CN100518020C - Method for transmitting control information of OFDM system - Google Patents
Method for transmitting control information of OFDM system Download PDFInfo
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- CN100518020C CN100518020C CNB2006100656904A CN200610065690A CN100518020C CN 100518020 C CN100518020 C CN 100518020C CN B2006100656904 A CNB2006100656904 A CN B2006100656904A CN 200610065690 A CN200610065690 A CN 200610065690A CN 100518020 C CN100518020 C CN 100518020C
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Abstract
The invention discloses a transmission method of orthogonal frequency dividing multiplexing system control information; base station provides areola searching information for user by transmitting data frame with synchronous channel information and broadcasting channel information, it characterized in that that there is a fixed interval between the moment said base station sends broadcasting channel information and sends synchronous channel information. Further, the moment that said base station sends broadcasting channel information is adjacent to moment that said base station sends reference mark which can be used to estimate channel. At the receiving end, the user equipment receives timing of synchronous channel, and obtains the timing of broadcasting channel directly based on said fixed interval, then broadcasting channel information can be picked up. The invention increases the searching speed of areola, decreases the complexity of areola searching, and guarantees the demodulation property of BCH information in dicky channel.
Description
Technical field
The present invention relates to the Cell searching technology of OFDM (Orthogonal Frequency Division Multiplexing, OFDM) system, specifically, relate to the transmission method of control information of OFDM system.
Background technology
As a kind of multi-carrier transmission pattern, OFDM is converted to one group of low-speed parallel data flow transmitted by the data flow with a high-speed transfer, system is reduced greatly to the susceptibility of multidiameter fading channel frequency selectivity, the introducing of Cyclic Prefix has further strengthened the ability of the anti-intersymbol interference of system again.In addition, the bandwidth availability ratio height, realize that characteristics such as simple make OFDM more and more wider in the application in radio communication basin.Such as, WLAN (Wireless Local Area Network, WLAN (wireless local area network)) system, WiMAX (wide Inter-operability Microwave Acces) system etc.Even in the 4th generation mobile communcations system in future, the OFDM technology also is most important alternative technique.
When the initial connecting system of travelling carriage, at first will to obtain sequential synchronous with the signal of some sub-districts in the system.It is this that to relate to the synchronous process of sequential from nothing be exactly the cell search process of travelling carriage.In the Cell searching of ofdm system, relate generally to two kinds of channels: synchronizing channel (SynchronizationChannel, SCH) and broadcast channel (Broadcast Channel, BCH).
Usually, SCH has certain correlation in time domain and/or frequency domain, and the SCH signal that the travelling carriage utilization receives can be realized initial time synchronized and Frequency Synchronization with the base station.The BCH signal then comprises and specific cell system associated information, such as system bandwidth information, and cell identification information, circulating prefix-length information etc.Therefore, the control information that BCH comprised is for travelling carriage, particularly utilized SCH to obtain the travelling carriage of initial time synchronized and Frequency Synchronization, also need the travelling carriage of further connecting system or switching, is vital.
Therefore, how reasonably to transmit the BCH signal between base station and the travelling carriage, for the performance of Cell searching, and equipment implementing complexity all has great importance.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of transmission method of control information of OFDM system, with the performance of raising Cell searching, and reduces equipment implementing complexity.
For solving the problems of the technologies described above, the invention provides a kind of transmission method of control information of OFDM system, the base station carries the Frame of synchronous channel information and broadcast channel information by transmission, for subscriber equipment provides the Cell searching control information, comprise the steps: that (a) described base station sends synchronous channel information; (b) behind fixing interval, described base station sends broadcast channel information;
Wherein, described fixing interval, can determine by following steps:
The Cyclic Prefix of equal length is all adopted to the data burst that all send synchronous channel informations in the base station, and is identified for sending the fixed position of the OFDM symbol of synchronous channel information in this subframe;
The position of base station any OFDM symbol except the described OFDM symbol that is used for sending synchronous channel information in this subframe fixingly selects a position to be used for sending broadcast channel information.
Perhaps, described fixing interval, can determine by following steps:
The Cyclic Prefix of equal length is all adopted to the data burst that all send synchronous channel informations in the base station, and is identified for sending the fixed position of the OFDM symbol of synchronous channel information in this subframe;
Send broadcast channel information on the position of last OFDM symbol of base station in any subframe except that this subframe.
Perhaps, described fixing interval, also can determine by following steps:
Send synchronous channel information on the position of last OFDM symbol of base station in any subframe;
The base station sends broadcast channel information on the position of last OFDM symbol of any subframe except the described data burst that is used for sending synchronous channel information.
Further, base station of the present invention sends the moment of broadcast channel information, is close in the moment that described base station sends the reference symbol that can be used for channel estimating.
Wherein, described reference symbol is the pilot tone that can be used for channel estimating, or can be used for the synchronizing symbol of channel estimating.
Among the present invention,, can extract control information as follows at receiving terminal:
By subscriber equipment a time constant is set, this constant equals described base station and sends the moment of broadcast channel information and send fixed intervals between moment of synchronous channel information;
Subscriber equipment according to the time constant of described setting, obtains the timing of broadcast channel after the timing that obtains synchronizing channel;
Subscriber equipment extracts broadcast channel information according to the timing of the broadcast channel of described acquisition.
Fixing interval of the present invention can be a fixing lead or retardation.
The present invention adopts fixed intervals to send synchronous channel information and broadcast channel information, simplified the realization of transmitting terminal, at receiving terminal, subscriber equipment utilizes the timing and the described fixed intervals of synchronizing channel, can directly obtain the timing of broadcast channel, extract broadcast channel data and be more prone to fast, and then improved the speed of Cell searching, and reduced the equipment implementation complexity of Cell searching.In addition, because the base station always sends control information near transmission can be used for the reference symbol of channel estimating, this has just guaranteed the demodulation performance of broadcast channel information under abominable channel (as the high-speed mobile channel, postpone greatly extended channel etc.).
Description of drawings
Fig. 1 is the described frame structure schematic diagram of the embodiment of the invention;
Fig. 2 is that the embodiment of the invention is described when sending the situation of SCH information on several OFDM symbols in the middle of the subframe of base station, sends the schematic diagram of BCH information;
When Fig. 3 sends the situation of SCH corresponding to the base station for the embodiment of the invention is described on several OFDM symbols that subframe begins, send the schematic diagram of BCH information;
Fig. 4 sends the schematic diagram of BCH information when to be that the embodiment of the invention is described send the situation of SCH corresponding to the base station on several OFDM symbols at subframe end;
Fig. 5 sends the schematic diagram of BCH information when to be that the embodiment of the invention is described send the situation of SCH corresponding to the base station on last 1 OFDM symbol of subframe;
Fig. 6 is that the embodiment of the invention is described when sending the situation of SCH on the discontinuous OFDM of base station in subframe, sends the schematic diagram of BCH information;
Fig. 7 is that the embodiment of the invention is described when sending the situation of SCH on the discontinuous OFDM of base station in subframe, sends the schematic diagram of BCH information;
Fig. 8 is the described schematic diagram that sends BCH information in non-adjacent subframe corresponding to Fig. 2 of the embodiment of the invention.
Embodiment
For a better understanding of the present invention, at first provide one below and use ofdm system of the present invention.As shown in Figure 1, in this ofdm system, the time span of a radio frames is 10ms, and a frame comprises 20 subframes, subframe 0, subframe 1 ... subframe 19, each subframe lengths are 0.5ms.0.5ms the circulating prefix-length that subframe adopted can have two kinds: long loop prefix and short Cyclic Prefix.
Usually, when sending channel delay spread sensitivity professional, the base station can select to adopt long loop prefix length subframe; When sending the insensitive business of channel delay spread, the base station can select to adopt short circulating prefix-length subframe.Because the uncertainty of type of service, the subframe type of base station selected employing are uncertain also the time for receiver.
Short Cyclic Prefix subframe is shown in the subframe in the accompanying drawing 11, and each subframe comprises 7 OFDM symbols; The long loop prefix subframe is shown in the subframe in the accompanying drawing 12, and each subframe comprises 6 OFDM symbols.In accompanying drawing 1, there is the rectangle frame of oblique line to represent the circulating prefix-length of subframe, the narrower short Cyclic Prefix of oblique line rectangle frame 1 expression; The oblique line rectangle frame 2 expression long loop prefixes of broad.In addition, pilot tone is positioned on the part carrier wave of first OFDM symbol of each subframe and third from the bottom OFDM symbol, the zone of pointing to as label among Fig. 13.
In the prior art, owing to send being at interval and depending on the parameter that circulating prefix-length changes between moment of BCH and SCH, therefore, described two between constantly is an amount with the circulating prefix-length variation at interval.
Owing to there is not " employing fixed intervals " this theory in the prior art, therefore, at transmitting terminal, the base station needs could determine the delivery time of BCH according to the circulating prefix-length of selecting for use, the delivery time of SCH, has increased the complexity that transmitter is realized.At receiving terminal, also relatively more difficult even travelling carriage after the timing that obtains SCH, obtain the timing of BCH, and then increased the complexity that receiver is realized, reduce receiver and obtained the speed of BCH information, and reduced the speed of Cell searching.And, in the prior art, because the type of the Cyclic Prefix that strides across between sending at interval (long or short) difference also causes fixedly total length.
And core thinking of the present invention is " adopting fixing lead or retardation ", and makes this amount become a constant that does not rely on the circulating prefix-length variation.
In order to make the moment that sends BCH have a fixing interval with respect to the moment that sends SCH, the base station can adopt multiple mode that fixed intervals are set, for example, and can be by the following steps setting:
The Cyclic Prefix of equal length is all adopted to the data burst that all send synchronous channel informations in the base station, and is identified for sending the fixed position of the OFDM symbol of synchronous channel information in this subframe;
Send broadcast channel information on the position of last OFDM symbol of base station in any subframe except that this subframe.
Perhaps, also can be by the following steps setting:
The Cyclic Prefix of equal length is all adopted to the data burst that all send synchronous channel informations in the base station, and is identified for sending the fixed position of the OFDM symbol of synchronous channel information in this subframe;
The position of base station any OFDM symbol except the described OFDM symbol that is used for sending synchronous channel information in this subframe fixingly selects a position to be used for sending broadcast channel information.
Perhaps, also can be by the following steps setting:
Send synchronous channel information on the position of last OFDM symbol of base station in any subframe;
The base station sends broadcast channel information on the position of last OFDM symbol of any subframe except the described data burst that is used for sending synchronous channel information.
Below, the invention provides several specific embodiments and come this is described respectively.
First embodiment:
As shown in Figure 2, provided according to the described a kind of BCH information transmission schematic diagram of the embodiment of the invention.It sends the situation of SCH information on several OFDM symbols in the middle of the subframe corresponding to the base station.In Fig. 2, SCH information is arranged in and has that (implication of fixed cycles prefix length is: all send the subframe of SCH information on fixed cycles prefix length subframe reciprocal the 3rd and the second-to-last OFDM symbol here, always adopt changeless circulating prefix-length, promptly adopt the Cyclic Prefix of equal length).
Under these circumstances, the base station can send BCH on any one subinterval in interval [last symbol of the previous subframe of SCH place subframe, the 4th symbol of the inverse of SCH place subframe].Here, need to prove that the included OFDM number of symbols of the SCH information among the figure is an illustrative, such as, SCH can also only be arranged in to be had on fixed cycles prefix length subframe the 3rd the OFDM symbol reciprocal.
Sending BCH information with the base station on second OFDM symbol of SCH place subframe is example, the BCH information that the base station sends has a fixing lead with respect to sending SCH information, this lead is one and does not rely on the time quantum that circulating prefix-length changes, fixedly OFDM symbol lengths+1 a long loop prefix length of lead constant=1 a long loop prefix length.
Utilize this character, at receiving terminal, after travelling carriage utilizes SCH information acquisition symbol regularly, timing with SCH is a benchmark, puies forward previous Preset Time amount again, promptly, OFDM symbol lengths+1 of 1 a long loop prefix length long loop prefix length, just can obtain the timing of BCH, utilize this timing, can directly extract the BCH data of reception.
Need to prove, aforementioned constant: OFDM symbol lengths+1 of 1 a long loop prefix length long loop prefix length, just example explanation, in fact can to equal M OFDM symbol lengths (can be long loop prefix OFDM symbol to this constant, also can be short OFDM symbol, also can be both mixing)+1 circulating prefix-length (can be long loop prefix, also can be short Cyclic Prefix), wherein, M is an arbitrary integer.
Usually, this constant should not surpass a frame, i.e. 10ms; Do the time spent when SCH has channel estimating, this constant should not surpass subframe, i.e. a 0.5ms.
In addition, because pilot tone is positioned on the part carrier wave of first OFDM symbol of each subframe and third from the bottom OFDM symbol, when sending BCH on second OFDM symbol of base station in SCH place subframe, the BCH that sends is positioned at the position near pilot tone, the simple channel estimation methods of receiver utilization just can guarantee the demodulation performance of BCH information under abominable channel (as the high-speed mobile channel, postponing extended channel etc. greatly).
Second embodiment
As shown in Figure 3, provided according to another kind of BCH information transmission schematic diagram of the present invention.It sends the situation of SCH on several OFDM symbols that subframe begins corresponding to the base station.In Fig. 3, SCH information is arranged in to be had on the 1st of fixed cycles prefix length subframe and the 2nd the OFDM symbol, for guaranteeing that the BCH information that the base station sends and the SCH information of transmission have a fixing delay or lead, the base station can send BCH information on last symbol of a subframe on the subframe of SCH information place, perhaps the interval of the norator in interval [the 4th OFDM symbol of the inverse of SCH place subframe, 2 OFDM symbols of the inverse of SCH place subframe] sends BCH information.
The 3rd embodiment:
As shown in Figure 4, provided according to the described another kind of BCH information transmission schematic diagram of the embodiment of the invention.It sends the situation of SCH on several OFDM symbols at subframe end corresponding to the base station.In Fig. 4, SCH is arranged in to be had on the 1st of fixed cycles prefix length subframe inverse and the second-to-last OFDM symbol.Under these circumstances, the base station can be at the interval BCH that sends of the norator in interval [last symbol of the previous subframe of SCH place subframe, the 3rd symbol of the inverse of SCH place subframe].
The 4th embodiment:
As shown in Figure 5, provided according to another kind of BCH information transmission schematic diagram of the present invention.It sends the situation of SCH on last 1 OFDM symbol of subframe corresponding to the base station, and, SCH can be arranged in the subframe of any circulating prefix-length, under these circumstances, the base station sends BCH on last symbol of another one subframe (not sending the subframe of SCH), the length of the Cyclic Prefix that BCH place subframe adopts also can be unfixed.
The 5th embodiment:
When the included OFDM symbol of SCH in the subframe is discontinuous, also can use the present invention, as Fig. 6, shown in Figure 7, the base station is arranged at SCH to be had on fixed cycles prefix length subframe second-to-last and the 4th the OFDM symbol reciprocal, for guaranteeing that the BCH that the base station sends and the SCH of transmission have a fixing delay or lead, the base station can be at interval [last symbol of the previous subframe of SCH place subframe, the 5th symbol of the inverse of SCH place subframe] in any one subinterval on send BCH (as shown in Figure 6), perhaps on third from the bottom symbol of SCH place subframe, send BCH (as shown in Figure 7).
The 6th embodiment:
Corresponding to Fig. 2, BCH can be arranged in other OFDM symbol of the subframe identical with SCH, also can be positioned on last symbol of previous subframe of SCH place subframe.In fact, BCH also can be positioned at last symbol of other subframe.As shown in Figure 8, be the described schematic diagram that in non-adjacent subframe, sends BCH information of the embodiment of the invention.The time span that it should be noted that each subframe all is identical, although number of symbols wherein can be different.Like this, when BCH is positioned at last symbol of other subframes (with the non-conterminous subframe of subframe that sends SCH), because the time span of each subframe that the transmission between BCH and the SCH is striden across at interval is identical, therefore, although the type of the Cyclic Prefix that these subframes are used may be different, the number of sub-frames that only need calculate its process is just passable.
Claims (7)
1, a kind of transmission method of control information of OFDM system, the base station carries the Frame of synchronous channel information and broadcast channel information by transmission, for subscriber equipment provides the Cell searching control information, it is characterized in that, comprises the steps:
(a) described base station sends synchronous channel information;
(b) behind fixing interval, described base station sends broadcast channel information;
Described fixing interval, determine by following steps:
The Cyclic Prefix of equal length is all adopted to the data burst that all send synchronous channel informations in the base station, and is identified for sending the fixed position of the OFDM symbol of synchronous channel information in this subframe;
The position of base station any OFDM symbol except the described OFDM symbol that is used for sending synchronous channel information in this subframe fixingly selects a position to be used for sending broadcast channel information;
Perhaps, described fixing interval, determine by following steps:
The Cyclic Prefix of equal length is all adopted to the data burst that all send synchronous channel informations in the base station, and is identified for sending the fixed position of the OFDM symbol of synchronous channel information in this subframe;
Send broadcast channel information on the position of last OFDM symbol of base station in any subframe except that this subframe;
Perhaps, described fixing interval, determine by following steps:
Send synchronous channel information on the position of last OFDM symbol of base station in any subframe;
The base station sends broadcast channel information on the position of last OFDM symbol of any subframe except the described data burst that is used for sending synchronous channel information.
2, the method for claim 1 is characterized in that, described base station sends the moment of broadcast channel information, is in close proximity to the moment that described base station sends the reference symbol that can be used for channel estimating.
3, method as claimed in claim 2 is characterized in that, described reference symbol is the pilot tone that can be used for channel estimating, or can be used for the synchronizing symbol of channel estimating.
4, the method for claim 1 is characterized in that, further comprises:
By subscriber equipment a time constant is set, this constant equals described base station and sends the moment of broadcast channel information and send fixed intervals between moment of synchronous channel information;
Subscriber equipment according to the time constant of described setting, obtains the timing of broadcast channel after the timing that obtains synchronizing channel;
Subscriber equipment extracts broadcast channel information according to the timing of the broadcast channel of described acquisition.
5, the method for claim 1 is characterized in that, described fixing interval is a fixing lead or retardation.
6, the method for claim 1 is characterized in that, described fixed intervals are no more than a frame.
7, the method for claim 1 is characterized in that, does the time spent when described synchronous channel information has channel estimating, and described fixed intervals are no more than a subframe.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2006100656904A CN100518020C (en) | 2006-03-21 | 2006-03-21 | Method for transmitting control information of OFDM system |
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| CNB2006100656904A CN100518020C (en) | 2006-03-21 | 2006-03-21 | Method for transmitting control information of OFDM system |
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| CN100518020C true CN100518020C (en) | 2009-07-22 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101159488B (en) | 2007-11-12 | 2013-06-05 | 中兴通讯股份有限公司 | Physical broadcasting channel transmitting method of TDD system |
| US8243678B2 (en) * | 2008-03-10 | 2012-08-14 | Motorola Mobility, Inc. | Hierarchical pilot structure in wireless communication systems |
| CN101808281B (en) * | 2009-02-12 | 2014-12-10 | 中兴通讯股份有限公司 | Method, system and device for transmitting MBMS (Multimedia Broadcast Multicast Service) control signaling scheduling information |
| US9451625B2 (en) * | 2013-09-19 | 2016-09-20 | Telefonaktiebolaget Lm Ericsson (Publ) | System and method for providing interference characteristics for interference mitigation |
| US10009916B2 (en) * | 2014-12-23 | 2018-06-26 | Intel Corporation | Communication device and method for processing received signals |
| WO2016138653A1 (en) * | 2015-03-04 | 2016-09-09 | 华为技术有限公司 | Wireless communication apparatus, wireless communication node and transmission method for control information |
| CN106534021A (en) * | 2015-09-15 | 2017-03-22 | 普天信息技术有限公司 | Communication method and system |
| CN111372298B (en) * | 2020-02-27 | 2022-03-25 | 上海金卓科技有限公司 | Wireless access method, device, equipment and storage medium |
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