CN100428837C - A method for optimizing wireless link disconnection strategy - Google Patents

Abstract

The present invention relates to a method for optimizing a wireless link unlinking strategy, comprising: there are two or more uplink sets between a base station (NodeB) and a user equipment (UE), and a radio network controller (RNC) acquires the uplink sets The link quality of some link sets; if the link quality of one of the link sets becomes worse, the RNC deletes the link set; before the link set quality deteriorates to be deleted, its corresponding NodeB sends Send a transmit power control command word to control the slow increase of its uplink transmit power. The method of the invention fundamentally solves the problem that when there are two or more uplink sets at the same time, the uplink TPC command word of the bad link caused by the uplink quality difference causes the uplink quality of the good link to deteriorate. At the same time, when there is only one link set, the uplink transmission power will not increase rapidly by sending the Pattern.

Description

A method for optimizing wireless link disconnection strategy

technical field

The invention relates to the field of wireless communication, in particular to a method for optimizing a wireless link disconnection strategy.

Background technique

In the WCDMA system, according to the provisions of protocol 25.214, the uplink physical layer link failure startup process is as follows: if the base station (Node B) continuously receives N_OUTSYNC_IND (configurable parameters, refer to the protocol for specific settings) out-of-sync primitives, Node B will start a disconnection timer T_RLFAILURE. During the timing of T_RLFAILURE, if Node B continuously receives N_INSYNC_IND (configurable parameters, refer to the protocol) synchronization primitives, NodeB will stop the timing of T_RLFAILURE. If T_RLFAILURE times out, Node B The RL Failure (radio link failure) process will be triggered, and at the same time, the state of the radio link set changes to an out-of-gait state. Once the RL Failure failure process is triggered, the wireless link set enters the link disconnection process, and the RNC (Radio Network Controller, radio network controller) deletes the wireless link set through a certain signaling process. The value of T_RLFAILURE is generally at the second level.

From the above description, it can be seen that from the deterioration of the uplink quality to the final deletion of this link, it takes a second-level time in the middle, which will cause the following problems:

As shown in Figure 1, during the process of soft handover and same-frequency hard handover, there may be two uplink link sets RLS1 and RLS2 at the same time. It is assumed that the quality of RLS1 is already very poor, but because the configured value of T_RLFAILURE is at the second level, Deleting RLS1 also takes seconds.

To facilitate the distinction, we define the two power control command words that control the NodeB transmit power and the UE transmit power as the downlink TPC (Transmit Power Control, transmit power control) command word and the uplink TPC command word respectively. It includes: 0 or 1, 0 means power down, 1 means power up. If the channel quality of the link set RLS2 is normal, and the two link sets send uplink TPC command words to the UE at the same time, the optimal power control strategy of the UE is to perform power control according to the uplink TPC of RLS2. However, according to the protocol, when the quality of the two downlink channels is good, the UE will increase its transmit power only when both uplink TPC command words increase the power. There are four combinations of the above two uplink TPC command words : 00, 01, 10, 11. The former one is the TPC command word sent by the cell NodeB1 corresponding to RLS1, and the latter one is the TPC command word sent by the cell NodeB2 corresponding to RLS2. In these four combinations, the UE will increase its transmit power only when it receives 11. In the current situation, RLS1 adopts two power control strategies: one is to send all 1s, and the other is to send Patterns. Described below:

Scenario 1: In the scenario shown in Figure 1, if the uplink TPC command word corresponding to the poor-quality link set RLS1 sends all 1s, it is possible to perform uplink power control according to the requirements of the good-quality link set RLS2. However, in many In this case, the NodeB cannot know how many link sets exist in the air interface for the same UE. Therefore, even if there is only one link set, the NodeB must adopt such a power control strategy, and CDMA is a self-interference system. The signal of a UE is the interference of other users, and the TPC command word is 1, which means that it is increased by 1dB. One power control command word is sent in one time slot. The time of one time slot is 2/3ms, and 1500 power control command words will be sent in 1 second. In this way, the power of UE will rise to the maximum value in a short time. If When the UE transmits at full power, it will cause great interference to other users in the cell and seriously affect the capacity of the cell. Therefore, this strategy of sending all 1s should be avoided as much as possible.

Scenario 2: Generally, if the NodeB finds that the quality of the link set is very poor, it will send a pattern: that is, 010101010101....011, 0 and 1 are sent alternately, increased by 1dB and then decreased by 1dB, after several pairs of 01, an extra 1 is sent. In fact, a strategy of slowly increasing power is realized. Then: in the scenario in Figure 1, because the current RLS2 is normal, the number of TPC commands sent by the cell NodeB2 corresponding to RLS2 to the UE is approximately the same, and at this time the cell NodeB1 corresponding to RLS1 sends one Pattern, according to the UE's power control strategy when two radio link sets exist, at this time, the number of UE power downs will actually be more than the number of power ups. Therefore, for the transmission power required by RLS2, the UE's transmission power is low, because it takes a second to delete RLS1, so this low time will last for a long time, which will bring RLS2 The consequences of uplink loss of synchronization or even link disconnection are very serious, because RLS1 is also very poor, and both link sets are poor, and users may drop calls.

It can be seen from the above analysis that, in fact, when the quality of a wireless link set deteriorates, there are two completely different optimal uplink power control strategies depending on whether the number of link sets in the air interface is unique. When there is only one link set in the air interface, sending Pattern is the optimal strategy; in the process of soft handover and same-frequency hard handover, two wireless link sets (or more) exist at the same time, if the quality of the uplink is good and the other is bad , the link set with bad quality sends all 1s is the optimal power control strategy. However, NodeB itself cannot distinguish between these two states, and can only choose one of the two. No matter which one is selected, it will inevitably fail to achieve the global optimum.

Contents of the invention

The invention provides a method for optimizing a wireless link disconnection strategy to ensure efficient operation of a system.

A method for optimizing a wireless link disconnection strategy provided by the present invention includes:

When there are two or more uplink sets between the NodeB and the UE, the RNC obtains the link quality of these link sets; Road set deletion; before the quality of the link set deteriorates enough to be deleted, its corresponding NodeB sends a transmit power control command word to the UE to control the slow increase of its uplink transmit power; and,

When there is only one link set between the NodeB and the UE, and the uplink quality of the link set deteriorates, the corresponding NodeB sends a transmit power control command word to the UE to control the slow increase of its uplink transmit power.

According to the above method of the present invention, the transmit power control command word is a Pattern command word.

According to the above method of the present invention, when there are two or more uplink sets between the NodeB and the UE, the RNC obtains the link quality of these link sets, and determines that the link quality of a certain link set is degraded , including:

The RNC receives the out-of-sync primitive reported by the NodeB;

When the number of consecutive out-of-sync primitives in a link set exceeds a preset value, it is determined that the quality of the corresponding link set is degraded.

According to the above method of the present invention, when there are two or more uplink sets between the NodeB and the UE, the RNC obtains the link quality of these link sets, and determines that the link quality of a certain link set is degraded , including:

The RNC regularly obtains the bit error rate, block error rate and/or signal-to-noise ratio of the wireless link reported by the NodeB;

When the bit error rate, block error rate and/or signal-to-noise ratio of the wireless link exceeds or falls below a certain preset value, it is determined that the quality of the corresponding link set deteriorates.

The method of the invention fundamentally solves the problem that when there are two or more uplink sets at the same time, the uplink TPC command word of the bad link caused by the uplink quality difference causes the uplink quality of the good link to deteriorate. At the same time, when there is only one link set, the uplink transmission power will not increase rapidly by sending the Pattern.

Description of drawings

FIG. 1 is a schematic diagram of the relationship between a base station and a mobile station in a handover state.

Detailed ways

If there are two or more link sets between the NodeB and the UE, the RNC obtains the link quality of these link sets. When the uplink quality of one of the link sets deteriorates, the RNC immediately It does not need to go through a second-level time. At this time, when the link set with poor quality deteriorates to be deleted, the uplink TPC command word of the corresponding cell sends Pattern.

When there is only one link set between the NodeB and the UE, if the uplink quality of the link set deteriorates, the corresponding NodeB sends the uplink TPC command word Pattern to the UE, and the disconnection timer assigned to the NodeB by the RNC is as follows: second level.

Detecting the quality of the uplink is performed by the NodeB corresponding to the link set. The quality of the uplink is actually the quality of the service information and control information transmitted on the uplink. This quality can be determined by the block error rate and Measured by bit error rate, business information has quality indicator bits, through which the block error rate of business information can be obtained. Although control information has no quality indicator bits, bit error rate can also be obtained through other indirect ways; at the same time, it can also be measured by The signal-to-noise ratio of business information and control information is used to measure the quality of the uplink. To determine the quality of a link set is poor, you can generally set a threshold. For example, you can consider a bit error rate of 40% as poor quality, and you can also use different thresholds for different link sets. In short, you can use a variety of methods and standards to judge The quality of the link is good or bad.

There are many ways for the RNC to immediately delete the link set. An optional solution is: the time of the disconnection timer T_RLFAILURE assigned to the NodeB under the RNC is variable. When there is only one RLS in the uplink, the time of the disconnection timer The parameter is configured at the second level; when there are two or more RLSs in the uplink, the time parameter of the disconnection timer is configured as a small value (any value less than 1 second, such as 0), that is, once a certain If the uplink quality of the link set deteriorates, it will be deleted immediately. When only one RLS is left, it will be restored to the second level. The setting time of the timer is for all link sets of the same UE. When there are multiple link sets, the small value time setting is for all link sets. When there is only one link set, the second level Time corresponds to the rest of this link set.

Another solution is: when there are multiple link sets in the uplink, there is no need to set the time. Once the link disconnection timer T_RLFAILURE is started, the RNC will immediately delete the link through signaling; or the NodeB will report the timeout information of the link disconnection timer RNC or after the timer expires, start the radio link failure process, wherein the disconnection timer time parameter is any value less than 1 second; RNC after receiving the reported information or after the radio link failure process starts, through Signaling deletes the link set.

Another solution is: the NodeB directly reports the out-of-sync primitives to the RNC, and the RNC determines that the quality of the link set is degraded according to the number of consecutive out-of-sync primitives exceeding a preset value, and immediately deletes the link set.

Another solution is: RNC directly deletes the link set through signaling according to the obtained quality of the radio link set (according to the current agreement, the RNC will obtain part of the quality information of the radio link set); The quality of the radio link set is reported to the RNC, and the RNC decides whether to delete the radio link set according to the information.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (4)

1. A wireless link disconnection strategy optimization method, characterized in that it comprises: When there are two or more uplink sets between the base station NodeB and the user equipment UE, the radio network controller RNC obtains the link quality of these link sets; if the link quality of one of the link sets changes If the link set is poor, the RNC immediately deletes the link set; before the quality of the link set becomes so bad that it is deleted, its corresponding NodeB sends a transmit power control command word to the UE to control the slow increase of its uplink transmit power; and, When there is only one link set between the NodeB and the UE, and the uplink quality of the link set deteriorates, the corresponding NodeB sends a transmit power control command word to the UE to control the slow increase of its uplink transmit power. 2. The method according to claim 1, characterized in that the transmit power control command word is a Pattern command word. 3. The method according to claim 1, characterized in that: when there are two or more uplink sets between the NodeB and the UE, the RNC obtains the link quality of these link sets, and determines the link quality of a certain link set. The link quality of the road set deteriorates, including: The RNC receives the out-of-sync primitive reported by the NodeB; When the number of consecutive out-of-sync primitives in a link set exceeds a preset value, it is determined that the quality of the corresponding link set is degraded. 4. The method according to claim 1, characterized in that: when there are two or more uplink sets between the NodeB and the UE, the RNC obtains the link quality of these link sets, and determines the link quality of a certain link set. The link quality of the road set deteriorates, including: The RNC regularly obtains the bit error rate, block error rate and/or signal-to-noise ratio of the wireless link reported by the NodeB; When the bit error rate, block error rate and/or signal-to-noise ratio of the wireless link exceeds or falls below a certain preset value, it is determined that the quality of the corresponding link set deteriorates.

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