KR20070008525A - Call case controlled bler target setting - Google Patents

Abstract

A method and system are disclosed for call case controlled block error rate (BLER) or bit error rate (BER) target setting in WCDMA and other CDMA technologies for Mobile to Mobile (MTM) and Mobile to Public Switched Telephone Network (MTPSTN) communication systems, whereby first an overall BLER/BER target value is defined. ® KIPO & WIPO 2007

Description

Call target controlled when calling {CALL CASE CONTROLLED BLER TARGET SETTING}

The present invention relates to mobile phone uplink and downlink power control, and more particularly to block / bit error rate (BLER / BER) measurements for obtaining optimal power settings.

In Wideband Code Division Multiple Access (WCDMA) (and other code division multiple access techniques such as CDMA2000), see chapter 9.2 in Reference [1], the first power control mechanism is an essential element of the air interface. Although there is a difference between uplink and downlink power control, for the understanding of the present invention, this difference is insignificant. The following description will be valid for both links.

The idea described here can also be applied to GMSK Gaussian Minimum Mobile Key and EDGE (Enhanced Data Rate for GSM Improvement) radio access networks (GERAN), which provide low power control or any other modern cellular radio connection to the radio connection. have.

The inner loop of the so-called power control algorithm allows to maintain the received signal-to-interference-ratio (SIR) at a particular level (SIR target). As the SIR is lowered, the power control instructs the transmitter at the other end of the link to increase its output power to maintain the SIR, thereby increasing the quality of the received signal at an acceptable level. On the other hand, if the SIR is very high, the transmitter is commanded to lower its output power in order not to cause other users unnecessary interference.

In order to further increase the efficiency of power control, there is also an outer loop of power control. For example, a voice code block is sent over the air interface and a cyclic redundancy checksum (CRC) is calculated at part of the voice block. Checksums are sent with voice blocks and have been used by receivers to detect faulty blocks. The outer algorithm of the power control loop uses block error rate measurement (BLER) to adjust the SIR target to a level that provides a specific BLER (BLER target). If the measured BLER is lower than the BLER target, the outer loop changes the SIR target to a lower value, and if the measured BLER is higher than the BLER target, the SIR target will be higher.

Therefore, under normal operating conditions, the actual BLER of the WCDMA voice call is close to the BLER set by the BLER target parameter in the WCDMA system.

Selecting a value for the BLER target is a trade off between quality and radio cell capacity. Apart from the loss of high transmitter power, a low BLER target provides good voice quality, thus lowering cell capacity, i.e. the number of concurrent users in a cell in this radio link direction.

Today, BLER targets are set up for all radio links without considering whether the call is a mobile phone to public switched telephone network (MTPSTN) call or a mobile phone to mobile phone (MTM) call.

In mobile phone to PSTN calls, there is one radio link in each direction of the path between the end points, whereas in mobile phone to mobile phone calls, there are two radio links in each direction. At the BLER level, which provides acceptable voice quality (eg, nearly 1%), one BLER level can generally add BLER from two radio links to obtain the total BLER in mobile phone-to-mobile phone calls. This means that if the BLER target is set to 1% for each radio link, the resulting total BLER in mobile phone-to-mobile phone calls will be nearly 2%.

When the only unique BLER target is the one chosen for the MTPSTN and MTM calls, the compromise should be made if the quality of the mobile phone to mobile call is lower than desired or the capacity of the mobile phone to PSTN call is lower than possible.

The method and system are in the case of controlled block error rate (BLER) or bit error rate (BER) targets in code division multiple access (CDMA) mobile phone to mobile phone (MTM) and mobile phone to public switched telephone network (MTPSTN) communication systems. A setting is disclosed, whereby, for example, all BLER / BER target values are defined. The decision determines whether the call consists of MTM or type or MTPSTN type. If there are other mobile phone links in the path, this can be done, for example, by examining which frame type only occurs in the downlink. As a result, the first BLER / BER value for the uplink and the first link is the difference remaining in the overall BLER / BER for counting the frames that are not good and for setting the second BLER / BER for the downlink or the second link. Is determined by using. Initially, the first BLER / BER value of the uplink may be set to a maximum value that is half of the total BLER / BER target value.

The following discussion focuses on circuit switched voice services, but may equally apply to video telephony and any other service whose quality depends on the quality of the received information.

The solution to the existing problem is to have different BLER / BER target values for mobile phone to PSTN calls and mobile phone to mobile phone calls, and the ideal solution is always to use each individual link to achieve the same total BLER / BER. It would have to have different BLER / BER targets for two uplinks, two downlinks).

For the uplink direction, which is always the first radio link in this voice path direction, it is easy to detect erroneous voice frames by this radio link: these are usually all bad frames. In the case of mobile phone to PSTN calls, the BLER / BER is set to the desired value for the entire BLER. In the case of a mobile phone to mobile phone call, the BLER / BER for this first radio link may be set to only half of the desired value for the entire BLER / BER in the first solution.

For the downlink direction, which is the first wireless link in this voice path direction for PSTN to mobile phone calls but the second wireless link in this voice path direction for mobile phone to mobile phone calls, results from the failure of the first wireless link. It is not easy to distinguish between a bad voice frame that has been made and a bad voice frame resulting from an error in the second radio link. However, this distinction is important, otherwise the (external) power control loop can start even in a non-desirable or unsuitable behavior.

In the GERAN case, the distinction between the two error sources may be made within the mobile station based on how the CRC calculation is defined for the downlink air interface, as shown in TS 48.060 or TS 48.061. Poor voice frames arriving by the downlink at the base transceiver station (BTS) are located by " Layer 2 Fill Frames " or to the mobile station, except that they have inverted CRC bits. Can be sent.

For the Universal Mobile Telecommunication System (UMTS) Terrestrial Radio Access Network (UTRAN), the difference is that the Radio Network Controller (RNC) completely ignores frames that are not good, so that the UE does not receive voice frames or nodes This is possible within the mobile station due to the fact that (B) inverts the CRC bits for the poor voice frame (but this is not standardized).

In both GERAN and UTRAN, another way to distinguish between two sources of error is to report this poor frame as a whole by simply counting the bad frames that arrive there from the remote radio link, as reported by the mobile station. By subtracting from the number of frames that are not, it is possible in BTS, individual node B. This solution, where the division is done within the BTS (Node B), is desirable if no standardization is achieved because no change is required at the mobile station.

In the case of PSTN versus mobile phone calls, BLER / BER is set to the desired value for the overall BLER / BER. In the case of a mobile phone to mobile phone call, the BLER / BER for this second radio link is set to only half of the desired value for the entire BLER / BER in the first solution. An alternative solution for setting the BLER / BER target value for mobile phone to mobile phone calls is advantageous for the fact that the interference conditions are typically not the same in both radio calls.

It should be remembered that the count for any end-user is total BLER / BER and must persist under some limit (eg 1%) to satisfy the end-user. However, it does not matter whether one radio link is (very) completely error free and the other radio link causes all allowed errors.

Without feedback going back from the second radio link to the first radio link (such feedback is not currently standardized), it is impossible to find a "symmetrical" solution, where BLER / BER is in a "fair" way. Is distributed. But this is not a big drawback.

Typically the uplink direction must carry less overall traffic than the downlink direction (primarily due to the increased use of streaming data retrieval and Internet browsing), so more transmitter power may be allowed for the individual uplink. The BLER / BER target for the uplink may be set to a low value. The first radio link is able to adapt its BLER / BER target value for the uplink permanently according to the changing load and interference conditions in its uplink direction. The second downlink can easily determine the BLE / BER from the first radio link by counting bad frames, and as a result can use all remaining differences in the overall BLER / BER target for its BLER / BER target setup. have. In this way, the load in the second cell in the downlink direction can be reduced without disturbing the voice quality target.

Therefore this second alternative solution is one preferred solution because it optimizes the critical downlink direction. This has another desirable advantage: It automatically works for all call types, PSTN vs. mobile phones and mobile vs. mobile phones because it uses only the remaining BLER / BER differences for its target setting.

In the case of PSTN versus mobile phone calls, the first connection is typically completely error free. One problem may arise in the case of MTPSTN calls in that the ER / BER target on the uplink radio channel is set too low to allow the headroom needed for the potential second downlink channel on average. However, it does not exist in the MTPSTN call.

An additional advantage of the second solution is that it can also take into account transmission errors at the fixing part of the connection. Such errors are typically rare, but especially when packet-based forwarding (such as Internet Protocol (IP) or Asynchronous Transfer Mode (ATM)) may be used or may increase in unfavorable weather conditions (eg microwave link Increase in busy time due to increased traffic and load).

As a result, increased capacity and / or voice quality can be achieved in WCDMA systems as well as in any other radio access network (RAN), such as GERAN.

Implementation of the method and system according to the idea of the present invention includes the planning and realization of a transcoder free operation (TrFO) or a serial free operation (TFO), where the system is a mobile telephone to PSTN or mobile telephone stand. Recognizes whether it is a mobile phone call. Since some frame types (eg SPEECH_BAD, SID_BAD) only occur in the downlink data when there are other mobile phone links in the path, it is also possible to detect mobile phone-to-mobile call by examining the frame type of voice data. .

Another possibility for detecting mobile phone-to-mobile phone calls is by number analysis, that is, whether the called phone number belongs to a fixed line service or a mobile phone service.

Therefore, this is acceptable for additional systems including power control similar to WCDMA and CDMA2000 and WCDMA. This can be used for other WCDMA services, such as videotelephony, and can also be applied to systems with slow power controls. The basic principle of the present invention is not limited to the use of block error rate (BLER) to control the transmit power. This is equally acceptable for other parameters such as, for example, bit error rate (BER).

Reference

[1] H.Holam, A. Toskala "WCDMA for UMTS", John Wiley & Sons, 2001

Claims (14)

Code Division Multiple Access (CDMA) Controlled Block Error Rate (BLER) or Bit Error Rate (BER) when called on a radio link in a mobile-to-mobile (MTM) and mobile-to-public switched telephone network (MTPSTN) communications In the setting method, Defining a desired total BLER / BER target value; Detecting whether the call is MTM or MTPSTN; And In the case of an MTM call, controlling the BLER / BER on a second link to provide the total BLER / BER following the total BLER / BER target; How to set bit error rate (BER). The method of claim 1, Detecting whether the call is an MTM or MTPSTN by examining a frame type to be transmitted on the second link. 16. The method of claim 1, wherein the block error rate (BLER) or bit error rate (BER) is controlled. The method of claim 1, The first BLER / BER target for the first link and the second BLER / BER target for the second link so that the sum of the first link and the second BLER / BER target are equal to the total BLER / BER target. And separately setting the block error rate (BLER) or bit error rate (BER) setting method in the case of a call. The method of claim 3, wherein Setting the first BLER / BER target for the first link to 50% of the total BLER / BER target, wherein the block-controlled block error rate (BLER) or bit error rate ( BER) How to set. The method of claim 3, wherein And setting the second BLER / BER target in the block to be transmitted on the second link to the difference between the total BLER / BER target and the measured BLER / BER. How to set error rate (BLER) or bit error rate (BER). A method of setting a controlled block error rate (BLER) or bit error rate (BER) target for a radio link in a code division multiple access (CDMA) mobile telephone to public switched telephone network (MTPSTN) communication system, the method comprising: Defining a desired total BLER / BER target value; Estimating a BLER / BER of a block to be transmitted on the downlink; and Controlling a BLER / BER on a second link to provide a total BLER / BER equal to the desired total BLER / BER target, wherein the controlled block error rate (BLER) or bit error rate (BER) target How to set up. The method of claim 6, Control the BLER / BER of the second link separately using the difference between the desired total BLER / BER and the estimated BLER / BER in the block to be transmitted on the downlink as the BLER / BER target for the second link. And controlling the block error rate (BLER) or bit error rate (BER) target when controlled. Controlled Block Error Rate (BLER) or Bit Error Rate (BER) Target Setting System for Mobile Phone to Mobile Phone (MTM) and Mobile Phone to Public Switched Telephone Network (MTPSTN) Communication with Code Division Multiple Access (CDMA) To Preferred total BLER / BER target values are defined for the system; Detecting a call that is an MTM or MTPSTN; In the case of an MTM call, controlling the BLER / BER on a second link to provide a total BLER / BER that conforms to the total BLER / BER target. Rate (BER) target setting system. The method of claim 8, Block error rate (BLER) or bit error rate (BER) target setting system, characterized in that an MTM or MTPSTN call is detected by examining the type of frame to be transmitted on the second link. The method of claim 8, The BLER / BER of the first link and the second link is controlled and the first BLER / BER target and the second BLER / BER target are set individually so that the sum of the first and second BLER / BER targets is the total BLER / A controlled block error rate (BLER) or bit error rate (BER) target setting system when characterized in that it will be the same as the BER target. The method of claim 10, And if the BLER / BER for the first link is set to 50% of the total BLER / BER target, controlled block error rate (BLER) or bit error rate (BER) target setting system. The method of claim 10, A block error rate (BLER) controlled when the second BLER / BER target is set to a difference between the total BLER / BER target and an estimated BLER / BER in data to be transmitted on the second link or Bit Error Rate (BER) Target Setting System. In a block / bit error rate (BLER / BER) target setting system controlled when calling in a mobile telephone to public switched telephone network (MTPSTN) using code division multiple access (CDMA), The desired total BLER / BER target value is defined for the communication; A BLER / BER of a block or bit to be transmitted on the second link is estimated; And The block / bit error rate (BLER / BER) target setting system controlled on a call basis, wherein the BLER / BER on the second link is controlled to provide the same total BLER / BER to the desired total BLER / BER target. The method of claim 13, The BLER of the second link controls by individually using the difference between the desired total BLER / BER and the estimated BLER / BER in the data to be transmitted on the second link as the BLER / BER target for the downlink. Block / bit error rate (BLER / BER) target setting system controlled in case of a call.