CN1747359A - Load-Based Adaptive Rate Control Method in Mobile Communication System - Google Patents

Abstract

The invention can efficiently assign and dispatch resources in real time between many service requests to improve speed control method and utilization of system resources.

Description

In the mobile communication system based on the adaptation rate control method of load

Technical field

The present invention relates to the method for rate control in a kind of mobile communication system, especially in the mobile communication system of supporting the several data transmission rate, be between the service request under the different transmission conditions and distribute transmission rate, thereby when satisfying each requested service quality, improve the whole service efficiency of system.Speed realization reasonable resources distribution and scheduling that rate controlled is distributed by being adjusted into different user, therefore, rate controlled also is a kind of implementation method of scheduling strategy.

Background technology

Flourish along with mobile communication, various new business emerge in an endless stream, and wherein the development of data service is particularly rapid.And the limitation of radio spectrum resources and communication environments has influenced the raising of data traffic transmission speed to a certain extent.Therefore, the research focus that how to make full use of system resource, provides high as far as possible transmission rate to become moving communicating field for the user.The proposition of rate control techniques has well solved this problem.This method according to the current transmission rate of each service request, system resource current utilize situation, can the transmission rate of each service be carried out in time, effectively adjust, thereby system resource is fully used in conjunction with specific probability system of selection.

Two important bases for estimation are in the method for rate control: system resource utilization situation and probability system of selection.The criterion of utilization of resources situation and the value of probability all can produce material impact to the result of rate controlled.The method of rate control criterion that must use simply, easily measure and reasonably probability value efficiently.Common rate control techniques adopts parameters such as system's available horsepower, system load and system's residual capacity to weigh as the standard of system resource utilization situation, carries out the speed adjustment based on fixation probability.The method of adjustment of fixation probability is easy to realize, but the variation of adaptive system utilization of resources situation dynamically.

Summary of the invention

For the tracking system loading condition, and adjust the rate controlled probability in real time to adapt to the variation of utilization of resources situation, the inventor has proposed a kind of method of rate control based on system load, adaptive adjustment speed lifting probability.Its basic principle is that judge according to the load value of current system should raising speed rate or the transmission of reduction of speed rate, and calculate the probability of raising speed rate or reduction of speed rate according to load-threshold value, probability is adjusted speed according to this, and the maximum rate that provides of frame of reference available horsepower, determines the transmission rate of following one-period.

The concrete performing step of the present invention is:

Step 1: the load value of adding up each controlling party at network side.

Step 2: determine the overload indication bit of each controlling party according to the load value in the step 1, whether the receiver that indication bit has indicated current base station transships, and as overload, then requires the power from user side that it received to reduce, otherwise can improve.

Step 3: determine the speed adjustment strategy that user side should be taked according to the overload indication bit of each controlling party in the controlling party set (abbreviation control sets) of user side association in this controlling party: raising speed rate or reduction of speed rate.

Step 4: adjust strategy and load-threshold value according to the speed of determining in the load value of adding up in the step 1, the step 3, calculate the tactful probability value of user side speed accent that each controlling party is controlled, i.e. the probability lower limit of the probability upper limit of raising speed rate or reduction of speed rate.

Step 5: overload indication bit and speed according to each controlling party in the user side control sets are adjusted probability, determine the rate value of method of rate control decision.

Step 6: calculate the maximum rate value that each user side allows transmission according to system's available horsepower.

Step 7: select rate value less in step 5 and the step 6 as the final transmission rate of determining.

After the next rate controlled cycle began, repeating step 1 was to step 7.

Determine that according to the different loading condition of each controlling party speed adjusts strategy in the top step 3, and in step 4, determine in real time that according to current load value and load-threshold value speed adjusts the limiting value of probability.What calculate for the raising speed rate is the probability upper limit, if the probability of raising speed rate, then can cause this controlling party overload greater than this probability upper limit; What calculate for the reduction of speed rate is the probability lower limit, if the probability of reduction of speed rate, equally also can cause this controlling party overload less than this probability lower limit.Step 7 takes into account the supporting factor of available horsepower to speed.The present invention measures and probability calculation by real-time, the tracking system loading condition, and in time take measures to prevent system overload and guarantee making full use of system resource.

Description of drawings

In conjunction with the following drawings and instantiation will be convenient to understand principle of the present invention, step, characteristics and advantage to the detailed description done of invention, in the accompanying drawing:

Fig. 1 is the job step of expression the present invention in the CDMA2000 example;

Fig. 2 represents the present invention in the CDMA2000 example, the curve chart and the growth ratio curve of sector average load value when sector average load value and employing fixation probability.Each sector has two voice users and several data users.Axis of abscissas is represented each sector data user number, and axis of ordinates is represented the average load and the growth of load percentage of sector.

Fig. 3 represents the present invention in the pairing CDMA2000 example of Fig. 2, the curve chart and the throughput increase percentage of sector average throughput when sector average throughput and employing fixation probability.

Embodiment

Because the implementation of data service is a lot of in the mobile communication,, using a kind of representative and blanket example at this for the ease of understanding---method of rate control proposed by the invention is set forth in CDMA2000 suggestion (being formulated by 3GPP2).The present invention generally is suitable for for the application scenario that all have essential characteristic in this example.

Use formula (1) to calculate the load contribution of user i to Active Set sector j:

${\mathrm{\η}}_{i,j}=\frac{1}{1+\frac{W}{{(E_b/N_0)}_i\×R_i\×{\mathrm{\υ}}_i}}---\left(1\right)$

Wherein, W is a system bandwidth, E _b/ N ₀Be user's bit energy and the ratio of background heat noise power spectral density, R _iBe transmission rate, υ _iBe the voice activation factor.For the data user, the voice activation factor is 1.According to " 1xEV-DVEvaluation Methodology (V13) " literary composition of 3GPP2, the voice activation factor of getting voice user is 0.406.

It is the user load contribution sum of Active Set with this sector that the load value of sector equals all:

${\mathrm{Load}}_j=\underset{j\∈\mathrm{ActiveSet}\left(i\right)}{\mathrm{\Σ}}{\mathrm{\η}}_{i,j}---\left(2\right)$

The determination methods of sector overload indication bit is:

${\mathrm{OLB}}_j=\left\{\begin{array}{cc}0& {\mathrm{Load}}_j<{\mathrm{<figure-callout\; id="1"\; label="Load\; TH"\; filenames="A20051010260100101.png,A20051010260100111.png"\; state="\{\{state\}\}">Load</figure-callout>}}_{\mathrm{TH}}\\ 1& {\mathrm{Load}}_j\&GreaterEqual;{\mathrm{Load}}_{\mathrm{TH}}\end{array}---\left(3\right)\right.$

Stipulated maximum load value, the threshold value Load of load just in " IS-2000 Release C Simulation Configuration Specification " literary composition of 3GPP2 _THBe 0.45.When sector load greater than 0.45 the time, show that current sector load is bigger, the user answers the transmission of reduction of speed rate; Otherwise, illustrating that there is surplus resources current sector, the user can the transmission of raising speed rate.But raising speed rate and reduction of speed rate will be according to certain probability, can not all users raising speed rate or reduction of speed rates simultaneously.If all users are reduction of speed rates simultaneously, can cause system resource idle suddenly, thisly be idle in next time that rate controlled can cause all user's raising speed rates again, thereby cause system overload in the cycle.And so forth, system fluctuates under idle and overload, causes the instability of system.Main method of the present invention is exactly by adjusting the probability of ascending, descending speed, making the approaching as much as possible threshold value that still is no more than of load value of system.Details are as follows for the computational methods of speed adjustment probability.

For the situation of sector j permission user raising speed rate, promptly current Load _j＜Load _TH, establishing user i present rate is R _i, the speed probability that rises to the present rate twice is p _j ^↑(0≤p _j ^↑≤ 1), keeps present rate R _iProbability be l-p _j ^↑Use speed estimation function Ev (R _i, p _j ^↑) calculate the speed of following one-period and bring the load calculation formula into.The mathematic expectaion function that uses transmission rate in the next rate controlled cycle in this example is as the speed estimation function: $\mathrm{Ev}(R_i,p_j^{\&UpArrow;})=\stackrel{\&OverBar;}{R_{\&UpArrow;}}=2\&times;R_i\&times;p_j^{\&UpArrow;}+R_i\&times;(1-p_j^{\&UpArrow;})=R_i\&times;(1+p_j^{\&UpArrow;}).$ Will

Bring the load calculation formula into, obtain

$\stackrel{\&OverBar;}{{\mathrm{Load}}_j}=\underset{j\&Element;\mathrm{ActiveSet}\left(i\right)}{\mathrm{\&Sigma;}}\frac{1}{1+\frac{W}{{(E_b/N_o)}_i\&times;(1+p_j^{\&UpArrow;})\&times;R_i\&times;{\mathrm{\&upsi;}}_i}}---\left(4\right)$

Formula (4) is variable p _j ^↑(0≤p _j ^↑≤ 1) increasing function.Find the solution satisfied $\stackrel{\&OverBar;}{{\mathrm{Load}}_j}<{\mathrm{Load}}_{\mathrm{TH}}$ Maximum probability p under the condition _j ^↑, be the maximum raising speed rate probability that makes sector j nonoverload.

For the situation of sector j requirement user reduction of speed rate, the promptly current Liad that goes up _j〉=Load _TH, establish user i speed reduced to R _i/ 2 probability is p _j ^↓(0≤p _j ^↓≤ 1), keeps present rate R _iProbability be 1-p _j ^↓The same mathematic expectaion function that uses transmission rate in the next rate controlled cycle is as the speed estimation function: $\mathrm{Ev}(R_i,p_j^{\&DownArrow;})=\stackrel{\&OverBar;}{R_{\&DownArrow;}}=R_i\&times;p_j^{\&DownArrow;}/2+R_i\&times;(1-p_j^{\&DownArrow;})=R_i\&times;(1-p_j^{\&DownArrow;}/2).$ With each user

Bring in the load calculation formula, obtain:

$\stackrel{\&OverBar;}{{\mathrm{Load}}_j}=\underset{j\&Element;\mathrm{ActiveSet}\left(i\right)}{\mathrm{\&Sigma;}}\frac{1}{1+\frac{W}{{(E_b/N_o)}_i\&times;(1-p_j^{\&DownArrow;}/2)\&times;R_i\&times;{\mathrm{\&upsi;}}_i}}---\left(5\right)$

Formula (5) is variable p _j ^↓(0≤p _j ^↓≤ 1) subtraction function.Find the solution satisfied $\stackrel{\&OverBar;}{{\mathrm{Load}}_j}<{\mathrm{Load}}_{\mathrm{TH}}$ Minimum probability value p _j ^↓As making sector j change the reduction of speed rate probability of lucky nonoverload into, thereby realize making full use of to system resource by overload.

According to " 1xEV-DV Evaluation Methodology (V13) ", can comprise three sectors in user's the Active Set at most.In order to satisfy the requirement that each activates the sector nonoverload, have only when all activated sector requires the raising speed rate, Cai the transmission of user's raising speed rate, and final raising speed rate probability is the minimum value of all raising speed rate probability.As long as there is an Active Set sector to require user's reduction of speed rate, then reduction of speed rate transmission of user, the probability of reduction of speed rate is got the maximum of all reduction of speed rate probability.Therefore, the finally definite overload indication bit of user can be expressed as its Active Set sector overload indication bit sum:

${\mathrm{OLB}}_i=\underset{j\&Element;\mathrm{ActiveSet}\left(i\right)}{\mathrm{\&Sigma;}}{\mathrm{OLB}}_j---\left(6\right)$

The probability system of selection of user i is expressed as:

$p_i^{\&UpArrow;}=\underset{\mathrm{RA}{B}_j=0}{\underset{j\&Element;\mathrm{ActiveSet}\left(i\right)}{\min }{p}_j^{\&UpArrow;}},({\mathrm{OLB}}_i=0)---\left(7\right)$

$p_i^{\&DownArrow;}=\underset{\mathrm{RA}{B}_j=1}{\underset{j\&Element;\mathrm{ActiveSet}\left(i\right)}{\max }}{p}_j^{\&DownArrow;},({\mathrm{OLB}}_i=1)$

Produce the random number in [0, the 1] scope that is evenly distributed at random, if this random number is less than p _i ^↑(p _i ^↑), then the user is 2 times (1/2 times) of present rate with the speed rising (decline) of next rate controlled in the cycle.

In addition, also considered of the restriction of system's available horsepower among the present invention to speed.Select speed less in the transmission rate that supported peak transfer rate of current available horsepower and rate controlled obtain as final speed.

As can be seen, what the present invention proposed adjusts the adaptive algorithm of speed lifting probability in real time at system loading conditions, has following characteristics more than comprehensive:

1. be purpose with the whole utilization ratio that improves system resource, for data service, promptly obtain bigger throughput of system.

2. avoid the generation of system overload phenomenon, also guarantee the stability of system simultaneously.

3. the consideration high real-time along with the continuous variation of system status, is adjusted speed lifting probability in real time, avoids the blindness under the fixation probability situation.

4. insensitive to concrete implementation and protocol specification, possess compatibility.

In a word, the present invention is a kind of resource allocation and dispatching technique of flexible practicality, its objective is the efficient of adjusting with resource allocation and speed in the method raising mobile communication of simple structure and easily realization.

Claims (13)

1. A rate control method for mobile communication resource allocation and scheduling, based on communication resources including communication equipment in the system, available transmission power and communication frequency bands, etc., aiming at communication composed of different divisions and combinations of communication resources Channel, the network-side controller bases its decision-making on the basic information of the system and the status information of the user terminal. These status information include: system bandwidth, transmission rate of the user terminal, channel status, activation factor, and then make the system resource utilization according to the system design goals. Efficiency and the quality of service obtained by the user end and other indicators are optimized, and the transmission rate is dynamically adjusted and allocated among various users. In this process, the adaptive probability selection method is adopted. Through the probability calculated according to the current load status and the load threshold value, the user end can adjust the probability of the rate change in real time, so as to accurately track the change of the system load status, and make Make corresponding adjustments to adapt to load changes, so that the system load tends to the threshold value but does not exceed the threshold value, that is to say, the system resources are fully utilized on the premise that the system is not overloaded. The basic implementation steps of this method are: Calculate the load of the controller on the network side, and compare the load with the load threshold, and set the overload indication bit of the controller according to the comparison result: if the load is greater than the load threshold, set the overload indication bit to indicate that the current system is in an overload state, and the load is less than Load threshold, setting the overload indication bit to indicate that the current system still has remaining resources; Determine the rate adjustment trend of the user terminal controlled by the controller according to the overload indication bit: if the overload indication bit indicates that the system still has idle resources, the rate will increase, otherwise, the rate will decrease; Calculate the rate adjustment probability that the user terminal in the sector should adopt according to the current load, load threshold, rate adjustment trend and rate estimation function; For each user, according to the comprehensive status of one or more network side controllers, determine the overload indication bit and rate adjustment probability of the user end. In order to ensure that each controller is not overloaded, the probability of increasing the rate is the minimum value of the probability of increasing the rate of the controlling party, and the probability of decreasing the rate is the maximum value of the probability of decreasing the rate of the controlling party. The UE determines its transmission rate in the next control period according to its overload indication bit and the probability of rate increase or decrease determined in the previous step. Select the smaller rate among the maximum transmission rate of the user terminal allowed by the available power of the system and the transmission rate determined by the rate control method as the final transmission rate. 2. The rate control method for mobile communication resource allocation and scheduling as claimed in claim 1, characterized in that: the basic information of the system and the state information of the user terminal on which the network side is based include the allocation and scheduling processing of resources and All possible information on which the rate control method is based, and the generation and acquisition of such information. 3. The rate control method for mobile communication resource allocation and scheduling as claimed in claim 1, wherein the information on which the rate control decision is based mainly includes: dynamic changes of the system state and information of the user terminal wireless propagation environment, etc., The former includes system bandwidth, load threshold value and obtained load statistics information, etc., and the latter includes channel condition measurement and transmission rate measurement and prediction of each user end. 4. The rate control method for mobile communication resource allocation and scheduling as claimed in claim 1, wherein the user end is characterized by representing competing service requests, which are scheduled and assigned by the rate control party that masters resource scheduling The transmission rate allowed by the corresponding system resources. In this process, the network side dynamically adjusts the probability of the rate change of the user end according to the criterion of optimizing the resource utilization efficiency in the system and the quality of service obtained by the user end. According to this probability and its situation, including the state of each controller and its own state, adjust its transmission rate. 5. The rate control method for mobile communication resource allocation and scheduling as claimed in claim 1, wherein the network side controller, its role is to receive and process the user terminal to report to it when the rate control is based on information, and make decisions to inform the client of the control information it has. Both the network side and the user end include a rate control method, and the two-part method finally realizes rate control through communication in a certain way. 6. The rate control method for mobile communication resource allocation and scheduling as claimed in claim 1, characterized in that: the network side control side is set to calculate a dynamic criterion for adjusting the probability, and the criterion includes a dynamic rate-up probability and a rate-down rate The calculation of the probability avoids the rapid change of the system load caused by the simultaneous increase or decrease of the user end rate by setting the dynamic criterion, and the adverse impact of the chain reaction on the system stability caused by it. 7. the rate control method that is used for mobile communication resource allocation and scheduling as described in claim 1, it is characterized in that: set the rate adjustment criterion of user end, this criterion comprises user end overload indicating bit and corresponding rate adjustment probability Determined, and through the probability selection criterion, it is guaranteed that the system resources are fully utilized on the premise that each controller is not overloaded. 8. As claimed in claim 6, the feature of the probability calculation belonging to the dynamic criteria of the network side controller is: use the rate estimation function of the user end in the next period to replace the user end in the load calculation formula used in the probability calculation Transmission rate. 9. as claimed in claim 6, the feature of calculating the rate of increase rate belonging to the dynamic criteria of the network side control side is that: under the condition that the control side is not overloaded, the transmission rate of the user terminal is improved with the highest probability, and the network side is realized. The load increases and approaches but does not exceed the load threshold, thereby realizing full utilization of network resources. 10. as claimed in claim 6, the rate reduction probability calculation belonging to the network side controller dynamic criterion is characterized in that: in the overloaded state of the controller, reduce the transmission rate of the user terminal with the minimum probability, so that the network side The load is close to and lower than the load threshold, and while solving the overload phenomenon on the network side, full utilization of network resources is realized. 11. The rate adjustment probability selection belonging to the user end rate adjustment criterion as claimed in claim 7 is characterized in that: among the adjustment probabilities calculated by a plurality of network side controllers, all network side controllers that satisfy the user end are selected. The probability that none of them are overloaded and the load of each controller is closest to the load threshold. When the user end overload indication bit indicates the user's rate increase, select the smallest probability among the rate increase probabilities calculated by the controller that allows the user to increase the rate; when the user end overload indication bit indicates the user's rate decrease, select all the controllers that require the user to decrease the rate The largest probability among the rate-down probabilities calculated by the square. 12. The rate estimation function as claimed in claim 8 is characterized in that: it can be a mathematical expectation of all possible transmission rates, or other estimation functions that can characterize the rate characteristics of the user end. 13. The rate control method for mobile communication resource allocation and scheduling as claimed in claim 1, characterized in that its basic implementation steps are: Calculate the load of the controller on the network side, and compare the load with the load threshold, and set the overload indication bit of the controller according to the comparison result: if the load is greater than the load threshold, set the overload indication bit to indicate that the current system is in an overload state, and the load is less than Load threshold, setting the overload indication bit to indicate that the current system still has remaining resources; Determine the rate adjustment trend of the user terminal controlled by the controller according to the overload indication bit: if the overload indication bit indicates that the system still has idle resources, the rate will increase, otherwise, the rate will decrease; Calculate the rate adjustment probability that the user terminal in the sector should adopt according to the current load, load threshold, rate adjustment trend and rate estimation function; For each user, according to the comprehensive status of one or more network side controllers, determine the overload indication bit and rate adjustment probability of the user end. In order to ensure that each controller is not overloaded, the rate-up probability is the minimum value among all rate-up probabilities, and the rate-down probability is the maximum value among all rate-down probabilities. The UE determines its transmission rate in the next control period according to its overload indication bit and the probability of rate increase or decrease determined in the previous step. Select the smaller rate among the maximum transmission rate of the user end supported by the system power and the transmission rate determined by the rate control method as the final transmission rate.

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