Technical background
As everyone knows, traditional cellular mobile communication system (such as, GSM mobile communication system, cdma mobile communication system etc.) with sub-district (cell) as basic communication unit.In each sub-district, the base station receives the signal from a user terminal as the signal relay center, gives the purpose user terminal with this signal forwarding then.This shows that in traditional cellular mobile communication system, user terminal only carries out direct communication with the base station, and does not communicate with the base station after can not transmitting signal via other user terminal again.
In traditional mobile communication system, because the coverage (coverage) of each sub-district is limited, and in the relatively more rare zone of personnel, reason owing to cost etc., can not arrange that a large amount of sub-districts covers these zones fully, so when user terminal is positioned at regional that the sub-district can not cover, user terminal can not communicate with the base station again.
In addition, because complicated building is arranged in the big city, can in the coverage of some sub-districts, form the zone of communication blind spot by name (dead spot).In the communication blind spot, user terminal had not both received from signal of base station, signal can not be sent to the base station.
Above-mentioned said all be the intrinsic defective of traditional mobile communication system.In order to overcome these defectives, that is to say, make user terminal be positioned at outside the coverage of sub-district or also can communicate during the communication blind spot with the base station, the enhancement techniques of a kind of multi-hop by name (multihop) has been proposed in traditional mobile communication system.
The multi-hop technology is a kind ofly to be used for peer-to-peer network originally, to make user terminal carry out signal forwarding (relaying) and relaying (relay) technology that communicates with the user terminal of apart from each other via other user terminal.By introduce the multi-hop technology in traditional mobile communication system, in the time of outside user terminal is positioned at communication blind spot or cell coverage area, it can communicate with the base station then by other user terminal forward signals.
Fig. 1 is a kind of schematic diagram of existing trunking traffic technology of the TD-SCDMA of being used for communication system.As shown in the figure, because user terminal UE0 is far away apart from base station 10, can not carry out direct communication with base station 10, so user terminal UE0 sends to base station 10 after signal n time by user terminal UE1...UEn transmitted, base station 10 sends to purpose user terminal (not shown) with the signal of receiving via radio network controller (RNC) 20 and core network (CN) 30 again.
Referring to Fig. 1, when signal was forwarded (relaying), the user terminal that sends this repeating signal communicated by directly being connected (direct connection) with the user terminal/base station that receives this repeating signal.For the convenience of narrating, will be called link (link) at user terminal that sends this repeating signal and the direct connection that receives between the user terminal/base station of this repeating signal below, as shown in Figure 1 direct connection L0, L1...Ln-1 and Ln are called link.
For a source user terminal, connected each bar link all is called a direct link (direct link) of this source user terminal.The source user terminal can send signal to each the trunk subscriber terminal as relaying via each direct link, again via each trunk subscriber terminal, forwards a signal to the trunk subscriber terminal or the base station of each next stage.With Fig. 1 is example, when the UE0 as the source user terminal sends signal via direct link L0, user terminal UE1 is as first order trunk subscriber terminal, forward a signal to the next stage user terminal, the user terminal of next stage is transmitted signal again, transmit through the n level at last, trunk subscriber terminal UE n passes the signal to base station 10 via link Ln.
As mentioned above, by in traditional mobile communication system, introducing the multi-hop technology, user terminal can communicate with the base station via the signal forwarding of other trunk subscriber terminal, but since the disposal ability of trunk subscriber terminal generally the disposal ability not as the base station is strong, so the trunk subscriber terminal can not be handled the data flow of two-forty as the base station, therefore, the link of source user terminal expectation by constituting by the trunk subscriber terminal, in the mode of this relaying, the data flow that sends two-forty to the base station is impossible.
In addition, even if transmission than the data of low rate because the signal handling capacity of trunk subscriber terminal is not as the base station, if adopt mode transmission signals shown in Figure 1, transmitting the back through the n level, to arrive signal of base station general more weak, is difficult to satisfy the requirement of communication quality.
Detailed Description Of The Invention
Basic thought of the present invention is: when a source user terminal can not be carried out direct communication with when the base station sends data flow with the base station, whether the data-handling capacity that this source user terminal detects the trunk subscriber terminal in its each direct link satisfies the requirement of transmitting data, that is: the streaming rate that whether sends greater than this source user terminal desire of the streaming rate that can handle of the trunk subscriber terminal of each direct link.If the streaming rate that the streaming rate that each trunk subscriber terminal can be handled sends less than this source user terminal desire, then this source user terminal is divided into the sub data flow that several these trunk subscriber terminals can be handled with the data flow that desire sends, and then these sub data flows is forwarded to the base station via each trunk subscriber terminal.And if the streaming rate that the streaming rate that the trunk subscriber terminal can be handled sends greater than this user terminal desire, then this user terminal is forwarded to the base station via each trunk subscriber terminal respectively with the data flow with identical content that desire sends.
In order to make thought of the present invention clearer, be described in detail below in conjunction with Fig. 2.
As shown in Figure 2, when source user terminal UE 0 is want data flow is sent to base station 10, but can not carry out direct communication with the base station again the time, source user terminal UE 0 at first detects each coupled direct link, therefrom to select can be used as the link of relaying.If selected m direct link, that is: link L11, L12, L13 ..., L1m, then source user terminal UE 0 detect this m direct link L11, L12, L13 ..., the trunk subscriber terminal UE 1 of L1m, UE2, UE3 ..., whether the data-handling capacity of UEm satisfy the requirement of forwarding data.
If the speed data stream that source user terminal UE 0 sends is higher, user terminal UE1, UE2, UE3, ..., the streaming rate that the streaming rate that UEm can handle sends less than source user terminal UE 0 desire, then the source user terminal UE 0, the state (as: channel conditions of direct link according to each direct link in m the direct link, the energy state of the battery of the data-handling capacity of trunk subscriber terminal and trunk subscriber terminal), the data flow that desire is sent splits into m sub data flow, and via direct link L11, L12, L13, ..., L1m sends to trunk subscriber terminal UE 1, UE2, UE3, ..., UEm.Via trunk subscriber terminal UE 1, UE2, UE3 ..., m sub data flow transmitting of UEm after (being the n level shown in the figure) step by step forwarding by follow-up each trunk subscriber terminal, respectively via repeated link Ln1, Ln2, Ln3 ..., Lnm arrives base station 10.Because source user terminal UE 0 has split into m the data flow that speed is lower with the speed higher data stream that desire sends, therefore, each sub data flow after the fractionation can not be that very strong trunk subscriber terminals at different levels are forwarded to base station 10 via data-handling capacity.
If the speed data stream that the source user terminal sends is lower, user terminal UE1, UE2, UE3 ..., the streaming rate that sends greater than source user terminal UE 0 desire of the streaming rate that can handle of UEm, then the source user terminal UE 0, the data flow that content is identical respectively via direct link L11, L12, L13 ..., L1m send to trunk subscriber terminal UE 1, UE2, UE3 ..., UEm.Via trunk subscriber terminal UE 1, UE2, UE3 ..., the identical data flow of m content transmitting of UEm after (being the n level shown in the figure) step by step forwarding by follow-up each trunk subscriber terminal, respectively via repeated link Ln1, Ln2, Ln3 ..., Lnm arrives base station 10.Because source user terminal UE 0 has been passed through m bar repeated link with the data flow of the identical content of desire transmission and has been forwarded to base station 10, therefore, be equivalent to each road signal is sent to base station 10, thereby the method that base station 10 can utilize diversity to merge obtains than the measured signal of single channel relaying matter by space diversity.
Base station 10 receive from repeated link Ln1, Ln2, Ln3 ..., after m the data flow of Lnm, this m data stream is detected, if testing result shows m the sub data flow that obtains after this m data flow is split by source user terminal UE 0, then base station 10 merges this m sub data flow being reduced into the data flow before splitting, and the data flow after will reducing sends to the purpose user terminal via radio network controller (RNC) 20 and core network (CN) 30; If testing result show this m data flow be not through fractionation and be data flow with identical content from same source user terminal UE 0, then this m data flow is handled in the mode of diversity merging, to obtain the data flow of signal reinforcement; And the data flow after will merging sends to the purpose user terminal via radio network controller (RNC) 20 and core network (CN) 30.
Below in conjunction with flow chart shown in Figure 3, what the invention described above was described improves the method for the relaying performance of mobile communication system by user terminal UE0 being used to of carrying out.
When source user terminal UE 0 can not be directly and base station 10 communicate when sending data flow, this source user terminal UE 0 at first detects each coupled direct link, therefrom to select can be used as the link (step S10) of relaying, whether this user terminal UE0 data-handling capacity of detecting the trunk subscriber terminal of selected each direct link satisfies the requirement of transmitting data then, that is: the streaming rate (step S20) that whether sends greater than this source user terminal desire of the streaming rate that can handle of the trunk subscriber terminal of each direct link.
If the streaming rate that the streaming rate that the trunk subscriber terminal of 1 each direct link can be handled sends less than this user terminal desire
Source user terminal UE 0, according to the state of each direct link, the data flow that desire is sent splits into a plurality of sub data flows, and sends to each trunk subscriber terminal (step S30) via each selected direct link.Wherein, the state of each direct link, can comprise: the energy state of the data-handling capacity of the channel conditions of this direct link, trunk subscriber terminal and the battery of trunk subscriber terminal, source user terminal UE 0 can adopt to each direct link and send broadcast and obtain the state of each direct link from the report message that each direct link is replied.The state of corresponding each direct link, the source user terminal also is different for the load of the data flow of its distribution, if the streaming rate that the trunk subscriber terminal of the channel conditions of this direct link good (such as signal to noise ratio (snr) higher or bit error rate (BER) is lower), this direct link can be handled is higher and the energy content of battery abundance of trunk subscriber terminal, thereby this direct link can carry the higher data load in the unit interval, distributes transmission rate higher data stream then can for this moment this direct link; Otherwise, then distribute the lower data flow of transmission rate for this direct link.Corresponding different message transmission rates, the spreading factor that uses when the trunk subscriber terminal is transmitted sub data flow are also different, and data rate is high more, and spreading factor is low more.Because the reduction of spreading factor can cause the processing gain of trunk subscriber terminal to reduce, therefore, when data flow is split into each sub data flow, need to decide according to the state of each direct link, different direct link can carry the data of different load amount.
After the forwarding step by step by follow-up each trunk subscriber terminal, a plurality of sub data flows of transmitting via each repeated link are sent to base station 10 (step S40) respectively.
If the streaming rate that the trunk subscriber terminal of 2 each direct link can be handled is not less than the speed of the data flow of this user terminal desire transmission
Source user terminal UE 0, the data flow that content is identical send to each trunk subscriber terminal (step S70) via each direct link respectively.After the forwarding step by step by follow-up each trunk subscriber terminal, the identical a plurality of data flow of transmitting via each repeated link of content are sent to base station 10 (step S80) respectively.
Below in conjunction with flow chart shown in Figure 4, what the invention described above was described improves the method for the relaying performance of mobile communication system by base station 10 being used to of carrying out.
At first, a plurality of data flow (step S100) that base station 10 receives from each repeated link, then, 10 pairs of these a plurality of data flow in base station detect (step S110).
(1) if testing result shows a plurality of sub data flows that obtain after these a plurality of data flow are split by source user terminal UE 0, then base station 10 merges these a plurality of sub data flows being reduced into the data flow before splitting, and the data flow after will reducing sends to purpose user terminal (step S130); Wherein, if source user terminal UE 0 adopts a plurality of sub data flows after different frequency expansion sequences sends fractionation, then base station 10 can merge these a plurality of sub data flows the data flow that is reduced into before splitting according to the corresponding frequency expansion sequence of a plurality of sub data flows of receiving.
(2) if testing result show these a plurality of data flow be not through fractionation and be data flow with identical content from same source user terminal UE 0, then these a plurality of data flow are handled in the mode that diversity merges, thereby obtain the data flow that signal is strengthened, and the data flow after will merging sends to purpose user terminal (step S140); Wherein the mode of high specific merging or the mode of equal gain combining can be adopted in the base station, these a plurality of data flow are merged obtain the data flow that signal is strengthened.
The method that is used for improving the relaying performance of mobile communication system of the present invention both can be realized by the software module that operates in user terminal and base station, also can realize, can also adopt way of hardware and software combination to realize by hardware module with corresponding software function.
According to one embodiment of the invention be used to improve the mobile communication system the relaying performance composition as shown in Figure 5, wherein, the parts identical with legacy user terminals with the legacy network system are not shown in Figure 5.
As shown in Figure 5, user terminal 200 comprises: a detecting unit 204 is used to detect each direct link of this user terminal; A selected cell 205 is used for according to testing result, selects operable a plurality of direct link from each direct link; The data-handling capacity of the trunk subscriber terminal (relayer) of 204 pairs of each selected direct link of detecting unit detects; If the data-handling capacity of each trunk subscriber terminal satisfies the requirement of transmitting data, then by transmitting element 202, each selected direct link via this transmits the data flow that desire sends respectively; If the data-handling capacity of each trunk subscriber terminal can not satisfy the requirement of transmitting data, then by split cells 201, state of each selected direct link according to this, the data flow that desire is sent splits into the data flow that each selected direct link can be handled, and a plurality of data flow that fractionation obtained via transmitting element 202 send via each selected direct link of correspondence.Wherein, the state of direct link comprises the channel conditions of this direct link, the data-handling capacity of trunk subscriber terminal and the energy state of trunk subscriber end cell.
Receiving element 101 in the network system 100 by detecting unit 102, detects a plurality of data flow of this reception after a plurality of data flow of receiving from each repeated link; If testing result shows that these a plurality of data flow are the same data flow from same source user terminal that do not split, then merge cells 103 will these a plurality of data flow merge obtain data flow that signal strengthens after, via transmitting element 105, the data flow after merging is sent to the purpose user terminal; If testing result shows each sub data flow that these a plurality of data flow were split, then utilize reduction unit 104, after will these a plurality of sub data flows merging the data flow that is reduced into before splitting, the data flow after will reducing via transmitting element 105 again sends to the purpose user terminal.