CN100393171C - Method and device for improving connection rate in code division multiple access mobile communication system - Google Patents

Abstract

The invention discloses a method and equipment for improving the connection rate in a code division multiple access mobile communication system. In the initial stage of call establishment, when the mobile station uses the open-loop power control method, the base station judges the quality of the forward link according to the strength Ec/Io of the pilot signal at the receiving end reported by the mobile station. When the forward link becomes weak, the base station tries its best to satisfy the mobile station by timely adjusting the transmission power and number of signaling frames directed to a specific mobile station on the paging channel, as well as the transmission power of the initial traffic frame on the forward traffic channel. The reception quality requirements of the station for the channel, so as not to affect the processing of the normal call flow, and improve the connection rate. Its technical characteristics are suitable for call access areas where the front and reverse links are unbalanced due to wireless environmental factors such as fast fading of the forward link or strong interference.

Description

Method and device for improving connection rate in code division multiple access mobile communication system

technical field

The present invention relates to a code division multiple access mobile communication system, in particular to a method and equipment for improving connection success rate and connection failure in the code division multiple access mobile communication system.

Background technique

Mobile communication is one of the most active and fastest-growing fields in today's communication, and it has a great impact on human life and social development in the 21st century. Code Division Multiple Access (CDMA) technology has become a very competitive digital mobile communication system because of its high frequency utilization rate and strong anti-interference ability. With the in-depth development of CDMA mobile network construction, users' requirements for network quality are increasing day by day.

The connection rate index of the wireless network will most directly affect the user experience. In the initial stage of network construction, system operators mainly solve coverage and capacity problems. On the basis of completing the preliminary network construction, improving the connection rate is one of the goals pursued by each operator.

When mobile communication on land, the mobile station often works in the environment with complex urban buildings and various terrain features, and the characteristics of its transmission channel change anytime and anywhere, so the mobile channel is a typical random channel. In the UHF frequency band (300-3000MHz), the radio wave propagation methods include direct waves (line-of-sight propagation), ground reflected waves, and reflected waves (sometimes called scattering) of various obstacles (including buildings, various vehicles), so that wireless Channels are varied and difficult to control. Since both the signaling frame and the service frame are transmitted through the wireless channel, changes in the wireless environment of the forward and reverse channels will directly affect the success rate of frame reception.

In the CDMA communication system, when doing network planning and link budget, the wireless coverage is obtained by calculating some factors that affect the gain and loss of the front and back wireless links. The goal of this kind of budget planning is to make the coverage of the front and reverse links basically the same, and the signal loss suffered by the reverse link is equal to and similar to the loss suffered by the forward link, so as to ensure the balance of the two channels, so as to achieve correct demodulation at the receiving end Purpose of signaling frame or traffic frame. However, due to the irrelevance of the forward and reverse links, the fast fading characteristics of the two wireless channels cannot be predicted in the link budget, and the impact of other sudden interference sources on the transmission of the two channels of signals, etc., resulting in unbalanced system links , causing system performance to deteriorate.

In the CDMA system, considering the change of the system load, the fast and slow change of the channel state, and the influence of the fading of the channel on the signal transmission, two power control methods, open-loop and closed-loop, are adopted to achieve correct reception and demodulation. Open-loop estimation means that the mobile station roughly estimates the channel propagation environment based on the received signal strength from the base station, and adjusts its reverse transmit power accordingly, which is a unilateral adjustment. But this ignores the fact that the forward channel and the reverse channel are not related, which will lead to large errors in a short period of time, and it is impossible to estimate the influence of factors such as fast fading characteristics and strong interference on the wireless channel. Closed-loop calibration refers to the rapid correction of the transmission power according to the power control command received by the receiving end on the basis of the open-loop estimation. The power control command (up or down) is a loop control power transmission mechanism generated after the dedicated channel is established. , is determined by the sender according to the quality of the signal it receives.

In the initial stage of call establishment, because there is no dedicated traffic channel and control channel between the mobile station and the base station, the mobile station only adopts an open-loop power control method. Generally, base station equipment manufacturers set a fixed value for the transmission power. The transmission power of the signaling frame on this channel is the same as the transmission power of the common signaling channel, and will not change when the coverage area is fixed. There is no independent setting for the transmission mode of signaling frames sent on the common signaling channel. At the same time, for all mobile stations within the coverage area, the base station sends the initial service frame of the forward dedicated channel with the same fixed value power. These two setting methods do not fully consider the impact of the variable wireless channel on the receiving end of the mobile station in the open-loop power control mode, and the forward link is often weakened due to factors such as fast fading of the forward channel signal or strong interference. , so that the mobile station cannot receive the forward signaling frame or the initial service frame in time, resulting in the failure of call establishment and the decline of the network connection rate.

Considering the limitations of the forward channel frame control mode of the above system under the condition of open-loop power control, it will cause the situation that the mobile station cannot be captured in time. Therefore, it is necessary to adjust the forward signaling frame and The way to send the initial service frame, so that the mobile station can capture it in time, so as not to affect the processing of the normal call flow. This has a very important impact on the improvement of network quality.

Explanation of terms:

Ec/Io: Pilot signal strength

PCH_GAIN: paging channel transmit power

FDCH_INIT_GAIN: forward traffic channel initial transmit power

PCH_SIG_DELTA_GAIN: Compensation power of signaling frames directed to specific mobile stations on the paging channel

FDCH_DELTA_GAIN: forward traffic channel initial traffic frame compensation power

PCH_SIG_GAIN: Points to the specific mobile station signaling frame transmission power

FDCH_INIT_ADJ_GAIN: transmit power of forward traffic channel initial traffic frame

PCH_MAX_GAIN: maximum transmit power of paging channel signaling frame

FDCH_MAX_GAIN: Maximum transmit power of the forward traffic channel initial traffic frame

RES_PWR: base station redundant power

PCH_Allowed_Limit: Paging channel redundancy power threshold

FDCH_Allowed_Limit: forward traffic channel redundancy power threshold

T_INTF_PCH: Paging channel power compensation threshold

T_INTF_FDCH: forward traffic channel power compensation threshold

Specific mobile station: the mobile station for which the base station makes forward link judgments based on the pilot signal strength Ec/Io reported by the mobile station

Contents of the invention

The purpose of the present invention is to provide a code division multiple access (CDMA) mobile communication system that improves the connection success rate and improves the method and equipment for the problem of connection failure, so as to solve the problems caused by the fast fading of the forward channel signal or strong interference. The weakening of the link makes it impossible for the mobile station to receive the forward signaling frame or the initial service frame in time, resulting in the failure of call establishment and the decline of the network completion rate.

The technical solution of the present invention is that at the initial stage of call establishment (that is, the mobile station uses an open-loop power control method, and the forward common channel power of the base station and the initial power of the forward dedicated channel use fixed transmission power), by detecting the quality of the forward link signal, it can be judged Whether the forward and reverse links are balanced, and according to the judgment, timely adjust the sending mode of the forward public channel signaling frame and the forward dedicated channel initial service frame, so as to increase the number of mobile stations successfully receiving signaling frames and initial service frames probability to improve network quality.

The present invention is mainly concerned with the situation where the forward link is weakened in the forward reverse link imbalance. Among them, the forward link mainly includes forward common channel and forward dedicated channel.

The base station judges whether the forward link becomes weak according to the wireless environment on the mobile station side provided by the mobile station. When the quality of the forward link is lower than the channel power compensation threshold, it is determined whether the forward link is weakened, and the situation of unbalanced forward and reverse links occurs.

In the CDMA system, the paging channel is mainly used as the forward common channel, and this channel sends signaling frames. The base station determines the transmission power and the number of transmission times of the signaling frame according to the wireless environment on the mobile station side provided by the mobile station.

In the CDMA system, the forward basic business channel is mainly used as the forward dedicated channel, and this channel sends the initial business frame. The base station determines the transmit power of the initial service frame according to the wireless environment on the mobile station side provided by the mobile station.

When the mobile station is in a poor wireless environment, it is necessary to strengthen the transmission power of the signaling frame and the initial service frame. At the same time, in order to avoid the influence of network capacity due to excessive power, a limit condition needs to be added.

The equalization of the front and reverse links is a very important design goal in the CDMA system. If the system links are not balanced, the system performance will be degraded. In the early stage of call establishment, when the mobile station uses open-loop power control, it only roughly estimates the channel propagation environment according to the received signal strength of the base station, and adjusts its reverse transmit power accordingly, ignoring the irrelevance of the forward channel and the reverse channel The facts will lead to large errors in a short period of time, and it is impossible to estimate the fast fading characteristics of the wireless channel and the sudden strong interference (such as the mobile station moving to the shadow area during the access process, the multi-pilot cell border handover area, etc. and areas with strong interference), resulting in unbalanced system links and degraded system performance. Therefore, in order to improve the low connection rate in areas with multi-cell borders and poor wireless environments, a mechanism is required for the base station to adjust the forward frame in time when the front reverse link burst is unbalanced and the forward link becomes weak. The transmission mode ensures that the mobile station can receive and demodulate correctly.

The present invention proposes to judge whether the forward link becomes weak according to the wireless environment situation of the mobile station side measured and reported by the mobile station for Ec/Io. When the base station sends the signaling frame directed to a specific mobile station on the paging channel and the initial service frame on the forward traffic channel, it usually sets a fixed power gain for sending. However, in areas with poor wireless environments, this fixed gain cannot meet the mobile station’s requirements for receiving quality on the forward channel. It is possible to cause the forward link to fail. Therefore, in order to ensure that the mobile station can correctly receive the forward frame, the base station needs to adjust the generation mode of the forward link in time according to the wireless environment on the mobile station side. The forward link pilot signal strength Ec/Io information provided by the mobile station is an important basis for the base station to judge the quality of the forward link. The base station performs forward link quality judgment and power compensation according to the pilot signal strength Ec/Io: when Ec/Io exceeds the power compensation threshold, the signaling frame and initial service frame only need to be transmitted according to the fixed power setting ; When Ec/Io is smaller than the power compensation threshold, it is necessary to increase the compensation gain related to Ec/Io to strengthen the transmit power. The characteristic of the compensation gain is the gain of the difference between the power compensation threshold of the signaling frame or the initial service frame and Ec/Io.

At the same time, due to the limited forward power, a power limiter needs to be added to control the transmission power of the signaling frame directed to a specific mobile station on the paging channel and the initial traffic frame on the forward traffic channel. In addition, the base station can use different parameter values to set the power limiter of the signaling frame and the service frame according to different quality factors of the receiving end. Because CDMA is a self-interference system, high-power transmission is a strong interference to surrounding base stations, thus affecting the capacity of the entire system. Therefore, the base station needs to limit the transmission power of the forward channel, and set the maximum signaling frame power and service frame power respectively according to the mobile station's requirements for receiving quality factors of different channels. This limiting method can greatly improve the success rate of call connection without affecting the capacity of the existing network.

Finally, in order to further improve the sudden unbalanced phenomenon of the previous reverse link caused by factors such as fast signal fading or strong interference, and ensure the success rate of frame reception, the present invention uses The method of sending 3 times continuously reduces the probability of frame loss caused by rapid changes in the wireless environment, thereby improving the success rate of reception.

technical effect

In the CDMA system, adopting the method for improving the connection rate of the present invention can obtain the following technical effects:

1. In the present invention, at the initial stage of call establishment, the mobile station only adopts the open-loop power control mode, and it is impossible to estimate the weakening of the forward link caused by wireless environmental factors such as channel fast fading or strong interference. To the limitation of the channel frame control method, the transmission power is determined according to the wireless environment where the mobile station is located. When the wireless environment where the mobile station is in is bad, increase the transmission power to ensure that the mobile station correctly receives the call control message. The base station sends the signaling message directed to the specific mobile station on the paging channel and the initial service frame on the forward traffic channel. The method for calculating the call control message according to the strength of the pilot signal at the location of the mobile station can greatly reduce the call connection failure caused by the wireless environment. This has a very important impact on the improvement of network quality.

2. In the present invention, different power compensators and limiters are used for the signaling frame of the paging channel and the initial service frame of the forward traffic channel. Since the quality factors required by the mobile station to demodulate the forward signaling frame and service frame are different, in the case of poor forward link, in order to ensure the accurate reception of the mobile station, according to the quality factor characteristics of the signaling frame and service frame , choose a different device setting. This separate setting method can greatly improve the reception success rate of the receiving end without affecting the system capacity.

3. The present invention uses a power compensator to accurately calculate the transmission power when determining the transmission power of the signaling frame and the initial service frame. The power compensator accurately calculates the transmission power of the required signaling frame according to the Ec/Io at the mobile station side. This calculation method not only ensures that the mobile station can successfully receive signaling messages, but also avoids the waste of power resources caused by excessive transmission power of signaling frames, thereby further reducing the impact on system capacity. The power compensator is a transmission method of power adaptation.

4. The present invention uses a power compensator, a power limiter, and a power compensation threshold and a redundancy threshold when determining the transmission power of the signaling frame and the initial service frame. On-site optimization engineers can optimize these devices and thresholds according to on-site wireless network conditions, providing flexible optimization methods for on-site network optimization.

The purpose, features and technical effects of the present invention will be further described below in conjunction with the accompanying drawings.

Description of drawings

Figure 1 is a flowchart of the base station processing call setup

Fig. 2 is a flow chart of the number of transmission times and transmission power of the forward common channel signaling frame power during the base station's determination of the call establishment process

Figure 3 is a flow chart of the transmit power of the initial traffic frame of the forward traffic channel when the base station determines the call setup process

Fig. 4 is a diagram of a sending device for a base station to adjust a signaling frame and an initial service frame according to a received wireless signal.

Specific implementation method

Fig. 1 is a flow chart of the base station processing call connection. For mobile stations above version 4, the IS-2000 specification requires that mobile stations above version 4 must include the RER (RadioEnvironment Report) field when sending ORM and PRSP. The RER field contains the pilot signal strength information of the location of the mobile station. After receiving the ORM or PRSP containing the RER field, the base station calculates the required transmit power for the paging channel signaling frame and the initial service frame of the traffic channel directed to a specific mobile station. When Ec/Io is greater than or equal to the paging channel power compensation threshold T_INTF_PCH, the transmission power and transmission times of the paging channel signaling frames directed to a specific mobile station are not adjusted; The paging channel signaling frame transmit power and number of occurrences are adjusted. At the same time, when Ec/Io is greater than or equal to the forward traffic channel power compensation threshold T_INTF_FDCH, the transmission power of the initial traffic frame of the forward traffic channel is not compensated; when Ec/Io is smaller than T_INTF_FDCH, the transmission of the initial traffic frame of the forward traffic channel Power is adjusted.

Fig. 2 is a flow chart for the base station to determine the number of transmission times and transmission power of the paging channel signaling frame power directed to a specific mobile station.

First, the base station generates a paging channel signaling frame directed to a specific mobile station.

Second, the transmission power of the signaling frame is initialized, and the transmission power is the paging channel power value PCH_GAIN.

Thirdly, calculate the redundant power RES_PWR of the base station, and then perform different processing according to the following discrimination conditions.

1. When RES_PWR<PCH_Allowed_Limit, no power compensation is performed.

2. When RES_PWR≥PCH_Allowed_Limit, proceed as follows:

a) Enter the signaling frame power compensator, and compensate the signaling frame power according to the pilot signal strength Ec/Io value measured by the mobile station.

According to the inverse relationship between the base station paging channel transmit power and the strength of the pilot signal received by the mobile station, the signaling frame compensation power directed to a specific mobile station on the paging channel is PCH_SIG_DELTA_GAIN=T_INTF_PCH-Ec/Io (dB).

After compensation, the transmission power of the signaling frame directed to the specific mobile station is PCH_SIG_GAIN=PCH_GAIN+PCH_SIG_DELTA_GAIN (dB).

b) Enter the signaling frame power limiter to limit the signaling frame power. In order to prevent the transmission power required by a specific mobile station in a poor wireless environment from being too large, the paging channel power limiter PCH_MAX_GAIN needs to be used when determining the transmission power.

3. It is determined to continuously send 3 signaling frames directed to the specific mobile station on the paging channel.

Finally, the base station sends a signaling message to the mobile station after determining the transmission power of the signaling frame and the number of consecutive transmission times according to the above steps.

In Fig. 2, there is the following derivation relationship between the pilot Ec/Io intensity received by the mobile station and the paging channel power value set by the base station.

$\frac{\mathrm{<span\; class="notranslate">\; Ec</span>}}{\mathrm{<span\; class="notranslate">\; Io</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; pilot</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; in</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; out</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

The strength of the pilot signal received at the mobile station is Ec/Io equal to the ratio of the pilot power R_pilot received by the mobile station to the interference. The interference includes internal interference (including thermal noise) I_in and external interference (including thermal noise) I_out.

${<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Eb</span>}}{\mathrm{<span\; class="notranslate">\; Nt</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; page</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Io</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

The ratio (Eb/Nt)p of the energy per bit to the noise power spectral density is equal to the paging power R_page received by the mobile station and the noise power spectral density Nt. The noise power spectral density Nt includes the thermal noise density No and the interference density Io. For the receiving end of the mobile station must meet the quality requirements in a specific environment, the paging channel requires a quality (Eb/Nt)p range of 7 to 9dB, except for thermal noise, generally does not contain other noise for the forward link, so the approximate Equivalent to the ratio of energy per bit to thermal noise density (Eb/No)p.

$\frac{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; page</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; pilot</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; page</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; pilot</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Eb</span>}}{\mathrm{<span\; class="notranslate">\; Nt</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; *</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Ec</span>}}{\mathrm{<span\; class="notranslate">\; Io</span>}}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; *</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Measured at the same receiving point, the interference of the pilot frequency and the paging channel are basically the same, and the path attenuation is basically the same. Therefore, the ratio of the paging power T_page transmitted by the base station to the pilot power T_pilot transmitted by the base station is basically the same as the paging power R_page and pilot power R_pilot received by the mobile station at the receiving end. According to the paging channel gain (W/R _b ), substituting (2) into (1), the relationship between the pilot and the paging channel in (3) can be obtained.

${<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Eb</span>}}{\mathrm{<span\; class="notranslate">\; Nt</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Ec</span>}}{\mathrm{<span\; class="notranslate">\; Io</span>}}<span\; class="notranslate">\; *</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; *</span>\frac{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; page</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; pilot</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Convert (3) into (4) to obtain the relationship between the strength Ec/Io of the pilot signal received by the mobile station and the power value of the paging channel set by the base station. When the quality value of the paging channel of the mobile station, the power value of the pilot channel of the base station and the gain of the paging channel are determined, the transmit power T_page of the paging channel of the base station is inversely proportional to the strength of the pilot signal received at the mobile station as Ec/Io . Therefore, the degradation of the paging channel quality of the mobile station caused by factors such as channel attenuation or strong interference can be compensated by increasing the transmit power of the paging channel of the base station.

The characteristic of the paging channel power PCH_GAIN in Fig. 2 is the required transmit power T_page of the base station traffic channel when the mobile station is in the coverage boundary area of the cell in formula (4). Wherein the pilot signal strength Ec/Io ranges from -11 to 15dB, the forward traffic channel receiving quality (Eb/Nt) _t ranges from 7 to 9dB, and the transmit pilot power accounts for 15 to 20% of the total power of the base station. Considering that in the cell, except for individual shadows, strong interference and border areas that need to be compensated, other areas are within the above reference value range. Therefore, the transmission power of the paging channel only compensates the signaling frames directed to specific mobile stations in shadows, strong interference and borders, etc., where Ec/Io is lower than T_INTF_PCH, so as to avoid system performance degradation caused by frequent adjustments.

The function of the signaling frame power compensator in Fig. 2 is to compensate the paging channel whose pilot signal intensity Ec/Io is smaller than the power compensation threshold T_INTF_PCH when sending the signaling frame directed to a specific mobile station. The compensation obtained by the signaling frame is equal to the difference between the power compensation threshold and Ec/Io. The range of T_INTF_PCH is -8 to -16dB.

The function of the signaling frame power limiter in Fig. 2 is to set the maximum power PCH_MAX_GAIN of the signaling frame directed to a specific mobile station. The range of PCH_MAX_GAIN is -1 to -10dB.

The characteristic of the redundant power RES_PWR of the base station in FIG. 2 is the ratio of the difference between the maximum transmit power of the base station and the current transmit power to the maximum transmit power of the base station.

The feature of the paging channel redundancy power threshold PCH_Allowed_Limit in FIG. 2 is the redundancy power threshold that can be used to compensate the paging channel signaling frame. The range of PCH_Allowed_Limit is 0 to 100%.

Fig. 3 is a flow chart of the base station determining the transmission power of the initial traffic frame of the forward traffic channel directed to a specific mobile station.

First, the base station completes the establishment of the forward traffic channel and prepares to send the forward initial traffic frame.

Second, initialize the transmission power of the service frame, and the transmission power is FDCH_INIT_GAIN.

Thirdly, calculate the redundant power RES_PWR of the base station, and then perform different processing according to the following discrimination conditions.

1. When RES_PWR<FDCH_Allowed_Limit, no power compensation is performed.

2. When RES_PWR≥FDCH_Allowed_Limit, perform the following processing.

a) Enter the initial service frame power compensator, and compensate the initial service frame power according to the pilot signal strength Ec/Io value measured by the mobile station.

According to the inverse relationship between the transmit power of the traffic channel of the base station and the strength of the pilot signal received by the mobile station, the compensation power of the initial traffic frame of the traffic channel is FDCH_DELTA_GAIN=T_INTF_FDCH-Ec/Io (dB).

After compensation, the transmit power of the initial traffic frame of the forward traffic channel is obtained as FDCH_INIT_ADJ_GAIN=FDCH_INIT_GAIN+FDCH_DELTA_GAIN (dB).

b) Enter the initial service frame power limiter to limit the power of the service frame. In order to prevent the transmission power required by a specific mobile station in a poor wireless environment from being too large, when determining the transmission power, it is necessary to pass through the initial service frame power limiter FDCH_MAX_GAIN of the forward traffic channel.

Finally, the base station sends the initial traffic frame to the mobile station after determining the transmission power of the initial traffic frame of the forward traffic channel according to the above steps.

In Figure 3, according to the following derivation relationship between the pilot signal strength Ec/Io received by the mobile station and the paging channel power value set by the base station, the pilot signal Ec/Io strength received by the mobile station and the previous value set by the base station can be obtained. The relationship between the initial power values of the traffic channels.

${<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Eb</span>}}{\mathrm{<span\; class="notranslate">\; Nt</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Traffic</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Io</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The ratio (Eb/Nt) _t of the energy per bit to the noise power spectral density is equal to the service power R_traffic received by the mobile station and the noise power spectral density Nt. For the mobile station receiving end must meet the quality requirements in a specific environment, the service channel requires a quality (Eb/Nt) _t in the range of 7 to 9dB.

${<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Eb</span>}}{\mathrm{<span\; class="notranslate">\; Nt</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Ec</span>}}{\mathrm{<span\; class="notranslate">\; Io</span>}}<span\; class="notranslate">\; *</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; *</span>\frac{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Traffic</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; pilot</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

From (6) the relationship between the strength Ec/Io of the pilot signal received by the mobile station and the power value of the traffic channel set by the base station is obtained. When the traffic channel quality value of the mobile station, the power value of the pilot channel of the base station and the gain of the traffic channel are determined, the transmit power T_traffic of the traffic channel of the base station is inversely proportional to the strength Ec/Io of the pilot signal received at the mobile station, which can be increased by increasing The transmit power of the traffic channel of the base station is used to compensate the degradation of the traffic channel quality of the mobile station caused by channel attenuation or strong interference.

The characteristic of the forward traffic channel initial traffic frame power FDCH_INIT_GAIN in Fig. 3 is the transmit power T_traffic of the base station traffic channel required when the mobile station is in the coverage boundary area of the cell in formula (6). Wherein the pilot signal strength Ec/Io ranges from -11 to 15dB, the forward traffic channel receiving quality (Eb/Nt) _t ranges from 7 to 9dB, and the transmit pilot power accounts for 15 to 20% of the total power of the base station.

The function of the initial traffic frame power compensator in Fig. 3 is to compensate the forward traffic channel whose pilot signal strength Ec/Io is smaller than the power compensation threshold T_INTF_FDCH when sending the initial traffic frame directed to a specific mobile station. The compensation obtained for the initial service frame is equal to the difference between the power compensation threshold and Ec/Io. The range of T_INTF_FDCH is -8 to -16dB.

The function of the initial service frame power limiter in Fig. 3 is to set the maximum power FDCH_MAX_GAIN of the initial service frame directed to a specific mobile station. The range of FDCH_MAX_GAIN is -1 to -10dB.

The characteristic of the redundant power RES_PWR of the base station in FIG. 3 is the ratio of the difference between the maximum transmit power MAX_PWR of the base station and the current transmit power CUR_PWR to the maximum transmit power of the base station.

The feature of the forward traffic channel redundancy power threshold FDCH_Allowed_Limit in Fig. 3 is the redundancy power threshold that can be used to compensate the initial traffic frame of the forward traffic channel. The range of FDCH_Allowed_Limit is 0 to 100%.

Fig. 4 is a diagram of a sending device for a base station to adjust a signaling frame and an initial service frame according to a received wireless signal.

In FIG. 4 , the base station wireless signal receiving device judges the incoming signaling frame and the initial service frame sending device according to the process in FIG. 1 . And the demodulated signal is output through the signal output device.

The base station wireless signal sending equipment in Figure 4 is adjusted according to the flow charts in Figure 2 and Figure 3, through the signaling frame power compensator, signaling frame power limiter, and initial service frame power compensator, initial service frame power limiter Signaling frame and initial service frame power, send modulated signal input signal input device.

The function of the signaling frame power compensator in Fig. 4 is to compensate the paging channel whose pilot signal intensity Ec/Io is smaller than the power compensation threshold T_INTF_PCH when sending the signaling frame directed to a specific mobile station. The compensation obtained by the signaling frame is equal to the difference between the power compensation threshold and Ec/Io. The range of T_INTF_PCH is -8 to -16dB.

The role of the signaling frame power limiter in Fig. 4 is to set the maximum power PCH_MAX_GAIN of the signaling frame directed to a specific mobile station. The range of PCH_MAX_GAIN is -1 to -10dB.

The function of the initial traffic frame power compensator in Fig. 4 is to compensate the forward traffic channel whose pilot signal strength Ec/Io is smaller than the power compensation threshold T_INTF_FDCH when sending the initial traffic frame directed to a specific mobile station. The compensation obtained for the initial service frame is equal to the difference between the power compensation threshold and Ec/Io. The range of T_INTF_FDCH is -8 to -16dB.

The function of the initial service frame power limiter in Fig. 4 is to set the maximum power FDCH_MAX_GAIN of the initial service frame directed to a specific mobile station. The range of FDCH_MAX_GAIN is -1 to -10dB.

Although specific embodiments of the present invention have been described in detail by way of example with reference to the accompanying drawings, various modifications and variations can be made to the present invention. Especially for those skilled in the art, according to the method of improving the connection rate proposed by the present invention and performing power compensation for the base station transmission frame, a solution to the failure of the connection rate caused by the weakening of the forward link can be proposed. It should be understood that the present invention is to cover all modifications, equivalent substitutions and variations falling within the spirit and scope of the present invention as defined by the appended claims.

Claims (8)

1. improve the method for call completing rate in the CDMA mobile communication systems, it is characterized in that: when the forward direction weak link, the send mode of in time adjusting signaling frame and initial service frame is adopted in the base station;

Described forward link dies down, and comprises following several determining step:

(1.1) at the call setup initial stage, the base station receives the access channel signaling message of the pilot signal strength that comprises the travelling carriage present position;

(1.2) the forward link situation of change that travelling carriage receives is judged according to the pilot signal strength of travelling carriage report in the base station:

(1.2.1) according to receiving terminal paging channel quality requirements, enter the judgement of paging channel link-quality;

(1.2.2) according to receiving terminal forward traffic channel quality requirements, enter the judgement of forward traffic channel link-quality;

The send mode of in time adjusting signaling frame and initial service frame is adopted in described base station, comprises following several steps:

(1.3) transmitting power and the transmission number of times of the signaling frame of the specific travelling carriage of sensing on the paging channel are adjusted;

(1.4) transmitting power of initial service frame on the forward traffic channel is adjusted.

2. improve the method for call completing rate in a kind of CDMA mobile communication systems according to claim 1, it is characterized in that: described according to receiving terminal paging channel quality requirements, enter the judgement of paging channel link-quality, comprise following several steps:

(2.1), the transmitting power and the transmission number of times of the signaling frame of the specific travelling carriage of sensing on the paging channel are not adjusted when pilot signal strength 〉=paging channel power back-off thresholding;

(2.2) when pilot signal strength＜paging channel power back-off thresholding, to the transmitting power of the signaling frame that points to specific travelling carriage on the paging channel with send number of times and adjust.

3. improve the method for call completing rate in a kind of CDMA mobile communication systems according to claim 1, it is characterized in that: described according to receiving terminal forward traffic channel quality requirements, enter the judgement of forward traffic channel link-quality, comprise following several steps:

(3.1) when pilot signal strength 〉=forward traffic channel power back-off thresholding, the transmitting power of initial service frame on the forward traffic channel is not adjusted;

(3.2) when pilot signal strength＜forward traffic channel power back-off thresholding, the transmitting power of initial service frame on the forward traffic channel is adjusted.

4. improve the method for call completing rate in a kind of CDMA mobile communication systems according to claim 2, it is characterized in that: described transmitting power and transmission number of times to the signaling frame of the specific travelling carriage of sensing on the paging channel adjusted, and comprises following several steps:

(4.1) base station generates the paging channel signaling frame that points to specific travelling carriage;

(4.2) to the transmit power initialization of signaling frame, transmitting power is the paging channel performance number;

(4.3) calculation base station redundant power, carry out different processing according to following criterion then:

(4.3.1), do not carry out power back-off when base station redundant power＜paging channel redundant power thresholding;

(4.3.2), carry out following processing when base station redundant power 〉=paging channel redundant power thresholding:

(4.3.2.1) enter the signaling frame power compensator, according to moving table measuring to pilot signal strength signaling frame power is compensated, compensation power is to point to specific travelling carriage signaling frame compensation power=paging channel power back-off thresholding-pilot signal strength on the paging channel;

(4.3.2.2) enter signaling frame power limiting device, signaling frame power is carried out amplitude limit, the signaling frame maximum power is a paging channel signaling frame maximum transmission power;

(4.3.3) determine on paging channel to send continuously the signaling frame that points to specific travelling carriage for 3 times;

(4.4) after the base station is determined the signaling frame transmitting power and sent number of times continuously according to 4.3 top each step, send signaling message to travelling carriage.

5. improve the method for call completing rate in a kind of CDMA mobile communication systems according to claim 3, it is characterized in that: described transmitting power to initial service frame on the forward traffic channel is adjusted, and comprises following several steps:

(5.1) foundation of forward traffic channel is finished in the base station, is ready for sending forward direction initial service frame;

(5.2) to the transmit power initialization of traffic frame, transmitting power is the forward traffic channel Initial Trans;

(5.3) calculation base station redundant power, carry out different processing according to following criterion then:

(5.3.1), do not carry out power back-off when base station redundant power＜forward traffic channel redundant power thresholding;

(5.3.2), carry out following processing when base station redundant power 〉=forward traffic channel redundant power thresholding:

(5.3.2.1) enter initial service frame power compensator, according to moving table measuring to pilot signal strength Ec/Io initial service frame power is compensated, compensation power is forward traffic channel initial service frame compensation power=forward traffic channel power back-off thresholding-pilot signal strength (dB).

(5.3.2.2) enter forward traffic channel initial service frame power limiting device, traffic frame power is carried out amplitude limit;

(5.4) after forward traffic channel initial service frame transmitting power is determined according to 5.3 top each step in the base station, send the initial service frame to travelling carriage.

6. improve the method for call completing rate in a kind of CDMA mobile communication systems according to claim 4, it is characterized in that: wherein said paging channel redundant power thresholding be characterized as the redundant power thresholding that can be used for compensating the paging channel signaling frame, the scope of paging channel redundant power thresholding is 0 to 100%.

7. improve the method for call completing rate in a kind of CDMA mobile communication systems according to claim 5, it is characterized in that: wherein said forward traffic channel redundant power thresholding be characterized as the redundant power thresholding that can be used for compensating forward traffic channel initial service frame, the scope of forward traffic channel redundant power thresholding is 0 to 100%.

8. improve the equipment of call completing rate in the CDMA mobile communication systems, it is characterized in that: when the forward direction weak link, the transmitting apparatus of in time adjusting signaling frame and initial service frame is adopted in the base station, comprising:

(8.1) signaling frame power compensator: when sending the signaling frame that points to specific travelling carriage, the paging channel of pilot signal strength less than paging channel power back-off thresholding compensated, the compensation that signaling frame obtains equals the difference of power back-off thresholding and pilot signal strength, and the scope of paging channel power back-off thresholding is-8 to-16dB;

(8.2) signaling frame power limiting device: set to point to the signaling frame maximum power paging channel signaling frame maximum transmission power of specific travelling carriage, the scope of paging channel signaling frame maximum transmission power be-1 to arrive-10dB;

(8.3) initial service frame power compensator: when sending the initial service frame that points to specific travelling carriage, the forward traffic channel of pilot signal strength less than forward traffic channel power back-off thresholding compensated, the compensation that the initial service frame obtains equals the difference of power back-off thresholding and pilot signal strength, and the scope of forward traffic channel power back-off thresholding is-8 to-16dB;

(8.4) initial service frame power limiting device: set to point to the forward traffic channel initial service frame maximum transmission power of specific travelling carriage, the scope of forward traffic channel initial service frame maximum transmission power be-1 to arrive-10dB.

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