Background technology
The data of transmitting in the mobile communication system can be divided into real time business and non-real-time service with regard to its characteristic.Real time business sudden smaller can have constant speed or variable bit rate in whole transmission (session) process, but real time of data transmission is required than higher; Non-real-time service then has higher sudden in whole transmission (session) process, and transmission rate presents bigger variation, generally can allow higher end-to-end propagation delay time.Real time business has higher priority usually, when system resource is nervous, needs the preferential transmission that guarantees real time business; Non-real-time service then after the general using carrying real time business remaining resource carry out the transmission of data.
In typical cell mobile communication systems, real time business adopts the transparent transmission mode and directly guarantees transmission quality with higher signal interference ratio on wave point in the data link layer of wave point usually; Non-real-time service is then because the wave point higher bit error rate, thereby need adopt in data link layer and retransmit (ARQ) technology automatically and satisfy the reliability of data transmission requirement.In addition, non-real-time service also obtains transmission reliability assurance end to end by transmission control protocol (TCP).
Because the difference between above-mentioned real time business and non-real-time service in the intrinsic propesties when the design cellular mobile communication networks, will be adopted diverse ways evaluating system capacity and service quality.For example, real time business can adopt traditional traffic theory to carry out the estimation and the Performance Evaluation of network size, and non-real-time service adopts the throughput of sub-district and estimation and the Performance Evaluation that propagation delay time (average delay or accumulation time delay) is carried out network size usually.
Because radio spectrum resources is a resource the most valuable in the whole cell mobile communication systems, the beehive network system of a maturation all will be pursued the high availability of frequency spectrum usually as much as possible.Like this, no matter be in the research of radio resource management techniques with in the middle of Performance Evaluation to existing network, the throughput of non-real-time service and delay parameter all are very important two indexs.Simultaneously, because how the complexity of mobile communication system service and network is further excavated some measurement parameters that can be used as the systematic function assessment and also all is in the positive exploratory development.
For the assessment of the beehive network system non-real-time service performance of a reality, can relate to dual mode and means substantially at present.The one, utilize the drive test terminal equipment, the statistics of in this equipment, carrying out throughput and propagation delay time according to length of data package information that Transmission Control Protocol provided and timestamp information by application layer.The 2nd, utilize network test equipment to hang between the interface of network node with standard interface, comprise Iub, Iu-PS, Gn and Gi interface etc., throughput is by the data total amount by network in the chronomere is measured, the measurement of propagation delay time then is to finish between two measurement points of network, by on two measurement points, catching the same IP bag at random that sends by same source point, their capture time and relatively by calculating propagation delay time.
Be not difficult to find by above analysis,, utilize the drive test terminal equipment can only carry out professional end to end propagation delay time at present and estimate propagation delay time; And on transport network interface, articulate network test equipment, can only carry out the propagation delay time of point-to-point on the special interface and estimate.For retransmitting the wave point propagation delay time that (ARQ) technology causes automatically owing to introducing in data link layer, then also do not find corresponding solution at present, this wave point propagation delay time is defined as the non-real-time service data and is transferred to the propagation delay time (seeing 3GPP standard TR25.853) of terminal equipment (UE) from wireless access network (RAN), and the reference measure point can be defined on two rlc protocol layer entities of equity in the network.
Fig. 1 has provided the schematic diagram of wave point propagation delay time, has only provided the main agreement of each entity in the network among the figure.Wherein, all protocol stacks (application layer, TCP, PDCP, RLC, MAC, L1) in terminal equipment (UE), have been comprised, the network side protocol stack reciprocity with it then is included in respectively in core net (CN) (application layer, TCP) and the wireless access network (RAN) (PDCP, RLC, MAC, L1), wherein PDCP (PDCP), radio link control (RLC), medium access control (MAC) agreement belong to the data link layer protocol in the communication system, L1 presentation layer 1 among the figure.Shown in the figure end to end propagation delay time be meant service data unit in the application layer (as application server) of core net (and other) to the propagation delay time between the terminal equipment application layer, this time delay can measure by the drive test terminal equipment.And from the service data unit of high level after being transferred to wireless access network, the Radio interface protocols stack can carry out segmentation and reassemble to these service data units, and then transmit, the transmission of the service data unit after these segmentations is controlled by rlc protocol.The transmission of the service data unit of a high level on wave point may just arrive the opposite end by once transmitting, also may need to retransmit because a certain segmentation wherein occurs wrong, whole so high-rise service data unit just need just can pass to high level after receiving terminal is waited for the regular hour, therefore, high-rise service data unit is different according to the difference of each service data unit segmentation and wireless network environment, and the variation of its wave point propagation delay time is very big.Wave point propagation delay time shown in the figure is meant that wireless access network PDCP protocol layer entity is to the propagation delay time between terminal equipment PDCP protocol layer entity in the Radio interface protocols stack, because it is can be uncared-for that the time delay that packet is handled through the PDCP protocol layer in the middle of transmission course is compared with the wave point propagation delay time, therefore the wave point propagation delay time that is defined between the reciprocity PDCP protocol layer of reference measure point is to equate substantially with the wave point propagation delay time that reference point is defined between the reciprocity rlc protocol layer, can be considered as same notion.
The method of existing two kinds of assessment mobile communications network propagation delay times all exists certain application limitation and shortcoming.First method, utilize of the measurement of drive test terminal equipment to propagation delay time, can only utilize Transmission Control Protocol to carry out according to the timestamp information of end entity, what measure is propagation delay time end to end, can not obtain the propagation delay time of wave point, be not enough to distinguish effectively the influence of Radio Link re-transmission to end-to-end propagation delay time, be optimized at network like this problem area, as when time delay is long, just can not provide more information to distinguish long propagation delay time effectively still is partly to be caused by core network by wireless access network on earth.Second method, the equipment that need have standard interface, and be connected on the network, need two measurement points in the while Measurement Network when measuring propagation delay time, employed network measure equipment is too expensive, thereby can not hang over for a long time on the network interface, and the data of using this method to obtain are difficult to directly feed back to network system equipment, can not make network system equipment at once network performance be carried out real-time control and adaptive optimization according to the result of Performance Evaluation, what is more important, the propagation delay time of measuring only is the propagation delay time between network node, is not the propagation delay time of the wave point on the meaning of the present invention.
Summary of the invention
The objective of the invention is to design the method for estimating non-real-time service wave point propagation delay time in a kind of wireless communication system, can measure the propagation delay time of wave point, simultaneously can obtain some special performance statistics parameters, and can more easily these performance statistics parameters be offered the network equipment, carry out real-time performance optimization for it, perhaps offer operation maintenance center-wireless portion (OMC-R) and carry out the performance statistics analysis, also can carry out the test and the optimization of network performance by the drive test terminal equipment.
Method of the present invention is applied in the cordless communication network, is that information and the automatic retransmission technique thereof that utilizes the data link layer related protocol to provide estimated the wave point propagation delay time.
The technical scheme that realizes the object of the invention is such: estimate the method for non-real-time service wave point propagation delay time in a kind of wireless communication system, it is characterized in that comprising:
A. on the radio link control layer entity of two equities, when the transmitting terminal high level is transferred to the radio link control layer with automatic functions of retransmission at the relevant primitive that utilizes the radio link control layer to provide with a certain service data unit, the system time Treq when the high-rise record of transmitting terminal sends this service data unit primitive
iI is the absolute serial number of described service data unit;
B. the transmitting terminal high level has been received when rectifying the relevant primitive of the radio link control layer that really receives receiving the arbitrary service data unit of indication, the system time Tconf of the high-rise record of transmitting terminal this moment
i
C. the high-rise absolute serial number of judging the service data unit that receives of transmitting terminal satisfactory order whether, if meet, the high-rise Tdelay that calculates of transmitting terminal then
i=Tconf
i-Treq
i, Tdelay
iFor the absolute serial number estimated is the wireless access propagation delay time of the service data unit of i; If do not meet, then wait until when determining to estimate the wave point propagation delay time of described service data unit, select a length of window n who investigates the absolute serial number of described service data unit, according to i, i-1 among the step B, i-2 ... n+1 corresponding system time Tconf of i-n relevant primitive record
i, Tconf
I-1, Tconf
I-2... Tconf
I-nIn, find a maximum of T conf
j, described n and i are positive integer, and i>n, and j is described Tconf
i, Tconf
I-1, Tconf
I-2... Tconf
I-nIn peaked subscript; The high-rise Tdelay that calculates of transmitting terminal
i=Tconf
j-Treq
i, Tdelay
iFor the absolute serial number estimated is the wave point propagation delay time of the service data unit of i.
Among the described step C, when considering that receiving terminal radio link control course transmitting terminal radio link control layer sends confirmation and transmitting terminal radio link control layer and receives time difference τ between this confirmation, the wireless access propagation delay time Tdelay of the described service data unit of described estimation
i=Tconf
i-Treq
i-τ, or Tdelay
i=Tconf
j-Treq
i-τ.。
Method of the present invention is automatic retransmission technique and an information of utilizing the data link layer rlc protocol to provide, and the service primitive that provides: RLC-AM-DATA.Req and RLC-AM-DATA.Conf are provided, estimates non-real-time service wave point propagation delay time.The transmitting terminal high level is noted corresponding system time Treq when using RLC-AM-DATA.Req primitive that service data unit is transferred to the rlc protocol layer
iThe transmitting terminal high level has been received when rectifying the relevant primitive LC-AM-DATA.Conf of the radio link control layer that really receives receiving the arbitrary service data unit of indication, the system time Tconf of record this moment
i
Method of the present invention can directly realize in the existing equipment of mobile communication system, can obtain some special performance statistics parameters, and can offer network equipment more easily and carry out real-time performance optimization or offer OMC-R carrying out the performance statistics analysis.When in the drive test terminal equipment, adopting method of the present invention, the information of utilizing the data link layer related protocol to be provided, can help to solve owing to the core net problem or because the long problem (end-to-end) of time delay that the wave point problem is caused, and the more property statistical parameter can be provided, help the performance optimization of network.Method of the present invention both can realize in the system equipment of cordless communication network, also can realize in the travelling carriage as the drive test terminal equipment, was used for assessing the network performance and the service quality of cordless communication network non-real-time data business.
Embodiment
The essence of the inventive method is to utilize wave point data link layer related protocol to estimate non-real-time service wave point propagation delay time in the wireless communication system.
With the 3GPP cell mobile communication systems is example, and protocol stack structure has as shown in Figure 1 been adopted in the transmission of non-real-time service, and wherein the data link layer of wave point has adopted Radio Link control (RLC) agreement with automatic re-transmission (ARQ) function.The reliability of application-layer data transmission is then by Transmission Control Protocol entity control end to end.
For example in the transfer of data of down direction, after the service data unit of core net application layer (SDU) enters the wireless access mesh portions, at first after handling, carry out the rlc protocol layer and handle through PDCP (PDCP) layer.Rlc protocol is to after handling with fixed packet progress row segmentation/serial connection of default from the service data unit (SDU) of high level, according to the scheduling of system segmented data block sent to low layer (L1) and transmits.The rlc protocol entity of opposite end (terminal equipment UE) must send confirmation to transmitting terminal after correctly receiving segmented data block, and after all segmentations that correctly receive from a certain high-rise SDU of transmitting terminal, just can carry out the refitting of this SDU and send to the local terminal high level, transmitting terminal rlc protocol entity is after receiving the affirmation information of receiving terminal rlc protocol entity to a certain high-rise all segmentations of SDU, think that just receiving terminal received that correctly local terminal should high level SDU, otherwise transmitting terminal will be retransmitted the segmented data block of not receiving confirmation.
Therefore, high-rise SDU is in the propagation delay time of wave point, can think by the high level of transmitting terminal rlc protocol layer to the rlc protocol layer send this SDU to receiving terminal RLC entity with this SDU refitting after indication to the time between the high level of rlc protocol layer.And high-rise SDU is smaller in the processing (comprising transmitting terminal PDCP and receiving terminal PDCP) of PDCP protocol layer for this time, so that can be left in the basket.
In addition, rlc protocol can be configured to whether adopt the In-sequence-delivery mode according to the needs of high level, and the purpose that this function is set is that requirement receiving terminal rlc protocol is indicated to high level according to the order that high level sends SDU.The for example high-rise order that sends SDU is 1,2,3,4,5, suppose that receiving terminal received that serial number is 1,4,5 high-rise SDU, and serial number is 2,3 high-rise SDU then since their a certain segmentation in transmission because of existing error code to need to retransmit, then serial number is that 1 high-rise SDU can be given high-rise by indication immediately, and serial number is 4,5 high-rise SDU is 2 at serial number only, after all correctly being received, all segmentations of 3 SDU just can indicate to high level by rlc protocol in order, so will increase an extra stand-by period, this is just in the definition of wave point propagation delay time, the time reference point selection of receiving terminal to be the rlc protocol layer indicate moment to high level with SDU, rather than correctly receive the reason in the moment of all segmentations of this SDU.
Because the equity of rlc protocol entity, the content of above-mentioned analysis also is suitable for the transmission of up direction data fully.
The automatic retransmission technique that adopts in the existing rlc protocol provides the possibility that realizes above-mentioned thought and has realized conveniently.For example, the RLC entity can provide two service primitive: RLC-AM-DATA.Req and RLC-AM-DATA.Conf for high level.
Contain following parameter in the RLC-AM-DATA.Req primitive: Da ta, CNF, DiscardReq, MUI, UE-ID type indicator.Whether wherein relevant with the inventive method CNF is used to identify needs the affirmation of all having received receiving terminal to the transmission of high-rise all segmentations of SDU of high level indication, and MUI is the sign of high-rise SDU (being the Data part).
Contain following parameter: Status, MUI in the RLC-AM-DATA.Conf primitive.Wherein Status is used to indicate this SDU successfully to be transferred to receiving terminal or to be dropped, and MUI is the sign of high-rise SDU (being the Data part).
Like this, the transmitting terminal high level is when using RLC-AM-DATA.Req primitive that SDU is transferred to the rlc protocol layer, can note corresponding system time Treq, SDU of high-rise every biography gives rlc layer simultaneously, all the MUI serial number is added 1, if do not consider the influence of MUI delivery, then MUI can be considered as the sign of the absolute serial number of SDU; When the some SDU of the high-rise indication of rlc protocol course were correctly received, the rlc protocol layer provided RLC-AM-DATA.Conf primitive for high level, when high level is received the RLC-AM-DATA.Conf primitive of rlc protocol, also notes corresponding system time Tconf; How the SDU that resets being transferred to the receiving terminal high level as for receiving terminal rlc protocol layer, then is not the problem that the present invention will be concerned about.In addition, correctly receive a data block and send confirmation and transmitting terminal at receiving terminal rlc protocol entity and receive and also have a time difference τ between this confirmation to transmitting terminal rlc protocol entity, if do not consider the possible re-transmission of this confirmation itself, this time difference can be thought the unidirectional transmission time delay between the reciprocity RLC entity, this time delay is a basic fixed in a specific sub-district, thereby can obtain, and can be used as operation and maintenance (O﹠amp by prior measurement; M) parameter is provided with to system.
Then for i high-rise SDU, the propagation delay time Tdelay of its wave point can be expressed as:
Tdelay
i=max(Tconf
i,Tconf
i-1,Tconf
i-2,...,Tconf
i-n)-Treq
i-τ (1)
N represents that (n and i are positive integer, and i>n), can set according to the needs of system for the length of window of the absolute serial number of SDU of investigating in the formula when specific implementation.Since i high-rise SDU, from n+1 corresponding system time according to n+1 RLC-AM-DATA.Conf primitive record, find a maximum, and then deduct the corresponding system time Treq that writes down according to RLC-AM-DATA.Req primitive and deduct time difference τ, just can obtain the wave point propagation delay time of a SDU with comparalive ease.In the specific implementation, only need to increase a real-time clock module to obtain system time Tconf and Treq (also can utilize the existing real-time clock module of system to obtain).What should be noted that is, if only need propagation delay time Tdelay under some situation
iWhen doing rough estimate, when promptly the unidirectional transmission time delay τ between reciprocity RLC entity can ignore, corresponding can being reduced to of calculating formula of the propagation delay time of formula (1) wave point:
Tdelay
i=max(Tconf
i,Tconf
i-1,Tconf
i-2,...,Tconf
i-n)-Treq
i
Formula 1 has just provided a kind of algorithm notion of asking the wave point propagation delay time, promptly will be to i high-rise SDU, an i-1 high-rise SDU, time maximizing when i-n high-rise SDU receives rlc protocol RLC-AM-DATA.Conf primitive.And if certain the high-rise SDU before i the high-rise SDU, suppose that k high-rise SDU also correctly do not received, this moment, the Tconf value of k high-rise SDU correspondence was above-mentioned i high-rise SDU, i-1 high-rise SDU, the maximum in i-n the pairing Tconf of high-rise SDU.
For this notion can be brought it into being, the present invention provides the example of an above-mentioned algorithm of specific implementation.
Because high-rise each RLC-AM-DATA.Conf that receives confirms that primitive is all at each high-rise SDU, therefore, after receiving this primitive, not only can whether need to carry out propagation delay time and estimate to judge, estimate to judge but also further whether absolute serial number is needed to carry out propagation delay time greater than other SDU of this SDU to this SDU.This process can be described as:
1. judge whether to confirm a RLC-AM-DATA.Conf who receives that this SDU of primitive carries out time delay and estimates;
2. estimate the propagation delay time of this SDU;
3. also need to judge whether absolute sequence number is confirmed that greater than a RLC-AM-DATA.Conf who is received other SDU of this SDU of primitive carries out time delay and estimates;
4. estimate the propagation delay time of other SDU.
In order to carry out the judgement in the above-mentioned steps 1,3, need carry out mark to the current SDU of confirmation signal that received, and state variable V1 and V2 need be set, wherein, what state variable V1 preserved is the current maximum serial number that has been identified the SDU that correctly receives, what V2 preserved is the serial number that has carried out the SDU of time delay estimation, and the initial value of V1 and V2 can be set to 0.
Concern between the absolute serial number of state variable V1 as shown in Figure 2, V2 and SDU, in the dynamic range represented by V1 and V2, being designated 1 this SDU of expression has been received to rectify and has really received, be designated 0 this SDU of expression and also be not received to rectify and really receive, the absolute serial number of SDU increases progressively from left to right among the figure.
Relation between state variable V1, the V2 has following feature: V1 is more than or equal to V2; When V1 was not equal to V2, the difference between V1 and the V2 was at least 2, and sequence number is that the sign one of SDU in Fig. 2 of V2+1 is decided to be 0, promptly also was not identified correctly to receive.Whether equal V2 according to V1, the concrete processing procedure of system can be different.
Referring to Fig. 3, carry out the realization flow block diagram that propagation delay time is estimated shown in the figure.Before carrying out following flow process, the transmitting terminal high level has been noted corresponding system time Treq when using RLC-AM-DATA.Req primitive that i SDU is transferred to the rlc protocol layer.
Step 301, transmitting terminal high level receive the rlc protocol layer Conf that the affirmation from receiving terminal correctly receives i SDU are confirmed primitive;
Step 302, the transmitting terminal high level judges whether to estimate the propagation delay time of i SDU, and the foundation of judgement is whether the absolute serial number of judging this i SDU shown in Figure 2 equals V2+1, is (MUI=V2+1), then continue execution in step 303, otherwise execution in step 306;
Step 303 is receiving the affirmation signal of i SDU, and the propagation delay time of this SDU is estimated by formula (2) Tdelay
i=Tconf
i-Treq
i-τ calculates;
Step 304, determine to estimate the propagation delay time of other which SDU, to be the absolute serial number of determining SDU as shown in Figure 2 begin to be identified as continuously those SDU of 1 (promptly correctly being received) from V2+2 to the foundation of determining, up to absolute serial number be V1 or middle have be identified as 0 SDU;
Step 305 is carried out propagation delay time to other SDU and is estimated, adopts estimation formulas (3) to calculate: Tdelay
j=Tconf
i-Treq
j-τ, subscript j represents that (the transmitting terminal high level has been noted corresponding system time Treq when using RLC-AM-DATA.Req primitive that j SDU is transferred to the rlc protocol layer for the absolute serial number of other SDU in the formula
j);
Step 306, update mode variable V 1, V2 promptly preserve the current maximum absolute serial number that has been identified the SDU that correctly receives by following principle update mode variable V 1 with V2:V1; V2 preserves the absolute serial number of the SDU that has carried out the time delay estimation.Must satisfy the relationship characteristic between aforementioned V1, the V2 between the state variable V1 after the renewal, V2.For example, establish V1 and V2 since 0, if then the 1st SDU confirmation has been received, then after estimating the propagation delay time of this SDU, V1 and V2 are changed to 1; Confirmation has been received if after this 3rd and the 4th SDU successively directly arranged, and then V1 successively is updated to 3 and 4, but owing to the 2nd SDU is not identified, so V2 can not upgrade; If confirmation has been received for the 2nd SDU afterwards, then at first estimate the propagation delay time of the 2nd SDU, estimate the propagation delay time of the 3rd and the 4th SDU then, after estimation was finished, V2 also was updated to 4.
Wave point estimation of propagation delay method is introduced in prior network device or the drive test terminal equipment, can the assisted diagnosis network problem, perhaps in real time the RRM strategy is carried out adaptive optimization, for example, if the mean transit delay of estimating is very little with respect to the requirement of business, the re-transmission of judging interface aloft simultaneously is fewer, then explanation does not make full use of the performance gain that re-transmission brings this moment, and also can carry out necessary adjustment to relevant RRM strategy and Control Parameter this moment.If the parameter that in the sub-district only is single business is compared the historic difference of appearance with other professional parameter, then this professional covering that connects the present position has occurred unusually often.
The ARQ function of utilizing the data link layer rlc protocol that this patent proposes is carried out wave point propagation delay time estimation approach and can be realized in existing equipment with comparalive ease.Only need to utilize existing or increase a module that the real-time clock function can be provided, and all the other information that need utilize can obtain in the primitive parameter from agreement, thereby only need make amendment existing software.The result of parameter Estimation can offer the RRM module of radio network controller (RNC) in the network, so that RNC carries out the adaptive optimization of RRM strategy and Control Parameter.The result of parameter Estimation also can replenish to be become the performance statistics of RNC equipment index and passes to OMC-R by the interface between RNC and the OMC-R, thereby can obtain real-time correlated performance statistics at OMC-R, analyzes for operator, and runs the adjustment of strategy.
The propagation delay time method of estimation that this patent proposes also can realize in the travelling carriage as the drive test terminal equipment.When the method for this patent realizes in the network equipment, can estimate the wave point propagation delay time of down direction, and when in travelling carriage, realizing, can estimate the wave point propagation delay time of up direction.Because the performance of our major concern down direction in the network equipment, road measuring device then is mainly used to investigate the situation of covering, at this moment the transmitting uplink data of non-real-time service more is concerned about.Therefore, the method for this patent proposition can provide more useful information for the performance of assessing wireless network fully.