CN100531453C - Method for establishing MBMS service channel and auxiliary publish control physical channel thereof - Google Patents

Abstract

The invention discloses a method for establishing an MBMS service channel and its auxiliary common control physical channel. The method includes the following steps: configuring the transmission power of each MBMS service; the MBMS service initiates a wireless bearer access attempt, and if the access is successful, then The radio bearer RB is established; otherwise, it enters the preemption process; the preemption switch is turned on and the preemption is successful, then the RB is established; if the preemption switch is off or the preemption switch is turned on, the preemption is unsuccessful, and then enters the step of judging whether the service duration is reached; judging whether the service is reached duration, if no, then return to the step of initiating a radio bearer access attempt, if yes, then the channel establishment process ends. Through the method of the present invention, the MBMS service channel and its secondary public control physical channel can be dynamically established and released according to whether there is MBMS service data transmission, thereby improving spectrum resource utilization and access success rate, and improving user experience.

Description

Method for establishing MBMS service channel and its auxiliary common control physical channel

technical field

The invention relates to a channel establishment technology in a communication system, in particular to a channel establishment technology in an MBMS system.

Background technique

Multicast and broadcast are ways of delivering data from one source to multiple destinations. In traditional mobile networks, Cell Broadcast Service (CBS, Cell Broadcast Service) allows low bit rate data to be sent to all users through the cell shared broadcast channel, which is a message-based service. Multimedia Broadcast Multicast Service (MBMS, Multimedia Broadcast Multicast Service) is a multimedia broadcast multicast service. The difference between it and traditional CBS is that it supports multimedia services, has larger bandwidth and better scalability.

The introduction of MBMS brings new channel models and signaling procedures, and also impacts and impacts on various traditional algorithms. After the introduction of MBMS, three new logical channels were added: MBMS Control Channel (MCCH, MBMS Control Channel), MBMS Traffic Channel (MTCH, MBMS Traffic Channel), and MBMS Scheduling Channel (MSCH, MBMS Schedule Channel). These logical channels can be mapped to a Forward Access Channel (FACH, Forward Access Channel) on a Secondary Common Control Physical Channel (SCCPCH, Secondary Common ControlPhysical Channel) for transmission.

The MCCH channel needs to always exist in the cell because it needs to notify the UE of relevant information about the MBMS service in time. The MTCH channel is necessary only when there is really MBMS service data to be sent, and the MSCH channel is used to send scheduling information related to the MTCH. Since the MSCH is always accompanied by the MTCH, in the following description, the MSCH is no longer considered separately, and all SCCPCHs where the MTCH is located can include the MSCH.

Regardless of whether there is MBMS service data transmission in a cell supporting MBMS, all relevant channels are established, including MCCH, MTCH, MSCH and the physical channel SCCPCH mapped thereto.

The service rate that MBMS service can support is very high, can reach 384kbps at present at most, but for high rate service, both power and code resources are extremely limited. When there is no actual MBMS data transmission, if the corresponding SCCPCH is also established, a spreading code with a smaller spreading factor will be occupied (384kbps needs to occupy a spreading factor of 8), causing other dedicated channel services to Insufficient characters lead to access failure, which affects the access success rate and user experience.

Contents of the invention

In view of this, the technical problem to be solved by the present invention is to provide a method for establishing MBMS and the secondary common control physical channel mapped thereto, by dynamically establishing and releasing the channel according to whether there is MBMS service data transmission, to achieve full utilization channel resources to improve the access success rate.

In order to solve the problems of the technologies described above, the purpose of the present invention is achieved through the following technical solutions:

The present invention provides a method for establishing an MBMS service channel and its secondary common control physical channel. The establishment process includes the following steps: configuring the transmission power of each MBMS service;

The step of configuring the transmission power of each MBMS service specifically includes: according to the rate of each MBMS service and the RAB priority of the radio access bearer, configure the maximum transmission power and the minimum transmission power for each MBMS service, and select Appropriate transmit power;

The maximum transmission power is configured according to the receivability of coverage edge users;

The method for selecting an appropriate transmission power according to the cell congestion state is:

If the current status of the cell is normal, configure the maximum transmit power;

If the cell reaches the set primary congestion state threshold, configure appropriate power according to the RAB priority;

If the cell reaches the set overload state threshold value, configure the minimum transmit power for all MBMS services;

If multiple MBMS services are multiplexed on the FACH on one SCCPCH, the largest transmission power is selected as the transmission power of the FACH.

The MBMS service initiates a radio bearer access attempt. If the access is successful, the radio bearer RB is established, and the channel establishment process ends; otherwise, it enters the preemption process;

When the preemption switch is turned on and the preemption is successful, the RB is established, and the channel establishment process ends; when the preemption switch is turned off or the preemption switch is turned on, the preemption is unsuccessful, and then enters the step of judging whether the service duration has been reached;

Judging whether the service duration is reached, if not, return to the step of initiating a radio bearer access attempt, if yes, then the channel establishment process ends.

The method includes setting up an SCCPCH in the cell to specially bear the MBMS control channel MCCH.

The method includes configuring the maximum transmission power Pmbmsfachmax for each MBMS service according to the receivability of coverage edge users;

The minimum transmission power Pmbmsfachmin is calculated according to the maximum transmission power by the following formula:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; mbmsfach</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; mbmsfach</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&times;</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 15</span>}}}{\mathrm{<span\; class="notranslate">\; 15</span>}}$

Wherein L is the radio access bearer (RAB, Radio Access Bearer) priority of the MBMS service, C ₀ corresponds to the coverage ratio that should be guaranteed by the highest priority MBMS service, and C ₁₅ corresponds to the coverage ratio that should be guaranteed by the lowest priority MBMS service .

The method includes, if the cell reaches the set primary congestion state threshold value, the specific method of configuring appropriate power according to the RAB priority is: configuring the minimum transmit power for MBMS services whose RAB priority is lower than the specified threshold , the maximum transmit power is still configured for MBMS services whose RAB priority is higher than or equal to the specified threshold. The method includes, before judging whether the service duration is reached, triggering a periodic trigger timer, and the MBMS service that fails to access the system for a while performs periodic access attempts. The method further includes, after the radio bearer is established, performing power recovery: recovering the maximum transmission power of the MBMS service when the cell load returns to normal.

The steps of the power recovery process are as follows:

Judging whether it is the maximum power of the MBMS service, if yes, ending the power recovery process, otherwise starting a periodic trigger timer;

Start a periodic trigger timer to prepare for the next attempt to restore power;

Judging whether the service duration Duration has arrived, if it has arrived, end the power recovery attempt, and the power recovery process ends; if not, enter the judgment of whether to increase the power;

Judging whether the power can be increased, if possible, then increase the power, otherwise return to the step of starting the cycle trigger timer.

As can be seen from the above technical solutions, the present invention establishes an MBMS service channel through a method of access attempt, and when access is temporarily inaccessible, an access attempt is made through a preemption switch. In this case, another access attempt is made within the duration of the service, realizing that the multimedia broadcast multicast service channel MTCH and its mapped secondary common control physical channel SCCPCH are dynamically established and released according to whether there is MBMS service data transmission. When there is no actual MBMS data transmission, there is no need to establish a corresponding SCCPCH, and it will not occupy a spreading code with a small spreading factor, and will not cause other dedicated channel services to fail to access due to insufficient codewords, which improves the utilization of spectrum resources rate and improve user experience.

Description of drawings

Fig. 1 is a flow chart of MBMS access in a preferred embodiment of the present invention;

Fig. 2 is a flow chart of the power recovery process in a preferred embodiment of the present invention.

Detailed ways

The basic idea of the present invention is that: the multimedia broadcast multicast service channel MTCH and the mapped secondary public control physical channel SCCPCH are dynamically established and released according to whether there is MBMS service data transmission. When there is no actual MBMS service data transmission, the corresponding SCCPCH is not established, and only when there is actual MBMS service data transmission, the corresponding SCCPCH is established. The MBMS traffic channel MTCH and its mapped SCCPCH are dynamically established using the following admission method: first configure the corresponding power according to the cell congestion situation, and then directly establish a radio bearer (RB, radio bearer) if it is judged to be admitted; If the preemption switch is turned on and the preemption is successful, the RB will be established; if the preemption switch is turned off or the preemption is unsuccessful, then the periodic judgment logic will be entered, and the decision to try again or end the channel establishment attempt will be determined according to the judgment conclusion .

During specific implementation, the following secondary common control physical channel SCCPCH is configured in each cell:

1. One SCCPCH is used to carry R99FACH, including FACH for signaling and FACH for transmitting user data in CELL_FACH state;

2. One SCCPCH only carries MCCH;

3. Several (can be one) SCCPCHs are used to carry MTCH and MSCH. These SCCPCHs used to carry MTCH and MSCH are only dynamically established when MBMS data needs to be sent, and will be dynamically released once the data transmission is completed.

After the corresponding radio bearer is established in the cell, the MBMS actually starts data transmission, so actions such as admission and preemption are completed before the establishment of the radio bearer RB.

The following specifically illustrates the process of dynamically establishing the MBMS service channel MTCH and its mapped SCCPCH. The algorithm flow chart is shown in Figure 1, and the specific steps are as follows:

101: RNC receives Session Start;

102: Determine the transmit power of each MBMS service;

Select the appropriate transmit power for each MBMS service according to the current load of the cell. In parameter configuration, it is required to configure the maximum and minimum transmit power for each MBMS service.

The specific implementation method of configuring the maximum and minimum power for each MBMS is as follows:

For the MBMS service, the MBMS service ID issued by the core network CN each time is not certain, and there is no strict corresponding relationship, so the transmit power cannot be configured for the MBMS service ID in the cell. Since the rate and RAB priority of each MBMS service must be known in the cell, the maximum and minimum powers are configured for these two attributes. It should be added that the power here refers to the power of the FACH channel where the MTCH is located. If multiple MTCHs of MBMS services are multiplexed on the same FACH, the power of this FACH is the maximum value corresponding to the power of these MBMS services. .

First, the maximum transmission power Pmbmsfachmax is configured for each rate, and this power mainly considers the acceptability of coverage edge users. The minimum transmit power Pmbmsfachmin is calculated according to the following formula:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; mbmsfach</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; mbmsfach</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&times;</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 15</span>}}}{\mathrm{<span\; class="notranslate">\; 15</span>}}$

Wherein L is the RAB priority of the MBMS service (that is, the Priority Level cell value, 0 is spare, 1 is the highest, 14 is the lowest, and 15 is no priority. In order to simplify the design, it is considered that 0 is the highest and 15 is the lowest) , C ₀ corresponds to the guaranteed coverage ratio of the highest priority MBMS service (for example, 80%), and C ₁₅ corresponds to the guaranteed coverage ratio of the lowest priority MBMS service (for example, 50%).

If the current status of the cell is normal, configure the maximum transmit power.

If the current state of the cell is primary congestion (this is a congested state, indicating that the current cell load is high and has approached the admission threshold, if the load continues to rise, it will lead to a large number of admission rejections, in practice, it is set according to the specific situation The threshold value of the primary congestion is used to determine whether the cell has reached the primary congestion state), then the minimum transmit power is configured for MBMS services whose RAB priority is lower than the specified threshold, and the maximum transmit power is still configured for MBMS services whose RAB priority is higher than or equal to the specified threshold. power.

If the current state of the cell is overloaded and congested (this is another congested state, it indicates that the current cell load is very high and is close to the limit of hardware capabilities, if no corresponding load control action is taken, it will cause a large number of users to drop calls or even the system to crash , actually set the threshold value of overload congestion according to the specific situation to judge whether the cell has reached the state of overload congestion), then only the minimum transmission power is configured for all MBMS services. If there are multiple FACHs with multiple MBMS services multiplexed on one SCCPCH, the largest transmission power is selected as the transmission power of the FACH.

103: The network side judges whether admission is possible according to the congestion status of the cell, and if so, directly proceeds to step 111 to establish an RB radio bearer, otherwise proceeds to the next step 104;

104: In the case of inaccessibility, judge the preemption switch; judge whether the preemption switch is on or off, if the preemption switch is on, enter the preemption process in step 105, and if the switch is off, enter step 107;

When a new user initiates a service call, if the network side finds insufficient resources (such as insufficient power, insufficient transmission resources, insufficient transmission channel codes, insufficient NodeB channel units, etc.), it cannot accept the user's service call request. At this time, radio resource management The algorithm (RRM algorithm) will judge whether the preemption algorithm switch is turned on. If it is turned on, it means that the system supports the preemption function at this time. Therefore, the RRM algorithm will judge the priority of the service that initiates the new call, and among the users who have already connected in the current network Find a user whose priority is lower than the new calling user to disconnect, and release resources for the new user to use. If the preemption algorithm switch is turned off, it means that the system does not support the preemption function, and the network will directly reject the call of the new user.

105: Preemption process;

Since the RAB of the MBMS service also has the Allocation/Retention Priority cell group, it can be regarded as a special DCH user, and its preemption process can call the ordinary RNC preemption process, that is, to determine the priority of the service that initiates the new call, and in Among the connected users in the current network, find a user whose priority is lower than the new calling user to disconnect, and release resources for the new user to use.

106: Determine whether the preemption is successful, if the preemption is successful, go to step 111, RB is established; if the preemption is unsuccessful, go to step 107;

107: trigger cycle trigger timer;

Since the MBMS service is a broadcast service in the entire community, it is not only for a single user. Even if it is temporarily unable to access or preempt, it does not make it impossible for the MBMS service to be re-established during the entire session duration period, so set here A periodically triggered timer makes periodic attempts to re-admit and preempt, so as to ensure that the MBMS service can be reestablished when there are idle resources in the cell. The period of this timer can be configured according to the actual situation.

Another way of triggering the periodic trigger timer is that in step 110, if the MBMS service is robbed or forcibly released, it also enters step 107 to trigger the periodic trigger timer. For the relatively low-priority MBMS services that are preempted or forcibly released by overload congestion control, as long as the session has not ended, the periodic trigger timer is started to perform periodic admission attempts, and the MBMS services will not be re-entered due to temporary preemption. also cannot be accepted.

108: Determine whether the service duration Duration has arrived, if yes, enter step 109, and the channel establishment process ends; if not, enter step 103, and re-perform the admission attempt;

There is a Session Duration information element in the Session Start signaling received by the RNC, which gives the duration of the MBMS service session. Only during this time will there be actual data transmission, so only within this time. The access attempt is meaningful; once the Duration is reached, it means that the MBMS service no longer has data to send, and it is no longer necessary to do the access and attempt of service establishment.

The value of the Session Duration cell is not exactly equal to the time difference between receiving the Session Stop and the Session Start. Therefore, the RNC may receive the Session Stop signaling during the timing process. At this time, the periodic trigger timer needs to be stopped, and the channel establishment process ends. In addition, if the RNC sends the MBMS RAB Release Request to the CN for other reasons and receives the MBMS RAB Release command from the CN, it also needs to stop the periodic trigger timer, enter step 109, and the channel establishment process ends.

111: Establish an RB bearer;

112: Perform power restoration of the MBMS service.

The power recovery process is a power adjustment for MBMS services during the session continuation process. The main consideration is that MBMS services can only be transmitted at the minimum power due to cell congestion during the initial admission process. After returning to normal, the power of the MBMS service can be restored to the maximum power.

After the radio bearer RB is established, it enters the power recovery process. The algorithm flow chart is shown in Figure 2. The specific steps are as follows:

201: Determine whether the current transmit power of the MBMS service is the maximum power configured by parameters. If yes, then enter step 206, and the power recovery process ends; if not, start the cycle trigger timer, and prepare for the next attempt to recover power;

202: periodic trigger timer; make periodic attempts;

In order to simplify the parameter configuration, the timer period here can directly use the period timer when the admission judgment is made; in addition, if the RNC sends an MBMS RAB Release Request to the CN for other reasons and receives the MBMS RAB Release command from the CN, it needs to stop Periodically trigger the timer, enter step 206, and the power recovery process ends;

203: Determine whether the Duration has arrived, if yes, then enter step 206, and the power recovery process ends, otherwise enter step 204;

There is a Session Duration information element in the Session Start signaling received by the RNC, which gives the duration of the MBMS service session. Only during this time will there be actual data transmission, so only within this time can recovery The power is meaningful; once the Duration is reached, it means that the MBMS service no longer has data to send, and it is no longer necessary to waste signaling to adjust the power;

204: Determine whether the power can be increased, and if so, enter step 205;

The specific judgment method is: first check whether the current cell status is normal, and then check whether the power increase will cause congestion. If there is no problem, the power increase is allowed. If one condition is not met, the power increase is not allowed. , continue to trigger the next cycle. The power increase is completed through the COMMON TRANSPORT CHANNEL RECONFIGURATION REQUEST signaling of the Iub interface.

205: increase power;

206: The power recovery process ends.

A method for establishing an MBMS service channel and its secondary public control physical channel provided by the present invention has been described above in detail. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only It is used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, this The content of the description should not be construed as limiting the present invention.

Claims (7)

1. A method for establishing an MBMS service channel and its secondary public control physical channel, characterized in that the channel establishment process comprises the following steps: Configure the transmit power of each MBMS service; The step of configuring the transmit power of each MBMS service specifically includes: according to the rate of each MBMS service and the RAB priority of the radio access bearer, configure the maximum transmit power and the minimum transmit power for each MBMS service, and configure the maximum transmit power and the minimum transmit power according to the congestion of the cell state to select the appropriate transmit power; The maximum transmission power is configured according to the receivability of coverage edge users; The selection of an appropriate transmit power according to the congestion state of the cell specifically includes: If the current status of the cell is normal, configure the maximum transmit power; If the cell reaches the set primary congestion state threshold, configure appropriate power according to the RAB priority; If the cell reaches the set overload state threshold value, configure the minimum transmit power for all MBMS services; If multiple MBMS services are multiplexed on the forward access channel FACH on a secondary common control physical channel SCCPCH, then select the largest transmission power as the transmission power of the FACH; Then, the MBMS service initiates a radio bearer access attempt. If the access is successful, the radio bearer RB is established, and the channel establishment process ends; otherwise, it enters the preemption process; When the preemption switch is turned on and the preemption is successful, the RB is established, and the channel establishment process ends; when the preemption switch is turned off or the preemption switch is turned on, the preemption is unsuccessful, and then enters the step of judging whether the service duration has been reached; Judging whether the service duration is reached, if not, return to the step of initiating a radio bearer access attempt, if yes, then the channel establishment process ends. 2. The method according to claim 1, characterized in that an SCCPCH is set up in the cell for carrying the MBMS control channel MCCH. 3. The method according to claim 1, characterized in that: according to the receivability of coverage edge users, configure the maximum transmission power Pmbmsfachmax for each MBMS service; The minimum transmission power Pmbmsfachmin is calculated according to the maximum transmission power by the following formula: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; mbmsfach</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; mbmsfach</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&times;</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 15</span>}}}{\mathrm{<span\; class="notranslate">\; 15</span>}}$ Where L is the RAB priority of the MBMS service, C ₀ corresponds to the guaranteed coverage ratio of the highest priority MBMS service, and C ₁₅ corresponds to the guaranteed coverage ratio of the lowest priority MBMS service. 4. The method according to claim 1, characterized in that: if the cell reaches the set primary congestion state threshold, then according to the RAB priority, the specific method for configuring appropriate power is: The minimum transmission power is configured for MBMS services whose RAB priority is lower than the specified threshold, and the maximum transmission power is still configured for MBMS services whose RAB priority is higher than or equal to the specified threshold. 5. The method according to claim 1, characterized in that, before judging whether the service duration is reached, a periodic trigger timer is triggered, and the MBMS service that fails to access the system temporarily tries to periodically access it. 6. The method according to claim 1, characterized in that the method further comprises, after the radio bearer is established, performing power recovery: recovering the maximum transmission power of the MBMS service when the cell load returns to normal. 7. The method according to claim 6, wherein the steps of the power recovery process are as follows: Judging whether it is the maximum power of the MBMS service, if yes, ending the power recovery process, otherwise starting a periodic trigger timer; Start a periodic trigger timer to prepare for the next attempt to restore power; Judging whether the service duration Duration has arrived, if it has arrived, end the power recovery attempt, and the power recovery process ends; if not, enter the judgment of whether to increase the power; Judging whether the power can be increased, if possible, then increase the power, otherwise return to the step of starting the cycle trigger timer.

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