CN101087229A - Apparatus and method for reporting a meassurement summary in a radio communication system - Google Patents

Abstract

Apparatus, and an associated method, for generating a message summary field. The message summary field (72) indicates whether 802.11-formatted data packets are communicated upon a frequency range to which a mobile station (12) operable in an IEEE 802.11 radio communication system (10) is tuned. An indicator (14) indicates whether an 802.11 data packet is detected. And, a reporter (56) generates a measurement summary (68) which includes a measurement summary field (72) populated with a value indicating the determination. Subsequent analysis of the value of the field (72) of the measurement summary (68) is utilized pursuant to dynamic frequency selection operations.

Description

In wireless communication system, be used to report apparatus and method of measuring summary

The cross reference of asking in relevant

The present invention requires the application number No.60/274 in application on March 8 calendar year 2001,175 priority.

The present invention relates generally to the communication of the communication station in a wireless communication system can operating according to first communication standard such as the IEEE802.11 standard, wherein, can also can be used by the another one wireless communication system by the frequency band that this system uses, this other wireless communication system can be operated according to the another one communication standard.More particularly, the present invention relates to a kind of equipment and correlation technique thereof, by it come at least in measuring summary identification according to the communication operation of first communication standard whether just institute of communication station be tuned to a frequency band carry out on partly.When in the 5GHz frequency band, when in can communication station, implementing, measure the summary field for one and be formed according to the IEEE802.11 standard operation, whether its indication communication station is tuned on the frequency band part that 802.11 formatted datas are transmitted.Whether be tuned to the frequency band part that 802.11 formatted datas are transmitted by the identification communication station, how communication station be tuned to the frequency band part on follow-up retune or traffic operation is done.

Background of invention

The progress of the communication technology has allowed the introducing of advanced communication system and has popularized.In this type of different advanced communication systems, the corresponding data quantity that message transmission rate and allowing is transmitted increases with respect to the communication system of existing type.

Advanced communication system is to have made communication technology progress result become the typical case of possible communication system.The communication channel of a wireless communication system is formed on the Radio Link, thus avoided to be operable in wherein transmission and the needs of the traditional wired connection between the receiving station.Therefore, compare with traditional wired system, a wireless communication system has allowed the communication flexibility that increases inherently.

Bandwidth constraints has limited the message capacity of communication system sometimes.That is to say, communication system can be used to send and receiving station between transmit the communication channel of information bandwidth capacity or channel be limited sometimes.And the limited capacity of communication channel or channel group has limited the increase of communication system message capacity.The message capacity of wireless communication system is vulnerable to especially because the influence of the capacity limit that the communication channel bandwidth restriction causes.Usually, a wireless communication system is assigned with a limited electromagnetic spectrum part, defines communication channel on described limited electromagnetic spectrum part.Therefore, the increase of a wireless communication system communicating capacity is subjected to the restriction of this kind distribution sometimes.Therefore, the increase of the message capacity of wireless communication system only just may when increasing the efficient of using the frequency spectrum that is assigned with sometimes.

Digital communication technology provides a kind of mode, and in this way, the communication bandwidth efficient in the communication system can increase.Owing in order effectively to utilize the frequency spectrum that distributes in this type systematic to be present in this specific needs in the wireless communication system, the use of digital communication technology particularly advantageously is performed therein.

When digital communication technology was used, the information that be transmitted was digitized.In a technology, digital information is formatted in the grouping, and grouping is transmitted so that finish communication.In a single day independent data are divided into groups or packet group can be transmitted with discontinuous interval, and are transmitted, just can be joined together and rebuild the information content that is included in wherein.

Because can transmit packet with discontinuous interval, so compare with the conventional need of circuit-switched communications, communication channel does not need to be exclusively used in fully the communication of the grouped data of a dispatching station generation of communicating by letter with a receiving station.What replace is that individual channel can be shared in a plurality of different transmissions and receiving station's centering.Because individual channel can be utilized to finish the right communication of a plurality of communication stations, so the message capacity of improvement becomes possibility.For example in traditional LANs (local area network (LAN)), finish block data communication.Can also be developed according to the wireless network that the mode similar to wired lan s operated and be utilized on a radio link, transmit packet, thereby finish communication between dispatching station connecting by radio link and the receiving station.

For example, an IEEE (Electrical and Electronic Engineering society) 802.11 standard definitions a system that is used for wireless local area network operation.This system defines according to the layering logic layers level and the running parameter of this each layer of system is defined in this standard.

Having proposed to propose to use a unauthorized frequency band that is positioned on the 5GHz and carried out usually can be according to a WLAN of IEEE802.11 standard operation.

Other system also can realize on the 5GHz frequency band.For example, a wireless communication system that is called HyperLan II system also is implemented on the 5GHz frequency band.HyperLan II system can operate according to the standard that ETSI announces.HyperLan II system also is a kind of wlan system.

Because above communication system is operable on the public frequency part of 5GHz frequency band, so be operable in the frequency band part that wherein communication system must dynamically select to finish communication.Need Dynamic Selection so that an above communication system does not use same frequency to attempt finishing communication simultaneously.

Europe administration committee (ERC) has proposed to be operable in the system requirements of those systems in the 5GHz frequency band.For example, comprise such requirement in these require: promptly, the system that is operable on the 5GHz frequency band produces the electromagnetic energy radiation, and this electromagnetic energy radiation is extended on the available frequency of definition therein.That is to say, must be approximately constant on very big band bandwidth at the interference level of the formation signal of communication energy that produces during the communication system operation.This interference must be expanded and must avoid hindering communicating by letter in satellite and the radar system equally.

And, for example, an IEEE802.11 or a mobile radio station of HyperLAN system requirements (STA) can be tuned on the current frequency band part of not used by a basic service set (BSS).And, in case be tuned to that, mobile radio station need be measured the existence of interference.In case measure, then measurement report must be returned to an access point (AP) of basic service set.This process is called as Measurement and analysis result's dynamic frequency and selects (DFS), and an access point of basic service set determines whether to select a new frequency range to be used for the mobile radio station operation.This process is called as dynamic frequency and selects (DFS).In a HyperLan II system, the mobile radio station report is as the indication of received signal intensity indication (RSSI) piece in the base band transceiver system of a DSF mechanism part.Yet the use of a RSSI indication does not provide an indication about interference signal source.

It is a kind of that can to promote to be operable in the mode that a dynamic frequency in the mobile radio station in the IEEE802.11 system selects better will be favourable.

It is to have considered and this relevant background information of wireless communication system operation, in this wireless communication system, has launched the remarkable dynamic frequency allocation of improving of the present invention and has been utilized.

Summary of the invention

Therefore, the invention provides: a kind of equipment and correlation technique thereof that uses in the wireless communication system that can operate according to first communication standard such as the IEEE802.11 standard, wherein: can also can be used by the frequency band that this system uses according to the another one communication system that the another one communication standards is operated.

By the operation of one embodiment of the invention, a kind of mode is provided, by it come at least one measure identification in the summary according to the communication operation of first communication standard whether institute of this communication station be tuned to frequency band carry out on partly.By the measurement summary is provided, can retune or judgement is made in the subsequent communications operation better communication station follow-up.Then, promote dynamic frequency to select by this.

In one aspect of the invention, can form one usually according to the mobile radio station (STA) that the IEEE802.11 standard in the 5GHz frequency band is operated by one and measure the summary field.Measuring the summary field is such numerical value: promptly, the indication mobile radio station whether be tuned to transmit a frequency band part of 802.11 data thereon.By sending a control appliance the access point (AP) in being operable in 802.11 systems to measuring the summary field, can to whether mobile radio station institute be tuned to the frequency band part on retune mobile radio station or begin to communicate by letter and make judgement.

In another aspect of this invention, fill measurement summary field with such numerical value, whether this numeric representation mobile radio station is tuned to a frequency range, and 802.11 packets are transmitted on this frequency range.If 802.11 packets mobile radio station be tuned to frequency range on be transmitted, then measure the summary field and fill with first numerical value.Conversely, if 802.11 packets not mobile radio station be tuned to frequency range on be transmitted, then measuring the summary field is the another one value.Comprise that of measuring the summary field measures summary and is moved station and sends an access point to, in this access point place execution control function so that control the subsequent operation of mobile radio station.

In another aspect of this invention, in case mobile radio station is tuned to a selected frequency range, then measuring is that the communication energy that transmits on this frequency range constitutes.If communication energy is detected, whether then communication energy is decoded forms packet-formatted data so that detect communication energy.Whether if packet-formatted data is detected, then carrying out the further analysis of packet so that determine this packet is one 802.11 formatted data grouping.After so detecting, measure the summary field and fill frequency range of this numeric representation with a numerical value: promptly, mobile radio station is tuned on this frequency range so that make the grouping of 802.11 formatted datas transmit thereon.Otherwise, indication be arranged in measure the summary field indicate 802.11 formatted datas not mobile radio station be tuned to frequency range on be transmitted.

In another aspect of this invention, detecting communication energy and it and after decoding in order to detect packet and to exist, further analyze so that whether the recognition data grouping is one 802.11 formatted data grouping, perhaps with respect to this 802.11 standard, whether this packet is PLCP (Physical Layer Convergence Protocol) format packets of an outside.Determine that by what communication system thus analyzed at physical layer and the logical layer place on physical layer that this divides into groups to carry out data packet type mobile radio station is exercisable in this communication system.In one 802.11 system, one effectively grouping determine by the suitable decoding of signal field, cyclic redundancy check (CRC) (CRD) and the active mac addresses form on the physical layer protocol data unit (PPDU).On the contrary, HyperLan II packet does not have corresponding 802.11 formatted data structures.Thereby the differential between the grouping of HyperLan II formatted data and one 802.11 formatted data grouping is carried out.

In one embodiment, provide equipment and method for a mobile radio station that is operable among the IEEE802.11 WLAN.Mobile radio station be tuned to a frequency range in the 5GHz frequency band.In case be tuned to this frequency range, then carry out a CCA (clear channel assessment) operation.Judge whether CCA represents that this frequency range will do.By detect this mobile radio station institute be tuned to frequency on whether exist communication energy to make described definite.Exist if detect communication energy, then mobile radio station determines further whether this communication energy forms according to the next formative data grouping of IEEE802.11 standard.Determine in order to make this, carry out decode operation so that detect the header portion of a data grouping.If the header portion of packet is detected, then on a signal field part of packet, carry out further decode operation.After so decoding, carry out the further inquiry of packet so that check where packet is addressed.If a MAC ID (identifier) is detected, then packet is one 802.11 formatted data grouping.Because the corresponding 802.11 formatted signal fields of HyperLan II formatted data grouping neither one (promptly, the PLCP header) and the MAC identifier, thus the operation of the embodiment of the invention can between a HyperLan II formatted data grouping and one 802.11 formatted data grouping, distinguish.

Therefore in aspect these and other, for first wireless communication system provides equipment and correlation technique thereof, in this first wireless communication system, a selected frequency band partly is dynamically selectable, transmits the first system type packet on this selected frequency band part.This frequency band also selectively by the second wireless communication system utilization, selectively transmits the second system type packet thereon.Execution about mobile radio station be tuned to this frequency band part whether be used to transmit the report of the first system type packet.Indicating device be coupled at least receive one about the first system type packet whether communication station be tuned to this frequency band part on be transmitted really that definiteness shows.This indicating device produces this index signal determining of expression.A report device is coupled and receives the index signal that is produced by indicating device.This report device produces a report message, and it comprises a field of filling with a numerical value, the index signal that this numeric representation is produced by indicating device.

A more complete evaluation of the present invention and scope thereof can obtain from the detailed description of the accompanying drawing of following short summary, the preferred embodiment of the present invention and additional claim.

Description of drawings

Fig. 1 has illustrated the communication system functionality block diagram that can operate the embodiment of the invention therein.

Fig. 2 has illustrated that one of the measurement summary frame that produces in one embodiment of the invention operating period can be imitated form.

Fig. 3 has illustrated the structure of the header portion of an IEEE802.11 formatted data grouping.

Fig. 4 has illustrated the functional-block diagram of the signal correction device of a delay.

Fig. 5 illustrated according to one embodiment of the invention operation, the imitated relation between a false alarm rate and detection probability.

Fig. 6 has illustrated a statement that is similar to as shown in Figure 4, but has a different delay factor here.

Fig. 7 illustrates the flow chart tabulating method of one embodiment of the invention.

Preferred forms

At first, can operate to provide packet radio communication with a communication system shown in 10 usually to a mobile radio station (STA) 12 referring to Fig. 1.

In but example was implemented, this communication system comprised a WLAN (WLAN (wireless local area network)), and this WLAN is configured usually and can operates according to IEEE (Electrical and Electronic Engineering society) 802.11 standards on the 5GHz frequency band.Mobile radio station 12 here usually can be according to the IEEE802.11 standard operation.This communication system is exemplary.Though will be embodied as the operation that one embodiment of the invention is described by an IEEE802.11 system with respect to communication system 10, instruction of the present invention can be applied in the communication system of other type similarly.

During communication system operation, utilize a selected access point (AP) to transmit data and transfer data to mobile radio station from mobile radio station, here, selected access point (AP) is a plurality of access points access points 14 of (two access point is as shown in the figure).Transmit data by the Radio Link 16 that between mobile radio station 12 and selected access point, forms.The data that mobile radio station sends access point to are called as a transmission on the reverse chain channel sometimes, and are called as a transmission on the forward link channel sometimes in the data that send mobile radio station to by access point 14 on the radio link 16.

When data were transmitted, on forward direction or reverse chain channel, the data that transmit with the electromagnetic energy form were called communication energy here.In the 5GHz frequency band, the channel allocation of regulation is not clearly distributed to a particular communication system.That is to say, the IEEE802.11 system that forms communication system 10 is not clearly distributed a frequency band partly to monopolize use for them.But other system also is allowed to be performed and operate on the same frequency field of this frequency band.Use in the time of for the same frequency field of stop band, be operable in the equipment that utilizes in the 5GHz band communication system and must utilize dynamic frequency to select (DFS) scheme.

Usually, in a dynamic frequency selection scheme, definite this band region was not used in other communication by the another one communication system after, the frequency band part was dynamically selected to be used for using.If a frequency range has been confirmed as in use, then a reserve frequency scope is selected, finishes communication thereon.By providing dynamic frequency to select, same frequency range is not attempted side by side to be used by two or more communication systems of separating.

As what point out in the above, a communication system comprises a plurality of access points, and two access point 14 as shown in the figure.Coverage of each access point definition is called as a sub-district sometimes.When a mobile radio station was positioned at a sub-district, mobile radio station utilized access point to finish with communicating by letter of communication system infrastructure part usually, access point definition mobile radio station sub-district wherein of living in.

Access point 14 is connected to a control hub 16.The control hub can be operated the operation of controlling the access point among the WLAN and communicate by letter.Sometimes the control hub that is embodied as a computer server is connected to a router, and router then is coupled to a packet data network (PDN) 24.Packet data network for example forms the Internet backbone.Then, a correspondent node (CN) 26 is coupled to Packet Data Network.Correspondent node is represented can be by packet data network and any communication equipment that transmits grouped data by a shapable communication path and mobile radio station 12.

This accompanying drawing further illustrates the frame structure of an IEEE802.11 format packets.A PLCP header fields 26 comprises the OFDM training symbol.This training symbol also triggers CCA mechanism.The IEEE802.11 form is almost completely identical with the PLCP header of HyperLAN II format packets.Frame structure also comprises a signal field 27.Signal field transmits the modulation (being described below) that is used in the PSDU field (being described below).Service field 29 comprises the disarrangement device initialization bit of data.PSDU field 31 forms a physical layer service data field, and where its identification emission data are gone to.Though do not illustrate respectively, a PLCP header of a combination of signal field and service field can be used.

Mobile radio station 12 comprises a receiving unit 32, and it can be operated and detect and act on the data that send mobile radio station by the forward link channel of radio link 16 to.And mobile radio station comprises a radiating portion 34, and it can operate the data that are transmitted to access point on the reverse chain channel that operates in radio link 16.

Mobile radio station also comprises the equipment 38 of the embodiment of the invention.According to the mobile radio station of communication system and the dynamic frequency selection operation of network portion, this equipment can operate allow mobile radio station this mobile radio station be tuned to frequency range on executive communication operation, perhaps replacedly, can operate the order mobile radio station be tuned to another frequency range.This equipment is coupled to the reception and the radiating portion of mobile radio station.

The element of equipment 38 is represented with regard to its function.Carry out the realization of the element of this equipment in any desired mode.In exemplary enforcement, those elements form at least in part can be by the algorithm of suitable treatment circuit execution.In case mobile radio station is tuned to a selected frequency range, the electric circuit inspection of receiving unit mobile radio station be tuned to frequency range in the forward link channel of radio link on communication energy.Detect or undetected communication energy indication is provided for the indicating device 44 of equipment 38 by circuit 42.

Indicating device 44 comprises an action determiner 46.The action determiner is carried out a clear channel assessment (CCA) operation here.Clear channel assessment operation determine mobile radio station be tuned to frequency range on whether have communication energy.Activity detector is coupled to a decoder 48.And decoder also is coupled the indication that receives the communication energy (if any) that is received by the receiving unit of mobile radio station by circuit 42.Decoder can be operated after the communication energy of motion detector detects and attempt decoding this communication energy.

And indicating device 44 also comprises a grouping address detection device.The grouping address detection device also is coupled to the indication that circuit 42 receives the communication energy (if any) that the receiving unit of mobile radio station receives.When the part of the header portion by detecting the packet that forms on physics (PHY) logical layer in 802.11 communication systems, decoder detects when having a data grouping, and the grouping address detection device is exercisable.Grouping address detection device 52 detects whether a MAC (media interviews control) layer grouping address is the part of this received communication energy.A HyperLan II formatted data grouping does not comprise 802.11 format signal fields and MAC layer grouping address.Thereby the grouping address detection device is distinguished between a HyperLan II formatted data grouping and one 802.11 formatted data grouping.

Equipment 38 also comprises a report device 56, and it is coupled to the grouping address detection device 52 of indicating device 44.Report device 56 can be operated and produce one and measure summary, measure summary and comprise a field of filling with a numerical value, this numerical value indication mobile radio station be tuned to frequency range whether comprise one 802.11 formatted data and divide into groups.If the packet of another one data packet type is detected, such as a HyperLan II formatted data grouping, then this field is filled with another one numerical value.Thereby this field represent at least mobile radio station be tuned to frequency range whether just be used to transmit the grouping of one 802.11 formatted data or one and coming formative packet according to a kind of outside PLCP (Physical Layer Convergence Protocol).

Measure summary and be provided for radiating portion 34 by circuit 58.Radiating portion is got back to access point to this measurement summary emission by a reverse chain channel that forms on radio link 16.Here, in case be received at access point, the indication of then measuring summary is routed to control hub 18 or other suitable structure.The analysis of measuring summary at control hub place, and the control hub select mobile radio station whether will keep be tuned to this frequency range or become and retune to the another one frequency range.

Fig. 2 has illustrated the measurement summary exemplary that the equipment 38 of mobile radio station as shown in Figure 1 forms, and is depicted as 68 usually.Measure summary and comprise a plurality of fields, these a plurality of fields comprise a field 72.Field 72 is individual bit fields,, is identified as the PLCP header fields of an outside here.When one measure interim mobile radio station be tuned to frequency range on when detecting a PLCP this field fill with a numerical value, if but do not have the useful signal field to be detected subsequently, such as when mobile radio station be tuned to frequency range in taken place when transmitting a HyperLan II formatted data grouping on the communication channel defining.Like this, this field 72 is another numerical value when one 802.11 formatted data grouping is detected.

Measure summary 68 and also comprise additional individual bit field 74,76,78,82,84,86 and 88 here.Field 74 is a BSS (basic service set) fields, and whether its value regulation is at least one effective mac header of measuring frequency channel-decoding.Field 76 is QBSS fields.The value of field 76 stipulates whether at least one BSS just operates among the QBSS.Have only when mobile radio station be IEEE802.11 (e) MAC when activating this bit just be set up. Field 82 and 84 is such numerical value: it is illustrated in the image duration that mobile radio station is measured, to DS field and whether being set up from the DS field.

Field 84 is one-period fields.Period field is such numerical value: whether busy and idle at least two continuous CCA (clear channel assessment) measured value of its regulation is periodic.If the busy duration of at least two continuous CCA and the busy time interval of CCA, a signal was classified as periodically when identical.Field 86 is expansion CCA report fields.Whether the busy busy duration and the busy time interval of CCA of part, CCA of the value regulation CCA of field 86 exists in report.And field 88 is BSS reports of an expansion.Whether the value specifying measurement report frame of field 88 comprises a detailed report.

Then turning to Fig. 3, is what provides a basic comprehension for clear channel assessment (CCA), is how the description and the header of IEEE802.11a header is used among the CCA below.In addition, emulation shows a system with the physical layer (PHY) that is similar to IEEE802.11a even can trigger CCA mechanism at low-down SNR place.Therefore, the importantly existence of detection system, this system uses and the similar PHY of IEEE802.11a, but has a different medium access control (MAC) and report this point during a dynamic frequency selects (DFS) to measure.

Header is as shown in Figure 3 appended in all data bursts in the IEEE802.11a wlan system in advance, and at this, " B " represents a Short Training code element, and its first Short Training code element 101 is examples.It is the waveform of 0.8us that short code unit produces one-period.Short code unit is the first of the grouping that received of the radio frequency (RF) in Orthodoxy Frequency Division Multiplex (OFDM) demodulator; Therefore, two code elements of beginning may be destroyed owing to the deposition of gain control loop and dependent quantization effect., eight short code units of residue are for detection of packets and clear channel assessment provide sufficient energy reliably.Key is to be to have enough influences that on average reduces additive noise.

Long symbols 105 is illustrated in figure 1 as " C ", at this, uses a Cyclic Prefix 121 that is expressed as CP to come separately long symbols and short code unit.CP121 has considered not have a channel estimating of the long symbols 105 of intersymbol interference ISI influence.105 duration of long symbols are 3.2us, encourage all frequencies in the band occupancy and provide enough sampling to be used for channel estimating.

Postpone correlation method

It is relevant with a delay form of itself received signal postponing with related side's ratio juris.This thought is to utilize the ad hoc structure of header so that obtain the reliable estimation of the beginning that data burst.The block diagram of this basic structure as shown in Figure 4.If input signal is made up of composite sampling r (i), correlator has one to postpone D and one and be the rolling average window size of L, and correlator is exported and can be written as so:

$P\left(k\right)=\underset{n=0}{\overset{L-1}{\mathrm{\Σ}}}{r}^{*}{(k+r+D)}_p$

Consider a received signal model,

R (k)=s (k) exp (j2 π f ₀T)+n (k) is so

$P\left(k\right)=\underset{n=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{\left|s(k+n)\right|}^2\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071010956100171.png,A20071010956100181.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{f}_{0}D\right)+n^{*}(k+n(k+n+D))$

At this, $s(k+n+D)=s(k+n){\exp }^{\left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071010956100171.png,A20071010956100181.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{f}_{0}D\right)}$ Suppose s (k) be from the cycle be sampling in the Short Training code element of mould D.Inspection obtains a maximum from top P (k) when k=D+L.

A risk function of IEEE802.11 MAC carrier sense, a plurality of access protocols obtains a clear channel assessment (CCA).CCA stood (STA) make and be used for determining whether channel empties and an access attempts whether may.When a header was detected, the IEEE802.11aWLAN specification requirement is equal to or greater than BPSK, and (82dBm) received signal level of minimum sensitivity made CCA represent " doing " to MAC.The probability that detects, that is, the CCA algorithm will correctly be discerned the probability of a busy condition, be PD＞9O% (as defining in the IEEE802.11a WLAN specification).

CCA can be considered to a dualism hypothesis and test to determine whether medium are busy.It is made up of indicating channel busy hypothesis H1 and the hypothesis HO of indicating channel free time.Under hypothesis H1, test statistics is defined as

$S=\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left|P\left(k\right)\right|}^2\&GreaterEqual;\mathrm{Th}$

And under hypothesis H0, be defined as

$S=\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left|P\left(k\right)\right|}^2<\mathrm{Th},$ At this Th is threshold value, and N is the quantity of redundant measurement.

When not having header, the amplitude of S reduces along with signal noise ratio (SNR) usually., by

$\underset{i}{\mathrm{\&Sigma;}}\frac{{({\left|P\left(i\right)\right|}^2-\stackrel{\&OverBar;}{S})}^4}{N{\left({\widehat{\mathrm{\&sigma;}}}^2\right)}^2}$ The kurtosis of definition increases.Here

Be an estimate variance and

It is the sampling mean.Simulation result here is described.

For the output of the CCA algorithm when an IEEE802.11a or HiperLAN II PHY are detected is shown, the simulation result with following hypothesis is presented:

(1) grouping size: 512 bits,

(2) speed: R=3/4 has and punctures and interweave,

(3) the generator multinomial of convolutional encoding: V1 (D)=(1+D2+D3+D5+D6) and V2 (D)=(1+D+D2+D3+D6), K=7, and dfree=10,

(4) be modulated to 64QAM,

(5) channel: tap is { 0.749,0.502,0.3365,0.2256 and the Rayleigh channel of 5 taps of 0.1512}.

The selection that is noted that modulation when header is detected will be less than influence to CCA.So 64 when because the SNR scope exceeds the about 20dB header of BPSK minimum sensitivity is not used in when determining in the channel status, QAM is selected as modulation type.

In this emulation, we have considered two schemes, (a) have the header code element and (b) do not have a header code element.

The first string comprises use header code element: the delay factor that is used in the correlation output calculating is 16 (that is, the distance between short code unit), and the MonteCarlo simulation methodology is used to estimated performance.Fig. 4 is Probability Detection 301 and 303, PD and false alarm speed 321, and PF, at this, Probability Detection 301 and 303PD increase along with the SNR that increases.For example, the PD of SNR=20 is shown as first function.In addition, this figure indicates a reliable false alarm rate, PF＜＜0.1 when PD ≈ 0.9.

The header code element is not used in the alternative plan operation: for the simulation status identical with the first string, Fig. 5 shows PD and the PF of different SNR.Because the distance between cylix prefix and an OFDM code element begin, so select one to be 64 delay factor.Fig. 5 indicates PD usually along with reducing with the SNR of the result of Fig. 4 coupling.We can also keep PF＜＜0.1 at PD ≈ 0.9 place.With the same in the first string, the Monte-Carlo emulation technology is used to find PD401,403 and 405.

Though the station that CCA is designed to allow in the IEEE802.11a wlan system estimates whether channel empties a kind of device that is used to transmit, CCA can also be used for determining being similar to the existence of the PHY of IEEE802.11a when DFS measurement of execution.In fact, when simulation result illustrates, can carry out it at SNR place near 0dB.Therefore, the following step is taked in the present invention's suggestion when carrying out a measurement for the purpose of DFS.

1.STA be tuned to an expected frequency carry out a measurement.

2. use the STA of the energy measurement characteristic of IEEE802.11a transceiver to measure the signal strength signal intensity (prior art) that receives.

3.STA check the output of CCA hypothesis test.

4. if CCA triggers very, then STA listens to from a beacon frame in the IEEE802.11a wlan system.

5. if STA can't discern an effective I EEE802.11a beacon frame, it determines that a PHY who is similar to IEEE802.11a is arranged here so, but MAC is outside.

6.STA report a PHY who finds to be similar to IEEE802.11a to AP, but MAC is outside.

Being used for that measurement data is sent to the frame of AP can be as shown in Figure 6, and it comprises frame control (501), the duration 503, DA505, SA507, BSSID509, sequence control 511, RSSI513, the true MAC of CCA outside be or not 515 and FCS517.

Table 2 show Europe WLAN operation Frequency Distribution and for HiperLAN II how to frequency preassignment.

Centre frequency (20MHz at interval)	Effective Radiated Power
		5180-5320	23dBm
5500-5680	30dBm
		5700	23dBm

Table 2

Fig. 7 has illustrated a method of one embodiment of the invention, is depicted as 550 usually.This method report at least mobile radio station be tuned to frequency band part whether be used to transmit the first system type packet.Communication station is operable in first wireless communication system, and therein, a selected frequency band partly is dynamically selectable, transmits the first system type packet on this selected frequency band part.This frequency band also selectively by the second wireless communication system utilization, selectively transmits the second system type packet thereon.

At first, as piece 552 expression, an index signal is produced, this index signal represent whether to determine first system data be grouped in institute of communication station be tuned to frequency band be transmitted on partly.Then, as piece 554 expression, a report message forms.Report message comprises a field of filling with a numerical value, this numeric representation index signal.

Thereby, form a report information, its indication according to the communication operation of first wireless communication system whether just institute of communication station be tuned to frequency band carry out on partly.The analysis of report message, follow-up retune or subsequent communications after, carry out the operation of carrying out by communication station.

The preferred description is to be used to realize that preferred exemplary of the present invention and scope of the present invention should not illustrate thus limits.Scope of the present invention is defined by following claim.

Claims (2)

1. in a communication station can within a frequency band that is also used, operating according to IEEE (Electrical and Electronic Engineering society) 802.11 standards by the another one communication system, a kind of measurement summary that is positioned at the communication station place improves equipment, and described measurement summary equipment comprises:

A selected field tucker (populator) is used for fill measuring with an indication a selected field of summary, this institute of indication indication communication station be tuned to frequency band partly whether just be used to transmit one 802.11 standard data and dividing into groups.

2. method that is used for changing channel allocation at the wireless local area network (WLAN) system that uses the clear channel distributor gear, this clear channel distributor gear is used for channel of random access, and described method comprises the steps:

Be tuned to desired frequency;

Carry out a clear channel assessment test;

Determine a beacon decodability; With

Give an access point physical layer and a medium access control report.

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