CN101022437A - Pilot frequency distributing method for quadrature frequency division multiplexing system - Google Patents
Pilot frequency distributing method for quadrature frequency division multiplexing system Download PDFInfo
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Abstract
A method for distributing pilot frequency of orthogonal frequency division multiplexing system includes confirming different pilot frequency distribution modes as per different mobile speed rates, detecting mobile speed rate of user end, selecting a corresponding pilot frequency distribution mode according to mobile speed rate of user end and feeding selected pilot frequency distribution mode information back to user terminal.
Description
Technical field
The present invention relates to the pilot design technical field of wireless telecommunication system, particularly a kind of pilot distribution method that is applicable to the ofdm system of field of wireless communication.
Background technology
OFDM (orthogonal frequency division multiplexi) demonstrates its powerful advantage in the development of wireless communication system, adopted by multiple standards, from European DAB (digital broadcasting), DVB (Digital Television) standard, U.S. high speed DSL modulation standard, to WLAN, WIMAX and LTE, ofdm system becomes the sign of the new generation of wireless communication technology.
The major technique advantage of ofdm system is the spectrum efficiency height, and the bandwidth autgmentability is strong, and anti-multipath decline ability is strong, is convenient to the flexible allocation frequency spectrum resource, is convenient to realize MIMO technology etc.
Based on above-mentioned advantage, OFDM has become one of the most competitive technology of new generation of wireless communication, but also there is the problem that must be noted that in inherent limitation and the design in this technology.Wherein, when ofdm system is realized channel estimating in design, say in a sense, than single carrier complexity.Need to consider when obtaining superior performance, to reduce expense as far as possible.In the ofdm system design, generally adopt the method for in data-signal, inserting pilot signal to carry out channel estimating.In ofdm system, employing is inserted the method for pilot signal and is carried out channel estimating in data-signal, pilot signal not only can be used as the necessary channel estimating of coherent demodulation/detect, and also needs to satisfy simultaneously channel status estimation and Cell searching and initialized demand.The ofdm system channel design should satisfy following requirement:
1, can satisfy low speed user and highspeed user's performance requirement;
2, be applicable to the actual physics channel condition;
3, can realize simple channel estimation method, satisfy performance requirement simultaneously;
4, be easy to expansion;
5, overhead is little;
6, be easy to system design and realization;
7, cross-correlation performance in minizone is good.
Present pilot design method normally with the pilot signal regular allocation in time-domain and frequency domain, according to the signal estimation pilot signals place of receiving terminal demodulation the time, frequency channel status, then by the time, places such as the interpolation estimating user data of frequency domain and control signaling the time, frequency channel status.
As shown in Figure 1, be the pilot configuration schematic diagram of ofdm system commonly used.
Wherein provided pilot frequency distribution structure commonly used at present, promptly by when predefined, frequency inserts the known pilot signal of terminal, when terminal is estimated this by detecting received signal after the demodulation, the channel conditions of frequency, use then channel estimation method such as interpolation obtain the data-signal place the time, the frequency place channel conditions.
Yet such pilot design can not adapt to situation and the rate variations that the user is in different rates well, promptly might cause the high rate user channel estimation error excessive, decreased performance, and it is excessive also may to cause pilot signal to take overhead.
And the pilot distribution method of existing ofdm system is by measuring the quality of subchannel quality, increase or reduce the density of distribution of pilot channel at frequency domain, and this method can not process user be in the situation of different rates and rate variation.
Summary of the invention
Technical problem to be solved by this invention is, a kind of pilot distribution method of ofdm system is provided, and can adjust the pilot frequency distribution pattern automatically according to the rate travel of mobile device terminal, improves precision of channel estimation, improves transmission quality.
For solving the problems of the technologies described above, the invention provides a kind of pilot distribution method of ofdm system, may further comprise the steps:
(1) definite different pilot frequency distribution pattern at different rate travel scopes;
(2) rate travel of detection user terminal;
(3) according to the affiliated scope of user terminal rate travel, select corresponding pilot frequency distribution pattern;
(4) selected pilot frequency distribution pattern information is fed back to user terminal.
In the described different pilot frequency distribution pattern, can comprise initial pilot frequency distribution pattern, the user can use this initial pilot frequency distribution pattern access network.
Described initial pilot frequency distribution pattern can be corresponding to low speed user speed.
Described step (2)-(4) can start behind accessing user terminal to network.
The timing length that described timing starts can be selected according to system and channel conditions.
Described step (2)-(4) can be for regularly starting.
In the described step (1), can rate travel high more, then the dedicated pilot quantity that increases in corresponding pilot frequency distribution pattern be many more, and pilot signal density is big more.
Described step (2) can be by the historical channel estimation value of system according to this user terminal, the rate travel of measuring and calculating user terminal.
Described measuring and calculating step can be used formula
Calculate, wherein E represents the rate travel scope,
Be illustrated in the k carrier wave, i channel estimating constantly, N is total available subcarrier number, P is an observation interval.
In the described step (3), selected pilot frequency distribution pattern information can feed back to portable terminal by physical layer signaling.
The pilot distribution method of ofdm system provided by the invention, can adjust the pilot frequency distribution pattern automatically according to the rate travel of mobile device terminal, improve precision of channel estimation, improve transmission quality, reduce the overhead of pilot signal simultaneously, the expanding system capacity.Simultaneously, the schedule information control signaling consumption of the present invention's feedback is little, is easy to realize.
Description of drawings
Fig. 1 is the pilot configuration schematic diagram of ofdm system commonly used;
Fig. 2 is the flow chart according to the pilot distribution method of the described ofdm system of the embodiment of the invention.
Embodiment
The situation that the embodiment of the invention is uneven at ofdm system user rate travel and user's rate travel changes has proposed a kind of efficient adaptive pilot design method.
The embodiment of the invention can realize that ofdm system is according to user's rate travel self adaptation adjustment allocation of pilots density, thereby both guaranteed the accuracy that system channel is estimated, satisfy the systematic function requirement, avoid simultaneously pilot signal too intensive and cause overhead excessive again, improved the whole volume of system.In addition, little for realizing that self adaptation is adjusted required control signaling consumption, guaranteed the feasibility that realizes.
The embodiment of the invention comprises user's rate travel testing process, pilot signal adjustment process and pilot frequency information feedback procedure three parts composition.User's rate travel testing process is responsible for according to historical channel estimation value, measuring and calculating user's rate travel, the user rate information that the pilot signal adjustment process is provided according to the rate detection module, carry out the function of adjusting pilot frequency distribution automatically, and the pilot frequency information feedback procedure feeds back to the user with the schedule information of system.
Under the real system situation, overwhelming majority user is in low, middling speed (being lower than 120 kilometers/hour) situation, simultaneously in order to improve service quality, system also must take into account highspeed user's performance requirement, the designing requirement of 3GPPLTE system at present can be supported the user access network of rate travel up to 350 kilometers/hour, therefore, the embodiment of the invention is from satisfying most of user's requests, according to the channel estimating performance Demand Design initial pilot frequency distribution of user under low speed environments, it is common pilot channel, the user is by using the common pilot channel access network, and according to the actual access rate self adaptation adjustment pilot tone time interval of user, promptly by the monitor user ' rate travel, increase user specific pilot channels for highspeed user's self adaptation, by physical layer signaling schedule information is handed down to user terminal then, to improve the channel estimating performance of user under high velocity environment.
The embodiment of the invention is applicable to utilizes pilot signal to carry out the ofdm system of channel estimating, and concrete channel estimation method can be selected according to system requirements.
As shown in Figure 2, be flow chart according to the pilot distribution method of the described ofdm system of the embodiment of the invention.Whole adjustment process can start behind user access network or regularly start by the base station.The user uses initial common pilot allocation model (promptly being applicable to the allocation model of low speed user) to carry out channel estimating, access network, and base station initiated (or regularly starting) this self adaptation is adjusted flow process.At first start user's rate travel testing process, by obtaining the channel estimation value measuring and calculating user rate travel scope in the certain hour section, mate corresponding dedicated pilot signal according to speed range under the user and distribute, notify terminal by physical layer signaling with scheduling result then.Concrete steps are as follows:
The initial pilot frequency distribution of (step 201) system configuration, i.e. common pilot channel satisfies the performance requirement of low speed user, user access network;
(step 202) system is according to the historical channel estimation value of this user, measuring and calculating user's rate travel.
Here use a very simple measuring method:
Wherein E represents the rate travel scope,
Be illustrated in the k carrier wave, i channel estimating constantly, N is total available subcarrier number, P is an observation interval.
Above method is calculated very simple, and estimation precision is limited, but in the present embodiment, the required precision of speed is not high, only need record the scope of user's rate travel, so this measuring method is simple and feasible.
(step 203) selects corresponding pilot frequency distribution pattern according to user's rate travel scope E.
Here according to the actual rate travel scope of user, can be divided into low speed user (being lower than 15 kilometers/hour), middling speed user's (15 kilometers/hour to 120 kilometers/hour), and highspeed user's (being higher than 120 kilometers/hour), difference design specialized pilot frequency distribution pattern, the highspeed user is increased dedicated pilot quantity, improve pilot signal density, dedicated pilot signal the time, frequency domain concrete basic of distribution real system realize and channel condition is selected, then according to the corresponding allocation model of user rate commensurate in scope.
(step 204) system call result issues.Utilize feedback mechanism, by physical layer signaling, the information of sending system pilot frequency mode, promptly allocation model is selected information.The user obtains pilot frequency information according to physical layer signaling, promptly whether has dedicated pilot (channel), the dedicated pilot (channel) pattern, thus the channel estimating performance of raising under high velocity environment transmits.
(step 205): start timer, wait timeout is selected the stand-by period according to real system and channel conditions, promptly adjusts frequency.
(step 206) judges whether transmission finishes: if process finishes; Otherwise, return step 202.
Claims (10)
1, a kind of pilot distribution method of ofdm system is characterized in that, comprises the steps:
(1) definite different pilot frequency distribution pattern at different rate travel scopes;
(2) rate travel of detection user terminal;
(3) according to the affiliated scope of user terminal rate travel, select corresponding pilot frequency distribution pattern;
(4) selected pilot frequency distribution pattern information is fed back to user terminal.
2, the method for claim 1 is characterized in that, in the described different pilot frequency distribution pattern, comprises initial pilot frequency distribution pattern, and the user uses this initial pilot frequency distribution pattern access network.
3, method as claimed in claim 2 is characterized in that, described initial pilot frequency distribution pattern is corresponding to low speed user speed.
4, the method for claim 1 is characterized in that, described step (2)-(4) start behind accessing user terminal to network.
5, method as claimed in claim 4 is characterized in that, the timing length that described timing starts is selected according to system and channel conditions.
6, the method for claim 1 is characterized in that, described step (2)-(4) are for regularly starting.
7, the method for claim 1 is characterized in that, in the described step (1), rate travel is high more, and the dedicated pilot quantity that increases in the then corresponding pilot frequency distribution pattern is many more, and pilot signal density is big more.
8, the method for claim 1 is characterized in that, described step (2) is by the historical channel estimation value of system according to this user terminal, the rate travel of measuring and calculating user terminal.
9, method as claimed in claim 8 is characterized in that, described measuring and calculating step is to use formula
Calculate, wherein E represents the rate travel scope,
Be illustrated in the k carrier wave, i channel estimating constantly, N is total available subcarrier number, P is an observation interval.
As the described method of claim l, it is characterized in that 10, in the described step (3), selected pilot frequency distribution pattern information feeds back to portable terminal by physical layer signaling.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101741443A (en) * | 2008-11-05 | 2010-06-16 | 中兴通讯股份有限公司 | Method and device for regulating in multiple-input multiple-output mode |
| CN101388719B (en) * | 2007-09-13 | 2012-11-28 | 中兴通讯股份有限公司 | Signaling feedback method based on TDD system and radio frame in TDD system |
| CN103974270A (en) * | 2014-05-22 | 2014-08-06 | 北京理工大学 | Capacity enhancing method for multi-user Massive MIMO wireless mobile communication system |
| CN105162502A (en) * | 2009-07-21 | 2015-12-16 | 开曼群岛威睿电通股份有限公司 | Device, method and system of reverse link mobile transmit diversity |
| WO2016023321A1 (en) * | 2014-08-15 | 2016-02-18 | 东南大学 | Coherence time-based pilot frequency distribution method for large-scale mimo system |
| WO2016082127A1 (en) * | 2014-11-26 | 2016-06-02 | 华为技术有限公司 | Information transmission method, apparatus and system |
-
2006
- 2006-02-16 CN CN 200610003132 patent/CN101022437A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101388719B (en) * | 2007-09-13 | 2012-11-28 | 中兴通讯股份有限公司 | Signaling feedback method based on TDD system and radio frame in TDD system |
| CN101741443A (en) * | 2008-11-05 | 2010-06-16 | 中兴通讯股份有限公司 | Method and device for regulating in multiple-input multiple-output mode |
| CN105162502A (en) * | 2009-07-21 | 2015-12-16 | 开曼群岛威睿电通股份有限公司 | Device, method and system of reverse link mobile transmit diversity |
| CN105162502B (en) * | 2009-07-21 | 2018-11-16 | 英特尔公司 | The mobile device for sending diversity of reverse link, method and system |
| CN103974270A (en) * | 2014-05-22 | 2014-08-06 | 北京理工大学 | Capacity enhancing method for multi-user Massive MIMO wireless mobile communication system |
| WO2016023321A1 (en) * | 2014-08-15 | 2016-02-18 | 东南大学 | Coherence time-based pilot frequency distribution method for large-scale mimo system |
| US20170264410A1 (en) * | 2014-08-15 | 2017-09-14 | Southeast University | Pilot allocation method based on coherence time for large-scale mimo system |
| US9912458B2 (en) * | 2014-08-15 | 2018-03-06 | Southeast University | Pilot allocation method based on coherence time for large-scale MIMO system |
| WO2016082127A1 (en) * | 2014-11-26 | 2016-06-02 | 华为技术有限公司 | Information transmission method, apparatus and system |
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