Summary of the invention
The objective of the invention is existence at the problems referred to above, provide a kind of frequency hopping synchronous motor of system that both can guarantee to be shaped on very high reliability, only need to use less supplementary just can finish whole frequency hopping synchronizing process effectively again and effectively reduce the synchronous implementation method of frequency hopping of OFDM of the efficiency of transmission of the complexity of system and cost and raising system.
The objective of the invention is to be achieved through the following technical solutions:
The synchronous implementation method of a kind of frequency hopping of OFDM is characterized in may further comprise the steps:
(1) increases at transmitting terminal the frequency hopping synchronization frame with frame synchronization and carrier wave frequency deviation compensation ability is arranged, make the Short Training prefix that includes the symbol synchronization information of the synchronous prefix that is used for assist in synchronization in the preamble word of Frame and cancel Frame the data frame structure that is sent out;
(2) receiving terminal receives after the data, at first carries out the processing that frequency hopping is intercepted and captured, and search and detection have or not the FH Synchronous Signals that includes symbol synchronization information;
(3) when receiving terminal is caught and confirm FH Synchronous Signals is arranged, the symbol synchronization information in the Frame preamble word extracted from this packet line data of going forward side by side is separated and is in harmonious proportion confirmation of synchronization and handles, and eliminates error capture and to set up correct frequency hopping synchronous; Then
(4) receiving terminal receives remaining synchronizing information (TOD, Time of date) data and detects synchronizing information (TOD) ending message, simultaneously each packet is carried out the BCH error-correcting decoding and despreading is handled and its result is stored foundation as next step judgement;
(5) when receiving terminal receives synchronizing information (TOD) ending message, synchronizing information (TOD) result who rules out is inserted local FH Sequence Generator, receiving-transmitting sides is realized synchronising frequency hopping and is begun to receive follow-up message command and data.
The present invention owing to adopt increases the frequency hopping synchronization frame and adopts slow searching method to carry out frequency hopping to intercept and capture the method that processing combines and realize that frequency hopping is synchronous in Frame; both utilized the frequency hopping synchronization frame with frame synchronization and carrier wave frequency deviation compensation ability of increase to improve the actual signal rate, the slow searching method that is lower than normal frequency hopping rate by employing carries out that frequency hopping is intercepted and captured and take omission protection and empty inspection protection to combine according to the signal message that receives guarantees that effectively the frequency hopping synchronous motor is shaped on very high reliability again.
Below in conjunction with the detailed implementation method of the present invention of accompanying drawing:
Embodiment
As Fig. 1~shown in Figure 3, the synchronous implementation method of the frequency hopping of OFDM of the present invention may further comprise the steps:
(1) increase has the frequency hopping synchronization frame with frame synchronization and carrier wave frequency deviation compensation ability in the data frame structure that transmitting terminal is being sent out, make the Short Training prefix that includes the symbol synchronization information of the synchronous prefix that is used for assist in synchronization in the preamble word of Frame and cancel Frame, the structure of frequency hopping synchronization frame and Frame includes in the frequency hopping synchronization frame and is used for the short preamble word that signal arrives detection and automatic gain control respectively as shown in Figure 1 and Figure 2 at this moment; Be used for the long preambles word that the estimation of FFT the window's position, frequency offset estimating, bit timing estimation and channel response are estimated; The hopping synchronization information that is used for Data Receiving.Be used for the long preambles word that frequency offset estimating and channel response are estimated and include in the Frame; The data message that is used for Data Receiving, bit timing tracking, information response's tracking.Therefore frequency hopping synchronously after because the original position of frame is known, do not had signal to arrive the demand that detects, only need carry out carrier beat compensation and channel estimating, thereby the short training that can cancel in the short data frame practise handwriting, to improve the actual signal rate greatly.
(2) receiving terminal receives after the data, at first carries out the processing that frequency hopping is intercepted and captured, and search and detection have or not the FH Synchronous Signals that includes synchronizing information, and wherein, it is the synchronous first step of frequency hopping that frequency hopping is intercepted and captured.Because frequency hopping rate is higher, adopt the search slowly that is lower than normal speed for this reason.Slowly search for the doubly normal hop period of N and realize, on the synchronizing information frequency set of determining by real-time time, search for.When receiving-transmitting sides had frequency to overlap, the recipient had detected synchronizing information by data analysis result judgement, was judged as signal and arrived state, changed the affirmation state of following the tracks of immediately over to, continued frequency hopping information is followed the tracks of and Data Receiving.Follow the tracks of to be judged as losing when synchronous when frequency hopping, then get back to the frequency hopping search condition, wait for catching of synchronizing information next time.
For ofdm signal, signal arrives to detect and obtains by the frequency hopping synchronization frame is carried out related operation.When the short preamble word structure in the frequency hopping synchronization frame occurred, a high step can appear in correlation, according to the appearance position of step, can judge the arrival of signal and rough sign synchronization estimated value.
(3) through aforesaid signal search and detection, when receiving terminal is caught and confirm to have the FH Synchronous Signals of a jump, the symbol synchronization information in the Frame preamble word extracted from this packet line data of going forward side by side is separated and is in harmonious proportion confirmation of synchronization and handles, carry out confirmation of synchronization according to the data that demodulate, eliminate error capture and to set up correct frequency hopping synchronous; Then
(4) receiving terminal receives remaining synchronizing information (TOD) data and detects synchronizing information (TOD) ending message, simultaneously each packet is carried out that BCH error-correcting decoding and despreading are handled and its result is stored foundation as next step judgement, owing to only can not judge the odd even order according to preamble word, so each packet is carried out BCH error-correcting decoding and despreading simultaneously, and storage is provided with the back judgement.If the confirmation of synchronization failure then returns to original slow search condition, proceed signal and arrive detection.
(5) when receiving terminal receives synchronizing information (TOD) ending message, synchronizing information (TOD) result who rules out is inserted local FH Sequence Generator, receiving-transmitting sides is realized synchronising frequency hopping and is begun to receive follow-up message command and data.
In this moment frequency-hopped ofdm of the present invention system handling process of receiving terminal as shown in Figure 3, it mainly may further comprise the steps:
(a), input signal is carried out the sample rate conversion of numeral by interpolation filtering;
(b), search for slowly, judged whether that synchronizing information arrives,, waited for catching of synchronizing information next time, if having, then if not then proceed to jump slowly search
(c), carry out the regularly synchronous affirmation of frequency hopping and carry out the empty inspection protection of omission to eliminate error capture, it is synchronous to set up correct frequency hopping;
(d), detect synchronizing information (TOD) ending message, judge whether frequency hopping is finished synchronously, then forward step (c) as unfinished to, finish then synchronously as the affirmation frequency hopping
(e), receive channel order and data and data are finished receiving judge, do not finish as receiving, and then continue to receive, confirmation of receipt is finished then and is searched for next time as data, repeats above-mentioned job step.