1287373 九、發明說明： 【發明所屬之技術領域】 本發明係關於無線區域網路之技術領域，尤指一種無 線區域網路之判斷傳送錯誤原因之方法及系統。 5 【先前技術】 1997年制定的IEEE 802.1 1為目前無線區域網路 (wireless local area network，簡稱WLAN)的主要標準，其 中規範了 WLAN中物理層（physic，簡稱PHY)和媒介存取控 10 制層（medium access control，簡稱 MAC)的運作。IEEE 802.11 DCF (distributed coordination function)定義 了無線行動裝置（station)存取無線媒介的基本方法。無線 網路是一個共享的媒介，DCF是一種以競爭為主的方式來 達到存取控制，使用CSMA/CA的觀念。由於無線區域網路 15 是個傳輸不穩定的媒介，DCF採用Positive ACK作為確認 是否正確接收的方式。如圖1(a)所示，Positive ACK係指在 一個傳送端送一訊框給接收端的過程裏，接收端每當正確 無誤地收到一個訊框後，會回覆一個確認（Acknowledge， 簡稱ACK);而發送端送出一個訊框後，直到收到接收端的 20 確認，才能送出下一個訊框。若是發送端在等待一段時間 (Retransmission Timeout)沒收到接收端的確認，會認定為 傳送失敗，而以指數形式增加延遲等待（Backoff)的機制， 再重新傳送這個訊框，以降低再發生衝撞（collision)的機率 而，如圖1 (b)所示。 1287373 别述播線網路環境隶大的特色就有較高的訊框遺失 率（frame loss rate)，而造成訊框遺失的因素很多，有可能 因為電波干擾、物體遮掩、多路徑（multi_path)干擾、或多 台機器同時發送造成衝撞等。而在IEEE 8〇211的]^人(：：設計 5中，每當發生訊框遺失，就假設此訊框遺失是由衝撞 (collision)所造成，所以一律採用指數形式增加延遲等待的 機制，以降低再發生衝撞的機率。然而，此種假設並不符 合現實世界的情形，而會造成網路效能無法充分發揮。進 一步來看，當若是訊框遺失是因非衝撞的因素所造成，則 10顯然延遲等待的機制會造成不必要多餘的等待，也讓這個 訊框的傳送被不必要的拖延。 由此了知，先鈾無線區域網路之重傳技術遭遇了如下 之缺點： 、（1)當訊框遺失是因非衝撞之因素造成時，802 11之 15指數形式增加延遲等待的機制的動作造成發送端不但沒有 減少發生衝撞的機率，且造成不必要之等待，並延長了傳 送的時間。 (2)因多餘的延遲等待，讓無線行動裝置沒有有效利 用無線頻帶珍貴資源。 20 (3)無線網路效能低落。 【發明内容】 M 、，’又月之主要目的係在提供-種無線區域網路之判 返錯决原因之方法及系統，其可預判訊框遺失（如⑽ 1287373 5 10 15 20 的因素’以選擇性地採用指數形式增加延遲等待的機 彳I重新傳送訊框’俾省去不必要的延遲等待時間，避免 頻页的浪費，而能有效利用無線頻帶珍貴資源，提高網路 系統效能，且加快重傳的速度。 仪據本I明之一特色，係提出一種無線區域網路之判 斷傳送錯誤原因之方法，其中，無線區域網路至少具有多 數：:泉:丁動即點及一無線存取器，每-無線行動節點可傳 达貝料錢，該方法包括步驟：⑷記錄目前與該無線存取 :連接的無線行動節點數目；(B)依據該已連接的無線行動 即點數目來決可能發生衝撞之機率值，該機率值正比 於已連接的無線行動節點數目；以及（c)t無線行動節點傳 送資料贿而產生訊框遺失時，依據該機率值而選擇性地 執行延遲等待，再重傳訊框。 ，依據本發明之另-特色，係提出一種無線區域網路之 二斷傳达錯誤原因之系統，包括：多數無線行動節點，每 一無線行動節點可傳送資料訊框；以及一無線存取器，記 錄有目前與其連接的無線行動節點數目，且週期性地將該 已連接的無線行動節點數目廣播給所有無線行動節點；其 中’當無線行動節點傳送資料訊框而產生訊框遺失時，依 據-可能發生衝撞之機率值而選擇性地執行延遲等待，再 重傳訊框，該機率值正比於已連接的無線行動節點數目。1287373 IX. Description of the Invention: [Technical Field] The present invention relates to the technical field of wireless local area networks, and more particularly to a method and system for determining the cause of transmission errors in a wireless local area network. 5 [Prior Art] The IEEE 802.1 1 developed in 1997 is the main standard of the wireless local area network (WLAN), which regulates the physical layer (physic, PHY for short) and medium access control in the WLAN. The operation of the medium access control (MAC). IEEE 802.11 DCF (distributed coordination function) defines a basic method for wireless mobile devices to access wireless media. The wireless network is a shared medium, and DCF is a competition-based approach to access control using the CSMA/CA concept. Since the wireless local area network 15 is a medium with unstable transmission, the DCF uses a Positive ACK as a means of confirming whether or not it is correctly received. As shown in Figure 1(a), Positive ACK refers to the process of sending a frame to a receiving end on a transmitting end. When the receiving end receives a frame correctly, it will reply with an acknowledgement (Acknowledge, ACK for short). After the sender sends out a frame, it will not send the next frame until it receives the 20 confirmation from the receiver. If the sender does not receive the acknowledgment from the receiver after waiting for a period of time (Retransmission Timeout), it will be deemed that the transmission fails, and the delay back (Backoff) mechanism is added exponentially, and then the frame is retransmitted to reduce the recurrence collision (collision) ), as shown in Figure 1 (b). 1287373 The characteristic of the broadcast network environment is that there is a high frame loss rate, and there are many factors that cause the frame to be lost. It may be due to radio interference, object obscuration, multi-path (multi_path). Interference, or multiple machines simultaneously sending a collision. In the IEEE 8〇211] (:: Design 5, whenever a frame is lost, it is assumed that the frame is lost due to collision, so the exponential form is used to increase the delay waiting mechanism. In order to reduce the chance of recurrence of collisions. However, this assumption does not correspond to the real world situation, and will cause the network performance to be insufficient. Further, if the frame loss is caused by non-collision factors, then 10 Obviously, the mechanism of delay waiting will cause unnecessary redundant waiting, and the transmission of this frame will be unnecessarily delayed. It is thus known that the retransmission technology of the uranium wireless local area network has encountered the following shortcomings: 1) When the frame is lost due to non-collision factors, the action of the 802 11-15 index form delay delay mechanism causes the sender to not only reduce the probability of collision, but also cause unnecessary waiting and extend the transmission. (2) The wireless mobile device does not effectively utilize the precious resources of the wireless band due to redundant delay waiting. 20 (3) The performance of the wireless network is low. 】 M,, 'The main purpose of the month is to provide a method and system for the determination of the cause of the wireless local area network, which can predict the loss of the frame (such as (10) 1287373 5 10 15 20 factors to choose Explicitly use the exponential form to increase the delay waiting mechanism. I re-transmit the frame', eliminating unnecessary delay waiting time, avoiding waste of frequency pages, and effectively utilizing the precious resources of the wireless band to improve the performance of the network system and speed up The speed of retransmission. According to one of the characteristics of this I, it is proposed to determine the cause of the transmission error in the wireless local area network, wherein the wireless area network has at least a majority:: Spring: Ding and Point and a wireless access The per-wireless mobile node can communicate the bill of lading, the method comprising the steps of: (4) recording the number of wireless mobile nodes currently connected to the wireless access: (B) determining the number of connected wireless actions according to the number of points The probability of a collision may occur, the probability value being proportional to the number of connected wireless mobile nodes; and (c) the wireless mobile node transmitting a bribe to generate a frame loss, according to the probability value And selectively performing delay waiting and re-transmitting the frame. According to another feature of the present invention, a system for communicating the cause of the error in the wireless local area network is proposed, including: most wireless mobile nodes, each wireless action The node can transmit a data frame; and a wireless access device records the number of wireless mobile nodes currently connected thereto, and periodically broadcasts the number of connected wireless mobile nodes to all wireless mobile nodes; wherein 'when wireless action When the node transmits the data frame and the frame is lost, the delay wait is selectively performed according to the probability value of the collision, and the frame is re-transmitted, and the probability value is proportional to the number of connected wireless mobile nodes.
【實施方式】 7 1287373 有關本發明之無線區域網路之判斷傳送錯誤原因之 方法及系統，請先參照圖2所示之系統架構圖，其為一有無 線存取器（AP)21之無線區域網路（infrastructure WLAN)環 境，其中，在一無線存取器21控制之範圍内有多數個無線 5 行動節點22，每一無線行動節點22可傳送資料訊框。 圖3顯示本發明之無線區域網路之判斷傳送錯誤原因 之方法的流程圖，一併參照圖2之系統架構圖所示，首先， 當所有無線行動節點22接上無線區域網路時，一定需要與 無線存取器21作連接（associate)的動作，因此無線存取器21 10 可以記錄到目前與其連接的無線行動節點22數目（步驟 S301)。 其次，無線存取器21利用信標（Beacon)訊框而週期性 地將此已連接的無線行動節點數目廣播給所有無線行動節 點22(步驟S302)。 15 而當一無線行動節點22傳送資料訊框後（步驟S303)， 如在預定時間（Retransmission Timeout)内收到回覆 ACK(步驟S304)，則表示傳送成功而可再繼續傳送下一資 料訊框，否則表示傳送錯誤而需進一步判斷傳送錯誤之原 因（步驟S305)。 20 在步驟S305中，係依據步驟S302中所收到之已連接的 無線行動節點數目、及該已連接的無線行動節點22於 Backoff過程中所發生暫停之次數來決定傳送錯誤之原 因，由於當網路内的無線行動節點數量愈多時，發生衝撞 的機會愈高，因此，當已連接的無線行動節點數目較大、 1287373 且該已連接的無線行動節點22於Backoff過程中所發生暫 停之次數較多時，無線行動節點22即可決定傳送錯誤係由 衝撞所造成。 為計算無線行動節點22之傳送錯誤係由衝撞所造成 5 之機會，可藉由以下之機率函式（1)所決定：[Embodiment] 7 1287373 Regarding the method and system for judging the transmission error of the wireless local area network of the present invention, please refer to the system architecture diagram shown in FIG. 2, which is a wireless device with a wireless accessor (AP) 21. An area network (infrastructure WLAN) environment in which a plurality of wireless 5 mobile nodes 22 are within the control of a wireless access device 21, and each wireless mobile node 22 can transmit a data frame. 3 is a flow chart showing a method for determining the cause of a transmission error in the wireless local area network of the present invention. Referring to the system architecture diagram of FIG. 2, first, when all the wireless mobile nodes 22 are connected to the wireless local area network, The action of associating with the wireless accessor 21 is required, so the wireless accessor 21 10 can record the number of wireless mobile nodes 22 currently connected thereto (step S301). Next, the wireless access device 21 periodically broadcasts the number of connected wireless mobile nodes to all the wireless mobile nodes 22 using a beacon frame (step S302). 15 When a wireless mobile node 22 transmits a data frame (step S303), if a reply ACK is received within a predetermined time (Retransmission Timeout) (step S304), it indicates that the transmission is successful and the next data frame can be further transmitted. Otherwise, it indicates a transmission error and it is necessary to further judge the cause of the transmission error (step S305). In step S305, the reason for the transmission error is determined according to the number of connected wireless mobile nodes received in step S302 and the number of pauses of the connected wireless mobile node 22 during the Backoff process. The greater the number of wireless mobile nodes in the network, the higher the chance of collision. Therefore, when the number of connected wireless mobile nodes is large, 1287373 and the connected wireless mobile node 22 pauses during the Backoff process. When the number of times is large, the wireless mobile node 22 can determine that the transmission error is caused by the collision. The opportunity to calculate the transmission error of the wireless mobile node 22 is caused by the collision, which can be determined by the following probability function (1):
Pr〇b. 〇f C〇l (Ng^ion) _ 〇，when Ngtation < 4， 0.3，when 4 ^Nstation < 10 ; 0.7 5 when 10 <Nstati〇n < 20; 0.9，when 20 ^Nstation o (1) 10 其中，NstatiQn為此網路内之無線行動節點總數。此函式代 表··當網路内無線行動節點總數低於四台時，發生衝撞的 機率為0 ;當網路内無線行動節點總數介於四和十台時，發 生衝撞的機率為0.3 ;當網路内無線行動節點總數介於十和 二十台時，發生衝撞的機率為0.7 ;當網路内無線行動節點 15 總數超過二十台時，發生衝撞的機率為0.9。 此外，以下之機率函式（2)為用以計算無線行動節點22 之傳送錯誤係由衝撞所造成之機會的另一範例，其同時考 量已連接的無線行動節點數目、及該已連接的無線行動節 點22於Backoff過程中所發生暫停之次數： 20 Pr〇b· 〇f C〇l (Nstation，Nbusy) - 〇, when Nstati〇n < 4, Nbusy <3， 0.3，when 4 ^Nstation < 10, 3 ^Nbusy <6 ; 0·7，when 10 ^Nstation < 20, 6 ^Nbusy <9 ; 0.9，when 20 ^Nstation，9 識usy 0 ⑺ 其中 ’ Nstatic>n 為此網路内之無線行動節點總數，Nbusy為該已 25 連接的無線行動節點22於Backoff過程中所發生暫停之次 1287373 數，如圖4所不’ Nbusy係為在一延遲等待（Back〇f〇過程中， 因忙轉^而造成暫停的次數。前述函式代表：當網路 内無線盯動即點總數低於四台、且在延遲等待中新停之·、 ί = 衝撞的機率為G;當網路内無二動節二 5…，於四：十台、且在延遲等待中暫停之次數介於三和 八，發生衝七的機率為〇.3;當網路内無線行動節點總數介 於十和二十台、且在延遲等待中暫停之次數介於六和九， 电生衝才里的機率為〇.7;當網路内無線行動節點總數超過二 =、且在延遲等待中暫停之次數超過九，發 10 率為0.9。 娜 前，機率值可由無線行動節點22算出，或由無線存取 二:异^，亚藉由週期性廣播的beac〇n訊框而將此機率值 傳送給無線行動節點22。 15 再請參照圖3所示無線行動節點22,當訊框遺失時’ ^虞此機率值判斷是否發生衝撞（步驟S305)，例如，當機 ^大G.5時，判定為沒有衝撞而直接再傳送訊框（步驟 否則’判定為發生衝撞而經延遲等待（Baekoff)(步 〃 S306)後’再重新傳送訊框（步驟s3〇3)。據此，指數形式 20 ==等待機制只在發生衝撞時才執行，如此將有效控制 双f囪框不致過高而影響到傳送的效率。 > 2以上之說明可知，纟發明係藉由根據已連接的無線 二ΓΓ點數目、及該6連接的無線行動節點22於心純 =程令所發生暫停之次數來預判訊框遺失的因素，當判斷 生衝撞時，即採用指數形式之延遲等待機制，當判斷 10 1287373 不是衝撞，便完全不用延遲等待。因此，能夠在與現行 802.11相容之下，省去不必要的延遲等待時間，避/免頻: 的浪費，而有效利用無線頻帶珍貴資源’提高網路系=效 能，且加快重傳的速度。 、、> 5 上述實施例僅係為了方便說明而舉例而已，本發明所 主張之權利範圍自應以申請專利範圍所述為準，而^僅限 於上述實施例。 【圖式簡單說明】 籲 10圖1⑷顯示WLAN中一個傳送端成功送出一訊框給接㈣ 的過程。 圖1(b)顯示WLAN中一個傳送端未能成功送出一訊框給接 - 收端而重新傳送的過程。 圖2為本發明之無線區域網路之判斷傳送錯誤原因之*** 15 的架構圖。 ” 圖3為本發明之無線區域網路之判斷傳送錯誤原因之方法 的流程圖。 圖4顯示在在-延遲等待之競爭f框中計算該已連接的無線 行動節點22於Back0ff過程中所發生暫停之次數的示意圖。 20 【主要元件符號說明】 21無線存取器 22無線行動節點 S301〜S306步驟 25 11Pr〇b. 〇f C〇l (Ng^ion) _ 〇, when Ngtation < 4, 0.3, when 4 ^Nstation <10; 0.7 5 when 10 < Nstati〇n <20; 0.9, when 20 ^Nstation o (1) 10 where NstatiQn is the total number of wireless mobile nodes in the network. This function represents that when the total number of wireless mobile nodes in the network is less than four, the probability of collision is 0; when the total number of wireless mobile nodes in the network is between four and ten, the probability of collision is 0.3; When the total number of wireless mobile nodes in the network is between ten and twenty, the probability of collision is 0.7; when the total number of wireless mobile nodes 15 in the network exceeds twenty, the probability of collision is 0.9. In addition, the following probability function (2) is another example for calculating the chance that the transmission error of the wireless mobile node 22 is caused by a collision, which considers the number of connected wireless mobile nodes and the connected wireless. The number of pauses taken by the action node 22 during the Backoff process: 20 Pr〇b· 〇f C〇l (Nstation, Nbusy) - 〇, when Nstati〇n < 4, Nbusy <3, 0.3, when 4 ^Nstation < 10, 3 ^Nbusy <6 ; 0·7, when 10 ^Nstation < 20, 6 ^Nbusy <9 ; 0.9,when 20 ^Nstation,9 know usy 0 (7) where 'Nstatic> The total number of wireless mobile nodes in the road, Nbusy is the number of times that the 25-connected wireless mobile node 22 pauses during the Backoff process, as shown in Figure 4. Nbusy is waiting for a delay (Back〇f〇 process) In the middle, the number of pauses caused by the busy turn ^. The above function represents: when the wireless in the network, the total number of points is less than four, and the new stop in the delay waiting, ί = the probability of collision is G; When there are no two movements in the network 2..., in four: ten, and paused in the delay waiting The number of times is between three and eight, and the probability of hitting seven is 〇.3; when the total number of wireless mobile nodes in the network is between ten and twenty, and the number of pauses in the delay wait is between six and nine, the electric rush The probability of being in the network is 〇.7; when the total number of wireless mobile nodes in the network exceeds two=, and the number of pauses in the delay waiting is more than nine, the rate of sending 10 is 0.9. Before the value, the probability value can be calculated by the wireless mobile node 22. Or by wireless access two: the same, the probability value is transmitted to the wireless mobile node 22 by the periodically broadcast beac〇n frame. 15 Referring again to the wireless mobile node 22 shown in FIG. When it is lost, the probability value is judged whether or not a collision occurs (step S305). For example, when the machine is large G.5, it is determined that there is no collision and the frame is directly retransmitted (step otherwise 'determined to be a collision and delayed waiting (Baekoff) (step S306) and then re-transmit the frame (step s3〇3). According to this, the exponential form 20 == the waiting mechanism is only executed when a collision occurs, so that the double-fitting frame will not be effectively controlled. High and affect the efficiency of transmission. > Description of 2 or more It is known that the invention is based on the number of connected wireless wireless points and the number of times the wireless mobile node 22 of the 6 connected wireless network node 22 is suspended. In the case of an exponential delay waiting mechanism, when it is judged that 10 1287373 is not a collision, there is no need to delay waiting. Therefore, under the compatibility with the current 802.11, it can save unnecessary delay waiting time, avoid/discard: waste, and effectively utilize the precious resources of the wireless band to improve the network system performance and speed up the retransmission. . The above-mentioned embodiments are merely examples for convenience of description, and the scope of the claims of the present invention is determined by the scope of the claims, and is limited to the above embodiments. [Simple description of the diagram] Call 10 Figure 1 (4) shows the process of successfully sending a frame to the fourth (4) in the WLAN. Figure 1 (b) shows the process in which a transmitting end of the WLAN fails to successfully send a frame to the receiving end and retransmits it. 2 is a block diagram of a system 15 for determining the cause of a transmission error in a wireless local area network of the present invention. 3 is a flow chart of a method for determining a transmission error of a wireless local area network according to the present invention. FIG. 4 shows that the connected wireless mobile node 22 is generated during the Back0f process in the competing f-frame of the delay-waiting operation. Schematic diagram of the number of pauses. 20 [Description of main component symbols] 21 wireless accessor 22 wireless mobile node S301~S306 Step 25 11