CN101111073B - Access method for long propagation delay wireless signal channel - Google Patents
Access method for long propagation delay wireless signal channel Download PDFInfo
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Abstract
An access method along a wireless channel during the long transmission process, the junction center puts a terminal ID in a VT and a DT request queue according to the VT or the DT sign in the request group and then arranges the slot of the next frame of an upstream channel according to a distribution strategy of the channel capacity, wherein, the residual idle slot is taken as the access slot, each access slot comprises M mini-slot, the access micro-slot aggregation is divided into two common parts, such as VTs reserve and VTs, and DTs which are called as the VT subaggregation and the common subaggregation, the length of the VT subaggregation is based on a periodical dynamic alignment of the predication; the junction station combines the slot arrangement of the next frame into a confirmation group and broadcast to various terminals on a downstream channel; after receiving the confirmation group, the terminal respectively sends the request micro-group and the information group on the access micro-slot and the information slot according to the arrangement of the slot. The present invention has the advantages of the flexibility, the fastness and the high efficiency, and can reduce the packet dropout frequency of the voice and the other real-time business and improve the throughput of the data business.
Description
Technical field
The present invention relates to have the wireless channel cut-in method of supporting speech and aggregation of data business in the mobile communication system that long pass prolongs sowing time.
Background technology
Channel access method is that the multiple access access (is the medium access control, MAC) method be used for solving a plurality of nodes of communication system or user how fast, efficient, fair, the problem of shared channel resources reliably, the distribution of its direct control channel resource has very important influence for systematic function.According to the mode of channel allocation, multiple access method is divided into fixed allocation, the three kinds of modes that insert and distribute according to need at random usually.
The multiple access method of fixed allocation is generally given the long-time fixed allocation of channel resource some node or all nodes of shared channel, the channel throughput height, but shortcoming is can not the self-adapted service characteristic, can cause the idle and waste of a large amount of channel resources under the more situation of burst service.
At random in the multiple access method of Jie Ruing, the common competitive channel resource of all nodes, overcome the wasting of resources problem of fixed allocation access way, and hour access delay is less relatively in traffic carrying capacity, but shortcoming is to increase especially burst service more for a long time when sending node number and network traffic, the probability of packet collisions can sharply increase, make average packet time delay, average packet loss ratio, channel throughput all significantly reduce, the unjust equality problem of shared channel also can appear simultaneously, so be not suitable for real-time application.
Each node is according to service conditions request channel resource in the demand assigned multiple access method, re-uses after preengaging successfully.Compare with access way at random, overcome its serious problem of packet collisions when network traffic is big, improved channel throughput, but shortcoming is when network traffic is low, reservation application and the expense of distributing are excessive, and the propagation delay time of gained is also bigger; In addition, compare with the fixed allocation method, when network traffic was higher, there were the problems such as fairness that the maximum channel throughput is not high enough, can not guarantee shared channel in allocation method based on demand.This method is fit to relative length of time and stream is professional more stably, is not suitable for the multimedia service that happens suddenly.
In summary, above-mentioned single channel access method all can not satisfy the requirement of burst service (bursts) (as speech), and burst service is very general in the mobile communication system.In order to support burst service preferably, use the method for salary distribution of hybrid-type channel access method in the mobile communication system usually as combining with distribution according to need at random.
Mobile communication system short for communication distance, that time delay is little such as Cellular Networks, Ad hoc network etc., their channel access method needs a large amount of information interactions and shakes hands, thereby expend the channel resource of a lot of preciousnesses, be not suitable for communication distance mobile communication system far away, reason is: at the information access periods, the distinctive big propagation delay of this type systematic is not allowed and is carried out frequent information interaction between central site and the terminal.In addition, Internet resources (as channel width, energy, internal memory, processing energy) are limited also is the significant challenge that channel access method must face.
Can support burst service at random better in order to make long propagation delay wireless signal channel, the dynamic assignment transmission capacity is a kind of effective channel resource allocation mode, the especially voice service of having relatively high expectations for real-time on the basis of single message (message) or single grouping (packet).Allocated channel capacity when terminal is in the sound phase of speech (talkspurts) only, the method for then not distributing when resting stage (silent phrases) can make full use of channel resource, improves channel utilization and throughput.
D.G Goodman in 1989 proposes packet reservation multiple access and inserts (packet reservationmultiple access, PRMA) method (is seen D.J.Goodman, R.A.Valenzuela, K.T.Gdyliard, and B.Ramamurthi, " Packet reservation multiple access forlocal wireless communicatiohs; " IEEE Trans.Commun., vol.37, pp.885-890, Aug.1989.), it has utilized above-mentioned principle at first, adopts the sound phase and the resting stage of speech activity detector (VAD) detection speech on terminal, in the sound phase, speech information in 1 frame time just is packaged as 1 grouping, and every frame sends 1 speech packet on the reservation time slot; Then discharge this time slot when transferring resting stage to.The shortcoming of this method is: data service can not be preengage time slot, packet can only be competed available time slot jointly with the request (also being 1 packets of voice simultaneously) of VTs, under the bigger situation of data business volume, can produce too much transmission conflict, cause performances such as the time delay of speech and packet loss sharply to descend, and the average message time delay of data service is bigger, so this method can only be supported the data service of low rate; And, the method of using whole time slot to send the request of access has limited the access efficiency of system greatly, the request that sends on, the channel big in traffic carrying capacity more for a long time, conflict too much causes system very unstable, and a lot of time slots can't utilize, and extremely waste channel resource.
2000, people such as Giuliano Benelli have proposed PRMA (the PRMA-Hindering States of band retardance state, PRMA-HS) method (is seen Giuliano Benelli, RomanoFantacci, Giovanni Giambene, and Carlo Ortolani, Voice and DataTransmissions with a PRMA-Like Protocol in High Propagation DelayCellular Systems, IEEE Transactions on Vehicular Technology, Vol.49, No.6, pp:2126-2147, November 2000), VTs must wait for 1 round propagation delay (round-trip delay at least in the PRMA method to overcome, RTD) just can obtain the channel allocation result that central station feeds back, could on dedicated time slot, send the shortcoming of grouping then.So-called " retardance state (Hindering States) ", promptly under the round propagation delay prerequisite of frame period greater than channel, real time business such as speech were constantly seized time slot and are sent grouping before obtaining preengaging the result, to realize the quick access to channel, reduce packet loss.But this when heavy duty, can constitute competition conflict aggravation of time slot method, the packet loss mis-behave seized merely; In addition, frame period is excessive, means that voice service that reservation is not successful and data service need wait for that all the longer time could continue to send request, and maximum available requests sends number of times and reduces (because D
MaxRestriction), cause the increase of voice service packet loss, service quality to reduce, the average packet time delay of data service increases, throughput reduces.
Based on the above method, people such as Romano Fantacci have proposed PRMA (the modified PRMA that revises in 2000, MPRMA) method (is seen Romano FantaccI, GiovanniGiambene, and Riccardo Angioloni, A Modified PRMA Protocol for Voiceand Data Transmissions in Low Earth Orbit Mobile Satellite Systems, IEEE Transactions on Vehicular Technology, Vol.49, No.5, September2000), the a part of idle time slot that it will be not be preengage by voice service is as access slot, competed jointly by speech and request of data, preengage successful voice service and use dedicated time slot to send speech packet, remaining idle time slot allocation is given the data service that has successfully sent the request that inserts outside the access slot.And, allow speech and the incidentally new access request of packet in order to reduce conflict.But this method also is to use whole time slot to send the request grouping, and conflict seriously causes waste of capacity when heavy duty.
Calendar year 2001, people such as A.Andreadis have proposed DRAMA+ (Dynamic ResourceAssignment Multiple Access-enhanced version) method and (have seen A.Andreadis, R.Angioloni, R.Fantacci, G.Giambene, Efficient integration of isochronousand data bursty traffics in low earth orbit-mobile satellite systems, Int.J.Satell.Commun.2002; 20:201-229.), it is divided into access slot and information time slot with time slot, contains the mini-slot of given number in 1 access slot, sends request for speech and data service, and every frame has the access slot of given number; The information time slot is used to transmit information block.Central station is according to incoming voice user, incoming voice user, data service user's priority orders is distributed time slot.Obtained the data service terminal that inserts can be in the end reserve requests incidentally in data grouping, thereby avoid intensified competition conflict once more.But in this method, the number of access slot is fixed, and can not dynamically adjust with the variation self adaptation of load, may cause access slot idle under the few situation of access request, the waste channel resource; In addition, for a communication process, under the situation that adopts speech packet transmission, can stand higher packet loss in the incipient stage, then wish to try not to interrupt in communication process, so generally, incoming voice user's priority is higher than and does not insert the user, all should be like this in time slot allocation and channel access phase, and the DRAMA+ method is not reasonably distinguished the classification of voice user at the channel access phase.
2004, people such as Ramano Fantacci have further proposed satellite PRMA (satellite-PRMA again, S-PRMA) method (is seen Ramano Fantacci, TommasoPecorella, and lbrahim Habib, Proposal and Performance Evaluation of anEfficient Multiple-Access Protocol for LEO Satellite Packet Networks.IEEE Journal on Selected Areas in Communications, Vol.22, No.3, April2004.), it is divided into two independently mini-slot set with access slot, be respectively applied for and send speech and request of data, make the request of voice service not influenced by sudden stronger data service, increased the stability of a system; In the sound phase, voice service uses dedicated time slot to send grouping, and use " retardance state ".The request of data of competition access is stored in the request of data formation at random, and idle time slot is distributed to the data terminal that is positioned at queue front with particular probability, has improved the data service throughput, can support the data service of higher rate.But the shortcoming of this method is: the mini-slot subclass is fixed, and can not adjust with the variation self adaptation of business; And use " retardance state " to need frame period greater than 1 RTD, mean that voice service that reservation is not successful and data service need wait for that all the longer time could continue to send request, cause the increase of voice service packet loss, service quality to reduce, the average packet time delay of data service increases, throughput reduces.
In a word, in summary, go back the channel access method that neither one is fit to long propagation delay wireless signal channel very much at present, can support speech and aggregation of data business preferably, and make full use of valuable channel resource, make terminal flexibly, access channel fast and efficiently.
Summary of the invention
The technical problem that the present invention solves: overcome the deficiencies in the prior art, proposed a kind of effective support speech and aggregation of data business flexibly, channel access method fast and efficiently, efficiently to utilize limited channel resource, the packet loss of real time business such as reduction speech, improve service quality, improve the throughput of data service.
Technical solution of the present invention: access method for long propagation delay wireless signal channel, its characteristics are: step is as follows:
(1) in the initial launch time, inserts (PRMA) method as initial channel access method with packet reservation multiple access;
(2) after the initial launch time, central station (Base Staion is called for short BS) is according to the terminal class sign in the terminal request grouping that receives, i.e. voice terminal VT (voice terminal, be called for short VT) or data terminal DT (data terminal, abbreviation DT), the ID with them puts the VT request queue respectively into, abbreviation VQ, with the DT request queue, be called for short DQ, according to the time slot of the next frame of channel capacity allocation tactical arrangement up channel, described channel capacity allocation strategy is then:
A. in next frame, each the voice terminal VTs that is in the sound phase (talkspurts) still continues to use dedicated time slot to send speech packet;
B. next frame is removed remaining time slot behind the dedicated time slot of VTs, the time slot that comprises the VTs release that sound phase end enters resting stage, be called stand-by time slot, successfully send request but the VTs that also do not obtain special-purpose reservation time slot before preferentially enjoys stand-by time slot, enter the VT request and handle;
C. the stand-by time slot that VTs in the next frame is not preengage is called idle time slot, checks whether also have idle time slot, if having, then with Probability p
aDistribute idle time slot to give the DTs of DQ front end, promptly enter the DT request and handle; If do not have, then this time the time slot allocation process finishes;
D. with the access slot of remaining idle time slot in the above-mentioned steps (c) as each terminal of described central station control, each access slot comprises M mini-slot (M value can according to the system situation adjustment), be used to send the request differential group of terminal, access slot integral body is divided into part and VTs and the shared part of DTs that aims at the VTs reservation, be called VT subclass and shared subclass, the size of VT subclass is dynamically adjusted based on predetermined period ground;
(3) central station is combined into an affirmation grouping with the arrangement of next frame time slot, broadcasts to each terminal of described central station control on down channel;
(4) each terminal is after the affirmation grouping that receives central station broadcasting, is arranged in to insert according to wherein time slot to send request differential group on the mini-slot, sends information block on the information time slot.
Invention advantage compared with prior art is:
(1) flexibility
Flexibility of the present invention is mainly reflected in:
A. aspect the distribution of access slot and access mini-slot (seeing step 2);
The access slot number of every frame is fixed in the DRAMA+ method, can not adjust with the load variations dynamic self-adapting, under the few situation of access request, can cause the access slot free time but can not be used to send information block, the waste channel resource, and the mini-slot number in the access slot is also fixing, can not adjust the ratio of speech and the distribution of data service access mini-slot according to the current business situation.In addition, the S-PRMA method is divided into two fixing subclass with the mini-slot of access slot and distributes to speech and data service request respectively, neatly the changeable traffic performance of self adaptation.
And among the present invention, the access slot number of every frame is the frame voice service part of idle time slot of reservation not as yet for this reason, changes with the load of system's current voice business; And the distribution of the mini-slot in the access slot is based on a kind of dynamic future mechanism that the prediction of voice service load is realized, can adjust flexibly according to the current business situation.
B. aspect the support of user's multipriority, (seeing step 2 and step 4);
The DRAMA+ method according to incoming voice user, incoming voice user and data service user's priority orders is not distributed time slot, is at allocated phase the voice user that request inserts to be distinguished, distribution principle is in fact as broad as long with additive method.And for a communication process, under the situation that adopts speech packet transmission, can stand higher packet loss in the incipient stage, in communication process, then wish to try not to interrupt, promptly need to ensure the success rate that incoming voice user inserts once more, so, also should be higher than the voice user that does not insert in the priority of access phase incoming voice user not only at allocated phase.The access state (inserted and insert) of the present invention by distinguishing VTs inserting the access phase of VTs after changing the sound phase into by silence periods, takes repeatedly to send the method for the request of access, and raising has inserted the access efficiency of VTs; And under the situation of channel capacity deficiency, the VTs that has inserted that priority is high can preferentially not obtain time slot than inserting VTs, and said method has ensured the service quality of the terminal of conversing.
(2) quick
Be mainly reflected in: aspect the distribution of access slot and access mini-slot (seeing step 2);
The VTs that is predicted as that the present invention is based on the VTs number that request in the system is inserted reserves mini-slot, makes VTs have enough resources can in time send request; But also can reduce even avoid and the conflicting of request of data, thereby improve the success rate of reservation, guaranteed the quick access of VTs to channel resource.And under the more heavily loaded situation of terminal, can the constitute competition conflict aggravation of the strategy of seizing time slot merely of PRMA-HS method, the packet loss mis-behave, and frame period is excessive, mean that voice service and data service that reservation is not successful all need wait for the longer time, cause the voice service packet loss to increase, service quality reduces, and the average packet time delay of data service increases, and throughput reduces.In addition, the S-PRMA method is divided into the request that two fixing subclass are respectively applied for transmission speech and data service with the mini-slot of access slot, under the bigger situation of voice service amount, insert the aggravation that will lead to a conflict of mini-slot number deficiency, the voice service quality reduces, if and the access mini-slot free time of distributing to data service at this moment can cause waste of capacity, can not make full use of channel resource.
(3) high efficiency (seeing step 2 and 4)
PRMA and MPRMA method send the request of access on whole time slot method causes idle, the waste of whole time slot when clashing, especially under heavily loaded situation, conflict increases severely and will cause the significant wastage of channel resource.And the present invention is divided into mini-slot with access slot, even request is too much, conflict is serious, also just occurs on the mini-slot, can not influence transmission of Information on the information time slot, thereby can make full use of the information time slot; And, reserve based on the prediction of the VTs number that request is inserted and to insert mini-slot, can reduce even avoid conflicting of voice request and request of data, thereby reduce the transmission conflict of whole system, the utilance of raising access slot at access phase.
(4) simultaneously, the present invention has also brought other advantages: reserve based on the prediction of the VTs number that request is inserted and insert mini-slot, can reduce even avoid conflicting of voice request and request of data, thereby reduce the transmission conflict of whole system at access phase, reduced the influence of the data service of burst, increased the stability of a system voice service.
Description of drawings
Fig. 1 is the flow chart of the inventive method;
Fig. 2 is the channel capacity allocation policy map of central station of the present invention;
Fig. 3 is the schematic diagram of the request of the VTs among the present invention in formation;
Fig. 4 is the schematic diagram of the request of the DTs among the present invention in formation;
Fig. 5 is the VT request processing flow figure among the present invention;
Fig. 6 is the DT request processing flow figure among the present invention;
Fig. 7 is being preferably VTs based on forecasting mechanism and reserving a certain amount of access mini-slot method flow diagram among the present invention;
Fig. 8 is that request sent process chart during the VTs access procedure in each terminal of the present invention was handled;
Fig. 9 is the VTs access procedure process chart in each terminal of the present invention;
Figure 10 is the DTs access procedure process chart in each terminal of the present invention.
Embodiment
As shown in Figure 1, specific implementation flow process of the present invention is as follows:
Step 1 is in the initial launch time T
aIn, with the PRMA method as initial channel access method.
Adopt PRMA to be: when just starting in system as the reason of initial channel cut-in method, intrasystem terminal all is an access state not, adopting mini-slot to send the access request can make the information time slot free time, cause waste of capacity, adopt PRMA can make full use of channel resource, make the quick access channel of terminal as initial channel access method.
Step 2 is in the initial launch time T
aAfterwards, central station is put requesting terminal ID into VT request queue (being called for short VQ) and DT request queue (abbreviation DQ) respectively according to terminal class (the being VT/DT) sign in the request that the receives grouping (terminal request of receiving this moment still is based on the PRMA mode), then according to the next frame time slot of channel capacity allocation tactical arrangement up channel.
As shown in Figure 2, the channel allocation strategy of central station is as follows:
(1) VTs of access that is in the sound phase still continues to use dedicated time slot in next frame;
(2) next frame is removed remaining time slot behind the dedicated time slot of VTs (comprising the time slot that VTs that the sound phase finishes to enter resting stage discharges) and be called stand-by time slot, the VTs that successfully sends request but also do not obtain special-purpose reservation time slot before preferentially enjoys stand-by time slot, enters the VT request and handles;
(3) the stand-by time slot that VTs in the next frame is not preengage is called idle time slot, checks whether also have idle time slot, if having, then with Probability p
aDistribute idle time slot to give the DTs of DQ front end, promptly enter the DT request and handle; If do not have, then this time the time slot allocation process finishes;
(4) with the access slot of remaining idle time slot in the above-mentioned steps (c) as each terminal of described central station control, each access slot comprises M (the M value can be provided with flexibly according to system situation) mini-slot, be used for sending request differential group, be divided into and aim at part and VTs and the shared part of DTs that VTs reserves, be called VT subclass and shared subclass, the size of VT subclass is dynamically adjusted based on predetermined period ground.Other is the information time slot except that access slot in the time slot of a frame as can be known, is used to send the information block of VTs and DTs.
N in above-mentioned determines according to following formula:
(value that is N is by R
c, R
s, T
fAnd H
vDecision)
R
cThe expression channel transmission rate
R
sExpression speech transmissions speed
T
fThe expression frame period
H
vExpression packets headers (packet header) length.
As shown in Figure 3, the VQ formation is divided into VQ
1And VQ
0Two subqueues, VQ
1In be the request that inserts VTs that forwards the sound phase from silence periods to, VQ
0In be the request that does not insert VT, the placement principle (queuing principle) of VTs request in the VQ formation is as follows in the step 2: central station checks that at first (1 for inserting for the VT class formative of asking in the differential group, 0 is to insert) to differentiate this terminal be " inserting " still " access ", then Termination ID put into corresponding subqueue afterbody.
As shown in Figure 4, the placement principle (queuing principle) of the request of the DTs in the abovementioned steps 2 in the DQ formation is as follows:
(1) if the DT request is from inserting mini-slot, then this request being put into DQ formation afterbody; If DT request be packet incidentally, then current DQ rear of queue is put in this request earlier, and is marked;
(2) after the up channel previous frame sends end, central station distributes before the time slot, check whether markd DT asks in the DQ formation, if have, then the DT request back of being marked is transferred, with the fairness that guarantees that terminal inserts, avoid some terminal to take time slot for a long time and other-end can't obtain capacity.
As shown in Figure 5, the method that the VT of (2) request is handled in the abovementioned steps 2 is as follows:
(1) central station judges whether next frame remains to be used time slot, if having, then gives VQ with stand-by time slot allocation earlier
1VTs in the formation, i.e. VQ
1Have precedence over VQ
0, with stand-by time slot according to VQ
1Sequencing in the formation is distributed to VTs one by one, turns to next step (2) then; If do not have, then do not distribute, successfully send request but the VTs that also do not obtain special-purpose reservation time slot before can only wait for the stand-by time slot that subsequent frame can be used, this time time slot allocation process finishes;
(2) check whether next frame is still waiting to use time slot,, then more remaining stand-by time slot is distributed to VQ one by one according to the sequencing in the formation if having
0In VTs, distribute to VQ
1And VQ
0In the time slot of VTs all finish up to this sound phase at subsequent frame as their dedicated time slot, be the next frame after this time slot becomes the free time this VT does not send speech packet again on this dedicated time slot after, this time slot just can use for other-end; If next frame has not had stand-by time slot, then do not distribute VQ
0In VTs can only wait for the stand-by time slot that subsequent frame can be used, this time time slot allocation process finishes.
As shown in Figure 6, the method that the request of the DT in (3) is handled in the abovementioned steps 2 is as follows:
(1) central station is with Probability p
aThe idle time slot allocation that (〉=0.5) VTs does not preengage is given the DTs that is positioned at DQ request queue front end;
(2) will distribute the IDs of the DTs of time slot to move on to afterbody from queue front, monopolize channel resource to avoid some terminal, guarantee the fairness that terminal inserts, in fact seldom and under the more situation of idle time slot, a DT may be assigned to a plurality of time slots in terminal in the DQ; And the request packet count of this DT correspondence in the DQ formation deducted institute's distributed time slot number, if the request packet count of certain DT is 0 in certain DQ formation, then these DT request clauses and subclauses are deleted in formation.
As shown in Figure 7, the partition strategy that (4) in the above-mentioned steps 2 insert the mini-slot set is based on forecasting mechanism and is preferably VTs and reserves a certain amount of access mini-slot, and concrete grammar is as follows:
(1) forecasting mechanism: with the initial launch time T
aBe the request VTs number of periodic accumulation in each cycle time, Forecasting Methodology 1: then obtain possible request VTs number in the next cycle time after being averaged; Method 2: adopt genetic algorithm is calculated the VTs of the request of access in the next cycle number.
(2) future mechanism:
A. based on the number of the VTs that the request of access is arranged that is predicted, periodically calculate the access mini-slot number of being reserved.For the access mini-slot that makes VTs enough well-to-do, the mini-slot number M of reservation
rShould be greater than the predict VTs number M that inserts
vSo,, set and satisfy following relation between the two:
M
r=M
v* f, 1≤f≤2 wherein, the f value is variable, can determine according to actual conditions.
B. for first is preferably voice service and reserves M as the idle time slot of access slot in the next frame
rIndividual mini-slot.If M
r＞M then earlier all distributes to VTs with the mini-slot of this access slot; If M
r＜M is then with the remaining M-M of this time slot
rIndividual access mini-slot is shared by DTs and VTs;
C. whether if this frame has access slot again, then calculating needs to reserve and need for VT again to reserve what mini-slot, and remaining then mini-slot is shared by VTs and DTs again.
More than explanation is: with the mini-slot priority allocation of access slot is the VT subclass, and remaining then mini-slot is shared by VTs and DTs.When the mini-slot of access slot only for or when being not enough to use for the VTs request of prediction, then all access mini-slot are distributed to VTs, promptly next frame DTs can not send any access request.
Step 3, central station will be combined into one to the arrangement of next frame time slot and confirm grouping, on down channel, broadcast to each terminal of described central station control, the form example of confirming grouping sees Table 2, " 1 " and " 0 " to represent respectively be voice service and data service in the table 2, and " ID " has been assigned with time slot terminals ID number; " A " represents the time slot of this position is access slot.
Table 2
| 1ID | 1ID | 1ID | 1ID | 1ID | 1ID | 1ID | 1ID | 1ID | 1ID | 0ID | 1ID | 1ID | A | 0ID | 1ID |
Step 4, each terminal are arranged in to insert according to wherein time slot and send request differential group on the mini-slot after the affirmation grouping that receives central station broadcasting, send information block on the information time slot.
As shown in Figure 9, the processing procedure of VTs comprises in each terminal in abovementioned steps 4: request sending process and packets of voice process of transmitting wherein, if VTs is transferred to the sound phase and also do not obtained reservation by silence periods, then enter request sending process:
(1) request sending process is as follows, as shown in Figure 8:
A. check the terminal access state, if " not inserting " changes step b over to; If " insert ", change step c over to;
B. on certain mini-slot that inserts mini-slot VT subclass with Probability p
v(0＜p
v≤ 1, can choose optimal value according to system's actual conditions) send reserve requests differential group at random;
C. adopt the method that sends that repeatedly (is generally 2 times), increase the reservation probability of successful.Method is except sending on the VT subclass, also sends once on the mini-slot that VT and DT share again.
(2) packets of voice process of transmitting:
A. the VTs that has sent request is in the affirmation grouping of receiving that central station is announced, check the time slot reservation result and learn preengage successfully after, just every frame is speech packet of transmission on the dedicated time slot of central station distribution.
B. wherein, among step (2) a, before sending, judge whether the wait time delay of first packets of voice in the buffering has surpassed maximum access delay D
Max, if not, then directly on dedicated time slot, send; If surpass, then abandon this grouping, next grouping becomes first grouping in the formation, and whether the wait time delay that rejudges first grouping in the formation is greater than D
Max, so, up to the access delay in the formation less than D
MaxFirst be grouped on the dedicated time slot and send;
C. after sending first speech packet, give tacit consent to access state originally and change to " inserting " for the VT of " inserting ";
D. each the transmission after the grouping, VT can judge whether this sound phase finish promptly whether to also have new grouping to need to send, if do not have, then stops to send on this reservation time slot and divides into groups, this time slot becomes idle time slot at this frame; If have, then on the dedicated time slot of every frame, continue to send grouping, finish up to this sound phase.
As shown in figure 10, the access processing procedure of the DTs in aforesaid step 4 in each terminal comprises the process of the request of transmission and sends the process of grouping, wherein, if DTs has data message to send, at first enters the process of the request of transmission:
(1) sends the process of request: insert on mini-slot with Probability p in certain of shared subclass
d(0＜p
d≤ 1, can choose optimal value according to system's actual conditions) send and ask the differential group; After receiving the next frame time slot allocation result of central station broadcasting, whether the request of checking sends success, if success, the state that then is provided with enters the grouping process of transmitting for inserting; If request does not send successfully, promptly take place to send conflict, when then waiting until next frame, on certain mini-slot that inserts the shared subclass of mini-slot, continue to send request.
(2) after the process of transmission grouping: DTs receives the affirmation grouping of central station broadcasting, check among the next frame time slot allocation result whether the time slot of distributing to oneself is arranged,, then on institute's distributed time slot, send packet if having; If do not have, then continue to wait for.So repeatedly, finish up to whole transmission of all packets of this message (message).
(3) in addition, certain DT needed to judge whether that new data message arrives before sending packet on the information time slot, if having, and the incidentally access request of next message when then waiting until last grouping that sends this message, if do not have, then carry out according to process described in above-mentioned (2).
Claims (9)
1. access method for long propagation delay wireless signal channel is characterized in that step is as follows:
(1) in the initial launch time, with the packet reservation multiple access cut-in method as initial channel access method;
(2) after the initial launch time, central station is according to the terminal class sign in the terminal request grouping that receives, be voice terminal VT or data terminal DT, put their I D into the VT request queue respectively, be called for short VQ and DT request queue, be called for short DQ, according to the time slot of the next frame of channel capacity allocation tactical arrangement up channel, described channel capacity allocation strategy is then:
A. in next frame, be in sound each interim voice terminal VTs and still continue to use dedicated time slot to send speech packet;
B. next frame is removed remaining time slot behind the dedicated time slot of VTs, the time slot that comprises the VTs release that sound phase end enters resting stage, be called stand-by time slot, successfully send request but the VTs that also do not obtain special-purpose reservation time slot before preferentially enjoys stand-by time slot, enter the VT request and handle;
C. the stand-by time slot that VTs in the next frame is not preengage is called idle time slot, checks whether also have idle time slot, if having, then with Probability p
aDistribute idle time slot to give the DTs of DQ front end, promptly enter the DT request and handle; If do not have, then this time the time slot allocation process finishes;
D. with the access slot of remaining idle time slot in the above-mentioned steps (c) as each terminal of described central station control, each access slot comprises M mini-slot, be used to send the request differential group of terminal, access slot integral body is divided into part and VTs and the shared part of DTs that aims at the VTs reservation, be called VT subclass and shared subclass, the size of VT subclass is dynamically adjusted based on predetermined period ground; Other is the information time slot except that access slot in the time slot of a frame as can be known, is used to send the information block of VTs and DTs;
(3) central station is combined into an affirmation grouping with the arrangement of next frame time slot, broadcasts to each terminal of described central station control on down channel;
(4) each terminal is after the affirmation grouping that receives central station broadcasting, is arranged in to insert according to wherein time slot to send request differential group on the mini-slot, sends information block on the information time slot.
2. access method for long propagation delay wireless signal channel according to claim 1 is characterized in that: the VQ formation in the described step (2) is divided into VQ
1And VQ
0Two subqueues, VQ
1In what place is the request that inserts VT that changes into the sound phase from silence periods, VQ
0In be the request that does not insert VT; The placement principle that the ID of voice terminal VTs in the described step (2) in each terminal is identified in the VQ request queue is: central station is at first checked the VT class formative that inserts in the request differential group, differentiating this terminal is to have inserted or do not inserted, and puts corresponding subqueue afterbody into according to their classification then.
3. access method for long propagation delay wireless signal channel according to claim 1 is characterized in that: the placement principle of DTs request in the DQ request queue in the described step (2) in each terminal is:
(1) if the DT request is from inserting mini-slot, then the formation afterbody being put in this request;
(2) if DT request be packet incidentally, then the afterbody of current queue is put in this request earlier, and is marked;
(3) after the up channel previous frame sends end, central station distributes before the time slot, check whether markd DT asks in the DQ formation, if have, then the DT request back of being marked is transferred, with the fairness that guarantees that terminal inserts, avoid some terminal to take time slot for a long time and other-end can't obtain capacity.
4. access method for long propagation delay wireless signal channel according to claim 2 is characterized in that: the method that the VT request among described step (2) b is handled is as follows:
(1) central station judges whether next frame remains to be used time slot, if having, then gives VQ with stand-by time slot allocation earlier
1VTs in the formation, i.e. VQ
1Have precedence over VQ
0, with stand-by time slot according to VQ
1Sequencing in the formation is distributed to VTs one by one, turns to next step (2) then; If do not have, then do not distribute, successfully send request but the VTs that also do not obtain special-purpose reservation time slot before can only wait for the stand-by time slot that subsequent frame can be used, this time time slot allocation process finishes;
(2) check whether next frame is still waiting to use time slot,, then more remaining stand-by time slot is distributed to VQ one by one according to the sequencing in the formation if having
0In VTs, distribute to VQ
1And VQ
0In the time slot of VTs all finish up to this sound phase at subsequent frame as their dedicated time slot, be the next frame after this time slot becomes the free time this VT does not send speech packet again on this dedicated time slot after, this time slot just can use for other-end; If next frame has not had stand-by time slot, then do not distribute VQ
0In VTs can only wait for the stand-by time slot that subsequent frame can be used, this time time slot allocation process finishes.
5. access method for long propagation delay wireless signal channel according to claim 1 is characterized in that: the method that the DT request in the described step (2) in each terminal is handled is as follows:
(1) central station is with Probability p
aGive the DTs that is positioned at the request queue front end with the idle time slot allocation that VTs does not preengage;
(2) will distribute the IDs of the DTs of time slot to move on to afterbody, monopolize channel resource, guarantee the fairness that terminal inserts, and the request packet count of this DT correspondence in the DQ formation deducted institute's distributed time slot number to avoid some terminal from queue front.
6. access method for long propagation delay wireless signal channel according to claim 1 is characterized in that: the partition strategy of access mini-slot among described step (2) d set is based on forecasting mechanism and is preferably VTs and reserves a certain amount of access mini-slot, and method is as follows:
(1) at first predicts that based on forecasting mechanism next inserts the number of VTs period, be designated as M
v: with the initial launch time T
aFor the request VTs number of periodic accumulation in each cycle time predicted Forecasting Methodology 1: then obtain possible request VTs number in the next cycle time after being averaged; Forecasting Methodology 2: adopt genetic algorithm is calculated the VTs of the request of access in the next cycle number;
(2) adopting future mechanism is that VTs reservation some is designated as M
rThe access mini-slot:
A. enough well-to-do for the access mini-slot that makes VTs, the mini-slot number M of reservation
rShould be greater than the number M that inserts request VTs that has of prediction in the step (1)
v, set and satisfy following relation between the two:
M
r=M
v* f, 1≤f≤2 wherein, the f value is variable;
B. for first is preferably voice service and reserves M as the idle time slot of access slot in the next frame
rIf individual mini-slot is M
r＞M then earlier all distributes to VTs with the mini-slot of this access slot; If M
r＜M is then with the remaining M-M of this time slot
rIndividual access mini-slot is shared by DTs and VTs;
C. whether if this frame has access slot again, then calculating needs to reserve and need for VT again to reserve what mini-slot, and remaining then mini-slot is shared by VTs and DTs again.
7. access method for long propagation delay wireless signal channel according to claim 1 is characterized in that:
The transmission of VTs in the described step (4) in each terminal comprises: request sending process and speech packet process of transmitting, wherein:
(1) request sending process is as follows:
A. when certain VT initiated new communication process, the state that oneself is set sent request differential group with Probability p v then at random for not inserting on certain mini-slot that inserts mini-slot VT subclass;
B. if the state of certain VT is for inserting, promptly be in the communication process, begin promptly when silence periods transfers sound phase to when the new sound phase, adopt the method that repeatedly sends request, increase the reservation probability of successful, method is except sending on the VT subclass, also sends once on the mini-slot that VT and DT share again;
(2) the speech packet process of transmitting is as follows:
A. the VTs that has sent request is after receiving the time slot reservation result that central station is announced and learning that reservation successfully obtains dedicated time slot, and just every frame sends a speech packet on the dedicated time slot that central station distributes;
B. wherein, among step (2) a, before sending, judge whether the wait time delay of first speech packet in the buffering has surpassed maximum access delay D
Max, if not, then directly on dedicated time slot, send; If surpass, then abandon this grouping, next grouping becomes first grouping in the formation, and whether the wait time delay that rejudges first grouping in the formation has surpassed maximum access delay D
Max, so, up to the wait time delay in the formation is not more than D
MaxFirst be grouped on the dedicated time slot and send;
C. after sending first speech packet, access state inserts for the VT that does not insert changes to originally;
D. each the transmission after the grouping, VT can judge whether this sound phase finish promptly whether to also have new grouping to need to send, if do not have, then stops at and sends grouping on this reservation time slot, this time slot becomes idle time slot at this moment; If have, then on the dedicated time slot of every frame, continue to send grouping, finish up to this sound phase.
8. access method for long propagation delay wireless signal channel according to claim 1 is characterized in that: the process of transmitting of the DTs in each terminal of described step (4) comprises:
1. send the process of request: on certain mini-slot of shared subclass, send request differential group with Probability p d; Send conflict if produce, i.e. competition is unsuccessful, when then waiting until next frame, continues to send request differential group on certain mini-slot that inserts the shared subclass of mini-slot;
2. after the process of transmission grouping: DTs receives the affirmation grouping of central station broadcasting, check among the next frame time slot allocation result whether the time slot of distributing to oneself is arranged,, then on institute's distributed time slot, send packet if having; If do not have, then continue to wait for; So repeatedly, finish up to whole transmission of all packets of current data message;
3. certain DT needed to judge whether that new data message arrives before sending packet on the information time slot, if having, and the incidentally access request of next data message when then waiting until last packet that sends current data message; If do not have, then according to step 2. described in process carry out.
9. access method for long propagation delay wireless signal channel according to claim 1 or 5 is characterized in that: described Probability p
a〉=0.5.
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| CN101848542B (en) * | 2010-04-06 | 2013-04-24 | 广州海格通信集团股份有限公司 | Method for transmitting real-time data and non-real time data by Ad Hoc web radio station |
| CN102547914B (en) * | 2010-12-28 | 2015-09-09 | 华为技术有限公司 | The method and apparatus of access network |
| CN103841653B (en) * | 2012-11-21 | 2017-09-29 | 电信科学技术研究院 | A kind of method and device of node access slot resource |
| CN106454553A (en) * | 2016-11-15 | 2017-02-22 | 深圳市视维科技有限公司 | A precise time delay live video network transmission control method |
| CN108347323B (en) * | 2017-01-25 | 2020-06-26 | 华为技术有限公司 | RS generating and receiving method, terminal and base station |
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| CN1228216A (en) * | 1997-05-30 | 1999-09-08 | 摩托罗拉公司 | System, device and method for contention-based reservation inshared medium network |
| US6747959B1 (en) * | 1998-10-07 | 2004-06-08 | At&T Corp. | Voice data integrated mulitaccess by self-reservation and blocked binary tree resolution |
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| CN1228216A (en) * | 1997-05-30 | 1999-09-08 | 摩托罗拉公司 | System, device and method for contention-based reservation inshared medium network |
| US6747959B1 (en) * | 1998-10-07 | 2004-06-08 | At&T Corp. | Voice data integrated mulitaccess by self-reservation and blocked binary tree resolution |
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