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Substation Automation and Relay Communications
Published in Walter A. Elmore, Pilot Protective Relaying, 2018
Although these 8-bit devices had the capability to communicate at rates of 19,200 bps, the actual data throughput was much slower. This was because the device’s protection function is assigned a higher priority than the communication process. In addition, the transmission of a single status indication (is a particular status set or reset?) required the transmission of 8 data bits (the ASCII character for T or F, or T or C, or some similar representation). In extreme cases, this inefficiency was made even worse by transmitting a complete word (“trip” or “close”) instead of a single character. In any case, the priority assigned to communications processes required control of either hardware or software data flow between the master and slave devices to ensure that the information was received and processed correctly. An example of hardware data flow control, also known as hardware handshaking, is when a master “requests to send” (RTS) data to the slave and the slave grants the master access through a “clear to send” (CTS) signal. When the slave device is not able to process any more data, it deasserts the CTS signal, thereby stopping the master from additional data flow. Once the slave is able to process more data, it asserts the CTS signal, thereby allowing the master to continue the data transfer. This stop-and-go process continues until the transaction is complete. This handshaking process also applies for communications in the reverse direction (i.e., for a slave’s response back to the master).
Electronic Devices and Communication Applications
Published in Mike Tooley, BTEC First Engineering, 2010
Flow control is the process of managing the transfer of data between two devices. It ensures that the data is sent at an appropriate rate and that the receiver is not overloaded by sending data that it can’t accept. In the dialogue between the printer and computer that we met earlier you should note that the computer is implementing a form of flow control by telling the printer that it is too busy to send data and is requesting that the printer should wait.
OSI and TCP/IP Reference Models
Published in James Aweya, Designing Switch/Routers, 2023
There are two types of Transport Layer communication:Connection-oriented: Connection-oriented service involves three phases; connection establishment, data transfer, and connection termination. Appropriate connection parameters must be agreed upon by both end-systems before a connection is established. This results in connection-oriented network services having more communication overhead than connectionless services.Connectionless: In a connectionless service, any end-system can send data without the need to establish a connection first. No connection parameters are established before data is sent. An end-system can simply send the data without the added overhead of creating and tearing down a connection.The parameters that are negotiated by connection-oriented protocols include:Flow Control (Windowing): Flow control is the process of regulating the rate of data transmission to ensure that a transmitting device does not overwhelm a slower receiving device with too much data. Flow control mechanisms manage data transmission between the devices so that the sending device does not transmit more traffic than the receiving device can process. Windowing (similar to what is used in TCP) is one example of a flow-control scheme. In windowing, the source device sends data but requires an acknowledgment from the destination after a certain number of packets have been sent. The windowing dictates how much data the source can send between acknowledgments from the destination.Congestion Control: Congestion control is about controlling the traffic sent into a network so as to avoid resource oversubscription and congestive collapse. This is done by allowing an end-system to take steps to reduce resource overconsumption, such as reducing the rate of sending data.Error-Checking: Error checking is different from error recovery. Error checking involves utilizing various mechanisms for detecting transmission errors, while error recovery involves taking action, such as requesting that data be retransmitted, to resolve any errors that occur during transmission. A common error-checking scheme is the Cyclic Redundancy Check (CRC), which when applied to received data, detects errors, allowing the receiver to discard corrupted data. Generally, the Transport Layer is responsible for making sure that the data is delivered error-free and in the proper sequence, but the Data Link Layer can also support such capabilitiesThe Transport Layer segments data into smaller units (called segments) for transport. Each segment is then assigned a sequence number, so that the receiving device can reassemble the segments in the right order on arrival to create the original data.
Proactive flow control using adaptive beam forming for smart intra-layer data communication in wireless network on chip
Published in Automatika, 2023
Dinesh Kumar T.R., Karthikeyan A.
Intelligent Head Agent: The wireless router in each cluster acts as a head node and is referred to as the Intelligent Head Agent (IHA) of the cluster. The proposed model consists of four IHA nodes in each layer. The primary objective of IHA (Wireless Router) is to perform intra-layer communication, i.e. the IHA employs communication via horizontal wireless links with its neighbour IHAs in the same layer. It comprises a mm Wave wireless transceiver and an on-chip zigzag Ansoft HFSS (High-Frequency Structural Simulator) antenna specifically characterized to initiate radiation in an angular pattern. The mm Wave transceiver's power of the wireless interconnect in IHA is optimized to cover the entire chip or the layer area. This enables intra-layer communication with neighbour IHAs in a single-hop fashion. The primary objective of IHA is to Exploit Admission Control using Fuzzy Inference (ACFI) for effective data communication via the Proactive Flow Control using Adaptive Beam Formation (PF_ABF) module.We significantly reduce congestion and interference caused in wireless channels through angular beam formation. The angular dispersion of information towards the target prevents data from being broadcast throughout the layer or the chip.Optimizes resource utilization by intelligently exploring neighbour's node status using metrics such as load, link quality, and service provided.Manages transmission by adaptively directing packets towards their destination by-passing potentially congested areas.
Energy Efficiency Analysis by Game-Theoretic Approach in the Next Generation Network
Published in IETE Technical Review, 2020
In this section, a non-cooperative game-theoretic method is introduced to adaptively allocate power in a two femtocell and one macrocell based HetNets. The aim is to optimize the network coverage with the limitation of the required signal to interference plus noise ratio (SINR) and the safety of an MU.1 A player is the resolution creators in the game. In cognitive-femtocell networks, FBSs are treated as the players. The actions are the set of options accessible to every player. At any moment in time, a player should select a component from the set of actions. Usually, a set of actions may be distinct for dissimilar players. In cognitive-femtocell networks, the set of actions are generally the selection of modulation coding scheme (MCS), bit rate, network protocol, flow control metric, adaptive BS transmit power, etc. Whilst any player selects an action, the leading “action profile” decides the consequences of the game. Generally, priorities are provided by defining a payoff function. A larger numerical value of the payoff function signifies that the consequence is of greater importance in contrast to a consequence with a smaller payoff function. In this analytical framework, for a broader aspect, we further consider that there are N number of macro networks. Let be the number of femtocells and FUEs be directly served by MBS in cogntive femtocell networks. In general, the numbers of FBSs and FUE are appealing to get connected to MBS is large, which is, . In every time slot, while a specific spectrum is utilized by an FBS, the goal of the FBS is to optimize its EE transmissions by assigning its power. Likewise, when the band is utilized by an MUE, an MBS does the energy-efficient power assignment. Depending upon the above exchange of views, the issue of resource allocation can be formulated for energy-efficient transmission in HetNets as a non-cooperative game problem, as explained in the following subsection.