A method and a network node for controlling output uplink and downlink power levels in a mobile communications system

The present invention generally relates to the field of mobile communications, in particular methods and networks for controlling the output uplink power levels of mobile stations and the output downlink power levels of base stations in mobile communication systems. Regarding nodes.

In mobile communication systems such as GSM (Global System for Mobile communications) and GPRS (General Packet Radio Service), the transmission power level of the mobile station and the transmission power level of the base station are usually the base station of the mobile communication system or It is controlled by a power control algorithm implemented in one of the base station controllers. One of the purposes of power control is to reduce interference in the network without jeopardizing the quality of the connection between the mobile station and the serving base station. In mobile communication systems, power control is particularly important because mobile stations are free to move or roam from one cell to another in the network and / or to another cell belonging to a different network.

For example, a mobile station may be handed over from one cell to its adjacent cell if other adjacent cells can communicate at a lower transmission power level than the original cell. In such a scenario, the power control algorithm determines the appropriate output power level and informs the mobile station of the appropriate output power level to use in the power control instruction. Handovers can also be used for load balancing between cells (eg mobile stations can be moved from congested cells to cells with less traffic).

In preparation for the handover, various types of wireless link measurements are required to determine if the mobile station needs to be handed over from the service providing cell to the target cell. As an example, a mobile station performs wireless link measurements on the downlink signal strength and quality of the target cell and the downlink signal strength and quality of the service provider cell, and transfers these measurements to a base station controller (BSC). It can be notified in measurement reports. The BSC can then decide if the handover should be performed. BSC is a base station of a service providing cell or BTS (base transceiver). It will receive measurement result reports from the station) and the BTS of the adjacent cell and will use them along with the reports from the mobile station to determine if the handover should be performed. If a handover decision is made, the BSC orders the mobile station to set up the resources in the selected target cell and switch to the selected target cell. After the handover is completed, the mobile station and BTS begin transmitting the measurement result report to the BSC in order to adjust the output power of the mobile station and BTS.

However, the power control algorithm in BSC requires some measurement report before instructing the mobile station and / or BTS to adjust the power. For this reason, mobile stations and / or BTS preferably use higher power (eg, maximum power) levels in the cell after handover. This is because the high transmission power level guarantees sufficient link quality regardless of the location of the mobile station with respect to the service-providing BTS. Therefore, after the handover, unnecessary interference is caused in the network before the power control algorithm can instruct the mobile station and / or BTS to use a stable (appropriate) output transmission level.

Moreover, the power control algorithm is a reason for stability because the measurement result reports used as inputs to the power control algorithm usually arrive periodically (eg, at intervals of 0.48 seconds in GSM). Therefore, it will take some measurement report to find a suitable power level, and therefore it will take several seconds to reach a suitable power level. This will result in shorter battery life in battery-powered mobile stations.

International application WO 95/35003 describes a power control method for handover in mobile communication systems. In that method, each cell is assigned the maximum transmit power that the mobile station is allowed to use in that cell, and the optimum power level for the uplink signal that the mobile station should achieve after the handover. According to this prior art method, after the handover, the initial transmit power that the mobile station should use in the target cell is as long as the measured reception level of the target cell is higher than the optimum level for the uplink signal. It is lower than the maximum transmit power of the target cell by an amount equal to the difference between the optimum level for the uplink signal and the reception level of the downlink signal of the target cell measured prior to the handover. Therefore, the method described in this prior art reduces the above-mentioned unnecessary interference caused in the network after the handover.

However, the drawback of the above method is that it jeopardizes the robustness of the handover signaling between the BTS of the target cell and the mobile station. Moreover, since the power control method is based on the optimum level value for the statically assigned uplink signal and the downlink reception level measured prior to the handover, the state of the wireless network. Does not adapt to changes in. Moreover, the method described in this prior art only deals with power control of uplink transmit power.

<p> An object of the present invention is to reduce unnecessary interference in a mobile communication system without jeopardizing the robustness of handover signaling, thus achieving more advanced spectrum utilization of the mobile station in the mobile communication system. Addressing the above and other needs by providing methods and network nodes for controlling the output uplink power level and the output downlink power level of the target base station. Further, the method and network node in the present invention can dynamically adapt to changes in the state of wireless communication.</p>

<p> According to the first aspect of the present invention, the above-mentioned problem is a means for controlling the output uplink power level of a mobile station and the output downlink power level of a target base station in a mobile communication system. Is solved by. The above method is: At the network node of the mobile system, receive a message from the original (originating) cell to the target cell indicating that the handover of the mobile station is completed; by the network node to the target base station. Instructed the mobile station to use the initial output uplink power to use the initial output downlink power, all of which were used at least once after the previous handover was completed. Includes level-based and; The previous handover is a handover performed between the original cell and the target cell and refers to a previously completed handover.</p><p> According to a further aspect of the present invention, the above-mentioned tasks are configured to control the output uplink power level of the mobile station and the output downlink power level of the target base station in the target cell of the mobile system. It is also solved by means of a network node of a mobile communication system. The network node includes a receiver configured to receive a message from the original cell to the target cell indicating that the mobile station's handover has been completed. After receiving the message, the network node can operate the target base station to instruct the target base station to use the initial uplink power level, and the mobile station to instruct the mobile station to use the initial uplink power level. It further includes operable instruction means, all based on at least the previous power control level used once after the previous handover between the original cell and the target cell was completed.</p><p> According to the present invention, the previous power control level used once after the previous handover is completed is stored in the database at the network node, and the new handover in the mobile communication system is completed. Will be updated after. In addition, the time after the previous handover adjusts the output uplink power level of the mobile station to an appropriate power level after the previous handover, and adjusts the output downlink power level of the target base station to an appropriate power level. You may refer to the time required for adjustment.</p>

Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments and accompanying drawings. However, it should be noted that the drawings below are only exemplary and that certain embodiments illustrated and described may be modified within the appended claims.

<figref num="1A">It is a block diagram which shows an example of the mobile communication system to which this invention is applied.</figref><figref num="1B">It is a block diagram which shows the example of another mobile communication system to which this invention is applied.</figref><figref num="2A">It is a block diagram which shows the transmission power control for the uplink after the completion of the handover HO.</figref><figref num="2B">It is a block diagram which shows the transmission power control for the downlink after the completion of the handover HO.</figref><figref num="3A">It shows the signaling message required to execute and complete the handover according to the embodiment of the present invention.</figref><figref num="3B">It shows the signaling message required to execute and complete the handover according to the embodiment of the present invention.</figref><figref num="4A">An exemplary configuration of a database according to an exemplary embodiment of the present invention is shown.</figref><figref num="4B">FIG. 5 is a graph showing iterations towards an initial power control level according to an exemplary embodiment of the present invention.</figref><figref num="5">It is a graph which shows the influence of the interference when the method according to the exemplary embodiment of this invention is used in comparison with the influence of the interference after the handover in the power control method of the prior art.</figref><figref num="6">A flowchart of a method according to an exemplary embodiment of the present invention is shown.</figref><figref num="7">It is a schematic block diagram of an exemplary embodiment of a network node according to an exemplary embodiment of the present invention.</figref>

The present invention will be described with respect to the context of a general GSM system. However, the present invention and embodiments thereof can be applied to any cellular or mobile communication system such as GPRS and EDGE (improved GPRS) or UMTS (Universal Mobile Telecommunications System), LTE (Long Term Evolution). Therefore, the present invention is not intended to be limited to a particular mobile communication system.

With reference to FIGS. 1A and 1B, some network elements of the two examples of GSM type mobile communication system 1 to which the present invention can be applied are shown very briefly. As shown in Figures 1A and 1B, GSM system 1 contains multiple cells featuring BTS (base transceiver systems (stations)) 1 11 and BTS 2 12 that define individual cells. Cell boundaries 15 are also illustrated. It should be noted here that in other mobile or cellular systems cells can be defined by RBS (radio base stations), but in GSM systems the term BTS is used. BTS is also known as Base Station (BS) in GSM.

In FIG. 1A, GSM system 1 also includes a base station controller (BSC) 13 used to control BTS (BTS1, BTS2, ...). One of the typical roles of BSC is to handle the handover from the original cell of the mobile station (for example, mobile station 10) to the target cell in the network. In Figure 1B, two base station controllers BSC1 13 and BSC2 14 are shown, one with BSC1 13 controlling BTS1 11 and the other with BSC2 14 controlling BTS2 12. As shown in Figure 1B, BSC1 13 and BSC2 14 are further interconnected by MSC (mobile services switching center) 16. Other relevant elements of the GSM system, such as Home Location Registers (HLRs) and Network Subscriber Management Registers, which handle subscriber information such as location, registration information and other subscriber information, are for clarity. It is not shown in either Figure 1A or Figure 1B.

As described above, the base station controller usually handles the handover from the original cell of the mobile station to the target cell. The handover decision is also made by the base station controller based on various handover parameters based on the measurement result reports by the mobile station and the base transceiver station. As an example, referring to Figures 1A and 1B, the MS10 monitors and measures the quality of the radio link and the level of the downlink signal on the BTS 1 11 before switching to the target cell serviced by the BTS 2 and also on the BTS 2 12 Monitors and measures the level of each downlink signal in adjacent cells, including. BTS1 11 monitors and measures the quality of the radio link and the level of the MS10 uplink signal. All measurement results are then transmitted to BSC 1 13 to determine if the MS 10 should be handed over from the original cell to the target cell.

After the handover, the MS 10 and BTS 2 12 begin to send measurement result reports to the base station controller that controls the BTS 2, BSC 13 in FIG. 1A and BSC 2 14 in FIG. 1B. The measurement result report sent by MS10 includes the reception level of the downlink signal received from BTS2 and the quality of the downlink signal. The measurement result report sent by BTS2 12 includes the reception level of the uplink signal received from the MS10 and the quality of the uplink signal. Based on some of these measurement report reports, and other power control parameters, the power control algorithm in the base station controller determines the appropriate output uplink power level that the MS10 should use and uses it for uplink power control. Send to MS10 in the command. The base station controller also determines the appropriate output downlink power level that BTS2 12 should use and sends it to BTS2 12 in a downlink power control instruction. These procedures are repeated several times until stable output levels (downlink and uplink) are reached.

2A and 2B show block diagrams of transmission power control for the prior art uplink (FIG. 2A) and downlink (FIG. 2B), respectively. It should be noted here that in FIG. 2A, the mobile station (MS) is initially instructed to use the maximum output uplink power MS_TXPWR_MAX after the handover (HO), and in FIG. 2B, the base transceiver station (BTS) After the handover, it is instructed to use the maximum output downlink power BTS_TXPWR_MAX. Pre-handover signal strength measurements in the target cell (or target BTS) are often not performed on the channel that should be used after the handover, and the measurements are performed only on the downlink, resulting in maximum power. Used early.

Moreover, the highest acceptable transmit power level ensures sufficient link quality regardless of the location of the mobile station with respect to the service-providing BTS. Moreover, the quality of the new channel in the target cell cannot be evaluated using these measurements. Therefore, the interference caused by the use of the maximum power level by MS and BTS is high at first, and the power control algorithm brings the power used by MS to the appropriate power level represented by MS_TXPWR_appr_level (see Figure 2A). After adjusting and adjusting the power used by BTS to the appropriate power level represented by BTS_TXPWR_appr_level (see Figure 2B), it is first reduced. It should be noted that the power used by MS and BTS is not always equal. Furthermore, the range in which MS can reduce its output power from MS_TXPWR_MAX to MS_TXPWR_appr_level during its transmission power control is not necessarily close to the range in which BTS can reduce its output power from BTS_TXPWR_MAX to BTS_TXPWR_appr_level. .. The extent to which MS and BTS reduce their power is usually a design parameter, especially depending on the type of mobile communication system used in the network.

According to the method according to an exemplary embodiment of the present invention, the output uplink power level used by the mobile station MS10 and the output downlink power level used by the base transceiver station BTS2 12 during and immediately after the handover procedure. Is high enough to ensure that the handover signaling is robust, and once the signaling is complete, the MS10 and BTS2 12 will use their power to complete the previous handover between the original cell and the target cell. It is instructed to reduce to an appropriate power level based on at least the previous power control level, which was used once after being used.

Before explaining how power control is performed according to the method according to an exemplary embodiment of the invention, it is important to explain the handover signaling required between the mobile station and the target base station. is there.

With reference to FIGS. 3A and 3B, the signaling messages used between the mobile station and the target BTS are shown before instructing the mobile station and the target BTS to adjust their output power in the present invention. .. It should be noted here that FIG. 3A shows the first handover scenario in which BSC 13 controls both the original BTS 1 11 and the target BTS 2 12 previously shown in FIG. 1A, while FIG. 3B. Indicates that the original BTS 1 11 is controlled by the first BSC 1 13 and the second BTS 2 12 is controlled by the BSC 2 14. BSCs 13 and 14 are interconnected by MSC16, as shown in the exemplary scenario in Figure 1B. For clarity, only signaling messages executed after the handover decision was made by the BSC are considered. The reason is that the handover decision is not essential to the present invention.

According to Figure 3A, after the decision is made by BSC13, BSC13 attempts to secure a traffic channel at target BTS2 12. If a traffic channel can be secured, in step 5A BSC 13 sends a channel activation (CH ACT) message to target BTS 2 12. In GSM, the channel activation message CH ACT contains the power command of the initial mobile station MS and the handover reference number, which is the type of channel requested. In response to the channel launch message, if the resource setup is successful in step 5b, goal BTS2 12 sends a channel launch acknowledgment (CH ACT ACK) message to BSC 13. In step 6a, the BSC 13 sends a handover instruction (HO CMD) message to the MS 10 by the original BTS 1 11 (step 6b) instructing the MS 10 to switch to the new channel set up by the target BTS 2 12. The HO CMD message also contains the power instructions that the MS10 should initially use on the new channel.

In response to the HO CMD message in step 7a, the MS10 releases the old channel, switches to the new channel, and in step 7b sends a handover detection (HO DECT) message to the BTS 2 12, which in turn informs the BSC 13. Start transmitting a Handover Access (HO ACC) burst. This message is also used to inform BSC13 that the MS10 has tuned to a new dedicated channel. The HO ACC burst is used to measure how the MS10 should adjust its transmission to the time slot structure, i.e. the HO ACC burst is used to measure the time alignment to be used by the MS10. It should be noted that it is used. Goal BTS 2 12 then begins sending physical information (PHY INFO) to MS 10 in step 8 including a time alignment instruction (spacing for transmit uplink) to MS 10. In steps 9a-9b, the MS10 is a PHY In response to INFO, start the handshaking procedure to set up Layer 2. This is known as SABM / UA (set asynchronous balanced mode / unnumbered acknowledgment) hand shaking. The handshaking procedure is completed by MS10, which terminates the handover procedure by sending a handover complete (HO COMPL) message to target BTS2 12 in step 10a. The BTS 2 12 then sends a Handover Complete (HO COMPL) message to the BSC 13 in step 10b.

According to one embodiment of the present invention, reception of a handover complete (HO COMPL) message by the target base station BTS 12 or base station controller BSC 13 is for controlling the output uplink power level of the MS 10 and the output downlink power level of the BTS 2 12. It will trigger control. Therefore, according to the present invention, the BSC 13 or the target BTS 2 12 can control the output power. As a result, the node that will control the output power of the mobile station and the output power of the target base station will be referred to below as the network node.

On the network node that received the HO COMPL message, MS10 completes the previous handover between the original cell (or original BTS 1 11) and the target cell (or target BTS 2 12) in step 11a (or step 11b). It is instructed in the MS power control command message MS_PWR to use the initial uplink power level based on the previous power control level used once after being done. When the network node also receives the HO COMPL message, it has been used once since the previous handover between the original cell (or original BTS1 11) and the target cell (or target BTS2 12) was completed. Instruct BTS2 12 in either step 12a (if the network node is BSC13) or internal step 12b (if the network node is BTS2 12) to use the initial downlink power level based on the power control level of To do. The instruction used is the base station power control command message, BS_PWR.

Figure 3B shows the signaling message when the original BTS 1 11 is controlled by BSC 13 and the second BTS 2 12 is controlled by BSC 2 14. BSCs 13 and 14 are connected by MSC16 as shown in the exemplary scenario of Figure 1B. This scenario differs from the one above in that after the decision made by the original BSC 1 13 (HO DECISION), BSC 1 13 makes a request to MSC 16 for the handover of MS 10 in the HO_RQD message in step 4a. There is. The MSC 16 then sends a handover request to target BSC 2 14 in the HO_REQ message in step 4b. The channel activation procedure (not shown) is then activated in the same way as described in relation to the previous scenario (Figure 3A). However, in this scenario, the MSC 16 is informed of the channel activation (not shown) and the original BTS 1 by the original BSC 1 13 (step 6a) in step 6c. Before sending the handover command message HO_CMD to MS10 via 11 (step 6b), the handover request acknowledgment message HO REQ ACK is received from target BSC2 14 in step 5c. In step 7a, MS 10 begins transmitting a handover access (HO_ACC) burst to BTS 2 12, which in turn informs BSC 2 14 by sending the handover detection message HO DECT in step 7b. MSC16 is also given information on the HO DECT message (step 7c).

Goal BTS2 12 then begins transmitting the physical information PHY INFO to MS10 in step 8 including a time alignment instruction to MS10 (interval adjustment for transmit uplink). In step 9a-9b, the MS10 initiates the handshaking procedure to set up layer 2 in response to the PHY INFO (step 8) in the same way as described above (SABM / UA handshaking). The handshaking procedure is completed by MS10, which terminates the handover procedure by sending a handover complete (HO COMPL) message to target BTS2 12 in step 10a. BTS2 12 then sends a Handover Complete (HO COMPL) message to BSC2 14 in step 10b. BSC2 14 also informs MSC 16 of the completion of the handover in step 10c. For clarity, Figure 3B does not include all signaling messages.

According to one embodiment of the present invention, the reception of the handover complete (HO COMPL) message by the target base station BTS 2 12 or the target base station controller BSC 2 14 is the output uplink of the MS 10, as in the scenario already described. It will trigger power level control and BTS2 12 output downlink power level control. It should be noted here that the BSC 2 14 or the target BTS 2 12 can control the output power in this scenario. As a result, the node that will control the output power of the mobile station and the output power of the target base station will also be called a network node.

As described above, the control of the output uplink power level and the control of the downlink power level are triggered by the reception of a handover complete (HO COMPL) message at the network node (BSC or BTS). The initial uplink power level is instructed in the MS_PWR message in step 11a (or step 11b) and the initial downlink power level is instructed in the BTS_PWR message in step 12a (or step 12b). It should be noted that the power level to be used for the initial signaling at the target base station during the handover is preferably high enough to ensure the robustness of the handover signaling. As an example, the power level during initial signaling may be equal to the maximum power level allowed. The present invention is not limited to the instructions to which the command message is transmitted / commanded, i.e. the BTS_PWR message (step 12a or step 12b) can occur prior to the transmission of the command message MS_PWR message (11a and 11b) to the mobile station. Should also be noted.

Output uplink and downlink power level control was used once after the previous handover between the original cell (or original BTS) and the target cell (or target BTS) was completed, previously or at least. Based on previous power control levels, these power control levels may be equal to, for example, the appropriate power levels MS_TXPWR_appr_level and BTS_TXPWR_appr_level above.

In one embodiment of the invention, a database containing power control levels is constructed for each neighbor relation. That is, the reached uplink power control level (eg MS_TXPWR_appr_level) and the reached downlink power control level (eg BTS_TXPWR_appr_level) are stored in the database for each handover between the previously executed original cell and the target cell. Will be done. Therefore, each field in the database corresponds to an adjacency. Figure 4A includes three adjacencies (BTS1-BTS2, BTS2-BTS3, BTS1-BTS3) to the power control level (uplink and downlink) reached once after the handover was completed between the adjacencies. An example of the corresponding database is shown. It should be noted here that the present invention is not limited to any particular number of adjacencies, nor is it limited to the power control level values illustrated in FIG. 4A.

In each adjacency, some handovers (PC) with iterations towards the power control level to reach the uplink power control level and the downlink power control level. HOs) is required. FIG. 4B is an example of a graph showing iterations towards the uplink power control level for an adjacency in which four handovers were performed with output power adjustments (PC1stHO, PC2ndHO, PC3rdHO, and PC4thHO). As shown in Figure 4B, the maximum uplink output power level is initially used by the mobile station, and after a few iterations after the handover (HO), it reaches the uplink power control level represented by MS_TXPWR_appr_level. To reach. It should be noted that for clarity, Figure 4B only shows the iteration towards the uplink power control level. According to the present invention, the iteration for the downlink is also performed to reach the downlink power control level BTS_TXPWR_appr_level. Therefore, in the database illustrated in FIG. 4A, the reached power control levels (ie MS_TXPWR_appr_level and BTS_TXPWR_appr_level) are populated for their respective adjacencies.

According to the present invention, the database is stored in a network node, eg, a BSC (or a target BSC in the case of a handover between BSCs) or a target BTS. The network node then completes the handover (HO) Upon receiving a COMPL) message, it initially commands the mobile station to reduce the output uplink power level from, for example, the maximum output uplink power level to the power control level MS_TXPWR_appr_level, and initially reduces the downlink output power level to, for example, the maximum output power. Instruct the target base station (or BTS) to reduce from level to power control level BTS_TXPWR_appr_level. BTS_TXPWR_appr_level is commanded by the network node in the base station power control command message, and MS_TXPWR_appr_level is commanded by the network node in the mobile station power control command message. After the mobile station and target BTS have reduced their output power to MS_TXPWR_appr_level and BTS_TXPWR_appr_level respectively, the usual power control algorithms may be used for further adaptation / correction of the mobile station and BTS power levels, if necessary. Good.

It should be noted here that after the handover, the mobile station and the target base station are instructed to reduce their power to the power control levels MS_TXPWR_appr_level and BTS_TXPWR_appr_level, respectively, which causes less interference in the network. This is because the initial output power control level of the mobile station and the target base station can reach the appropriate power control level (MS_TXPWR_appr_level, BTS_TXPWR_appr_level) immediately (or as soon as possible) after the handover. Further note is that battery power consumption is reduced because the mobile station can reach its appropriate uplink power control level immediately (or as soon as possible).

It should be noted that the extent to which BTS and MS can reduce their output power, for example from their maximum level, to BTS_TXPWR_appr_level and MS_TXPWR_appr_level, respectively, is a design choice. As an example, the range in which BTS can reduce its output power from, for example, its maximum power level can be nominally 30 dB consisting of 15 steps of nominally 2 dB, while MS reduces its output power from, for example, its maximum power level. The possible range can be, for example, a nominal 2 dB step. However, as mentioned above, the MS_TXPWR_appr_level and BTS_TXPWR_appr_level contained in the database can be reached immediately or as soon as possible otherwise. After reaching the appropriate level, normal power control algorithms may be used (if necessary) to adapt the power level.

The database according to the invention is updated with the power level reached after each handover performed in the network. As an example, after the first handover between the first cell and the second cell, the target BTS is instructed to use BTS_TXPWR_appr_level according to the power level shown in the database. Normal power algorithms can then be used to adjust the power level of the BTS to the new power level BTS_TXPWR_appr_level after the handover. The database is then updated with this power level. In the subsequent handover situation between the first cell and the second cell (ie, the same cell relationship), the BTS is instructed to use the updated power level BTS_TXPWR_appr_level shown in the database. Then a normal power control algorithm is used to adjust the output power of the BTS (if necessary), the database is updated again, and so on. It should be noted here that the above example is not limited to power control of the BTS power level, that is, the database is also updated by MS_TXPWR_appr_level after each handover performed.

Referring to FIG. 5, an example of the influence of interference by the method of the present invention (2) (2) in contrast to the influence of interference after handover by the power control method of the prior art (1) (only for the uplink). (Only for uplinks) is shown. Only the effect of interference on the uplink is considered in Figure 5 because the prior art method is limited to the uplink scenario. As shown, the initially used power level (MS_TXPWR_MAX) is higher than that of the prior art, but the interference caused is much less than that of the prior art method.

According to other exemplary embodiments of the invention, the mobile station initial uplink power level MS_TXPWR_appr_level and the target base station initial downlink power level BTS_TXPWR_appr_level are between the original cell and the target, represented by RXLEV_TCELL. Further based on the received power level of the downlink signal of the target base station (or target BTS) measured before the handover was performed in. The received power level RXLEV_TCELL may as a result be stored in the database in addition to the power control level. The received power level may also be updated in the database.

According to another exemplary embodiment of the invention, the mobile station initial uplink power level MS_TXPWR_appr_level and the target base station initial downlink power level BTS_TXPWR_appr_level were handed over between the original cell and the target. Further based on the received power level of the downlink signal of the target base station (or target BTS) measured later. The received power level of the downlink signal measured after the handover is also stored in the database and may be updated when the next handover occurs between the original cell and the target cell.

According to a further exemplary embodiment of the invention, the initial downlink power level of the target base station and the initial uplink power level of the mobile station are further based on the path loss in the target cell. The route loss information is further stored in the database and may be updated when the next handover occurs between the original cell and the target cell.

According to a further exemplary embodiment of the invention, the initial downlink power level of the target base station and the initial uplink power level of the mobile station are the target cells (or targets) whose values are further stored and updated in the database. Further based on the timing advance value in BTS) (eg, the distance between the mobile station and the target base station).

According to a further exemplary embodiment of the invention, the initial downlink power level of the target base station and the initial uplink power level of the mobile station are handed over between the original cell and the target cell (or target BTS). Further based on the time of occurrence. The timing of the above handover may be further stored and updated in the database.

According to the present invention, the initial power control level may be further based on other variables or parameters representing radio conditions before and / and after handover or measurement results. Variables or parameters or measurement results may also be stored and updated in the database. It should be noted that the initial power control levels BTS_TXPWR_appr_level and MS_TXPWR_appr_level are less than or equal to the maximum power level allowed / allocated for use by mobile and target base stations in the network. The maximum permissible power level can be used, for example, when the above measurement results indicate poor radio conditions.

According to the present invention, entries in the database are automatically new entries for each new handover performed between the original cell and the target cell in an adjacency to adapt to changes in network (or wireless) state. Will be updated to.

With reference to FIG. 6, as described above, a method for controlling the output uplink power level of the mobile station and the output downlink power level of the target base station in the target cell of the mobile communication system. The flowchart of is shown. As shown in FIG. 6, in step (1), the network node of the mobile communication system receives a message indicating that the handover of the mobile station from the original cell to the target cell has been completed. .. As already described, this message corresponds to a Handover Complete (HO COMPL) message. The Handover Complete Message (HO COMPL MSG) was previously referred to as Step 10a and Step 10b in Figures 3A and 3B. Therefore, the network node that receives the Handover Complete (HO COMPL) message may be a base station controller or a base transceiver station.

In step 2, the network node commands the mobile station to use the initial output uplink power level MS_TXPWR_appr_level and commands the target base station to use the initial output downlink power level BTS_TXPWR_appr_level. The initial output uplink power level and the initial output downlink power level were used at least once after the previous handover (HOs) between the original cell and the target cell was completed, at least the last power control (PC). Based on level. As previously described, conventional power control algorithms may be used for further adaptation / correction of mobile station and BTS power levels, if desired.

Referring to FIG. 7, a schematic block of an exemplary embodiment of network node 100 for mobile station output uplink power level control and target base station output downlink power level control in a target cell of a mobile communication system. The figure is shown. As shown, the network node has a receiver 110 configured to receive the HO COMPL messages 10a, 10b indicating that the mobile station's handover from the original to the target cell has been completed. Including. The network node is the HO at receiver 110 After receiving COMPL messages 10a, 10b, the mobile station can be operated to instruct the mobile station to use the initial output uplink power level MS_TXPWR_appr_level, and the target base station is instructed to use the initial output downlink power level BTS_TXPWR_appr_level. It further includes command means 120 configured as such. The initial output uplink power level and the initial output downlink power level are, according to the invention, used once after the previous handover between the original cell and the target cell was completed, at least the previous power control. Based on level.

According to the present invention, the network node 100 has a previous power control level used once after a previous handover between the original cell and the target cell, and a previous handover between cells in a mobile communication system. It is further configured to store at least the last power control level used once later in database 130. Database 130 and instruction means 120 need not be part of a single unit, i.e. they may be separated.

According to an exemplary embodiment of the invention, in the case of a handover between BSCs (ie, a handover between two cells controlled by different BSCs, see FIG. 3B), the target BSC is the original BSC. Given the information on the measured downlink signal strength of the target BTS measured in the cell of. Information may be sent, for example, by the original BSC to the target BSC in HO_RQD and HO_REQ messages (see Figure 3B).

The present invention and its embodiments are GPRS (General Packet Radio Service), EDGE (Enhanced Data rates for GSM Evolution), JDC (Japanese Digital Cellular), WCDMA (Wide band Code Division Multiplexing Access), CDMA2000 (Code Division Multiplex Access). The person skilled in the art naturally understands that it can be applied to any cellular or mobile communication system to which power control can be applied, such as LTE (Long Term Evolution) and WIMAX (Worldwide Interoperability for Microwave Access). As a result, the present invention is not intended to be limited to any particular mobile communication system.

Moreover, the present invention and embodiments thereof can be realized by many means. For example, one embodiment of the invention is a computer-readable medium that can be executed by a computer system to control the output uplink control level of a mobile station and the output downlink power level of a target base station. Includes stores of groups. The instructions, which can be executed by a computing system and are stored in a computer-readable medium, perform the method steps of the invention described in the claims.

The invention has been described in terms of some preferred embodiments, but includes alternatives, modifications, substitutions, and equivalents that will become apparent if one of ordinary skill in the art reads the specification and considers the drawings. There is. As a result, the claims attached below will include such substitutions, modifications, substitutions, and equivalents as belonging to the technical scope of the present invention.