaling of RRC specified "mobility connection establishment. state"

Having many user equipments in connected mode would waste network resources, handover related signaling and user equipment power if they are not properly configured. In order to make an optimal decision on when to keep the UE in connected mode and when in idle mode is required in

RAN2.

Summary of the invention

Based on the prior art described in the part background of the invention and the technical understanding of the existing technical problem, the present invention proposes: core network assisted base station parameters tuning aids the base station in optimizing RRC connection time and the value of the DRX cycle in order to minimize the user equipment state transitions and achieve optimum network behavior. For example, if the user equipment frequently changes its idle/active states, RAN could extend the RRC connection time of the user equipment compared to user equipment rarely changing its state. In addition, RAN could determine a longer DRX cycle for the user equipment in order to save the user equipment battery consumption.

A first aspect of the invention provides a method, implemented in a core network node of a mobile communication network, of assisting an access network node in establishing small data transmission connection, the method comprises:

(B) . the core network node counts first information about traffic pattern within a first time window; and

(C) . the first information is sent to the access network node to indicate to the access network node to configure wireless access network parameter,

wherein the first time window is longer than time duration of the last connection.

Those skilled in the art should understand that the time duration of the last connection herein is already known and the first time window is longer than time duration of the last connection, and advantageously the first time window is at least two times more than the time duration of the last connection. In addition, the first time window includes connected time, idle time etc.

In one embodiment of the present invention, the first information includes at least one of:

- connected time;

- idle time; and

- data packet inter-arrive time during the connected time.

In one embodiment of the present invention, each of the connected time, the idle time and the data packet inter-arrival time during the connected time includes a maximal value, a minimal value and/or an average value.

In one embodiment of the present invention, sending the first information to the access network node comprises adding the first information into an initial context setup request message and sending the initial context setup request message to the access network node via a context setup procedure.

In one embodiment of the present invention, the initial context setup request message is sent to the access network node via S 1AP.

In one embodiment of the present invention, the core network node is mobility management entity (MME).

Furthermore, the present invention provides a method of establishing small data transmission connection in an access network node of a mobile communication network, the method comprises:

(O). receiving first information about traffic pattern from a corresponding core network node, the first information being counted by the core network node within a first time window,

In one embodiment of the present invention, the first information is forwarded to a target access network node when the access network node receives a handover request.

In one embodiment of the present invention, forwarding the first information to the target access network node is performed by adding the first information into the handover request and sending the handover request to the target access network node via X2AP.

In one embodiment of the present invention, the access network node is a base station.

More specifically, these solutions for the details of assistance information for small data transmission are proposed in this invention.

Propose 1 : The counting of the traffic patterns should be implemented in the long duration and not only in the last connection in order to be reliable.

Propose 2: The information about the traffic pattern needs to include the connected time, the idle time and the packet inter-arrival time (during connected time). For each of the parameters here-above, the average, minimal and maximal value should be provided.

Propose 3 : The information about the traffic pattern is carried on the initial context setup procedure and added in the initial context setup request message. The information about the traffic patterns is added in X2AP in the handover request message.

It provides the details of assistance information to adjust the radio parameters for a given user equipment. Without this information it may takes some time in base station to find a more precise maximal value for the packet inter- arrival time/user equipment inactivity period and collect information that a user equipment is "stationary".

The proposals in this invention are very important for the solution of the core network assistance parameter tuning for SDTTE.

The mobility management entity, for instance, could provide core network assistance information to the RAN, which can enable the RAN to adjust/optimize the RAN parameters (DRX cycle, RRC user short/longer inactivity timer and statistics of packet inter-arrival time) applied to the user equipment and aid in the decision between handover and release of the user equipment and thus reduce the frequency of transitions between idle and connected states, minimize network signaling, and save UE battery consumption.

The details of assistance information never are discussed before and now this will be defined in the RAN3 as the final solution of the core network assistance parameter tuning for SDTTE.

To sum up, in the technical scheme of the present invention, core network assisted base station parameter tuning aids the base station in optimizing RRC connection time and the value of the DRX cycle in order to minimize the user equipment UE state transitions and achieve optimum network behavior. For example, if the user equipment UE frequently changes its idle/active states, RAN could extend the RRC connection time of the UE user equipment compared to user equipment UE rarely changing its state. In addition, RAN could determine a longer DRX cycle for the user equipment UE in order to save the user equipment UE battery consumption.

Brief description of drawings

Other features, objects and advantages of the invention will become more apparent upon review of the following detailed description of non-limiting embodiments taken with reference to the drawings in which:

Fig.l illustrates a flow chart 100 of the method 100, implemented in a core network node of a mobile communication network, of assisting an access network node in establishing small data transmission connection.

Identical or similar devices (modules) or steps will be denoted by identical or similar reference numerals throughout the drawings.

Detailed description of embodiments

The above described particular description of preferred embodiments will be given with reference to the drawings constituting a part of the invention. The drawings exemplarily illustrate particular embodiments, in which the invention can be practiced. The exemplary embodiments are not intended to exhaust all the embodiments of the invention. As can be appreciated, other embodiments can be possible or structural or logical modifications can be made without departing from the scope of the invention. Thus the following detailed description is not intended to be limiting, and the scope of the invention will be defined as in the appended claims.

Fig.l illustrates a flow chart of the method 100, implemented in a core network node of a mobile communication network, of assisting an access network node in establishing small data transmission connection in a core network node of a mobile communication network, as shown in Fig. 1, the method comprises the following steps:

First, in the method step 110, the core network node counts first information about traffic pattern within a first time window; and

Then, in the second method step 120, the first information is sent to the access network node to indicate to the access network node to configure wireless access network parameter, wherein the first time window is longer than time duration of the last connection.

- connected time;

- idle time; and

- data packet inter-arrival time during the connected time.

In one embodiment of the present invention, sending the first information to the access network node comprises adding the first information into an initial context setup request message and sending the initial context setup message to the access network node via a context setup procedure.

In one embodiment of the present invention, the initial context setup request message is sent to the access network node via S 1AP. In one embodiment of the present invention, the core network node is mobility management entity (MME).

receiving first information about traffic pattern counted by the core network node within a first time window from a corresponding core network node, wherein the first time window is longer than time duration of the last connection.

In one embodiment of the present invention, forwarding the first information to the target access network node is performed by adding the first information into the handover request and sending the handover request to the target access network node via X2AP. In one embodiment of the present invention, the access network node is a base station.

Core network assistance information is data derived by the MME. When user equipment becomes active, the information is provided by the MME to the base station enabling the base station to optimize the setting of RAN parameters in order to reduce the frequency of idle-active transitions, minimize network signaling, and save user equipment battery consumption. During handovers, the source base station forwards the assistance information to the target base station.

Details of Information RAN2 agreed that information about the traffic pattern (e.g. CDF of packet inter-arrival times, details for RAN3) could be provided from the core network to the RAN.

Here only the information of statistics of the last connection is not so good, because the traffic patterns may be far different between two successive connections. But in a long period, it will represent the steady status, for example, frequent or infrequent data. Therefore, the present invention proposes that these statistics are computed in a long duration, e.g. hours or days. This long duration is a period in which the user equipment actually represents the expected user equipment activity degree as a whole, such as high activity, activity or low activity.

The CDF of packet inter-arrival times would include many forms, for example, average, maximum, standard deviation or actual CDF curve. But on purpose to decrease the core network signaling load, these parameters are expected as simple as possible.

In order to describe the CDF of packet inter-arrival times, the present invention proposes the following simple parameters which are deemed as important:

average, maximal and minimal connected time

This statistics is computed by taking all connection phases experienced by the UE during the long duration period into account,

average, maximal and minimal idle time

This is the dual value of the last connected time. This statistics is computed by taking the time between any two connection phases experienced by the UE during the long duration period into account.

average, minimal and maximal inter-arrival time

Defined as the average (respectively minimum, maximum) of all inter-arrival times in the above total connected time i.e. by taking all phases when the UE was in connected mode during the long duration into account.

The base station which receives these parameters could determine the status of the data transmission. Therefore, the parameter of current connection, for example DRX and the inactivity timer could be set as the last observations.

Propose 2: The information about the traffic patterns needs include the connected time, the idle time and the packet inter-arrival time (during connected time). For each of the parameters here-above, the average, minimal and maximal value should be provided.

2. S IAP procedure and signaling

RAN2 has agreed that "the information shall cover all bearers of the UE and not just selected or individual bearers and activity generated by NAS signaling interactions shall be taken into account as well when computing the expected user equipment inactivity periods."

Since the statistics covers all bearers, the information would be sent to the base station at once the user equipment becomes active, i.e. the initial context setup procedure, establish an S 1UE context in the base station requested by the MME.

In addition, the parameters are assumed to be transferred to the target base station in case of handover. This requires including the information in the S IAP source base station to target base station transparent container and also in the X2AP Handover Request message.

Propose 3 : The information about the traffic patterns is carried on the initial context setup procedure and added in the initial context setup request message. The information on the traffic patterns is added in X2AP in the handover request message.

Those skilled in the art shall appreciate that the invention apparently will not be limited to the foregoing exemplary embodiments and can be embodied in other specific forms without departing from the spirit or essence of the invention. Accordingly the embodiments shall be construed anyway to be exemplary and non-limiting. Moreover apparently the term "comprising" will not preclude another element(s) or step(s), and the term "a" or "an" will not preclude plural. A plurality of elements stated in an apparatus claim can alternatively be embodied as a single element. The terms "first", "second", etc., are intended to designate a name but not to suggest any specific order.

Claims

1. A method, implemented in a core network node of a mobile communication network, of assisting an access network node in establishing small data transmission connection, the method comprising:

(B) . the core network node counting first information about traffic pattern within a first time window; and

(C) . sending the first information to the access network node to indicate to the access network node to configure wireless access network parameter, wherein the first time window is longer than time duration of the last connection.

2. The method according to claim 1, wherein the first information includes at least one of:

- connected time;

- idle time; and

- data packet inter-arrival time during the connected time.

3. The method according to claim 2, wherein each of the connected time, the idle time and the data packet inter-arrival time during the connected time includes a maximal value, a minimal value and/or an average value.

4. The method according to claim 1, wherein sending the first information to the access network node comprises adding the first information into an initial context setup request message and sending the initial context setup request message to the access network node via a context setup procedure.

5. The method according to claim 4, wherein the initial context setup request message is sent to the access network node via S 1AP.

6. The method according to claim 1, wherein the core network node is mobility management entity.

7. A method of establishing small data transmission connection in an access network node of a mobile communication network, the method comprising: (O). receiving first information about traffic pattern from a corresponding core network node, the first information being counted by the core network node within a first time window, wherein the first time window is longer than a time duration of the last connection.

8. The method according to claim 7, wherein the first information is forwarded to a target access network node when the access network node receives a handover request.

9. The method according to claim 8, wherein forwarding the first information to the target access network node is performed by adding the first information into the handover request and sending the handover request to the target access network node via X2AP.

10. The method according to any of claims 7 to 9, wherein the access network node is a base station.