CN103988537A

CN103988537A - TCP-relay for wireless applications

Info

Publication number: CN103988537A
Application number: CN201180075094.3A
Authority: CN
Inventors: 罗兰·史密斯; 伟志·罗; 斯蒂芬·雷蒙特
Original assignee: BelAir Networks Inc
Current assignee: BelAir Networks Inc
Priority date: 2011-12-16
Filing date: 2011-12-16
Publication date: 2014-08-13
Also published as: WO2013086604A1; MX2014005146A; KR20140113687A; EP2792183A4; EP2792183A1; MX339309B; CA2851170A1

Abstract

A system for improving TCP signal reception comprising a TCP-relay component, a wireless component and an antenna (e.g., a smart antenna) coupled to the wireless component. The system being configured to receive a TCP packet with sequence number "N", send that packet wirelessly (e.g., using 802.11) to a client, receive the client's wireless ACK indicating that the packet was received, and use the client's ACK as the trigger to send a TCP-Acknowledgement of the TCP sequence number "N".

Description

For the TCP repeater of wireless application

Technical field

The present invention relates to wireless communication system.More specifically, the present invention relates to comprise WLAN (wireless local area network) (WLAN), Wi-Fi and the microcellulor wireless communication system of IEEE802.11 system.

Background technology

The evolution of the wireless network driving along with the surge of the remarkable increase by radio data and transceiver, frequency spectrum interference becomes rapidly the limiting factor that determines cell size and coverage.

For Wi-Fi network, from other unwarranted band systems (for example, other Wi-Fi transceivers, strengthen digital cord-less communication (DECT) phone, blue-tooth device, microwave oven and other unwarranted devices) noise will produce interference level (or " Noise Background "), this interference level can be very large in city.For example, the measurement of doing in the environment of typical big city shows: the Noise Background in 2.4GHz ISM frequency band is within the scope of-70 to-80dBm, or than theoretical thermal noise background (for the channel of 20MHz frequency range, it is-103dBm) high about 20 to 30dB.Therefore, because all transmission are all limited to signal to noise ratio (SNR) and Wi-Fi network is designed to only move under 0dB SNR, so the Wi-Fi network moving in these frequency ranges will have compare little community; In the situation that maximum ratio merges (MRC), Wi-Fi network may be with slightly negative SNR operation.

Therefore, to be designed to loading operation under interference environment will be favourable to radio data network.Although there was trial before, but in the time for example using, such as confirmation (ACK) agreement (, transmission control protocol (TCP) and RUDP (RUDP)), still there is the demand to improving the system and method that damages the data throughout in radio environment.

Summary of the invention

The disclosure relates to a kind of system and method that damages the data throughout in radio environment that improves by confirmation agreement.More specifically, the application discloses a kind of for example, for using the system and method for confirming the operation of Data Transport Protocol (, TCP and RUDP) and the operation of IEEE802.11 agreement.

According to a first aspect of the invention, a kind of method receiving for improving TCP signal, comprises the following steps: receive the TCP package with sequence number N from server; Process described TCP package; Described TCP package is wirelessly delivered to client; From the wireless ACK package of described client, wherein, described wireless ACK package indicates described TCP package to be received by described client; Trigger TCP acknowledgment package (TCP-ACK) with described wireless ACK package, to confirm the reception of described TCP package; And described TCP-ACK is delivered to described server.Wireless functional can further comprise the described TCP package of transmission and/or receive described wireless ACK.Of the present invention, aspect some, the TCP relay part of access point (AP) can be carried out following steps: (i) receive the TCP package with sequence number N; (ii) process TCP package; And (iii) TCP-ACK is delivered to server.In other respects, described radio communication is according to IEEE802.11 standard, and can use smart antenna to improve wireless functional.

According to a second aspect of the invention, a kind of for improve TCP signal receive system, comprising: TCP trunking, its from server receive have sequence number N TCP package, process described TCP package and TCP-ACK be delivered to described server; Wired parts, for allowing communicating by letter between described TCP relay part and network; Radio parts, for being wirelessly delivered to described TCP package client, from the wireless ACK of described client; And smart antenna, it is connected to described radio parts; Wherein, the reception of the described wireless ACK from described client is used to trigger the transmission of described TCP-ACK to described server.

According to a third aspect of the invention we, the equipment based on processor that a kind of TCP signal with improvement receives, comprise: TCP trunking, its from server receive have sequence number N TCP package, process described TCP package and TCP-ACK be delivered to described server; Wired parts, for allowing communicating by letter between described TCP relay part and network; Radio parts, for being wirelessly delivered to described TCP package client, from the wireless ACK of described client; And smart antenna, it is connected to described radio parts, and the reception of the described wireless ACK from described client is used to trigger the transmission of described TCP-ACK to described server.

According to a forth aspect of the invention, the system that a kind of TCP signal with improvement receives, comprising: processor; Data storage; Wired connection; Its from server receive have sequence number N TCP package, process described TCP package and TCP-ACK be delivered to described server; Wireless connections, are allowed to wirelessly transmit described TCP package to client and from the wireless ACK of described client; And smart antenna, it is connected to described radio parts, wherein, the reception of the described wireless ACK from described client is used to trigger the transmission of described TCP-ACK to described server.

In some aspects, described radio communication is switched antenna according to IEEE802.11 standard and/or described smart antenna, wherein, switching-beam is optimized to improve reception and/or the SNR of described wireless ACK, or described smart antenna is beam forming antenna, wherein, beam forming is performed reception and/or the SNR of the wireless ACK that improves described client.

Brief description of the drawings

Below the detailed description and the accompanying drawings of reference, will readily appreciate that these and other advantages of the present invention, wherein:

Fig. 1 a shows typical 32 TCP segment structures;

Fig. 1 b shows the first system of carrying out the basic function of TCP transmission with ACK package;

Fig. 1 c shows the second system of carrying out the basic function of TCP transmission with ACK package, and wherein single ACK can be used for multiple transfer of data;

Fig. 2 a is the access point system receiving for improving TCP signal;

Fig. 2 b adopts smart antenna function to improve the access point system that TCP signal receives;

Fig. 3 a shows the access point with client terminal device and server communication;

Fig. 3 b shows the access point of Fig. 3 a communicating by letter with client terminal device with the second access point; And

Fig. 4 shows the flow chart of exemplary access point processing, and wherein wireless ACK (for example, IEEE802.11ACK) can be used to indicate and trigger TCP-ACK.

Embodiment

Below with reference to the accompanying drawings the preferred embodiments of the present invention are described.Unnecessary details in the following description, is not described in detail the function and structure of knowing, because may make the present invention unclear.Described herein is to be used to greatly improve the multiple steps, method and the solution that damage TCP signal reception in environment.Particularly, following examples relate to system and/or the method that can use such as the operation of confirmation digital transmission protocol and the operation of IEEE802.11 agreement of TCP and RUDP.For the disclosure, will be suitable for following term and definition.

Term " IEEE802.11 " and " 802.11 " refer to for 2.4,3.6 and 5GHz frequency band on carry out one group of standard of WLAN (wireless local area network) (WLAN) compunication.This group standard is safeguarded by IEEE LAN/MAN standard committee (IEEE802).

Term used herein " communication " and " communication " comprising: data are delivered to the stay of two nights and data are sent to communication media, system, channel, network, device, wire, cable, optical fiber, circuit and/or the link that is delivered to the stay of two nights to be passed from information source; Term used herein " communication " refer to the data transmitting or transmit.Term used herein " communication " comprising: one or more communication media, system, channel, network, device, wire, cable, optical fiber, circuit and/or link.

Term used herein " processor " refers to the software at hardware, visibly embodying or carries out and processing unit, equipment, program, circuit, parts, system and subsystem able to programme or that can not become in both.Term used herein " processor " includes but not limited to: one or more computer, hard-wired circuit, signal change device and system, for the device of control system and machine, CPU, programmable device and system, field programmable gate array, application-specific integrated circuit (ASIC), SOC (system on a chip), system, state machine, virtual machine, data processor, treatment facility and aforesaid combination in any by discrete component and/or the electric circuit constitute.

Term used herein " storage " and " data storage " refer to for retain data and one or more data storage devices, equipment, program, circuit, parts, system, subsystem, position and storage mediums of these reservation data are provided temporarily or forever." storage " used herein and " data storage " includes but not limited to: hard disk, solid-state driving, flash memory, DRAM, RAM, ROM, cassette and can store any other medium of mechanized data.

Term used herein " omnidirectional antenna " refers to the antenna of homogeneous radiation radio wave power in all directions, the power of institute's radiation along with on plane or under the angle of pitch drop to zero on antenna axis and reduce, thereby produce ring-type radiation diagram.

" orientation is to antenna " used herein refers to the antenna of radiation relatively high power in one or more direction, and it promotes transmission and receptivity and has reduced the interference from unhelpful information source.

TCP is one of core protocol in Internet protocol (IP) group, and it is collectively referred to as TCP/IP.The bit stream of the program from the first computer is delivered to reliably, according to priority another program on second computer by TCP.Therefore, TCP be most of internet, applications (such as, World Wide Web (WWW), Email, file transfer) agreement that relies on.

TCP, for needing the application of reliable communication channel that point-to-point channel is provided, comprises for example HTML (Hypertext Markup Language) (HTTP), file transfer protocol (FTP) (FTP) and Telnet.TCP is reliably, because it makes every effort to make three guarantees for application layer: (i) stay of two nights will receive this data with the order that sends data; (ii) stay of two nights will receive all data; And (iii) stay of two nights can not repeat to receive arbitrary data.In addition, TCP is two-way, once because connection is established, server just can carry out acknowledged client end by same connection.

Due to its reliability, TCP accounts for space of top prominence in cable network.But the performance of Transmission Control Protocol for example, is degenerated fast with the increase in (, between sending and receiving device) path delay between two nodes.Therefore, reduce transmission rate and prevented additional unhelpful congested formation or cumulative.Due to this reason, TCP performance depends on that how feedback information can promptly be turned back to dispensing device.

For example, a kind of design principle of TCP is: in the time of network congestion, TCP feeds back to reduce transmission rate for dispensing device provides.If up anonymity/random bandwidth request or 802.11 data packets are because interference is lost, can be significantly slowly such as the bidirectional protocol of TCP or RDUP, for example,, by by based on transmitting the success of package or unsuccessfully revising message transmission rate and automatically adjust to available bandwidth.If confirm that the TCP acknowledgment package (TCP-ACK) of the sequence number of the package receiving is lost, TCP transmission can slow down or stop until described TCP-ACK is received.Therefore,, in order to keep efficient transfer of data, it is necessary that TCP-ACK is provided efficiently.For example,, according to TCP standard, when the ACK of three repetitions package is received or when overtime generations of ACK, dispensing device is made a response to package loss.

In cable network, congestion level can represent by package Loss Rate, wherein, and the increase that congested increase causes package to be lost.But in wireless network, package is lost not only due to congested but also for example, produce due to link load (, distance, interference etc.).Although link layer often provides again transmission mechanism to reduce link load rate (it will be described in more detail hereinafter), this link load rate is still far above the Loss Rate in cable network.

With reference now to accompanying drawing,, Fig. 1 a shows typical 32 TCP segment structures.This TCP section comprises: the stay of two nights port (16) of the information source port (16) of identification transmit port and identification receiving port.This TCP section further comprises the sequence number that can serve as two roles, be represented as " N ".For example, if SYN (SYN) mark is set to 1, it is initial sequence number.Then, No. ACK in the sequence number of the first actual data byte and corresponding ACK adds 1 for initial sequence number.But if this SYN mark is set to 0, for current sessions, this is the accumulated sequence number of the first data byte of this package.About the further information of sequence number and function thereof, for example please refer to can be http:// www.freesoft.org/CIE/Course/Section4/9.htm" the Connected:An internet Encyclopedia-Sequence Number " that place obtains.

For No. ACK (32), if ACK mark is set up, the value of ACK field is that (it confirms the reception of all formerly bytes to the desired next sequence number of receiver, if any).An ACK who is sent by each end confirms the initial sequence number of the other end itself, but there is no data.Data-bias (4) is specified the size of TCP header by 32 words.Minimum dimension header is that 5 words and full-size header are 15 words, and therefore minimum dimension is that 20 bytes and full-size are 60 bytes, thereby allows the selection up to 40 bytes in header.This field is gained the name in the following fact: it is also the skew from the starting point of TCP section to real data.Reserved field (4) current designated in the future and current should be by zero setting.

TCP section further comprises 81 marks (8 altogether): (i) congestion window reduces (CWR) mark, it is by sending main frame setting, to show that it receives and has the TCP section that ECE mark arranges and responded in congestion control mechanism (adding header to by RFC3168); (ii) (ECE) mark is responded in explicit congested prompting, to show: if (a) SYN mark is set to 1, its TCP equity can be carried out ecn (explicit congestion notification) (ECN); And if (b) SYN mark is set to 0, the package in IP header arranges during normal transmission (adding header to by RFC3168) with congested experience mark is received; (iii) URG mark, in order to show that urgent pointer field is effective; (iv) ACK mark, in order to show confirming that field is effective (all packages after the initial SYN package being sent by client should have this mark and arrange); (v) push function (PSH) mark, request is pushed to buffered data to receive application; (vi) RST mark, resets to connecting; (vii) SYN (SYN) mark---(some other mark changes its meaning based on this mark only just should to have the setting of this mark from the first package of each end transmission, some mark is only just effective in the time that this mark is set up, and other marks when this mark during by zero setting just effectively); And (viii) FIN mark, in order to show to no longer include the data from transmitter.

Window size (16) represents the size of receive window, the byte number (beyond the sequence number of determining in field) that it specifies the current hope of receiver to receive, the flow process control in vide infra and window convergent-divergent.Verification and (16) are used to header and data to carry out verification.If URG mark is set up, urgent pointer (16) shows that this 16 bit field is the skew that distance shows the sequence number of an emergency data.

Option is variable 0-320 position, can be divided exactly by 32.The length of Option Field is determined by data-bias field.The length of option 0 and 1 is single byte (8).Remaining option shows the total length (with byte representation) of the option in the second byte.TCP header fill be used to guarantee TCP end of header in and data start from 32 bit boundarys, and only form by 0.

As mentioned above, for guaranteeing timely and accurate package transmission, the radio data system that is designed to move under interference environment can comprise package host-host protocol again.These again host-host protocol wireless data package can be transmitted repeatedly again until system receives the received confirmation of this data packet.Transmit package by the positive acknowledgement that remote equipment received in order to receive, again also customized parameter (for example, forward error correction (FEC), modulation rate, day line options etc.) of host-host protocol.For example, the in the situation that of IEEE802.11 wireless standard, transmit data packet suitably received after (for example,, in official hour window, in some cases immediately) send certainly ACK.But if ACK is received, this radio data system can continue again to transmit package until the trial of stipulated number, and may use technology such as regulating parameter, for increasing this package by possibility received and that confirm.

In transmitting step again, IEEE802.11 radio device relies on a default ACK time range (timeframe) conventionally.Therefore,, if dispensing device does not receive ACK from receiving system in default ACK time range, this dispensing device has been lost supposition package and may have been continued and again transmitted this package until receive ACK.This default ACK time range can be according to for example the following and difference: for example, distance between device, operation conditions, interference level and emitter and receiving system (node).The in the situation that of long-distance link, the time that sends message and reception ACK conventionally increases along with the increase of distance and may exceed this default ACK time range.For example, in the time sending multiple package, if dispensing device is not because ACK is by its timely reception and transmission again continuously, throughput can significantly be postponed, thereby has in fact lost throughput.Therefore, the in the situation that of long-distance link, increase ACK time range and can reduce the generation of transmission again, thereby improve the quality of link.But compared with short chain road in the situation that, in the time that in fact the first package is lost in transmission, large ACK time range may make dispensing device wait for the long time before again transmitting package, thereby reduce throughput.Therefore, should length and its dependent variable based on link regulate described ACK time range.

In order to address this problem, ieee standard provides the exemplary criterion and the constant that can be used to calculate ACK time range.About the further information that ACK time range is calculated, for example please refer to can be http:// www.air-stream.org/ACK_Timeouts" the ACK Timeouts and the Effects on Distance Links " that place obtains.Therefore, can the known technology of usage data transmission field calculate or select ACK time range, this technology includes but not limited to the technology of being managed or being advised by ieee standard.

With reference now to Fig. 1 b,, the figure shows the example system 100b that carries out the basic function of TCP transmission by ACK function.Be in operation, in the time that server 102 sends one or more data segment to client 104, client 104 is confirmed that the ACK of the reception of confirming described one or more data segment reply to send it back server 102.As shown in the figure, after each data segment transmission from server 102 to client 104, described client is returned to the ACK of identification data accepted.This processing guarantees that client 104 receives in the correct order the data segment of all expectations in avoiding repeating data transmission.In the situation that server 102 does not receive ACK from client 104, server 102 can again transmit these data for example, until (i) it has received ACK or (ii) till timer sends " overtime " marking signal (, based on attempt number of times or duration).But in order to increase transmission rate and/or the efficiency of ACK agreement, system 100b can be configured to, for multiple TCP sections, use single confirmation to reply.

Fig. 1 c for example understands for transmitting the system 100c of ACK to server 102, and this system 100c comprises for the single ACK of multiple TCP sections and confirm to reply, thereby allows the high-efficiency transfer of ACK.For example, be in operation, in the time that server 102 sends data segment (data 1, data 2, data 3, data 4) to client 104, client 104 can send it back single ACK definite response, shows that data segment (data 1, data 2, data 3, data 4) is received.Correspondingly, then server can send data segment (data 5, data 6, data 7, data 8) to client 104.Once receive these data segments, client 104 just can be confirmed that the 2nd ACK reply to send it back, and shows that data segment (data 5, data 6, data 7, data 8) is received.As in the system 101b of Fig. 1 b, in the situation that server 102 does not receive ACK from client 104, server 102 can again transmit data for example, until (i) it has received ACK or (ii) till timer sends " overtime " marking signal (, based on attempt number of times or duration).

In some cases, trunking can be used that package is relayed to second point from first.For example, package can from home interconnect network termination be relayed to ISP (ISP) otherwise or.The U.S. disclosure of the invention No.2009/0183252 that is entitled as " package trunking " of Motohide Nomi discloses a kind of exemplary package trunking, and it reduces for the package that is designated as checking target package by only retaining mac-address authentication the quantity that is transferred to the package of CPU from hardware.

Similarly, the paper that is entitled as " for the application layer relay device of wireless 802.11 grid networks " (" yellow paper ") of being delivered by Huang Dengren has compared TCP repeater system and there is no the performance of the system of repeater.The object of yellow paper is to increase the successful receiving velocity (for example, " goodput ", it is defined as, by receiver received useful information per second, not comprising mistake, its unit is kbps) of stay of two nights place.More specifically, as improved the solution of TCP performance in wired field, yellow paper has been discussed a kind of application layer relay method, and the method connects traditional end-to-end TCP to be divided into several short jumpings connections.Yellow paper also finds that the repeater with scheduling jumps in network and can realize the performance gain up to 50% at 4-.

As discussed in yellow paper, in the time that TCP package passes through via node, this via node retains the local replica of this package, and sends immediately ACK package to previous dive.Meanwhile, via node connects and sends described local replica to down hop via another TCP.In the time that down hop successfully receives described local replica, the copy receiving is deleted.If described package is lost in being forwarded to down hop, this package will be transmitted again by described via node instead of original transmitting terminal.Yellow paper points out that the advantage of application layer TCP repeater comprises, for example: (i) package of any loss again to transmit for preserving unnecessary in middle hop be local for again transmitting; (ii) two-way time, (RTT) became less, because the quantity of the jumping of TCP session is reduced, thereby accelerated feedback procedure, faster because the TCP of series connection connects the response of package being lost than single end-to-end connection; And (iii) less RTT is connected and has increased channel utilization with multiple TCP.

Yellow paper also discloses the technology of improving 802.11 transmission by TCP trunking method, because TCP repeater can more strictly be processed wireless side than wired side by for example sending additional information.

As disclosed herein, the reception of wireless ACK package can be used to (for example trigger in wired side via TCP repeater, be connected on the network of server) TCP-ACK, therefore got rid of the needs that receive actual TCP-ACK, thereby increased the efficiency of this system.In fact, the application has integrated the function (this is wireless, and ACK confirms the reception to 802.11 packages that comprise TCP, RUDP or other agreements) of wireless ACK (for example, 802.11ACK) package, to simulate TCP ACK or RUDP ACK.Be in operation, system is made following hypothesis: receive from client if wireless ACK package is access in point (AP), must be received by AP from the Ethernet package of the encapsulation of server.Therefore,, before receiving actual TCP-ACK package, the Ethernet package of encapsulation can be identified, thereby has improved efficiency and got rid of the demand to actual TCP-ACK package.In fact, TCP relay function for example can use, from the input of 802.11 transceivers (, for concrete TCP package, wireless ACK package is received), makes it think that TCP-ACK package is received with fraud system.

Therefore, the system and method for the present embodiment comprises two kinds of functions substantially: (i) TCP relay function; And (ii) 802.11MAC function.With reference now to Fig. 2 a,, show the exemplary AP system receiving for improving TCP signal.AP system 200a comprises: server 202, network 204 (for example, the Internet), AP222a and client 214.AP222a comprises TCP relay function 206a and 802.11MAC functional parts 208a substantially.Server 202 comprises the computer 226 (for example, the equipment based on processor) that is connected to data storage 224 substantially.These functions will be being performed in AP structure below in greater detail.

The functional 206a of TCP-RELAY is to conventionally processing via communicating by letter of network 204 between 802.11MAC/PHY functional parts 208a and end server 202, and 802.11MAC functional parts 208a (for example,, via 802.11 wireless links) provides aerial operation to arrive client 214.This 802.11 wireless link can be divided into two main layers: medium access control (MAC) layer and physical layer (PHY).These two layers allow the function of IEEE802.11 standard separate and individual data agreement can be used together from some different RF transmission technologys.MAC layer provides addressing and channel access controlling mechanism, and this makes some terminals or network node communicate by letter and become possibility in multidrop network (being generally LAN or metropolitan area network (MAN)).And PHY layer has defined different RF transmission technologys: Frequency Hopping Spread Spectrum/FHSS or FHSS, Direct Sequence Spread Spectrum or DSSS, infrared unrestrained transmitting and OFDM or OFDM.

The system of Fig. 2 a shows the data-interface between TCP relay function 206a and 802.11MAC functional parts 208a, this data-interface not only comprises the exchange of data packet, also allow additional wireless ACK instruction to send to TCP relay function 206a, this additional wireless ACK instruction shows that package for example, confirmed by client 214 (, wireless device).

But in some cases, the system of Fig. 2 a only can produce appropriate total throughout improvement in performance.The improvement of this appropriateness can be these limited facts of " up link " owing to most of outdoor AP systems, means than AP to client-side to, these outdoor AP systems in client to the link budget in AP direction with minimizing.In this case, the not received possibility of the received possibility of wireless ACK package and TCP-ACK is all little, therefore to server package (for example carry out, TCP-ACK package) confirm what to have received (for example, by using 802.11/ wireless ACK) the additional function of TCP repeater will aspect delay, provide little improvement because wireless ACK can be received prior to TCP-ACK a little.

In order to address this problem, except better agreement and relaying technique, other technologies can be used further to improve possibility and the speed of successfully transmission.For example, it may be favourable using the antenna system communicating with 802.11MAC functional module.

As discussed in this article, native system and method can be utilized the new technology in smart antenna field.Smart antenna uses (i) beam forming technique or (ii) wave beam control technology conventionally.Generally speaking, smart antenna is the aerial array with intelligent signal processing algorithm, this intelligent signal processing algorithm be used to identify spacing wave feature (such as, the direction of arrival (DOA) of signal), and be used to compute beam shaping vector to follow the trail of and positioning antenna wave beam in mobile radio station/target.Smart antenna and/or antenna system can be used to improve for example, Wi-Fi and microcellulor operation in interference-limited environment (, having the environment of high interference levels).Therefore, the object of such antenna system is to improve the SNR of signal, thereby increases active data communication.As known in the art, SNR refers to the level of signal and the comparison of background-noise level of expectation, and it is defined as the ratio of signal power and noise power.For example, the SNR value that is greater than 1:1 shows to have more signal than noise.A factor of considering is often to occur SNR problem at AP place, and especially all the more so for outdoor AP, outdoor AP is usually located at the eminence of pole or is mounted on the wall, thereby is exposed to much higher signal level, comprises the signal level from interference source.

Beam forming, can be used for the first location technology of 802.11 systems, refer to the particular radiation directional diagram that adds the phase place of signal and create aerial array by the direction along target/mobile radio station of expecting constructively, and by the method for the pattern null steering of the target/mobile radio station of do not expect/jamming target.This can be by using a for example finite impulse response (FIR) (FIR) tapped delay-line filter to realize.Use this technology, the weight of FIR filter also can be changed adaptively, thereby be used to the beam forming that provides optimum, in some sense, the lowest mean square root error (MMSE) between its beam pattern and actual beam pattern forming that has reduced to expect.In fact, use this processing, wave beam can modify to form by the phase place of the RF signal to sending to antenna and amplitude.About the additional information of beam forming and beam forming technique, for example please refer to can be http:// staff.washington.edu/aganse/beam-forming/beam-forming.ht mthe paper " An Introduction to Beam-forming " of the Experiment of Applied Physics chamber Andy Ganse that place obtains.

On the other hand, beam forming comprises the main lobe direction that changes antenna pattern---the in fact direction of control antenna.Wave beam control can realize in the following manner: switched antenna element, change drive this element RF signal relative phase and/or make electricity consumption and/or mechanical module with point to expect direction.For example, use the exemplary beams control method of parasitic antenna open in Electronic Beam-steering Using Switched Parasitic Smart Antenna Arrays mono-literary composition by P.K.Varlamos and C.N.Capsalis, referring to electromagnetism progress (Progress In Electromagnetics Research, PIER) the 36th phase 101-119 page in 2002.

Be used for the early stage small-sized linear polarization adaptive array antenna of communication system by the U.S. Patent No. 4 that is entitled as " Adaptive Array Antenna " (Milne antenna) of Robert Milne, 700,197 (Milne patents) are disclosed.As discussed in Milne patent, the directivity of Milne antenna beam and directive property can be controlled in plane to plane and pitching electronically in orientation.Milne patent points out, Milne antenna is found to have low RF loss and moves on relatively large communication bandwidth.As disclosed in Milne patent, in fact, Milne antenna comprises driving λ/4 monopole being surrounded by the coaxial parasitic antenna array being all installed on the ground level of finite size.Parasitic antenna can be connected to ground level via the switch module of PIN diode or equivalence.By applying suitable bias voltage, the parasitic antenna of expectation can be electrically connected to ground level and have strong reflection, thus the antenna pattern of control antenna.Although Milne patent shows exemplary smart antenna, any antenna that in fact can location client end device all can be used.Similarly, for specific application, the quantity of the parasitic antenna using in array and position can be customized.For example, a certain position that the parasitic antenna of greater number can be positioned at array is to aim at better wave beam.

In interference-limited environment, new novelty antenna system can dynamically be controlled its antenna beam with oriented towards client device, thereby improves the visible SNR in client terminal device place.Such as 802.11Wi-Fi system in the situation that, receive ACK package after positively-modulated package transmission time, antenna system can keep oriented towards client device until ACK is received.If antenna system can significantly improve the SNR that client observes, in the time that ACK is received, smart antenna can remain on identical direction significantly to improve the SNR of the ACK receiving.

This has the advantage of improving downlink throughput capacity (from the radio data system with smart antenna to client terminal device, being generally kneetop computer or portable radio device).For the transfer of data such as unacknowledged data agreement (UDP), the data throughout that these antenna systems that " aim at then shooting " can be improved.The additional SNR that transmits package and received ACK is improved and will obtain the corresponding increase of data throughout.But, because these antenna systems have multiple clients conventionally, so antenna possibly cannot keep pointing to for a long time specific client.On the contrary, system can turn back to certain form compared with low gain " omnidirectional " antenna or " orientation to " antenna mode, under this pattern, the SNR that antenna gain thereby the SNR that causes are obtained during by control and oriented towards client from this antenna starts to reduce.

As shown in Figure 2 b, antenna system 220 can be integrated significantly to improve the reception of wireless ACK package with the system 220a of Fig. 2 a, because antenna beam can face client 214 and keep aiming at the wireless ACK package to receive client between the transmission period of 802.11 packages.Therefore, for applying (most of flows are sent to client terminal device 214 from AP222b in these application) such as streaming media video, equity most of the Internets high-throughput shared and browse application, the high-gain of antenna system not only guarantees that package is transferred to client 214, and guarantees that wireless ACK and TCP-ACK are received.

With reference now to Fig. 3 a,, exemplary AP302 can comprise: processor 312, power supply 318, antenna 316, wire communication link 314, wireless connections interface 322 (for example, RF transceiver, RF front end etc.) and comprise the data storage of for example RAM310 and ROM308.As scheme described, AP302 can be by on-air radio link (for example, via 802.11 wireless links) for example, communicate by letter with client 320 (, wireless device), and communicate by letter with server 326 by network 324 via wire communication link 314.Server 326 comprises the computer 328 (for example, the equipment based on processor) that is connected to data storage 330 substantially.

Antenna 316 can be conventional antenna, or more preferably, smart antenna.Wired connection 314 can be allowed to receive the TCP package with sequence number N from server 326, and transmits TCP-ACK to server 326.Wireless connections 322 can be allowed to TCP package to be wirelessly delivered to client 320 from server 326 via AP302, and receive wireless ACK (for example, 802.11ACK) by the smart antenna 316 that is for example connected to wireless connections 322 from client 320.Be in operation, can be used to AP302 to the reception of the wireless ACK from client 320, to trigger, TCP-ACK is delivered to server 326, thereby increase efficiency.

With reference now to Fig. 3 b,, two identical AP302a as described in Fig. 3 a are shown to intercommunication mutually and communicate by letter with at least one client 320 with 302b.As shown in the figure, AP302a is not limited to and client 320 radio communications, but AP302a can with another AP302b and/or client 320 radio communications.Although it is identical with the AP302 of Fig. 3 a that AP302a and 302b are shown to, in order to communicate by letter them without identical.In fact the data that, gathered or created by AP302a also can be passed to another AP302b, client 320 or any other equipment that can wired or wireless communication.In certain embodiments, except antenna 316a and wave point 322a or replace antenna 316a and wave point 322a, AP302a even can come communicate with AP302b or client device 320 by wire communication link 314a.

Fig. 4 shows exemplary AP and processes 400 flow chart, and wherein, wireless ACK (for example, 802.11ACK) can be used to indicate and trigger TCP-ACK via for example TCP repeater.AP processes and is conventionally undertaken by the processor of AP, but also can be by carrying out with each AP one or more processor that be associated or that be connected to each AP.AP processes and starts from step 402.At step 404 place, AP determines that whether TCP package is received via for example TCP repeater.If TCP package is not received, AP returns to step 402.But if TCP package is received, AP enters step 404, in this step, package and/or sequence number are processed in step 422.Then, AP can enter step 406, and in this step, AP uses for example 802.11MAC/PHY radio parts that the TCP package receiving is wirelessly sent to given client end.In order to strengthen wireless functional, preferably, smart antenna can be connected to this MAC/PHY radio parts.This smart antenna can be, for example (i) switched antenna or (ii) beam forming antenna.In either event, the reception to the wireless ACK from client or the SNR from the wireless ACK of client will be modified.At step 408 place, AP determine wireless ACK whether in response to the transmission of the TCP package receiving by from client.

If AP does not receive wireless ACK in predetermined number of seconds, AP will return to step 406 and attempt Transmission TCP package again.This circulation can repeat until (i) received ACK or (ii) till step 412 place timer sends " overtime " marking signal at the AP of step 408 place.For example, for example, when the transmission attempt that meets predetermined number (, is attempted for 1 to 10 time, more preferably attempted for 1 to 5 time, most preferably attempt for 3 to 5 times) or when from initial transmission, the default duration has exceeded the time limit, timer can send overtime marking signal.If overtime mark is shown at step 412 place, AP returns to the starting position at step 402 place.In certain embodiments, at step 416 place, mistake can be labeled, to show that AP is not from the client of reception of confirming one or more package to ACK.Mistake can be recorded to for example data file and/or can be presented to AP user via for example audio frequency and/or video interface or other suitable alarm mechanisms.

If AP has received wireless ACK at step 408 place, be returned to server at the TCP-ACK of step 410 place and received by AP from the package of server showing.This technology is based on following hypothesis: if from client to wireless ACK package, must be received by AP from the package of server, thereby can before receiving actual TCP-ACK, be identified, as mentioned above, this has postponed processing conventionally by slowing down or stopping transmission until confirm to be received.

Once TCP-ACK has been returned to server at step 410 place, AP just can turn back to step 402, in this step, processes and can carry out repetition by for example another transmission of data packets.But, if send overtime marking signal at step 414 place timer, process and can be terminated.For example, when the package of predetermined quantity is transmitted, the predetermined duration exceeds the time limit, all data packets have been transmitted and/or have processed when the mode with other has been terminated by for example user or another system or equipment, timer can send overtime marking signal.

If overtime mark is shown at step 414 place, AP enters the end position at step 418 place.But system can be reset at step 420 place, thereby makes AP return to step 402.System can automatically be resetted by for example software, timer and/or counter, or is manually resetted by user or another system or equipment.

Correspondingly, as illustrational in Fig. 4 institute, a kind ofly can comprise the following steps for improving the method that TCP signal receives: 404, from server reception TCP package; 422, process described TCP package; 406, described TCP package is wirelessly delivered to client; 408, from the wireless ACK package of described client, wherein, described wireless ACK package shows that described TCP package is received by described client; Thereby use described wireless ACK package to confirm the reception of described TCP package to trigger TCP-ACK package; And 410, in response to described triggering, described TCP-ACK is delivered to described server.

Although above-mentioned steps can be carried out by multiple elements or parts in AP, a lot of functions are preferably carried out by TCP repeater.For example, preferably carry out following steps by TCP repeater components: (i) receive TCP package; (ii) manage package and/or sequence number everywhere in step 422; And (iii) at step 410 place the reception based on wireless ACK reply by confirmation.

The above-mentioned patent of quoting and patent are openly all as reference of the present invention.Although specific setting of reference element, feature etc. described various embodiment, it is not used in all possible setting of limit or feature, and in fact many other embodiment, amendment and modification are confirmable to those skilled in the art.Therefore, should be appreciated that and can put into practice the present invention in the mode outside above-mentioned specific descriptions.

Claims

1. the method receiving for improving TCP signal, comprises the following steps:

Receive TCP package from server;

Process described TCP package;

Described TCP package is wirelessly delivered to client;

From the wireless ACK package of described client, wherein, described wireless ACK package indicates described TCP package to be received by described client;

Trigger TCP-ACK package with described wireless ACK package, to confirm the reception of described TCP package; And

Described TCP-ACK is delivered to described server.

2. method according to claim 1, wherein, described radio communication is according to IEEE802.11 standard.

3. method according to claim 1, further comprising the steps: to use smart antenna to improve wireless functional.

4. method according to claim 3, wherein, described wireless functional comprises: transmit described TCP package and/or receive described wireless ACK package.

5. method according to claim 3, wherein, described smart antenna is switched antenna; And

Optimize described switching-beam by switching-beam being remained on to described client place after transmission until described ACK is received, to improve reception and/or the SNR of described wireless ACK.

6. method according to claim 3, wherein, described smart antenna is beam forming antenna; And

Until being received, described ACK carries out beam forming by wave beam being remained on to described client place after transmission, to improve reception and/or the SNR of wireless ACK of described client.

7. the system receiving for improving TCP signal, comprising:

TCP trunking, its from server receive have sequence number N TCP package, process described TCP package and TCP-ACK be delivered to described server;

Wired parts, for allowing communicating by letter between described TCP relay part and network;

Radio parts, for being wirelessly delivered to described TCP package client and from the wireless ACK of described client; And

Smart antenna, it is connected to described radio parts;

Wherein, the reception of the described wireless ACK from described client is used to trigger the transmission of described TCP-ACK to described server.

8. system according to claim 7, wherein, described radio communication is according to IEEE802.11 standard.

9. system according to claim 7, wherein, described smart antenna is switched antenna, and switching-beam is optimised, to improve reception and/or the SNR of described wireless ACK.

10. system according to claim 7, wherein, described smart antenna is beam forming antenna, and beam forming is performed, to improve reception and/or the SNR of wireless ACK of described client.

11. 1 kinds have the equipment based on processor of the TCP signal reception of improvement, comprising:

Smart antenna, it is connected to described radio parts;

12. equipment based on processor according to claim 11, wherein, described radio communication is according to IEEE802.11 standard.

13. equipment based on processor according to claim 11, wherein, described smart antenna is switched antenna, and switching-beam is optimised, to improve reception and/or the SNR of described wireless ACK.

14. equipment based on processor according to claim 11, wherein, described smart antenna is beam forming antenna, and beam forming is performed, to improve reception and/or the SNR of wireless ACK of described client.

15. 1 kinds have the system of the TCP signal reception of improvement, comprising:

Processor;

Data storage;

Wired connection, its from server receive have sequence number N TCP package, process described TCP package and TCP-ACK be delivered to described server;

Wireless connections, it wirelessly transmits described TCP package to client and from the wireless ACK of described client; And

Smart antenna, it is connected to described radio parts;

16. systems according to claim 15, wherein, described system is further allowed to communicate with other systems based on processor.

17. systems according to claim 15, wherein, described radio communication is according to IEEE802.11 standard.

18. systems according to claim 15, wherein, described smart antenna is switched antenna, and switching-beam is optimised, to improve reception and/or the SNR of described wireless ACK.

19. systems according to claim 15, wherein, described smart antenna is beam forming antenna, and beam forming is performed, to improve reception and/or the SNR of wireless ACK of described client.