1. Medium Access Control protocols for ad hoc wireless networks: A survey
指導教授:許子衡
學生:黃群凱
作者:Sunil Kumar , Vineet S. Raghavan , Jing Deng.
出處:Original Research Article Computer Networks, Volume 48, Issue 6, 19 August 2005, Pages
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2. IEEE MAC scheme
The IEEE specifies two modes of MAC protocol:
Distributed coordination function (DCF) mode (for ad hoc etworks)
Point coordination function (PCF) mode (for centrally coordinated infrastructure-based networks)
802.11的MAC方案
在IEEE802.11規定的MAC協議的兩種模式： 分佈式協調功能（DCF）模式（特設 etworks）  點協調功能（PCF）的模式（中央協調的基礎設施為基礎的網絡）
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3. IEEE MAC scheme
The DCF in IEEE is based on CSMA with Collision Avoidance (CSMA/CA),which can be seen as a combination of the CSMA and MACA schemes.
This is implemented in the form of a Network Allocation Vector (NAV), which is maintained by every node.
在IEEE802.11的DCF基於 CSMA是帶有衝突避免（CSMA/ CA）的，它可以被看作是一個組合的CSMA和馬卡計劃。 這是實現網絡的形式分配向量（NAV），這是由每一個節點
在NAV包含時間值，表示該時間到無線媒介預計將很忙，因為其他節點的傳輸。
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4. IEEE 802.11 MAC scheme 802.11 DCF的通道存取
Immediate access when medium is idle >= DIFS立即訪問時 媒介是空閒>= DIFS
Defer Access延遲訪問
Select Slot and decrement backoff as long as medium stays idle選擇時隙和遞減退避只要保持閒置中
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5. Multiple access collision avoidance-by invitation (MACA-BI)
The sending node needs to switch to receive mode (to get CTS) immediately after transmitting the RTS.
MACA-BI is a receiver-initiated protocol and it reduces the number of such control packet exchanges.
多重存取碰撞避免由邀請
發送節點需要切換到接收模式（得到CTS）的傳遞後，立即在RTS。 瑪卡- BI是一個接收器啟動的協議，它的數量減少了這種控制包交換。
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6. Multiple access collision avoidance-byinvitation (MACA-BI)
MACA-BI requires a receiver to request the sender to send the data, by using a Ready-To-Receive (RTR) packet instead of the RTS and the CTS packets.
瑪卡碧需要一個接收器，要求發送者發送數據，通過使用現成的接收（RTR）數據包，而不是RTS和CTS的數據包。
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7. Group allocation multiple access with packet sensing (GAMA-PS)
GAMA-PS incorporates features of contention based as well as contention free methods.
Every cycle is divided in two parts for
Contention transmission.
Group transmission.
分派多址接入數據包檢測
GAMA-PS採用基於競爭特點以及爭免費的方法。 每個週期分為兩部分 爭奪傳輸 小組傳輸。
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8. Group allocation multiple access with packet sensing (GAMA-PS)
Members of the transmission group take turns transmitting data.
This scheme may not work well for mobile ad hoc networks. When there is not enough traffic in the network
傳輸組中成員輪流傳輸數據。 這項計劃可能無法正常工作的移動 Ad Hoc網絡。當沒有足夠的流量在網絡中
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9. Power aware MAC protocols
First, collisions are a major cause of expensive retransmissions and should be avoided as far as possible.
Second, the transceivers should be kept in standby mode (or switched off) whenever possible as they consume the most energy in active mode.
Third, instead of using the maximum power, the transmitter should switch to a lower power mode that is sufficient for the destination node to receive the transmission.
能量感知MAC協議
首先，碰撞一個主要原因是昂貴的重傳，應該盡量避免。 其次，應保持收發器在待機模式（或關閉）只要有可能，因為他們是最消耗能量的主動模式。 第三，而不是使用的最大功率，發射機應該切換到低功耗模式，足以為目標節點接收傳輸
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10. Power aware MAC protocols
Power aware medium access control with signaling (PAMAS)
that all the RTS–CTS exchanges are performed over the signaling channel and the data transmissions are kept separate over a data channel.
Nodes listen in on the signaling channel to deduce when it is optimal for them to power down their transceivers.
能量感知介質訪問控制信號（PAMAS） 所有在RTS- CTS的交流是通過信令信道進行數據傳輸和保存在一個單獨的數據通道。 聽節點上的信號通道來推斷它是最佳的時候，他們斷電的收發器。
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11. Power aware MAC protocols
Dynamic power saving mechanism (DPSM)
Jung and Vaidya proposed DPSM based on the idea of using sleep and wake states for nodes in order to conserve power..
DPSM is found to be more effective than IEEE DCF in terms of power saving and throughput.
動態節能機制（DPSM） Jung和動態 Vaidya提出DPSM基礎上，主張使用睡眠和喚醒狀態為節點，以節省電力.. DPSM被發現是更有效比802.11 DCF的計算，省電和吞吐量。
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12. Power aware MAC protocols
DCF的節能機制：節點 A宣布一個緩衝的數據包B使用一ATIM幀。節點 B通過發送 ATIM答复- ACK和A和B都保持清醒，在整個燈塔間隔。實際的數據傳輸是從 A到B的時間間隔內完成指路明燈。由於 C沒有任何數據包發送或接收，它打瞌睡後ATIM視窗
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13. Power control medium access control (PCM)
The RTS and CTS packets are sent using the maximum available power, whereas the data and ACK packets are sent with the minimum power required to communicate between the sender and receiver
Another drawback of this scheme is the difficulty in implementing frequent changes in the transmit power levels..
RTS和CTS包發送使用最大可用功率，而數據和ACK數據包發送所需的最低功率之間的通信發送者和接收者 這項計劃的另一個缺點是很難實施的頻繁變動所的發射功率水平..
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14. Power controlled multiple access (PCMA)
Relies on controlling transmission power of the sender so that the intended receiver is just able to decipher the packet
This helps in avoiding interference with other neighboring nodes that are not involved in the packet exchange
PCMA uses two channels
sending out busy tones
other control packets
依靠控制發射功率，使發送者接收者是否能夠破譯只是包 這有助於避免干擾鄰近的節點不參與的分組交換  PCMA使用兩個通道 發送忙音信號  其他控制包
Dual busy tone multiple access (DBTMA)
The DBTMA scheme uses out-of-band signaling to effectively solve the hidden and the exposed terminal problems.
The sender of the RTS sets up a transmit-busy tone (BTt). Correspondingly, the receiver sets up a receive-busy tone (BTr) in order to acknowledge the RTS, without using any CTS packet.
Any node that senses an existing BTr or BTt defers from sending its own RTS over the channel.
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15. Multi channel CSMA MAC protocol
Dual busy tone multiple access (DBTMA)
The DBTMA scheme uses out-of-band signaling to effectively solve the hidden and the exposed terminal problems.
The sender of the RTS sets up a transmit-busy tone (BTt). Correspondingly, the receiver sets up a receive-busy tone (BTr) in order to acknowledge the RTS, without using any CTS packet.
Any node that senses an existing BTr or BTt defers from sending its own RTS over the channel.
該 DBTMA計劃用途的帶外信號，以有效地解決了隱藏終端和暴露的問題。
發件人的RTS設置了一個發射忙音信號（BTr）。相應地，建立了一個接收器接收忙音信號（BTr），以確認在RTS，CTS的不使用任何數據包。
任何節點的感官現有BTr或BTr延遲發送RTS，從對通道。
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16. Multi channel CSMA MAC protocol
A transmitter would use carrier sensing to see if the channel it last used is free or not.
if found free. Otherwise , another free channel is chosen at random.
If no free channel is found, the node should backoff and retry later
一個發射器將使用載波監聽通道，看看它最後使用的是自由或不。 如果發現免費的。其他方式，其他的免費頻道是隨意選擇。 如果沒有免費的通道被發現，該節點應該退避和稍後再試
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17. Multi channel CSMA MAC protocol
Hop-reservation multiple access (HRMA)
HRMA uses time-slotting properties of very- slow FHSS such that an entire packet is sent in the same hop.
HRMA requires no carrier sensing, employs a common frequency hopping sequence, and allows a pair of nodes to reserve a frequency hop (through the use of an RTS–CTS exchange) for communication without interference from other nodes.
HRMA使用時間開槽性能非常慢跳頻擴頻，使得整個數據包發送相同一跳。  HRMA無需載波監聽，採用了常見的跳頻序列，並允許對節點要預訂一個跳頻（通過使用一個 RTS- CTS的交換）通訊無干擾其他節點。
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18. Multi channel CSMA MAC protocol
Multi-channel medium access control (MMAC)
MMAC is an adaptation to the DCF in order to use multiple channels.
MMAC needs only one transceiver. At the beginning of every beacon interval, every node synchronizes itself to all other nodes by tuning in to a common synchronization channel on which ATIM packets are exchanged .
MMAC是一個適應性的DCF才能使用多種渠道。 MMAC只需要一個收發器。一開始每個信標間隔，每一個節點同步到所有其他節點本身通過調整到一個共同的同步通道，其ATIM包交換。
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19. Multi channel CSMA MAC protocol
Dynamic channel assignment with power control (DCA-PC)
Every node is equipped with two half-duplex transceivers.
The bandwidth is divided into a control channel and multiple data channels.
DCA-PC is a novel attempt at solving dynamic channel assignment and power control issues in an integrated fashion.
動態通道分配和功率控制（DCA排序，PC） 每個節點配有兩個半雙工收發器。 的頻寬分為一個控制通道和多個數據通道。 DCA- PC是一種新的嘗試在解決動態通道分配，功率控制問題，以綜合的方式。
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20. Protocols using directional antennas
MAC protocols for ad hoc networks typically assume the use of omni-directional antennas, which transmit radio signals to and receives them from all directions.
With directional antennas, it is possible to achieve higher gain and restrict the transmission to a particular direction.
Packet reception at a node with directional antenna is not affected by interference from other directions.
MAC協議的Ad hoc網絡通常假定使用全向天線，發射無線電信號，並接收他們從各個方向。 定向天線，可以實現更高的增益和限制傳輸到特定的方向。 在一個數據包接收節點與定向天線不會受到來自其他方向的干擾。
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21. Unidirectional MAC protocols
When low-power and battery-operated nodes coexist with more powerful nodes tethered to power sources in ad hoc networks.
A successful RTS–CTS exchange does not guarantee successful transmission of data.
proposed a scheme to extend the reach of RTS/CTS exchange information in the IEEE protocol.
單向 MAC協議
低功耗和電池供電的節點並存，功能更強大的動力源節點拴到在ad hoc網絡。 一個成功的RTS- CTS的交換並不能保證成功傳送的數據。 提出了一個計劃，以達到延長的RTS/ CTS的交換信息在IEEE802.11協議。
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22. QoS-aware MAC protocols
Issues affecting QoS
Several issues:
the service model
routing strategies
admission control
resource reservation
signaling techniques
MAC protocols
need to be considered in the context of providing QoS in ad hoc wireless networks.
這些問題影響的QoS支持Ad Hoc網絡中簡要討論如下，隨後進行了簡短說明選定協議。
影響服務質量的問題 幾個問題： 服務模式， 路由策略， 接納控制， 資源預留， 信令技術， MAC協議 需要考慮的範圍內提供QoS的Ad hoc無線網絡。
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23. QoS-aware MAC protocols
Signaling is used in order to negotiate, reserve, maintain and free up resources, and is one of the most complicated aspects of the network.
It should be performed reliably (including topology changes) with minimum overhead.
The MAC protocol should address issues caused by node mobility and unreliable time- varying channel.
信令使用，以洽談，儲備，保持和釋放資源，是一個最複雜的方面的網絡。 它應該進行可靠（包括拓撲結構的變化）與最低的開銷。 該 MAC協議應該解決的問題所造成的流動性和不可靠的節點時變信道。
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24. QoS-aware MAC protocols
Review of selected QoS-aware MAC protocols
MAC is a lower level function and needs to be closely integrated with upper layers such as the network layer for routing. Since centralized control is not available.
it is difficult to maintain information about connections and reservations
審查選定的QoS的MAC協議 MAC是較低層次的功能，需要緊密結合，如上層網絡層的路由。由於沒有集中控制。 這是難以維持的信息連接和保留
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25. QoS-aware MAC protocols
A common, globally synchronous slotted TDM frame is defined among clusters.
The other option is to use asynchronous approaches that do not require global time synchronization
一種常見的，全球同步的TDM框架時隙界定的集群。 另一種選擇是使用異步方法，不需要全球時間同步
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26. QoS-aware MAC protocols
Real-time MAC (RT-MAC)
In IEEE protocol, packets that have missed their deadlines are still retransmitted, even though they are not useful any more. This causes bandwidth and resources to be wasted
When an rt packet is queued for transmission, a timestamp is recorded locally in the node indicating the time by when the packet should be transmitted. The sending node checks whether a packet has expired at three points
即時的MAC及時- MAC地址） 在IEEE802.11協議的數據包已錯過最後期限仍然是重發，即使它們沒有用處了。這將導致帶寬和資源浪費 當一個 RT包排隊等待傳輸，時間戳記錄在本地的節點時所顯示的時間要傳送的數據包。發送節點檢查是否已過期的數據包三個點
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27. DCF with priority classes
That supports priority based access for different classes of data
The basic idea is to use a combination of shorter IFS or waiting times and shorter backoff time value
While normal nodes wait for the channel to remain idle after DIFS interval before they transmit data, a higher priority node waits for only PIFS.
DCF的優先級 支持基於優先級的訪問不同類別的數據 其基本思想是使用較短的組合 IFS或退避等待時間和更短的時間價值 而正常節點等待通道保持空閒 DIFS間隔之後，才發送數據，等待一個更高優先級的節點只PIFS。
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28. Enhanced DCF
It has been developed as a part of the hybrid coordination function (HCF) of IEEE e
proposed a fully distributed Virtual MAC (VMAC) scheme that supports service differentiation, radio monitoring, and admission control for delay-sensitive and best- effort traffic.
增強的DCF法 它已經發展成為一個部分的混合協調功能（）的IEEE 提出了一個完全分佈式的虛擬 MAC（VMAC）計劃，支持差異化服務，無線電監測和准入控制對延遲敏感和最努力的流量。
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29. Summary and future directions
A combination of control packets (e.g., RTS/ CTS/ACK) and carrier sensing (i.e., CSMA) has been found to reduce the probability of collisions caused by hidden terminals.
As devices shrink in size, their ability to carry larger battery packs will diminish.
控制數據包的組合（如RTS / CTS的/ ACK）和載波偵聽（即CSMA的）已被發現，以減少碰撞的概率造成的隱藏終端。 隨著器件尺寸的縮小，他們有能力進行更大的電池組將減少。
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30. Hidden/exposed terminal problems
Use of power control schemes and directional antenna to increase channel reuse can improve the performance.
Hidden/exposed terminal problems
Most of the MAC schemes addressing the hidden terminal problem do not effectively treat the exposed terminal problem.
introduction of ACK packet on the MAC layer prohibits the exposed terminals from reusing the channel.
使用電源控制方案和定向天線來提高通道重用可以提高性能。  隱藏 /暴露終端問題  大多數計劃的MAC解決隱藏終端問題不能有效治療暴露終端問題。 引進的ACK數據包的MAC層禁止暴露終端重用的通道。
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31. Interference-limited model
The transmission range of each node is usually assumed to be the same. The node will always overhear all transmissions sent within this range.
Energy conservation
Power conservation is another challenging aspect in ad hoc networks with mobile and battery operated devices (i.e., nodes).
干擾有限模型 在每個節點的傳輸範圍是通常被認為是相同的。該節點將所有的傳輸總是無意中聽到這個範圍內發送。 節約能源 節能是另一種挑戰性的Ad Hoc網絡的移動和電池供電裝置（即節點）。
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32. Single channel vs. multiple channels
Many MAC schemes employ certain control packets (such as RTS/CTS in MACA, FAMA, IEEE ) to negotiate the use of the channel before the data packet transmission starts.
Multi-hop networks
The information of the entire network is usually unknown before decisions can be made to start accessing the channel.
單通道多渠道對比 許多 Mac計劃採用一定的控制數據包（如RTS / CTS的在瑪卡，農夫，符合IEEE802.11）的使用進行談判前的通道傳輸的數據包開始。  多跳網絡  對信息的整個網絡之前通常是未知的，可以向作出決定開始訪問的通道。
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33. Fairness among competing nodes
An extreme example is to always allow one node to use the shared channel, while keeping all other nodes waiting.
Directional antennas
In the future, applications are likely to require more and more bandwidth, and these ad hoc networks may well be part of our daily lives.
節點之間的公平競爭 一個極端的例子是，總是讓一個節點使用共享信道，同時保持所有其他節點等待。 定向天線 在未來，應用程序可能需要更多的帶寬，這些特設網絡可能是我們日常生活的一部分。
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34. QoS issues
With the widespread availability of portable computing devices, more and more applications are being designed for mobile use.
Most schemes consider the wireless links between networks nodes as having constant characteristics (e.g., bandwidth and error rate).
Widely varying QoS requirements will be needed in future. Bandwidth allocation, admission control, and traffic policing all need to be considered together to satisfy various QoS flows.
QoS問題 隨著普及便攜式計算設備，越來越多的應用被設計為移動使用。 大多數計劃考慮無線網絡節點之間的聯繫為具有固定特徵（如帶寬和誤碼率）。 QoS的要求千差萬別，將需要在未來的。帶寬分配，接入控制，交通治安都需要綜合考慮，以滿足各種 QoS的流量。
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35. Conclusion
Most of these schemes, however, are not designed specially for networks with mobile nodes. On the other hand, the transaction time at the MAC layer is relatively short.
The effect of mobility will become less significant as the available channel bandwidth continue to grow.
Several international standards exist for MANETs, such as IEEE a, b, and g, HIPERNET, and Bluetooth.
大多數這些計劃，但是，沒有專門設計的網絡與移動節點。另一方面，交易時間在MAC層相對較短。 流動性的效果將變得不那麼重要，因為可用的信道帶寬繼續增長。 幾個國際標準已經存在的MANETs，如IEEE的802.11a，b和g，HIPERNET和藍牙。
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