CN1745520A - Small signal threshold and proportional gain distributed digital communications - Google Patents
Small signal threshold and proportional gain distributed digital communications Download PDFInfo
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- CN1745520A CN1745520A CN 200380109397 CN200380109397A CN1745520A CN 1745520 A CN1745520 A CN 1745520A CN 200380109397 CN200380109397 CN 200380109397 CN 200380109397 A CN200380109397 A CN 200380109397A CN 1745520 A CN1745520 A CN 1745520A
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Abstract
A method for signal gain adjustment in a multi-port, digital distributed antenna system uses a sorter to sort received signals in ascending order according to their signal levels. A threshold comparator generates a dynamic range fair threshold that is updated as any remaining system dynamic range is distributed amongst the remaining signals. Any received signal that is less than or equal to the threshold is attenuated with a unity gain factor. A signal that is greater than the threshold is attenuated with a gain factor that is inversely proportional to the signal level.
Description
The cross reference of related application
The application relates to and requires the priority of U.S. Provisional Patent Application numbering 60/430435 (submission on December 3rd, 2002).
Technical field
The relate generally to of the present invention communications field more particularly, relates to the signal gain control in the distributed antenna system.
Background technology
There has been the various wireless communication system to popularize in the whole world.For example, cellular communication system covers the main highway of main urban district of great majority and sensible remote zone.Cellular system allows to have the individual and the base station communication that is connected to public switched telephone network (PSTN) or some other communication network of cellular handset.
The same with the situation of any communication system, cellular system may stay covering " leak " in the place that base station signal can't arrive.This covering leak may be in the place that the avenue between tunnel, mountain valley, the high building or any other radio frequency (RF) signal are obstructed.
It is always unfeasible in these covering places, leak place extra base station to be set.Owing to except equipment cost is arranged, also have the land seizure cost, the cost that therefore sets up the base station is often very expensive.In addition, big antenna for base station may physics or aesthetic aspect do not match with on-the-spot zone.
A kind of scheme that covers leak that solves is to cover at needs but do not guarantee or littler distribution antenna is adopted in the place of not expecting to be provided with the base station.But, adopt distributed antenna system to have some problems.
Any system all has certain dynamic range of processing signals.For the system that has only an antenna port, whole dynamic range can be used for this single-port signal.When system has a plurality of antenna port,, share same dynamic range from the aggregate signal (aggregate signal) of all of the port as in the situation of distributed antenna system.When a plurality of ports were simultaneously in running order, this had reduced the dynamic range that each port can be used.The problem that distribution antenna exists on the single signal path is to exceed the dynamic range of system's permission along the aggregate signal of this signal path.Therefore need to control fully the aggregate signal in the single path distributed antenna system in the prior art.
Summary of the invention
Embodiments of the invention comprise a kind of method that is used for realizing in the system that contains a plurality of distribution antennas the proportional gain distribution.Read signal level on sampling function each antenna in a plurality of distribution antennas.In a plurality of signal levels each is shared threshold value (fair share threshold) with dynamic range fair compares.Make the signal level attenuation of sharing threshold value greater than dynamic range fair by gain coefficient, described gain coefficient is according to making after other signal level attenuation the remainder of total system dynamic range assign to determine.Make each signal level attenuation that is less than or equal to the shared threshold value of dynamic range fair by the unit gain coefficient.
Brief description
Fig. 1 shows the block diagram of the embodiment of distributed digital antenna system of the present invention.
Fig. 2 shows the block diagram of another embodiment of distributed digital antenna system of the present invention.
Fig. 3 shows the block diagram according to an embodiment of the remote unit of system shown in Figure 1.
Fig. 4 shows the block diagram according to an embodiment of the remote unit of system shown in Figure 2.
Fig. 5 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling and head end common aggregate attenuation function.
Fig. 6 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling and local common attenuation function.
Fig. 7 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling and local input attenuation function.
Fig. 8 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling and head end common attenuation.
Fig. 9 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling and head end common attenuation.
Figure 10 shows the block diagram of an embodiment of the justice be used for distributed summation of the present invention and gain control system and EQ Gain control method.
Figure 11 shows the flow chart of an embodiment of justice of the present invention and balanced damped system.
Describe in detail
By distribution signal decay and decay control, embodiments of the invention keep the original system dynamic range.Signal level thresholds prevents little but effective signal is attenuated to useless degree, simultaneously untapped dynamic range is redistributed the signal to the extra dynamic range of needs.
Embodiments of the invention relate between remote unit and master unit the optical fiber as communication media.But the communication media that remote unit is connected to master unit can be taked any form, comprises laser, the RF signal on the coaxial cable or the RF signal on the air interface on the air interface.
Fig. 1 shows the block diagram of the embodiment of distributed digital antenna system of the present invention.This system has the base station (100) that employing antenna (110) communicates on the RF link.This base station adopts any suitable air-interface standard to communicate by letter on the RF link.For example, this air-interface standard comprises one of following: Advanced Mobile Phone System (AMPS), code division multiple access (CDMA), time division multiple access (TDMA), global system for mobile communications (GSM) or any other air-interface standard that is fit to.
RF chain route base station (100) is used for constituting to the forward link of subscriber unit (150) transmission.Subscriber unit (150) returns to base station (100) by reverse link.Subscriber unit (150) is travelling carriage or the fixed station in the wireless local loop system for example.
Base station (100) has transmitter and receiver, allows subscriber unit (150) to communicate by letter with public exchanging telephone network (PSTN) (130).In one embodiment, the base station is linked to subscriber unit with other base station communications with subscriber unit (150).In one embodiment, base station (100) are connected to PSTN by mobile switching centre, and described mobile switching centre handles the calling exchange with a plurality of base stations.
Master unit (101) is connected to base station (100) by RF link (115).In one embodiment, this link (115) is a coaxial cable.Other embodiment adopt the connection of other types, as carry the air interface or the optical fiber of digital RF (radio frequency) signal, the U.S. Patent Application Serial Number 09/619431 that transfers ADC Telecommunication discloses digital RF signal, and this application is incorporated herein by reference.
The responsible light signal that will become to be convenient on optical medium, transmit of master unit (101) from the RF conversion of signals of base station (100).Master unit (101) also is responsible for converting the light signal that receives to the RF signal, so that transmit to base station (100).In other embodiments, master unit (100) is also carried out other functions.
One or more remote units (105-108) are connected to master unit (101) by the optical medium (as fibre circuit (120 and 125)) with daisy chain form configuration (daisy-chain arrangement).Remote unit (105-108) is located at for want of base station (100) and covers and the place that needs additional signal to cover.The RF link that these remote units (105-108) provide by remote unit antenna (135-138) is communicated by letter with the subscriber unit in the area of coverage of particular remote unit.
For purposes of illustration, four remote units (105-108) have been shown among the figure.But alternate embodiment can adopt the remote unit of other quantity.If have only geographic area among a small circle to need to cover, then adopt few to 1 remote unit (105).If the remote unit more than four is adopted in the covering that the highway in the remote zone need add usually.
The embodiment of Fig. 1 adopts independent fibre circuit of every communication direction.The wavelength that each bearing optical fiber is different.For example, the carrying of the fibre circuit (120) from master unit (101) to remote unit (105-108) wavelength X
1Fibre circuit (125) carrying wavelength X from remote unit (105-108) to remote unit (105-108)
2In alternate embodiment, each optical fiber can carry identical wavelength.
The digital optical signal that fibre circuit (120) carrying from master unit (101) to remote unit (105-108) sends for remote unit (105-108).The fibre circuit (125) that starts from remote unit (105-108) carries the digital optical signal that comprises from the received signal sum of each remote unit (105-108).Hereinafter will discuss from remote unit and generate this and signal.
Fig. 2 shows the block diagram of another embodiment of distributed digital antenna system of the present invention.This system is to embodiment illustrated in fig. 1 similar, and different is that remote unit (205-208) is connected to master unit (201) by single optical medium (220).
System shown in Figure 2 has the base station (200) that employing antenna (210) communicates by the RF link.This base station can adopt any air-interface standard to communicate by letter on the RF link.For example, described air-interface standard can be code division multiple access (CDMA), time division multiple access (TDMA), global system for mobile communications (GSM).
RF chain route base station (200) is used for constituting to the forward link of subscriber unit (250) transmission.Subscriber unit (250) returns to base station (200) by reverse link.Subscriber unit (250) can be travelling carriage or the fixed station in the wireless local loop system for example.
Base station (200) has transmitter and receiver, allows subscriber unit (250) to communicate by letter with public exchanging telephone network (PSTN) (230).The base station can also be linked to subscriber unit (250) the subscriber unit with other base station communications.In one embodiment, base station (200) are connected to PSTN by mobile switching centre, and described mobile switching centre handles the calling exchange with a plurality of base stations.
Master unit (201) is connected to base station (200) by RF link (215).In one embodiment, this link (215) is a coaxial cable.Other embodiment adopt the connection of other types, for example the optical cable of air interface or carrying digital RF signal.
The responsible digital optical signal that will become be used on optical medium, transmitting of master unit (201) from the RF conversion of signals of base station (200).Master unit (201) also is responsible for converting the light signal that receives to the RF signal, so that transmit to base station (200).In other embodiments, master unit (201) is also carried out other functions.
One or more remote units (205-208) are connected to master unit (201) by the optical medium (as fibre circuit (220)) with the configuration of daisy chain form.Remote unit (205-208) is located at for want of base station (200) and covers and the place that needs additional signal to cover.
For purposes of illustration, four remote units (205-208) have been shown among the figure.But according to concrete application, alternate embodiment can adopt the remote unit of other quantity.
The embodiment of Fig. 2 is used to a fibre circuit (220) to be to and from the communication of remote unit (205-208).This simple optical fiber (220) by a plurality of wavelength of carrying is realized.For example, fibre circuit (220) adopts wavelength X to the digital signal of (205-208) from the master unit to the remote unit
1Fibre circuit (220) also adopts wavelength X
2Carrying numeral and signal.This numeral and signal are the received signal sums from remote unit (205-208).Hereinafter will discuss from remote unit and generate this and signal.
Fig. 3 shows the block diagram of an embodiment of remote unit shown in Figure 1 (105).Each remote unit (105-108) embodiment illustrated in fig. 1 is basic identical on function is formed.
Remote unit (105) sends and receives the RF signal of communication by antenna (135).Reception and transtation mission circuit all are connected to antenna (135) by duplexer (301).Alternate embodiment also can adopt other number of antennas.For example, adopt three antennas to come three different sectors in the overlay area among embodiment.In further embodiments, adopted diversity antenna.
The analog signal that receives on the antenna (135) is sent to analog to digital converter (305) through duplexer (301) separation.Analog to digital converter (305) is by regularly to this signal sampling and with the analog signal digital that receives.Sampling operation generates described reception Analog signals'digital and represents.In one embodiment, this digital signal comprises the sample of 14 bits that receive analog signal.
Digitized received signal is input to adder (315), so as with from the daisy chain in the digitized signal addition of preceding remote unit.Therefore, the input of adder (315) output of being coupled to previous remote unit.The output of adder (315) is and signal to be coupled to the input or the master unit of subsequent remote unit with signal.That master unit therefore receives all signal sums that the remote unit (105-108) of expression system received and signal.
The digital signal of master unit is coupled to digital to analog converter (310).The numeral of analog to digital converter (310) delivery analog signal, and convert thereof into analog signal, so that send by antenna (135).
Optical-electrical converter (320-323) is located at the optical port (330 and 335) of remote unit (105) and locates.Each optical port (330 and 335) has the input and output of being coupled to optical-electrical converter (320-323) respectively.
Because remote unit (105) is handled the signal of telecommunication of being represented by the light signal that enters by optical port (330 and 335), convert light signal to the signal of telecommunication so optical-electrical converter (320-323) is responsible, so that remote unit (105) is handled.The signal of telecommunication that receives converts the representation of light to from the representation of electricity, so that transmit on optical fiber.
Fig. 4 shows the block diagram of an embodiment of remote unit shown in Figure 2 (205).Each remote unit (205-208) embodiment illustrated in fig. 1 is basic identical on function is formed.
Remote unit (205) sends and receives the RF signal of communication by antenna (435).Reception and transtation mission circuit all are connected to antenna (435) by duplexer (401).Alternate embodiment also can adopt other number of antennas.For example, embodiment adopts three antennas to come three different sectors in the overlay area.In further embodiments, adopt diversity antenna.
The analog signal that receives on the antenna (435) is sent to analog to digital converter (405) through duplexer (401) separation.Analog to digital converter (405) is by regularly to this signal sampling and with the analog signal digital that receives.Sampling operation generates described reception Analog signals'digital and represents.In one embodiment, this digital signal comprises the sample of 14 bits that receive analog signal.
Digitized received signal is input to adder (415), so as with from the daisy chain in the digitized signal addition of preceding remote unit.Therefore, master unit receive all signal sums that the remote unit (205-208) of expression system received and signal.
The digital signal of master unit is coupled to digital to analog converter (410).The numeral of digital to analog converter (410) delivery analog signal, and convert thereof into analog signal, so that send by antenna (435).
Optical-electrical converter (420-423) is located at the optical port (440 and 445) of remote unit (205) and locates.Each optical port (440 and 445) has the input and output of being coupled to optical-electrical converter (420-423) respectively.
Because remote unit (205) is handled the signal of telecommunication of being represented by the light signal that enters by optical port (440 and 445), convert light signal to the signal of telecommunication so optical-electrical converter (420-423) is responsible, so that remote unit (205) is handled.The signal of telecommunication that receives converts the representation of light to from the representation of electricity, so that transmit on optical fiber.
Wavelength division multiplexer (WDM) (430 and 431) is located at each optical port (440 and 445) and locates.WDM (430 and 431) carries out a plurality of light signals that will have a plurality of wavelength and makes up necessary optical processing operation.A plurality of wavelength separated that WDM (430 and 431) also carries out simple optical fiber arrive the necessary Optical Demultiplexing function of their signal paths separately.
In the above-described embodiments, if an antenna port is used up whole system dynamics scopes, then not having to need to increase total dynamic range thus for the dynamic range of other antenna ports utilizations.Required additional dynamic range amount (calculating with dB) is expressed as 20log N, and wherein N is the quantity of antenna port.The required added bit numerical table of expression aggregate signal is shown log2N in one frame.
As an operation embodiment, for 14 bits, dynamic range is 84dB.For the total dynamic range of 32 antenna ports is provided, need extra 30dB and 5 bits.In this case, the analog-to-digital conversion definition of each port still remains on 14 bits, but all antenna port signal sums are represented with 19 bits.
In order to keep former dynamic range and output signal level, the distributed decay of the embodiment of the invention is adopted attenuator at antenna port input, output or the two place.Distributed control can be adopted the distributed control of the controller based on head end that has to each antenna port feedback, the local controller that is located at each antenna port place or employing distributed Feedback.
Various embodiment of the present invention adopts automatic gain restriction (AGL) as gain control function.Some alternate embodiments adopt automatic gain control (AGC) as gain control function.AGL only just can enable when signal exceeds certain maximum.The decay of AGC Sustainable Control.
These embodiment of the present invention adopt different damped systems.These methods comprise stepped attenuation, continuity decay and fair balanced decay.
When all antenna port signal sums surpass max-thresholds, adopt stepped attenuation.In one embodiment, above-mentioned threshold value is 1.In the case, attenuator provides decay with discrete increment.For example, the increment of 6dB can be realized with binary number by carrying out the bit displacement along the direction of littler value.Once displacement equals 6dB, and twice displacement equals 12dB, and three displacements equal 18dB.This can continue to carry out the attenuation that needs up to reaching.For 32 antenna ports, the displacement of 5 6dB provides the attenuation of 30dB.
The value of decay is continuous continuously.Decay need not to carry out by fixing step-length, and can accurately adjust as required.In other words, attenuation can be directly proportional with the aggregate signal level that exceeds.If aggregate signal is for exceeding maximum 2.3dB, then attenuator is just introduced the decay of 2.3dB.
This damped system is realized by total value being multiply by suitable attenuation coefficient.In one embodiment, the attenuation coefficient scope is 0 (corresponding to infinite attenuation) and 1 (corresponding to unattenuated).
The pair set signal applies decay and means the same processing of all signal dos.The influenced maximum of minimum signal.In the reality, may be with very little signal attenuation to the level that is lower than least significant bit.At this moment, this type of signal will no longer exist.
The block diagram that has shown fair balanced damped system among Figure 10.This method is carried out minimal attenuation to minimum signal, and peak signal is carried out maximum attenuation.Some very little signal can not be subjected to any decay.Added advantage is that any part of dynamic range all can be used, because it distributes to bigger signal with progressive mode.In one embodiment, the function of Figure 10 realizes in numeric field.
With reference to Figure 10,, adopt sampling function well known in the art to read each antenna port input, to determine each incoming signal level in order to carry out fair balanced damped system.Each signal level is added on the sorting unit (1001).
Sorting unit (1001) (is expressed as x according to the antenna port signal
j) level by ascending order they are sorted.In this example, j=1 is minimum, and j=N is maximum, and wherein N is the quantity of antenna port.The signal of ordering is input to threshold value comparator (1005) and gain calculator (1007)." fair sharing " threshold value also is input to the threshold value comparator.Dynamic range fair is shared threshold k and is calculated as follows: K=T/ (n-j), wherein total available system dynamic range is unit value (unity), is expressed as T.In alternate embodiment, the threshold value calculation method that can adopt other to be fit to.
Dynamically redefine fair shared threshold value, so that between remaining signal, distribute any remaining dynamic range.Residue dynamic range calculator (1009) calculates total remaining system dynamic range, and is entered into threshold value comparator (1005).Residue dynamic range calculator (1009) uses the total dynamic range that is assumed to unit value from the range of signal of gain calculator (1007) input and present embodiment.The total surplus dynamic range is expressed as T=T-y
i, y wherein
iIt is the output signal of antenna port.Alternate embodiment also can adopt other total dynamic ranges.
Gain calculator generates G according to the threshold value comparative result
j, so that be that port one-port N generates gain coefficient by ascending order with progressive mode.The process of Figure 10 can be expressed as:
Ifx
j≤ K, then input signal, x
j, less than fair share
do for j＝1to N
G
j＝1
y
j＝G
j*x
j
T＝T-y
j
K＝T/(N-j)
end do
The remaining input signal of else is more than fair share
G
j=K/x
jGain is input as reciprocal relation with signal level
y
j=G
j* x
jReduce level in proportion
end if
The fair balanced decay embodiment of Figure 10 has been described in the example that following employing decays continuously.
| Call number j | Input x j | The fair K that shares | Gain G j | Output y j | Residue dynamic range T | The quantity of |
| 1 | 4 | |||||
| 1 | 0.1 | 0.25 | 1 | 0.1 | 0.9 | 3 |
| 2 | 0.3 | 0.3 | 1 | 0.3 | 0.5 | 2 |
| 3 | 0.4 | 0.3 | 0.75 | 0.3 | 0.3 | 1 |
| 4 | 0.5 | 0.3 | 0.6 | 0.3 | 0 | 0 |
As can be seen from the above table, minimum signal (x for example
j=0.1) remains unchanged.It is decayed by the unit gain coefficient.Inferior small-signal (x for example
j=0.3) utilizes the untapped dynamic range of first signal.It is also decayed by the unit gain coefficient.
Inferior large-signal (for example, x
j=0.4) carries out decay by 0.75 gain coefficient.Peak signal (for example, x
j=0.5) carries out maximum attenuation by 0.6 gain coefficient.
The process of Figure 10 also can be applied to stepped attenuation embodiment.Following table illustrates this type of embodiment.It should be noted, for purpose of explanation, employing be the step-length of 6dB, but the present invention is not limited to any attenuation incrementation.
| Call number j | Input x j | The fair K that shares | Gain G j | Output y j | Residue dynamic range T | The quantity of |
| 1 | 4 | |||||
| 1 | 0.1 | 0.25 | 1 | 0.1 | 0.9 | 3 |
| 2 | 0.3 | 0.3 | 1 | 0.3 | 0.6 | 2 |
| 3 | 0.4 | 0.3 | 0.5 | 0.2 | 0.4 | 1 |
| 4 | 0.5 | 0.3 | 0.5 | 0.25 | 0.15 | 0 |
This table shows that minimum signal remains unchanged, because it is decayed by the unit gain coefficient.Inferior small-signal utilizes the untapped dynamic range of first signal.It is also decayed by the unit gain coefficient.
Inferior large-signal is carried out decay by 0.5 gain coefficient.This is the step-length of 6dB.Similarly, peak signal is carried out decay by 0.5 gain coefficient.In the present embodiment, the part of dynamic range (for example 0.15) is not used.
Following embodiment discusses definite transmission path and aggregate signal level (for example signal level of 14 bits).This only is used for illustration purpose.The present invention is not limited to any transmission path size or aggregate signal level.
Figure 11 shows the flow chart of an embodiment of the balanced damped system of justice of the present invention.This method starts from judges whether incoming signal level is less than or equal to threshold k (1101).
If they do not wait, then gain is defined as this threshold value divided by incoming signal level (1111).Output signal level equals incoming signal level subsequently and multiply by gain (1113).
If incoming signal level is less than or equal to threshold value (1101), then gain is made as and equals 1 (1103).Output signal level is calculated as incoming signal level subsequently and multiply by gain (1105).Remaining dynamic range deducts the output signal level (1107) that calculates subsequently.Described threshold value is recalculated as the residue dynamic range divided by remaining port number (1109).
Fig. 5 shows the block diagram of an embodiment who is provided with the system with distributed summation function and head end common attenuation and gain controlling.For simplicity's sake, the function equivalent cell list of above-mentioned remote unit is shown the antenna (509) of being with add character (513) in present embodiment and subsequent embodiment.
As mentioned above, the embodiment of Fig. 5 comprises four remote units (501-504) and master unit (505).Each remote unit (501-504) has the antenna (506-509) that receives the RF signal, and this RF signal is through digitlization and any signal plus of remote unit the preceding (510-513).
Sum operation (510-513) and should have enough dynamic ranges to the transmission path (530-532) of each remote unit is to provide the total dynamic range.For example, in one embodiment, for 32 ports, complete dynamic range is 19 bits.This embodiment supposes that all remote units are basic identical.
In the embodiment of Fig. 5, the master unit (505) that is located at head end is carried out AGL (515) and decay (525) function.AGL sampling function (515) is to coming independent unit (505) aggregate signal (534) sampling (520) of last remote unit (504) before).For the dynamic range of 114dB, 19 bits of this signal demand.Other embodiment adopt other amount of bits to represent different dynamic ranges.
If AGL function (515) is determined the dynamic range that aggregate signal (531) allows greater than maximum, then AGL function (515) indication attenuation function (525) is carried out decay to this signal.Attenuation function (525) can adopt stepped attenuation, continuously the decay or other decay modes.
At aggregate signal shown in Figure 5 is in the example of 19 bits, and attenuation function attenuates the signal to 14 bits.Thus, mail in the dynamic range that signal of base station will be in permission from master unit (505).
Fig. 6 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling and local common attenuation.This embodiment adopts the transmission path (601-604) (for example 14 bits) of standard by its aggregate signal being applied local decay.
Each remote unit (620-623) is carried out decay to its public output level, so that maximum level is not exceeded.The total result of all add operations (615-618) and attenuation operations (605-608) produces the head end aggregate signal (630) that is no more than maximum level.
The AGL function (610-613) of each remote unit (620-623) is to signal level output (601-604) sampling from each adder unit (615-618).If signal level is greater than the dynamic range that allows, then AGL function (610-613) instructs its corresponding attenuation function (605-608) that this signal specific is carried out decay.
Fig. 7 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling and local input attenuation.In this embodiment, each remote unit (701-704) utilizes AGL function (725-728) to control the attenuation function of importing at addition (730-733) (710-713 and 720-723).
The input signal that is attenuated in the present embodiment comprises antenna port signal and downlink port signal.For example, in a remote unit (702), AGL function (726) is to downstream signal path (750) and antenna port input (751) sampling.If the dynamic range of any one input signal is greater than the maximum that allows, then the attenuation function (711 and/or 721) of the corresponding input of AGL function (726) instruction is carried out decay to this signal specific.
Fair balanced damped system can be used among the embodiment of Fig. 7, as shown in Figure 10 and Figure 11.But the present invention is not limited to any damped system.
Fig. 8 shows the block diagram of an embodiment of the system of the distributed attenuation function with distributed summation function and gain controlling and head end control.This embodiment goes up at master unit (825) and adopts AGL function (820), to provide feedback (830) to remote unit (801-804).
Each remote unit (801-804) is provided with attenuation function (810-813) at the antenna port place, so that input signal is carried out corresponding decay.AGL function (815-818) is to the received signal level sampling of antenna port, so that provide corresponding attenuation instructions to attenuation function (810-813).
The embodiment of Fig. 8 has adopted the AGL function (820) that is located on the master unit (825) in addition, so that final aggregate signal (831) is sampled.The AGL function (820) of this master unit provides head end feedback attenuation signal (830) to the AGL of remote unit function (815-818), to use in conjunction with the input communication signal level of sampling.The form of this feedback signal (830) is (825) one or more bits to the data that remote unit (801-804) transmits along optical medium from master unit just.
For the situation of continuous decay, this feedback attenuation signal is the attenuation coefficient that is made of certain value between 0 and 1.For example, 2 non-aggregate signal (an unattenuatedaggregate of 2) through decay will be by 0.5 attenuation coefficient representative.This attenuation coefficient does not directly apply to the attenuation function (810-813) of each remote unit.But in port signal 0.5 o'clock greater than total dynamic range, the AGL function (815-613) of this remote unit instructs corresponding attenuation function (810-818) this port input signal to be used 0.5 attenuation coefficient.If this signal is equal to or less than 0.5, then do not use decay.
Because some signal may not be attenuated, so resulting aggregate signal may be still a little too high.In the case, the AGL function (820) located of master unit (825) is the value (for example 0.4) of any needs with its feedback attenuation coefficient adjustment.This value can dynamically be adjusted, and can be reduced to till the aggregate signal level that obtains expectation.
Utilize this continuous damped system, the AGL function (820) of master unit is to from aggregate signal (831) sampling of the remote unit (804) of close head end.If the level of this final aggregate signal (831) is too big, then master unit (825) provides since 1 and slowly towards the subzero feedback attenuation coefficient that falls.When final aggregate signal level in scope when (promptly less than maximum dynamic range), master unit keeps this attenuation coefficient.
If final aggregate signal level reduced enough lowly afterwards, then master unit (825) slowly gos up attenuation coefficient towards 1.According to the balanced damped system of above-mentioned justice, all remote units (801-804) only apply decay to its oneself port.This means that the decay that is applied depends on the incoming level and the feedback factor (830) of each antenna port.
Utilize above-mentioned stepped attenuation method, master unit (825) is to from aggregate signal (831) sampling of the remote unit (804) of close head end.If this final aggregate signal (831) is too big, then master unit (825) provides feedback attenuation signal, and this feedback attenuation signal is to start from 0 and to 6 attenuation coefficients that increase progressively.The step-length of 6dB is adopted in this supposition.Other embodiment can adopt other increments.
When final aggregate signal level was less than or equal to 0dB (unit gain), the AGL function (820) of master unit kept this numerical value.If final aggregate signal level be reduced to predetermined level (for example ,-12dB) time, master unit makes this numerical value successively decrease to 0.Because the end-to-end response of system is so decrement operations occurs in after certain delay.
In one embodiment, according to the balanced damped system of above-mentioned justice, all remote units (801-804) only apply decay to its oneself port.This means the decay that is applied depend on each antenna port incoming level and the feedback numerical value.
An example of the fair decay of stepping that following table key diagram 8 embodiment are used.
| The step-length numbering | The maximum possible attenuation | The actual attenuation that applies | ||||
| The port signal level | ||||||
| ＞-6dB | ＞-12dB | ＞-18dB | ＞-24dB | ＞-30dB | ||
| 0 | 0dB | 0 | 0 | 0 | 0 | 0 |
| 1 | 6dB | -6 | 0 | 0 | 0 | 0 |
| 2 | 12dB | -12 | -6 | 0 | 0 | 0 |
| 3 | 18dB | -18 | -12 | -6 | 0 | 0 |
| 4 | 24dB | -24 | -18 | -12 | -6 | 0 |
| 5 | 30dB | -30 | -24 | -18 | -12 | -6 |
By this table as can be seen, the decay of remote unit only influences the port signal of itself.The window that 12dB is arranged between the decision-making of increase attenuation and reduction attenuation.If all of the port has identical signal level, then incremental step is influential all to them, and causes the decay more than the 6dB simultaneously on independent signal level and aggregate signal level.If but some signal level difference then only makes peak signal decay 6dB.This makes total additional levels decay less than 6dB.
Fig. 9 shows the block diagram of an embodiment of the system with distributed summation function and gain controlling.This embodiment allows each remote unit (901-904) do the decay decision-making, but still the attenuation coefficient feedback is provided.
In one embodiment, final aggregate signal is sampled, and transmit the feedback attenuation coefficient to the tail end of system.Can be by realizing feedback in the Frame that the attenuation coefficient embedding is sent to remote unit by communication media.Data frame format and use are the technology of knowing in this area, therefore are not discussed further.In other embodiments, adopt some dedicated bit or successive value to realize feedback.
Similarly, the AGL function (910-913) of each remote unit (901-904) the output place pair set signal sampling of the addition function of this discrete cell (920-923) also.The AGL function (910-913) that sampling AGL function is delivered to attenuation coefficient at preceding remote unit in Frame then.
For example, the AGL function (913) of head end remote unit (904) is sampled to final aggregate signal level, and generates attenuation coefficient.This coefficient feeds back to next remote unit (903) in the daisy chain along the tail end direction.This remote unit (903) is sampled to the signal level of addition function (922) output at this place, unit, and generates attenuation coefficient based on this level.This coefficient feeds back to the next remote unit (902) in the daisy chain.
The AGL function (910-913) of each remote unit (901-904) has two attenuation coefficients: this locality assessment (being local deamplification) that comes from its antenna port, one comes from the upstream cell direction of head end (promptly towards).AGL (910-913) is applied to its port decay with tighter in these two a coefficients coefficient, and caudad transmits this coefficient.
In the present embodiment, master unit generates the highest attenuation coefficient, because its aggregate signal maximum.Because feedback, all remote units all adopt this coefficient to apply decay.Because all remote units are also to the sampling of its oneself antenna port, so they can not apply decay or apply very little decay abundant little signal.Remote unit also applies the high attenuation amount to large-signal.
If interrupt in the feedback path, the pair set signal sampling can prevent that the aggregate signal of any unit from overflowing on each remote unit.In addition, the unit of all from the tail end to the point of interruption will realize that the justice of pair set signal is shared.Similarly, the justice that also will carry out the pair set signal from all unit that the point of interruption is held is to the end shared.But the tail end group is dominant than head end group.
According to above-mentioned principle, can modifications and variations of the present invention are.Therefore want clear and definite, in the appended claims scope, can implement the present invention with above-mentioned different mode.
Claims (22)
1. comprise a plurality of distribution antennas and have a kind of gain allocation method in the system of total system dynamic range, described method comprises:
Read signal level on each antenna in described a plurality of distribution antennas;
At least one and dynamic range fair in described a plurality of signal levels are shared threshold; And
By gain coefficient each the comparison signal level greater than the shared threshold value of described dynamic range fair in described at least one comparison signal level is decayed, described gain coefficient is to assign to determine according to the remainder of described total system dynamic range after other signal level attenuation in described a plurality of signal levels.
2. method as claimed in claim 1 is characterized in that: described dynamic range fair is shared threshold value and is determined by the inverse of the quantity of described a plurality of distribution antennas at first.
3. method as claimed in claim 1 is characterized in that described method also comprises the steps:
Before relatively, described signal level of reading is sorted by ascending order; And
By untapped total system dynamic range being distributed to the signal level of follow-up decay, after making each signal level attenuation, upgrade described total system dynamic range.
4. method as claimed in claim 1 is characterized in that also comprising: be less than or equal to the signal level that described dynamic range fair is shared threshold value by the unit gain decay.
5. method as claimed in claim 1 is characterized in that: if described signal level is shared threshold value greater than described dynamic range fair, the gain coefficient and described first signal level that then are applied to first signal level are inversely proportional to.
6. method as claimed in claim 5 is characterized in that: described gain coefficient is substantially equal to K/x
j, wherein K is the inverse of the quantity of described a plurality of distribution antennas, and x
jIt is described first signal level.
7. have a kind of gain allocation method in the distributed antenna system of total dynamic range, described method comprises:
Will be from a plurality of signal level orderings of described distributed antenna system;
In the signal level of described ordering each is shared threshold ratio with dynamic range fair;
Share threshold value if first signal level is less than or equal to described dynamic range fair, then the unit gain coefficient is applied to described first signal level, and between the residual signal level of described a plurality of signal levels, distribute remaining total dynamic range; And
If described first signal level is shared threshold value greater than described dynamic range fair, then use the gain coefficient that is inversely proportional to described first signal level.
8. method as claimed in claim 7 is characterized in that: the described gain coefficient that is substantially equal to the inverse of described first signal level equals the quantity of distribution antenna in the described distributed antenna system divided by described first signal level.
9. method as claimed in claim 7 is characterized in that: by ascending order described a plurality of signal levels are sorted.
10. have a kind of gain allocation method in the distributed antenna system of system dynamics scope, described method comprises:
Will be by ascending order from a plurality of signal level orderings of described distributed antenna system;
First signal level in the signal level of described a plurality of orderings and dynamic range fair are shared threshold ratio;
If being less than or equal to described dynamic range fair, described first signal level shares threshold value, then to the described first signal level application units gain coefficient;
If state signal level application units gain coefficient to described first, then upgrade described dynamic range fair and share threshold value, between the residual signal level, to distribute the remaining system dynamic range; And
Share threshold value if institute first states signal level greater than described dynamic range fair, then use first gain coefficient, described first gain coefficient is substantially equal to described dynamic range fair and shares threshold value divided by described first signal level.
11. method as claim 10, it is characterized in that also comprising: if the secondary signal level is shared threshold value greater than described dynamic range fair, then to described secondary signal level application second gain coefficient, described second gain coefficient is substantially equal to described dynamic range fair and shares threshold value divided by described secondary signal level.
12. method as claim 10, it is characterized in that also comprising: if state signal level application units gain coefficient to described first, then upgrade described system dynamics scope, described remaining system dynamic range is deducted used described first signal level of described gain coefficient.
13. have a kind of gain allocation method in the distributed antenna system of system dynamics scope, described method comprises:
Read the signal level of each signal from a plurality of signals that described distributed antenna system receives;
By ascending order described a plurality of signal levels are sorted;
First signal level in the signal level of described a plurality of orderings and dynamic range fair are shared threshold ratio;
If being less than or equal to described dynamic range fair, described first signal level shares threshold value, then to the described first signal level application units gain coefficient;
If state signal level application units gain coefficient to described first, then upgrade described dynamic range fair and share threshold value, between the residual signal level, to distribute the remaining system dynamic range; And
Share threshold value if institute first states signal level greater than described dynamic range fair, then use first gain coefficient, described first gain coefficient is substantially equal to described dynamic range fair and shares threshold value divided by described first signal level.
14. a distributed antenna system that has total dynamic range and adopt gain allocation, described system comprises:
A plurality of distribution antennas are used to receive a plurality of signals that have certain signal level respectively;
Sorting unit sorts described received signal according to each signal level;
With the threshold value comparator of described sorting unit coupling, it is according to the signal of ordering and with the relatively generation comparative result between the shared threshold value of the dynamic range fair of remaining system dynamic range renewal;
Residue dynamic range calculator, it generates described remaining system dynamic range by making described total dynamic range deduct each signal level through decay; And
With the gain calculator of described sorting unit and the coupling of described residue dynamic range calculator, it generates gain coefficient according to described comparative result with progressive mode.
15. distributed antenna system as claimed in claim 14 is characterized in that: described distribution antenna is coupled on the communication media by the distributed summation device.
16. distributed antenna system as claimed in claim 15 is characterized in that: described communication media is an optical medium.
17. distributed antenna system as claimed in claim 14 is characterized in that: described sorting unit sorts described received signal by ascending order according to each signal level.
18. a distributed antenna system that has total dynamic range and adopt gain allocation, described system comprises:
A plurality of distribution antennas, it receives a plurality of signals that have certain signal level respectively;
Read the signal level sampling function of each signal level;
Sorting unit, it sorts described received signal by ascending order according to each signal level;
With the threshold value comparator of described sorting unit coupling, it is according to the signal of ordering and with the relatively generation comparative result between the shared threshold value of the dynamic range fair of remaining system dynamic range renewal;
Residue dynamic range calculator, it generates described remaining system dynamic range by making described total dynamic range deduct each signal level through decay;
With the gain calculator of described sorting unit, described threshold value comparator and the coupling of described residue dynamic range calculator, it generates gain coefficient by ascending order for each received signal with progressive mode according to each comparative result; And
A plurality of separately with the attenuator of certain received signal coupling, be used for it being carried out decay according to the gain coefficient of each received signal.
19. system as claimed in claim 18 is characterized in that: share threshold value if the signal level of received signal is less than or equal to described dynamic range fair, then described gain calculator is that described received signal generates the unit gain coefficient.
20. system as claimed in claim 18 is characterized in that: described gain coefficient generates with the form of discrete increment.
21. a distributed antenna system that has total dynamic range and adopt gain allocation, described system comprises:
A plurality of distribution antennas, it receives a plurality of analog signals that have the signal level of representing with digital form respectively;
Analog to digital converter, it becomes digital signal with described analog signal conversion;
Sorting unit, it sorts described digital signal according to each signal level;
With the threshold value comparator of described sorting unit coupling, it is according to the signal of ordering and with the relatively generation comparative result between the shared threshold value of the dynamic range fair of remaining system dynamic range renewal;
Residue dynamic range calculator, it generates described remaining system dynamic range by making described total dynamic range deduct each signal level through decay; And
With the gain calculator of described sorting unit, described threshold value comparator and the coupling of described residue dynamic range calculator, it generates gain coefficient according to described comparative result with progressive mode.
22. have a kind of gain allocation method in the distributed antenna system of system dynamics scope, described distributed antenna system is coupled by optical-fiber network, described method comprises the steps:
Receive a plurality of analog signals;
Each analog signal conversion is become to have the digital signal of the signal level of representing with number format;
They are sorted by ascending order according to described a plurality of digital signals signal level separately;
First digital signal level and the dynamic range fair of described a plurality of digital signals are shared threshold ratio;
If described first digital signal level is shared threshold value less than described dynamic range fair, then to the described first digital signal level application units gain coefficient;
If to the described first digital signal level application units gain coefficient, then upgrade described dynamic range fair and share threshold value, between the remaining digit signal, to distribute the remaining system dynamic range; And
If described first digital signal level is shared threshold value greater than described dynamic range fair, then use first gain coefficient, described first gain coefficient is substantially equal to described dynamic range fair and shares threshold value divided by described first digital signal level.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US43043502P | 2002-12-03 | 2002-12-03 | |
| US60/430,435 | 2002-12-03 | ||
| US10/414,907 | 2003-04-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1745520A true CN1745520A (en) | 2006-03-08 |
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ID=36140054
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200380109397 Pending CN1745520A (en) | 2002-12-03 | 2003-12-03 | Small signal threshold and proportional gain distributed digital communications |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1745520A (en) |
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2003
- 2003-12-03 CN CN 200380109397 patent/CN1745520A/en active Pending
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