CN203492043U - Self-adaptive equalizer of Bluetooth 4.0 low-power-consumption receiver - Google Patents

Abstract

The utility model relates to a self-adaptive equalizer of a Bluetooth 4.0 low-power-consumption receiver. A forward equalizer FFE is connected with a decision device through an adder. The output end of the adder is connected with a backward equalizer FBE. The input end of an error generator is connected with the input end and the output end of the decision device. The output end of the error generator is connected with the input end of a first tap coefficient updater and the input end of a second tap coefficient updater. The output end of the first tap coefficient updater is connected with the forward equalizer EFE. The output end of the second tap coefficient updater is connected with the backward equalizer FBE. The output end of the backward equalizer FBE is connected with the adder. The self-adaptive equalizer of the Bluetooth 4.0 low-power-consumption receiver is optimized and improved at aspects of eliminating ISI and tolerating symbol timing phase error. A symbol-separated decision feedback equalizer is used for eliminating known inter-symbol interference introduced from a starting end, thereby facilitating PER reduction at a BT4.0LE signal receiving end and improving stability of the receiver.

Description

Bluetooth 4.0 low-power consumption receiver adaptive equalizers

Technical field

The utility model relates to a kind of bluetooth 4.0 low-power consumption receiver adaptive equalizers, belongs to WLAN (wireless local area network) transmission technique field.

Background technology

In December, 2009, bluetooth sig (Bluetooth Special Interest Group, SIG) release in advance for the first time bluetooth 4.0 versions, and in the end of the year 2010, in Seattle, formally announce the related data of bluetooth core specification 4.0 versions, bluetooth 4.0 versions comprise that by past three kinds of bluetooth compliants three kinds of specifications such as traditional bluetooth technology, bluetooth Low-power Technology and blue teeth high speed technology integrate.

Low-power Technology can say the important breakthrough of bluetooth 4.0 versions, possesses ultralow peak value (Peak), mean value and stand-by power consumption, and seeing through standard button cell is enough to use the several years, supports the compatibility between plurality of devices, and strengthens range.Support very short data packet, 8octet to 27octet, its transmission speed is up to 1Mbps.The Bluetooth technology of bluetooth Low-power Technology and other versions is the same is all to use AFH, to reduce the interference of 2.4GHz ISM wave band other technologies as far as possible.Bluetooth low power dissipation design mainly provides 3 kinds of application schemes: independent operating mode (Stand-alone), dual-mode of operation pattern (Dual Mode) and integration mode.In bimodulus application, the function of bluetooth low-power consumption can be integrated in existing traditional bluetooth controller, shares existing radio frequency and the function of traditional bluetooth technology, and the cost increasing compared to traditional Bluetooth technology is less.In addition, manufacturer can utilize the storehouse of upgrade version bluetooth Low-power Technology, integrates traditional bluetooth chipset such as current bluetooth 3.0 high speed versions or 2.1+EDR, the new usefulness of promoting traditional blue-tooth device.In addition, the independent running chipset of low-power consumption is a highly integrated device, the link layer (Link Layer) that possesses light weight, can, under the prerequisite of least cost, support that the standby mode of low-power consumption, easy device are found, the transfer of data of point-to-multipoint, the encryption link of safety etc. reliably; Be arranged in the link layer of above-mentioned controller, be applicable to network connecting sensor, and guarantee in wireless transmission, all can transmit by bluetooth low-power consumption.

BT4.0LE(bluetooth 4.0 Low-power Technology) in, the GFSK of physical layer use h=0.5 is its modulation system, and combining adaptive frequency hopping (AFH) makes its random frequency hopping on 40 possible channels.Its frame structure has the feature of physical layer frame structure in the general communication technology, and frame is initial by the lead code (Preamble) of a 8bit, after followed by the access address (Access Address) of 32bit, be PDU and CRC byte afterwards.Preamble and Access Address can be by scramblings in transmitting procedure.Because BT4.0LE is GFSK modulation, so being all contained in, all transmission informations receive in signal transient frequency, in order to be that the frequency spectrum that transmits is compacter, the FM signal of GFSK has been passed through Gassian low-pass filter to reduce the high fdrequency component for the treatment of tonal signal before carrying out frequency modulation.The side effect of such way is to have introduced intersymbol interference (ISI), and ISI has vital impact to receptivity in communication.

It to the reception of physical frame in BT4.0LE, is the non-coherent demodulation method that uses frequency detection mode, signal after demodulation according to sign synchronization, estimate the sampling phase obtain to frequency discriminator output carry out direct sampling and obtain the restituted signal with symbol rate sampling, and directly hard decision obtains information bit.Impact due to the existence of additive noise and the intersymbol interference (ISI) of gaussian filtering introducing, make now directly in the output bit of hard decision generation, easily to produce error code, always can there is certain error in the sampling phase that sign synchronization obtains simultaneously, this phase place has further been introduced intersymbol interference, and this intersymbol interference is unpredictable, therefore the existence of sign synchronization phase error sharply declines the output error performance of direct hard decision, and the chance that these error codes are not eliminated specially and reduced in existing technology.

Utility model content

The purpose of this utility model is to overcome the deficiency that prior art exists, and a kind of bluetooth 4.0 low-power consumption receiver adaptive equalizers are provided.

The purpose of this utility model is achieved through the following technical solutions:

Bluetooth 4.0 low-power consumption receiver adaptive equalizers, feature is: comprise forward equalizer FFE, backward equalizer FBE, the first tap coefficient renovator, the second tap coefficient renovator, decision device and error generator, forward equalizer FFE is connected with decision device through adder, the output of decision device connects backward equalizer FBE, the input of error generator is connected with output with the input of decision device, the output of error generator is connected with the input of the second tap coefficient renovator with the input of the first tap coefficient renovator, the output of the first tap coefficient renovator connects forward equalizer FFE, the output of the second tap coefficient renovator connects backward equalizer FBE, the output of backward equalizer FBE is connected with adder.

Further, above-mentioned bluetooth 4.0 low-power consumption receiver adaptive equalizers, described forward equalizer FFE is the FFE equalizer on ffe_N rank, described ffe_N is greater than 1 integer; The FBE equalizer that described backward equalizer FBE is fbe_N rank, described fbe_N is greater than 1 integer.

Further, above-mentioned bluetooth 4.0 low-power consumption receiver adaptive equalizers, described forward equalizer FFE and backward equalizer FBE are FIR finite impulse response filter.

Further, above-mentioned bluetooth 4.0 low-power consumption receiver adaptive equalizers, described forward equalizer FFE and backward equalizer FBE are transversal filter or transposed form filter.

The substantive distinguishing features of technical solutions of the utility model and progressive being mainly reflected in:

1. to the signal after frequency demodulation in receiver, before carrying out hard decision, use sef-adapting filter to carry out signal processing, eliminate between the symbol (bit) of being introduced by the Gaussian filter of transmitting terminal and disturb and expanded the tolerance to sampling phase deviation simultaneously; Because filter also has the forward taps of part FIR structure, therefore this sef-adapting filter has the effect that self adaptation is adjusted sampling phase, when sign synchronization exists certain phase error constantly, filter can self adaptation be adjusted wrong sampling phase to optimum sampling phase place, thereby reaches the effect that improves receiver error performance;

2. relative prior art is making and is optimizing and improve aspect elimination ISI and tolerance Symbol Timing phase error, by the DFF of mark space, eliminate the intersymbol interference that knows of making a start and introducing, by the adaptive algorithm of specially selecting, make equalizer can correct the Symbol Timing phase error in certain limit simultaneously, therefore being conducive to BT4.0LE signal receiving end reduces PER, improves the stability of receiver.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, technical solutions of the utility model are described further:

Fig. 1: the structural representation of the utility model equalizer;

Fig. 2: equalizer application schematic diagram.

Embodiment

As shown in Figure 1, bluetooth 4.0 low-power consumption receiver adaptive equalizers, comprise forward equalizer FFE1, backward equalizer FBE6, the first tap coefficient renovator 4, the second tap coefficient renovator 7, decision device 3 and error generator 5, forward equalizer FFE1 is connected with decision device 3 through adder 2, the output of decision device 3 connects backward equalizer FBE6, the input of error generator 5 is connected with output with the input of decision device 3, the output of error generator 5 is connected with the input of the second tap coefficient renovator 7 with the input of the first tap coefficient renovator 4, the output of the first tap coefficient renovator 4 connects forward equalizer FFE1, the output of the second tap coefficient renovator 7 connects backward equalizer FBE6, the output of backward equalizer FBE6 is connected with adder 2,

Signal inputs to forward equalizer FFE1, the output signal of decision device 3 is given backward equalizer FBE6, error generator 5 adopts the input signal of decision device 3 and output signal to produce the error component for carrying out tap coefficient renewal, and the first tap coefficient renovator 4, the second tap coefficient renovator 7 upgrade each tap coefficient of equalizer according to the input value adjustment of the output of error generator 5 and current equalizer.

Wherein, forward equalizer FFE1 is the FFE equalizer on ffe_N rank, and ffe_N is greater than 1 integer; The FBE equalizer that backward equalizer FBE6 is fbe_N rank, fbe_N is greater than 1 integer.Forward equalizer FFE1 and backward equalizer FBE6 are FIR finite impulse response filter.Forward equalizer FFE1 and backward equalizer FBE6 are transversal filter or transposed form filter, and its filter coefficient is provided by two tap coefficient renovators of correspondence respectively.

During concrete application, as shown in Figure 2, the baseband sampling signal rx(n receiving) through low pass filter, interference and noise outside band are carried out to frequency discriminator computing after suppressing, it is output as FD(n), when the sign synchronization estimation module of receiver is judged after Symbol Timing phase place, FD(n) from initial sampling rate is down-sampled, to character rate, obtain FD(OSR*n+offset) and send into adaptive equalizer, wherein integer offset represents symbol sampling phase, by Symbol Timing module, determined, OSR is positive integer, the ratio that represents initial sample rate and symbol rate, 0<offset<OSR,

In adaptive equalizer when work,, in each mark space, the input of forward equalizer FFE has a new frequency discriminator output valve FD(OSR*n+offset) enter forward equalizer FFE; FFE_out (n) is the output valve of FFE in n mark space, and FBE_out (n) is the output valve of backward equalizer FBE in n mark space, and EQ_out (n) is the input value of decision device in n mark space; The computing of each value in each symbol period calculated by following formula above, wherein, ffe_coef(k, n) and fbe_coef (k, n) represent that respectively forward equalizer FFE and backward equalizer FBE are at n k tap coefficient constantly;

$\mathrm{FFE}\_\mathrm{out}\left(n\right)=\underset{k=0}{\overset{\mathrm{ffe}\_N-1}{\mathrm{\&Sigma;}}}\mathrm{FD}\&lsqb;\mathrm{OSR}(n-k)+\mathrm{offset}\&rsqb;\&CenterDot;\mathrm{ffe}\_\mathrm{coef}(k,n)$

$\mathrm{FBE}\_\mathrm{out}\left(n\right)=\underset{k=0}{\overset{\mathrm{fbe}\_N-1}{\mathrm{\&Sigma;}}}\mathrm{sign}\&lsqb;\mathrm{EQ}\_\mathrm{out}(n-k)\&rsqb;\&CenterDot;\mathrm{fbe}\_\mathrm{coef}(k,n)$

EQ_out(n)=FFE_out(n)+FBE_out(n)

Simultaneously tap coefficient in each symbol period according to below more new formula iteration upgrade:

ffe(k,n+1)=ffe(k,n)+μ·err(n)·FD[OSR(n-k)+offset]

fbe(k,n+1)=fbe(k,n)+μ·err(n)·sign[EQ_out(n-k)]

err(n)=sign[EQ_out(n)]-EQ_out(n)

The error signal of adjusting for tap coefficient that wherein err (n) produces in each symbol period for error generator; μ is for adjusting step-length; Sign () is for getting symbolic operation, the input that EQ_out (n) is decision device, sign[EQ_out (n)] be the output of decision device;

The output sign[EQ_out (n) of decision device] information of next stage module in order to recover to receive of sending into receiver as the final effectively output of adaptive equalizer.

In sum, the utility model was used sef-adapting filter to carry out signal processing to the signal after frequency demodulation in receiver before carrying out hard decision, eliminated between the symbol (bit) of being introduced by the Gaussian filter of transmitting terminal and disturbed and expanded the tolerance to sampling phase deviation simultaneously.Because the Gaussian filter response of making a start knows, thus the intersymbol interference causing also know, the filter of therefore designing a mark space decision-feedback structure according to the response of Gaussian filter is eliminated intersymbol interference.Because filter also has the forward taps of part FIR structure, therefore this sef-adapting filter has the effect that self adaptation is adjusted sampling phase, when sign synchronization exists certain phase error constantly, filter can self adaptation be adjusted wrong sampling phase to optimum sampling phase place, thereby reaches the effect that improves receiver error performance.

The making and optimizing and improvement eliminating aspect ISI and tolerance Symbol Timing phase error of the relative prior art of the utility model.By the DFF of mark space, eliminate the intersymbol interference that knows of making a start and introducing, by the adaptive algorithm of specially selecting, make this equalizer can correct the Symbol Timing phase error in certain limit simultaneously, therefore being conducive to BT4.0LE signal receiving end reduces PER, improves the stability of receiver.

With the adaptive decision feedback equalizer of a mark space, eliminate the intersymbol interference that knows of making a start and introducing, by the adaptive algorithm of specially selecting, make this equalizer can correct the Symbol Timing phase error in certain limit simultaneously.

Equalizer consists of feed forward equalizer (FFE) and feedback equalizer (FBE), and main tapping is positioned at feed forward equalizer and register configuration can be passed through in its position; The input of feed forward equalizer is the frequency discriminator output through Symbol Timing, and the input of feedback equalizer is the output decision value (2 level) of whole equalizer.Adaptive equalization algorithm is used " decision-directed least mean-square error " algorithm (DD-LMS).

It is to be understood that: the above is only preferred implementation of the present utility model; for those skilled in the art; do not departing under the prerequisite of the utility model principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection range of the present utility model.

Claims (7)

1. bluetooth 4.0 low-power consumption receiver adaptive equalizers, it is characterized in that: comprise forward equalizer FFE(1), backward equalizer FBE(6), the first tap coefficient renovator (4), the second tap coefficient renovator (7), decision device (3) and error generator (5), forward equalizer FFE(1) through adder (2), be connected with decision device (3), the output of decision device (3) connects backward equalizer FBE(6), the input of error generator (5) is connected with output with the input of decision device (3), the output of error generator (5) is connected with the input of the second tap coefficient renovator (7) with the input of the first tap coefficient renovator (4), the output of the first tap coefficient renovator (4) connects forward equalizer FFE(1), the output of the second tap coefficient renovator (7) connects backward equalizer FBE(6), backward equalizer FBE(6) output is connected with adder (2).

2. bluetooth 4.0 low-power consumption receiver adaptive equalizers according to claim 1, is characterized in that: be described forward equalizer FFE(1) the FFE equalizer on ffe_N rank.

3. bluetooth 4.0 low-power consumption receiver adaptive equalizers according to claim 2, is characterized in that: described ffe_N is greater than 1 integer.

4. bluetooth 4.0 low-power consumption receiver adaptive equalizers according to claim 1, is characterized in that: be described backward equalizer FBE(6) the FBE equalizer on fbe_N rank.

5. bluetooth 4.0 low-power consumption receiver adaptive equalizers according to claim 4, is characterized in that: described fbe_N is greater than 1 integer.

6. bluetooth 4.0 low-power consumption receiver adaptive equalizers according to claim 1, is characterized in that: described forward equalizer FFE(1) and backward equalizer FBE(6) be FIR finite impulse response filter.

7. bluetooth 4.0 low-power consumption receiver adaptive equalizers according to claim 1, is characterized in that: described forward equalizer FFE(1) and backward equalizer FBE(6) be transversal filter or transposed form filter.

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