WO2014111806A1

WO2014111806A1 - Method and apparatus for energy saving

Info

Publication number: WO2014111806A1
Application number: PCT/IB2014/000112
Authority: WO
Inventors: Chongxian Zhong; Tao Yang
Original assignee: Alcatel Lucent
Priority date: 2013-01-17
Filing date: 2014-01-13
Publication date: 2014-07-24
Also published as: CN103945502B; CN103945502A

Abstract

The present invention provides a method and apparatus for energy saving in a wireless communication network. The method includes steps performed by a first base station in the wireless communication network of: sending a measurement request to at least one second base station of a plurality of second base stations; receiving, from the at least one second base station, user-related information, wherein the user-related information is sent by the at least one second base station in response to receiving measurement results of their served users, and wherein the measurement results are obtained by the served users of the at least one second base station by measuring RSRPs of the first base station and the at least one second base station in response to the measurement request; and sending a compensation decision to the plurality of second base stations to enable at least a subset of the second base stations to enter a energy saving mode, if it is determined based on the user-related information that coverage can be provided to at least the subset of the plurality of second base stations.

Description

METHOD AND APPARATUS FOR ENERGY SAVING

FIELD OF THE DISCLOSURE

The present invention relates to energy saving (ES) in a wireless communication network, and in particular to energy saving in the wireless communication network with Quality of Service (QoS) requirements of users taken into account.

BACKGROUND

Energy efficiency in the infrastructure and terminal is an essential problem in Long Term Evolution (LTE)/Long Term Evolution- Advanced (LTE-A). In Release 9/10/11, specific work has been done for Evolved-Universal Territorial Radio Accessing Network (E-UTRAN) network energy saving respectively, including intra-eNB energy saving solution, inter-eNB cell switching on/off in overlapping scenario, inter-Radio Access Technology (RAT) cell switching on/off and cell probing enhancement. At RAN plenary#58 meeting, a new Study Item (SI) "Study on Energy Saving Enhancement for E-UTRAN" was approved as an important topic to be discussed in RAN3. In this SI, some potential problems are listed, among which the inter-eNB energy saving solution for non-overlapping scenario is an important issue. Although some high- level approaches have been generally described in the Technology Regulations of Rel-10 SI "Network Energy Saving for E-UTRAN", detailed implementation of candidate solutions has not been fully discussed. As one of the most important cases for energy saving in E-UTRAN, Case 1 of non-overlapping inter-eNB scenario should be further investigated, and new strategies for the energy saving of this case should be proposed accordingly.

Energy saving for non-overlapping scenario has been initially investigated under the Rel-10 SI "Network Energy Saving for E-UTRAN" (see "Network Energy Saving for E-UTRAN", CMCC, RAN#47 meeting). Three fundamental approaches were specified in TR 36.927, including Operations, Administration, and Maintenance (OAM)-based, signaling-based, and hybrid OAM & signaling -based approaches. However, these solutions were generally described in high-level and have not been fully discussed in Rel-11.

Moreover, the objective of these approaches is to guarantee the continuity of LTE coverage during ES operation. Although the continuity of LTE coverage could be guaranteed using these approaches, the QoS of some users may be negatively impacted when switching off some ES cells. This is undesirable especially for the users paying additional fee to access services with higher QoS requirements.

According to the above reasons, new strategies of switching off some cells for energy saving are necessary for Case 1 of inter-eNB non-overlapping scenario. As shown in Fig. 1, in the Case 1 of inter-eNB non-overlapping scenario, the basic coverage of ES cells (Cell B, Cell C, Cell D, Cell E, Cell F, Cell G, for example) is provided by one compensation cell (Cell A, for example) at off-peak time. In this case, there is a higher probability that the compensation cell cannot guarantee the QoS of all users if all the neighboring ES cells enter dormant mode. Generally, although the compensation cell could guarantee the basic coverage of all the neighboring cells, only a part of the neighboring cells can be switched off in order to guarantee the QoS of users, especially for the users paying additional fee to access services with higher QoS requirements. Therefore, it is necessary to decide which cell(s) can enter dormant mode for energy saving.

In order to guarantee the QoS requirements of different users, some important information should be exchanged between the compensation cell and ES cells or even between the core network and the involved cells. For example, QoS Class Identification (QCI) is an important parameter related to QoS which could be exchanged between the compensation cell and ES cells. However, QCI is just coarse information related to QoS. Other information, such as the type of users (gold, silver and etc.), the number of users, the position of users (edge user or center user) etc., will also impact the satisfaction degree of users' QoS. Therefore, an improved solution is needed for energy savings by utilizing a compensation cell in a wireless communication network, with the QoS requirements of different users taken into account.

SUMMARY

According to a first aspect of the present invention, there is provided a method for energy saving in a wireless communication network, including steps performed by a first base station in the wireless communication network of: sending a measurement request to at least one second base station of a plurality of second base stations; receiving, from the at least one second base station, user-related information, wherein the user-related information is sent by the at least one second base station in response to receiving measurement results of their served users, and wherein the measurement results are obtained by served users of the at least one second base station measuring RSRPs of the first base station and the at least one second base station in response to the measurement request; and sending a compensation decision to the plurality of second base stations to enable at least a subset of the plurality of second base stations to enter an energy saving mode, if it is determined based on the user-related information that coverage can be provided to at least the subset of the plurality of second base stations.

According to a second aspect of the present invention, there is provided a method for energy saving in a wireless communication network, including steps performed by a second base station in the wireless communication network of: receiving a measurement request from a first base station in the wireless communication network, wherein the measurement request is sent by the first base station to a plurality of second base stations including the second base station in the wireless communication network; sending user-related information to the first base station, wherein the user-related information is sent by the second base station in response to receiving measurement results of users served by the second base station, and wherein the measurement results are obtained by the served users measuring RSRPs of the first base station and the second base station in response to the measurement request; and receiving a compensation decision from the first base station to enter an energy saving mode, wherein the compensation decision is made based on the user-related information by the first base stations.

According to a third aspect of the present invention, there is provided an apparatus for energy saving in a wireless communication network, including: a measurement request sending unit configured to send a measurement request to at least one second base station of a plurality of second base stations; a user information receiving unit configured to receive, from the at least one second base station, user-related information, wherein the user-related information is sent by the at least one second base station in response to receiving measurement results of their served users, and wherein the measurement results are obtained by the served users of the at least one second base station measuring RSRPs of the first base station and the at least one second base station in response to the measurement request; and a compensation decision sending unit configured to send a compensation decision to the plurality of second base stations to enable at least a subset of the plurality of second base stations to enter an energy saving mode, if it is determined based on the user-related information that coverage can be provided to at least the subset of the plurality of second base stations.

According to a fourth aspect of the present invention, there is provided an apparatus for energy saving in a wireless communication network, including: a measurement request receiving unit configured to receive a measurement request from a first base station in the wireless communication network, wherein the measurement request is sent by the first base station to a plurality of second base stations including the second base station in the wireless communication network; a user information sending unit configured to send user-related information to the first base station, wherein the user-related information is sent by the second base station in response to receiving measurement results of users served by the second base station, and wherein the measurement results are obtained by the served users measuring RSRPs of the first base station and the second base station in response to the measurement request; and a compensation decision receiving unit configured to receive a compensation decision from the first base station to enter an energy saving mode, wherein the compensation decision is made based on the user- related information by the first base station.

Using the solutions of the present invention, not only a basic coverage can be provided to neighboring cells that entered ES mode, but also the QoS requirements of users in these cells can be guaranteed.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will be understood better and other objectives, details, features and advantages of the present invention will become more evident from the description of specific embodiments of the invention given in conjunction with the following figures, wherein:

Fig. 1 illustrates a schematic drawing of an inter-eNB non-overlapping scenario Casel in a wireless communication network;

Fig. 2 illustrates a signaling chart of an energy saving method according to a first embodiment of the present invention; Fig. 3 illustrates a signaling chart of an energy saving method according to a second embodiment of the present invention;

Fig. 4 illustrates a signaling chart of an energy saving method according to third embodiment of the present invention;

Fig. 5 illustrates a signaling chart of an energy saving method according to a fourth embodiment of the present invention;

Fig. 6 illustrates a schematic drawing for determining a final state of a potential ES cell by utilizing position information of a user according to an embodiment of the present invention;

Fig. 7 illustrates a schematic drawing of an apparatus for energy saving in the wireless communication network according to an embodiment of the present invention; and Fig. 8 illustrates a schematic drawing of an apparatus for energy saving in the wireless communication network according to an embodiment of the present invention.

Identical or similar numbers are used to indicate identical or similar or corresponding features and function throughout the figures. DETAILED DESCRIPTION

Preferred embodiments of the present invention will now be described in more details in conjunction with accompanying figures. Although preferred embodiments of the present invention are shown in the accompanying figures, it should be understood that the present disclosure can be embodied in various ways without being limited by the embodiments depicted herein. In contrast, the embodiments are provided herein to make the disclosure more throughout and complete and to convey the scope of the present disclosure to those skilled in this art.

Fig. 1 illustrates a schematic drawing of an inter-eNB non-overlapping scenario Casel in a wireless communication network. A coverage diagram for Cells A-G in a normal operation sate is shown in the left side of the Fig.l, while it's shown in the right side of the Fig.l that during an off-peak time, Cells B-G are switched off to enter a energy saving mode and Cell A is used as a compensation cell with its coverage extended to provide fundamental coverage for cells in the energy saving mode. According to the existing proposals, there are only two operation modes, in one of which all cells are in the energy saving mode and in the other of which no cell is in the energy saving mode. In the present disclosure, according to the context of the term "cell" being used, the term "cell" may refer to coverage of a base station and/or a base station or a base station subsystem for serving the coverage. In the present disclosure, according to the context, term "cell" can be used interchangeably with "base station", "eNB", etc. Moreover, according to different communication systems involved, "cell" may also refer to sector and so on. In view of this, the present disclosure proposes a solution that considers the QoS requirements of all users for energy saving by utilizing a compensation cell, so as to enable all or a subset of candidate ES cells to enter the energy saving mode.

Fig. 2 illustrates a signaling chart of an energy saving method 200 according to a first embodiment of the present invention. In the embodiment shown in Fig. 2, the ES method 200 is triggered by a base station of a cell that is to enter the ES mode, such as the base station of Cell B, and during the ES procedure only the ES Cell B is switched off. Therefore, in such an embodiment, information exchange for cell switching off and cell coverage extension is only required between the ES cell that triggers the ES procedure and a compensation cell. Herein, the neighboring cells other than the compensation cell A and the ES cell B, such as Cells C, D, E, F and G in Fig. l, are all called as potential ES cells.

As shown in Fig. 2, the method 200 starts at step 202. In step 202, the base station of the cell B decides to enter the ES mode based on an OAM configuration or property information so that the ES procedure is triggered. The property information per se is knowledge such as User Equipment (UE) measurement result, interference state and/or load information, etc..

Next, the base station of the ES cell B which triggers the ES procedure sends a compensation request to the compensation cell A (step 204). Upon receiving the compensation request, the base station of the compensation cell A transmits its Common Reference Signal (CRS) with a higher transmitting power (step 206), and sends a measurement request to the ES cell B (step 210). Herein, the transmitting power of the CRS should be high enough to guarantee that all users served by the neighboring cells can receive the CRS respectively. In one embodiment, the measurement request is used to request all users served by the ES cell B to measure the Reference Signal Receiving Powers (RSRPs) of its serving cell (i.e. Cell B) and the compensation cell A.

Upon receiving the measurement request, the base station of the ES cell B requests the users served by the ES cell B to measure the RSRPs of Cell B and the RSRP of the compensation cell A and to return the measured RSRPs to the base station of the ES cell B (step 212).

Upon receiving the measured RSRPs from the users of the ES cell B, the base station of the ES cell B sends user-related information to the compensation cell A via an X2 interface (step 220).

In one embodiment, the user-related information includes information related to QoS requirements of users such as types of users, number of users, serving types of users, and/or relative position relations between the users and the base stations of the compensation cell A and the ES cell B (for example, whether the user is an edge user or a center user of a cell).

Upon receiving the user-related information, the compensation cell A determines whether it is able to provide coverage for the ES cell B according to the received user-related information (step 222). In one embodiment, determining whether it is able to provide coverage for the ES cell B includes determining whether it is able to provide the coverage continuity for the ES cell B and whether it is able to satisfy the QoS requirements of all the users served by the ES cell B. If the compensation cell A determines that it is not able to provide coverage for the ES cell B according to the received user-related information, the energy saving method 200 ends, and the compensation cell A returns to its CRS transmitting power to a normal level and each cell, including all Cells A to G, keeps in its initial state. If the compensation cell A determines that it is able to provide coverage for the ES cell B according to the received user-related information, it sends a compensation decision to the ES cell B and all the neighboring potential ES cells (i.e. Cells C, D, E, F and G) (step 230).

According the compensation decision, the compensation cell A enters the compensation mode to extend its coverage to cover the ES cell B (step 232). According the compensation decision, the ES cell B enters the ES mode to switch off its base station to save energy (step 234).

According the compensation decision, the potential ES cells, i.e. Cell C, Cell D, Cell E, Cell F and Cell G, initiate corresponding Inter-Cell Interference Coordination (ICIC) schemes to mitigate the interferences caused by the extension of the compensation cell A (step 236). In one embodiment, the ICIC schemes used may be a conventional ICIC scheme. In another embodiment, the ICIC schemes used may be an enhanced ICIC (e-ICIC) scheme.

Fig. 3 illustrates a signaling chart of an energy saving method 300 according to a second embodiment of the present invention. In the embodiment shown in Fig.3, the method 300 is triggered by a base station of the cell that is to enter the ES mode, such as the base station of Cell B, and during the ES procedure, not only the ES Cell B that triggers the ES procedure but also all neighboring potential ES cells (such as Cells C, D, E, F and G in Fig. 1) are switched off. Therefore, in this embodiment, information exchange for cell switching off and cell coverage extension is required not only between the ES cell that triggers the ES procedure and the compensation cell but also between all neighboring potential ES cells and the compensation cell. As shown in Fig.3, steps 302, 304 and 306 of the method 300 are substantially the same with steps 202, 204 and 206 of the method 200 as shown in Fig. 2, therefore they are not described in detail.

The method 300 is different from the method 200 shown in Fig.2 in that in step 310, the base station of the compensation cell A sends a measurement request not only to the ES cell B but also to all neighboring potential ES cells (such as cells C, D, E, F, and G in Fig. 1). In one embodiment, the measurement request is used to request all users served by the ES cell B and all potential ES cells C, D, E, F and G to measure RSRPs of the corresponding serving cell and the compensation cell A.

Upon receiving the measurement request, base stations of cells B to G request users served by each of them to measure the RSRPs of the corresponding serving cell and the RSRP of the compensation cell A, respectively, and return the measured RSRPs to corresponding base stations (step 312).

Upon receiving the RSRPs measured by each of users of cells B to G, each base station of cells B to G sends user-related information to the compensation cell A via an X2 interface (step 320).

Upon receiving the user-related information, the compensation cell A determines whether it is able to provide coverage for the ES cell B and all potential ES cells C to G, according to the received user-related information (step 322). In one embodiment, determining whether it is able to provide coverage for the ES cell B and all potential ES cells C to G includes determining whether it is able to provide the coverage continuity for the ES cell B and all potential ES cells C to G and whether it is able to satisfy the QoS requirements of all the users served by the ES cell B and all potential ES cells C to G. If the compensation cell A determines that it is not able to provide coverage for the ES cell B and all potential ES cells C to G according to the received user-related information, the energy saving method 300 ends, and the compensation cell A returns to its CRS transmitting power to a normal level and each cell, including all cells A to G, keeps in its initial state.

If the compensation cell A determines that it is able to provide coverage for the ES cell B and all potential ES cells C to G according to the received user-related information, it sends a compensation decision to the ES cell B and all the potential ES cells C to G (step 330).

According to the compensation decision, the compensation cell A enters the compensation mode to extend its coverage to cover the ES cell B and all potential ES cells C to G (step 332).

According to the compensation decision, the ES cell B and all potential ES cells C to G enter the ES mode to swith off their base stations to save energy (step 334). Fig. 4 illustrates a signaling chart of an energy saving method 400 according to a third embodiment of the present invention. In the embodiment shown in Fig.4, the ES method 400 is triggered by a base station of a cell that is to enter the ES mode, such as the base station of the cell B, and during the ES procedure, not only the ES cell B that triggers the ES procedure but also a subset of the neighboring potential ES cells (such as cells C, F, and G in Fig. 4) are switched off. Similar to the method 300 shown in Fig. 3, in this embodiment, information exchange for cell switching off and cell coverage extension is required not only between the ES cell that triggers the ES procedure and the compensation cell but also between all neighboring potential ES cells and the compensation cell. As shown in Fig.4, steps 402, 404, 406, 410, 412, and 420 of the method 400 are substantially the same with steps 302, 304, 306, 310, 312, and 320 of the method 300 as shown in Fig. 3, therefore they are not described in detail.

The method 400 is different from the method 300 shown in Fig.3 in that upon receiving the user- related information, the compensation cell A determines whether it is able to provide coverage for the ES cell B and all potential ES cells C to G, according to the received user-related information (step 422). In one embodiment, determining whether it is able to provide the coverage for the ES cell B and all potential ES cells C to G includes determining whether it is able to provide the coverage continuity for the ES cell B and all potential ES cells C to G and whether it is able to satisfy the QoS requirements of all the users of the ES cell B and all potential ES cells C to G.

If the compensation cell A determines that it is not able to provide coverage for the ES cell B according to the received user-related information, the energy saving method 400 ends, and the compensation cell A returns to its CRS transmitting power to a normal level and each cell, including cells A to G, keeps in its initial state. If the compensation cell A determines that it is able to provide coverage for the ES cell B and all potential ES cells C to G, but it is only able to satisfy the QoS requirements of a subset of the users of these potential ES cells C to G, according to the received user-related information, the compensation cell A subsequently determines the final state in which each of the potential ES cells C to G should keep according to the received user-related information and sends a compensation decision to the ES cell B and all potential ES cells C to G (step 430). A method for determining the final state of a potential ES cell is described below in connection with Fig. 6. The compensation decision includes which one or more of base stations of ES cells C to G should enter the ES mode, which one or more of base stations of ES cells C to G should reduce its or their transmitting power and/or which one or more of base stations of ES cells C to G should keep in its or their normal state. For example, in one embodiment, the compensation decision includes that the potential ES cells C, F and G should enter the ES mode, the potential ES cell E should reduce its transmitting power and the potential ES cell D should keep in its normal state.

According to the compensation decision, the compensation cell A enters the compensation mode to extend its coverage to cover the ES cell B and potential ES cells that are determined to enter the ES mode, such as cells C, F, and G shown in Fig. 4 (step 432).

According to the compensation decision, the ES cell B and potential ES cells C, F, and G that are determined to enter the ES mode enter the ES mode to switch off their base stations to save energy (step 434).

According to the compensation decision, the potential ES cell E reduces its transmitting power, potential ES cell D keeps in its normal state, and the potential ES cells which do not enter the ES mode (such cells D and E) initiate corresponding ICIC schemes to mitigate the interferences caused by the extension of the compensation cell A (step 436). As mentioned above, the ICIC schemes used may be a conventional ICIC scheme or an e-ICIC scheme.

It can be seen from above that in all the above three embodiments, the ES procedure is triggered by the ES cell which decides to enter the ES mode per se. An energy saving method in which the ES procedure is triggered by the compensation cell A will be described below.

Fig. 5 illustrates a signaling chart of an energy saving method 500 according to a fourth embodiment of the present invention. In the embodiment shown in Fig.5, the ES method 500 is triggered by a compensation cell A, and in the ES procedure, all or a part of neighboring potential ES cells (such as cells B, C, F, and G shown in Fig.5) are switched off. Here, all neighboring cells of the compensation cell A are called as potential ES cells, such as cells B to G in Fig.l.

As shown in Fig. 5, the method 500 starts at step 502. In step 502, the base station of the compensation cell A decides to enter the compensation mode based on an OAM configuration or property information so that the ES procedure is triggered. As mentioned above, the property information is knowledge such as UE measurement result, interference state and/or load information, etc. Next, upon triggering the ES procedure, the base station of the compensation cell A transmits its common reference signal (CRS) with a higher transmitting power (step 506), and sends a measurement request to all the neighboring potential ES cells B to G. In this embodiment, the measurement request may also be regarded as an energy saving request or be included in an energy saving request. In one embodiment, the measurement request is used to request users served by the neighboring potential ES cells B to G to measure RSRPs of the corresponding serving cell and the compensation cell A.

Upon receiving the RSRPs measured by the users of all neighboring potential ES cells B to G, base stations of neighboring potential ES cells B to G send user-related information to the compensation cell A via an X2 interface, respectively (step 520).

In one embodiment, the user-related information includes information related to QoS requirements of users such as types of users, number of users, service types of users, and/or relative position relations between the users and the base stations of the compensation cell A and the neighboring potential ES cells B to G (for example, whether the user is an edge user or a center user of a cell).

Upon receiving the user-related information, the compensation cell A determines the final state in which each of the neighboring potential ES cells B to G should keep, according to the received user-related information (step 522), and sends a compensation decision to all the neighboring potential ES cells B to G (step 530). A method for determining the final state of potential ES cells is described in connection with Fig. 6 below.

The compensation decision includes which one or more of base stations of the potential ES cells B to G should enter the ES mode, which one or more of base stations of the potential ES cells B to G should reduce its or their transmitting power and/or which one or more of base stations of the potential ES cells B to G should keep in its or their normal state. For example, in one embodiment, the compensation decision includes that the potential ES cells B, C, F and G should enter the ES mode, the potential ES cell E should reduce its transmitting power and the potential ES cell D should keep in its normal state.

According to the compensation decision, the compensation cell A enters the compensation mode to extend its coverage to cover potential ES cells that are determined to enter the ES mode, such as potential ES cells B, C, F, and G shown in Fig.5 (step 532). According to the compensation decision, the potential ES cells B, C, F and G that are determined to enter the ES mode enter the ES mode to switch off their base stations to save energy (step 534).

According to the compensation decision, the potential ES cell E reduces its transmitting power, the potential ES cell D keeps in its normal state, and potential ES cells that do not enter the ES mode (such as cells D and E) initiate corresponding ICIC schemes to mitigate the interferences caused by the extension of the compensation cell A (step 536). As mentioned above, the ICIC schemes used may be a conventional ICIC scheme or an e-ICIC scheme.

It can be seen that when performing the energy saving solutions of the present invention, the QoS requirements of different users are considered. Generally, the user-related factors that impact QoS requirements could be outlined as follows:

- Number of served users

The larger the number of served users, the harder to guarantee the QoS requirements of all these users.

- Types of served users (gold, silver, ...)

The QoS requirements of the user with a higher priority should be satisfied firstly.

- Service types of served users

Generally, different services have different QoS requirements. The higher the QoS requirements, the more the resources allocated to these users.

- Distance between the base station and the served users

Considering the impact of channel fading, the larger the distance between the eNB and the served user, the more the resources allocated to the users to guarantee their QoS requirements.

Considering the impact of all these user-related factors, the information of the number of served users, the types of the served users, the types of different users, and the locations of the served users should be transferred from the potential ES cells to the compensation cell. Upon receiving the above information, the compensation cell may decide which one or more of the nodes should enter ES mode, which one or more of the nodes should keep in normal state, and which one or more of the nodes could reduce transmitting power based on the following criteria. (1) . Firstly, the QoS of the users initially served by the compensation cell and that of the users served by the cell which triggers the ES procedure should be guaranteed.

(2) In order to switch off more potential ES cells whose users could be served by the compensation cell after its coverage expansion, all the potential ES cells should be listed in an ascending order in terms of the resources needed to satisfy their served users' QoS requirements. The cells in the forepart of the list have higher priority to be switched off. In this way, the potential ES cells could be switched off as many as possible.

(3) Users with higher priority should be paid more attention to. The cell with larger number of high priority users, such as gold users, has lower priority of entering ES mode since if this cell is switched off, many high priority users' QoS requirements may not be guaranteed.

(4) Services with higher QoS requirements should be paid more attention to. The cell with larger number of higher QoS requirements users has lower priority of entering ES mode considering the fact that the higher the QoS requirement, the more the resources allocated to the user to guarantee its QoS requirement. (5) Edge users should be paid more attention to. Here, the "edge users" mean not only the edge users of the serving potential ES cells, but also the edge users of the compensation cell after its coverage expansion, especially for the latter ones. The potential ES cell serving more edge users of the compensation cell after coverage expansion has lower priority of entering ES mode considering the fact that the larger the distance between the base station and the served user, the more the resources required to guarantee its QoS.

Generally, criteria (l)-(4) are relatively easy to be implemented currently. However, the criterion

(5) cannot be implemented based on the existing specification. A user served by a potential ES cell can decide whether it is a potential edge user of the compensation cell after coverage expansion, using the RSRP measurement of the current serving cell.

In the following section, we propose a new scheme to determine whether a user served by a potential ES cell is an edge user of the compensation cell after coverage expansion.

In methods 200-500 described in connection with Figs. 2-5, in response to the measurement request of the compensation cell A, users measure the RSRPs of their serving cells and the compensation cell, and report the results to their serving cell accordingly. Based on the measured RSRP of the compensation cell, the position of a user is decided as follows: If RSRPcompensation ^{< Threshold}compensation for user u, it is determined that the user u is an edge user of the compensation cell; otherwise it is a center user of the compensation cell. where RSRP_c ^u _ompemation represents the RSRP of the compensation cell A measured by the user u, and Threshold_c ^u _ompensation represents a threshold preset for the RSRP of the compensation cell A measured by the user u.

In order to guarantee the QoS requirements better, the RSRP of each user's serving cell is also needed to be measured and reported. Based on the measured RSRP of the serving cell, the position of a user is decided as follows:

If RSRP"_erving < Threshoid"_erving for user u, it is determined that the user u is an edge user of the serving cell; otherwise it is a center user for the serving cell. where RSRP_s ^u _erving represents the RSRP of the user u's serving cell measured by the user u, and Threshold"_erving represents a threshold preset for the RSRP of the user u's serving cell measured by the user u.

Fig. 6 illustrates a schematic drawing for determining a final state of a potential ES cell by utilizing position information of a user according to an embodiment of the present invention. In methods 400-500 described above in connection with Figs. 4-5, the schematic drawing of Fig. 6 can be used to determine the final state of potential ES cells.

As shown in Fig. 6, if a user in a potential ES cell is an edge user of the serving cell and a center user of the compensation cell, this potential ES cell (e.g. Cell C in Fig.6) has a higher priority to enter ES mode.

If a user in a potential ES cell is both an edge user of the serving cell but also an edge user of the compensation cell, this potential ES cell (e.g. Cell D in Fig.6) has a lower priority to enter ES mode.

If most of the users in a potential ES cell are center users of the serving cell, and if the QoS requirements of all the users cannot be satisfied when this potential ES cell enters dormant mode, this potential ES cell (e.g. Cell E in Fig.6) can reduce its transmitting power for energy saving.

Fig. 7 illustrates a schematic drawing of an apparatus 700 for energy saving in the wireless communication network according to an embodiment of the present invention. The apparatus 700 may be or may be implemented on the base station of the compensation cell A in the embodiments described in connection with Figs. 1 to 6 above.

As shown, the apparatus 700 includes: a measurement request sending unit 710 configured to send a measurement request to at least one second base station of a plurality of second base stations (such as the base stations of cells B to G described in connection with Figs. 1 to 6); a user information receiving unit 720 configured to receive, from the at least one second base station, user-related information, the user-related information being sent by the at least one second base station in response to receiving measurement results of their served users, and the measurement results being obtained by the served users of the at least one second base station measuring RSRPs of the first base station (such as the base station of the compensation cell A described in connection with Figs. 1 to 6) and the at least one second base station in response to the measurement request; and a compensation decision sending unit 730 configured to send a compensation decision to the plurality of second base stations to enable at least a subset of the second base stations to enter an energy saving mode, if it is determined based on the user-related information that coverage can be provided to at least the subset of the plurality of second base stations.

In one embodiment, the measurement request sending unit 710 is further configured to send the measurement request to the at least one second base station of the plurality of second base stations in response to receiving a compensation request from one of the plurality of second base stations.

In one embodiment, the compensation decision is further configured to enable the first base station to enter a compensation mode.

In one embodiment, the first base station entering a compensation mode further comprises extending the coverage of the first base station to cover at least the subset of the second base stations.

In one embodiment, the compensation decision is further configured to enable second base stations, among the plurality of second base stations, that do not enter the energy saving mode to utilize ICIC technology to mitigate the interferences caused by the first base station.

In one embodiment, the user-related information comprises information related to QoS requirement of a user. In one embodiment, the user-related information comprises at least one of: types of users, number of users, service types of users, and relative position relations between the users and the first base station and the second base station.

Fig. 8 illustrates a schematic drawing of an apparatus 800 for energy saving in the wireless communication network according to an embodiment of the present invention. The apparatus 800 may be or may be implemented on the base station of the ES cell B in the embodiments described in connection with Figs. 1 to 6 above.

As shown, the apparatus 800 includes a measurement request receiving unit 810 configured to receive a measurement request from a first base station (such as the base station of the compensation cell A described in connection with Figs. 1 to 6) in the wireless communication network, the measurement request being sent by the first base station to a plurality of second base stations including the second base station (such the ES cell B) in the wireless communication network; a user information sending unit 820 configured to send user-related information to the first base station, the user-related information being sent by the second base station in response to receiving measurement results of users served by the second base station, and the measurement results being obtained by the served users measuring RSRPs of the first base station and the second base station in response to the measurement request; and a compensation decision receiving unit 830 configured to receive a compensation decision from the first base station to enter an energy saving mode, wherein the compensation decision is made based on the user-related information by the first base station.

In one embodiment, the apparatus 800 further comprises a unit configured to send a compensation request to the first base station.

In one embodiment, the compensation decision is further configured to enable the first base station to enter a compensation mode. In one embodiment, the first base station entering a compensation mode comprises extending the coverage of the first base station to cover at least the subset of the second base stations.

In one embodiment, the compensation decision is further configured to enable second base stations, among the plurality of second base stations, that do not enter the energy saving mode to utilize ICIC technology to mitigate the interferences caused by the first base station. In one embodiment, the user-related information comprises information related to QoS requirement of a user. In one embodiment, the user-related information comprises at least one of: types of users, number of users, service types of users, and relative position relations between the users and the first base station and the second base station.

Furthermore, according to another aspect of the present invention, a new strategy for the maintenance and exit of the ES state is considered with the QoS requirements for entering ES state taken into account.

If it is permitted to switch off only a subset of neighboring cells, the subset of neighboring ES cells should be re-evaluated to guarantee the QoS requirements of all served users. Some representative cases are described below.

Switching off more neighboring cells: When the QoS requirements of the users served by some neighboring normal state cells could be satisfied by the compensation cell, these cells could enter ES mode for further energy saving.

Switching on some neighboring ES cells: When the QoS requirements of all users served by the compensation cell cannot be satisfied, one or multiple ES cells should be switched on accordingly. In order to guarantee switching off more other neighboring cells in the near future, ES cells which may cover more users with higher QoS requirements should be switched on with a higher priority.

Similar to what is discussed above, once these ES cells are switched on, the corresponding ICIC schemes should be applied to mitigate the high inter-cell interference caused by the expansion of the compensation cell.

Exiting compensation state:

When all the neighboring cells enter normal state for satisfying the QoS requirements, the compensation cell should enter normal state since none of the neighboring cells needs compensation any longer.

In order to properly maintain and exit the ES/compensation state with the constraint of QoS requirements taken into account, some signaling and QoS related information should be exchanged between the compensation cell and all its neighboring cells including the normal state cells and ES cells. Moreover, the criteria and procedures for the maintenance and exit of the ES/compensation state should be aligned with the decisions taken for entering the ES state. While in some embodiments of the present invention the ES mode is described with the dormant mode as an example, those skilled in this art will understand that energy saving (ES) modes are not limited to the dormant mode, but any other modes under which the power consumption is lower than that of a normal operation state can be used. Moreover, the methods of the present disclosure have been described with reference to accompanying figures. It is understood by those skilled in this art that any specific order of steps illustrated in the accompanying figures and described in the description is only illustrative in that the method steps and/or actions can be performed in other orders other than the specific order of steps illustrated in the accompanying figures and described in the description while remaining within the scope of the present disclosure.

In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer- readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or performed by a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Those of skill would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

What is claimed:

1. A method for energy saving in a wireless communication network, comprising steps, performed by a first base station in the wireless communication network, of: sending a measurement request to at least one second base station of a plurality of second base stations; receiving, from the at least one second base station, user-related information, wherein the user-related information is sent by the at least one second base station in response to receiving measurement results of their served users, and wherein the measurement results are obtained by the served users of the at least one second base station measuring Reference Signal Receiving Powers (RSRPs) of the first base station and the at least one second base station in response to the measurement request; and sending a compensation decision to the plurality of second base stations to enable at least a subset of the plurality of second base stations to enter an energy saving mode, if it is determined based on the user-related information that coverage can be provided to at least the subset of the plurality of second base stations.

2. The method of claim 1, wherein sending the measurement request to the at least one second base station of the plurality of second base stations comprises sending the measurement request to the at least one second base station of the plurality of second base stations in response to receiving a compensation request from one of the plurality of second base stations.

3. The method of claim 1, wherein the compensation decision is further configured to enable the first base station to enter a compensation mode.

4. The method of claim 3, wherein the first base station entering a compensation mode further comprises extending coverage of the first base station to cover at least the subset of the second base stations.

5. The method of claim 1, wherein the compensation decision is further configured to enable second base stations, among the plurality of second base stations, that do not enter the energy saving mode to utilize Inter-Cell Interference Coordination (ICIC) technology to mitigate the interferences caused by the first base station.

6. The method of claim 1, wherein the user-related information comprises information related to Quality of Service (QoS) requirement of a user.

7. The method of claim 1, wherein the user-related information comprises at least one of: types of users, number of users, service types of users, and relative position relations between the users and the first base station and the second base stations.

8. A method for energy saving in a wireless communication network, comprising steps, performed by a second base station in the wireless communication network, of: receiving a measurement request from a first base station in the wireless communication network, wherein the measurement request is sent by the first base station to a plurality of second base stations including the second base station in the wireless communication network; sending user-related information to the first base station, wherein the user-related information is sent by the second base station in response to receiving measurement results of users served by the second base station, and wherein the measurement results are obtained by the served users measuring Reference Signal Receiving Powers (RSRPs) of the first base station and the second base station in response to the measurement request; and receiving a compensation decision from the first base station to enter an energy saving mode, wherein the compensation decision is made based on the user-related information by the first base station.

9. The method of claim 8, further comprising: sending a compensation request to the first base station.

10. The method of claim 8, wherein the compensation decision is further configured to enable the first base station to enter a compensation mode.

11. The method of claim 10, wherein the first base station entering a compensation mode comprises extending the coverage of the first base station to cover at least a subset of the plurality of second base stations.

12. The method of claim 8, wherein the compensation decision is further configured to enable second base stations, among the plurality of second base stations, that do not enter the energy saving mode to utilize Inter-Cell Interference Coordination (ICIC) technology to mitigate the interferences caused by the first base station.

13. The method of claim 8, wherein the user-related information comprises information related to Quality of Service (QoS) requirement of a user.

14. The method of claim 8, wherein the user-related information comprises at least one of: types of users, number of users, service types of users, and relative position relations between the users and the first base station and the second base station.

15. An apparatus for energy saving in a wireless communication network, comprising: a measurement request sending unit configured to send a measurement request to at least one second base station of a plurality of second base stations; a user information receiving unit configured to receive, from the at least one second base station, user-related information, wherein the user-related information is sent by the at least one second base station in response to receiving measurement results of their served users, and wherein the measurement results are obtained by the served users of the at least one second base station measuring Reference Signal Receiving Powers (RSRPs) of the first base station and the at least one second base station in response to the measurement request; and a compensation decision sending unit configured to send a compensation decision to the plurality of second base stations to enable at least a subset of the plurality of second base stations to enter an energy saving mode, if it is determined based on the user-related information that coverage can be provided to at least the subset of the plurality of second base stations.

16. The method of claim 15, wherein the measurement request sending unit is further configured to send the measurement request to the at least one second base station of the plurality of second base stations in response to receiving a compensation request from one of the plurality of second base stations.

17. The apparatus of claim 15, wherein the compensation decision is further configured to enable the first base station to enter a compensation mode.

18. The apparatus of claim 17, wherein the first base station entering a compensation mode further comprises extending coverage of the first base station to cover at least the subset of the second base stations.

19. The apparatus of claim 15, wherein, the compensation decision is further configured to enable second base stations, among the plurality of second base stations, that do not enter the energy saving mode to utilize Inter-Cell Interference Coordination (ICIC) technology to mitigate the interferences caused by the first base station.

20. The apparatus of claim 15, wherein the user-related information comprises information related to Quality of Service (QoS) requirement of a user.

21. The method of claim 15, wherein the user-related information comprises at least one of: types of users, number of users, service types of users, and relative position relations between the users and the first base station and the second base station.

22. An apparatus for energy saving in a wireless communication network, comprising: a measurement request receiving unit configured to receive a measurement request from a first base station in the wireless communication network, wherein the measurement request is sent by the first base station to a plurality of second base stations including the second base station in the wireless communication network; a user information sending unit configured to send user-related information to the first base station, wherein the user-related information is sent by the second base station in response to receiving measurement results of users served by the second base station, and wherein the measurement results are obtained by the served users measuring Reference Signal Receiving Powers (RSRPs) of the first base station and the second base station in response to the measurement request; and a compensation decision receiving unit configured to receive a compensation decision from the first base station to enter an energy saving mode, wherein the compensation decision is made based on the user-related information by the first base station.

23. The apparatus of claim 22, further comprising: a unit configured to send a compensation request to the first base station.

24. The apparatus of claim 22, wherein the compensation decision is further configured to enable the first base station to enter a compensation mode.

25. The apparatus of claim 24, wherein the first base station entering a compensation mode comprises extending the coverage of the first base station to cover at least a subset of the plurality of second base stations.

26. The apparatus of claim 22, wherein the compensation decision is further configured to enable second base stations, among the plurality of second base stations, that do not enter the energy saving mode to utilize Inter-Cell Interference Coordination (ICIC) technology to mitigate the interferences caused by the first base station.

27. The apparatus of claim 22, wherein the user-related information comprises information related to Quality of Service (QoS) requirement of a user.

28. The apparatus of claim 22, wherein the user-related information comprises at least one of: types of users, number of users, service types of users, and relative position relations between the users and the first base station and the second base station.