There are two mechanisms standardized (STANAG and STANAG ) which are discussed here. These provide similar characteristics to the IP user, and. 25 Jul Unid UTC USB, STANAG Fast Link setup (FLSU) bursts followed by Low rate Data Link (LDL) forward transmissions. 5 Jan Quoting from STANAG “Transmitting N Async_FLSU_Request PDUs guarantees that all other scanning stations will scan the calling.
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A TCP based application could give reasonable performance if the following factors are all present:. The Transmit 45388 Control TLC sequence gives the transmitter and the receiver opportunity syanag find a steady state before the preamble sequence is received. Where it is available as an option, ACP has. The burst waveforms employ code combining for data transmissions: They key issue for TCP is to minimize turnarounds. ACP works by dividing the data to be transferred into multiple packets.
4358 exchange is shown at the IP level. Since the retransmission of additional code bits is requested on a packet-by-packet basis, the code rate and therefore the effective data rate of each packet is reduced from the initial high rate only so far as is necessary for correct reception.
Each recipient will inform the sender of any missing packets so that they can be re-transmitted and at the end tells the sender that it has all of the packets. The above diagram notes how the TCP data flow causes turnarounds:. After the TLC sequence follows the preamble sequence which gives the receiver opportunity to detect the presence of the waveform.
This leads to many application turnarounds, where one end waits for the other. In summary, efficiency will depend significantly on the TCP implementations, and how they react to the network stnaag.
This will give the duration of total 1. This is very inefficient. If data is lost, this will be handled by the ACP protocol. When packets are lost, a TCP receiver will reduce close down the window, which will in turn reduce the data rate.
With some of these papers, it is important to read the details and look at the numbers, which are all in line with the findings in this paper. The window is the mechanism used by TCP to control how fast it goes. The key performance stanwg with a rate based protocol and HF is getting the rate correct.
However, this arrangement does not take full advantage of the 3G calling channel congestion avoidance techniques. Reliable applications fall into two major classes according to how data transfer rate is controlled: When it is desired to be able to reach all network members with a single call, and traffic on the network is expected to be light, up to 60 network member stations may be assigned to the same dwell group.
It can be seen that there is only stanab single turnaround, after the data has been sent as ARQ is not used. Note that this exchange was to transfer a very short message, which fitted into a single IP packet. The mapping is very simple: There are two general issues relating to performance that are now described. The link may be shared with other STANAG applications which may have stsnag precedenceand their use will not be visible. The data link protocol is closely associated with the burst waveforms defined in the standard.
It can be seen that if a suitable size of window is chosen, ongoing data transfer can be mapped efficiently onto the underlying HF data exchange. A key problem is that there is no feedback to the application if more data is sent than can be handled by the link.
The data link protocol is closely connected with the burst waveforms stana in the standard, and cannot be run with other waveforms. It will inform the application later when it can send data again. The core Stsnag protocol is “chatty”. It also includes a couple of other parameters essential for the link setup. In a network operating 458 synchronous mode, these addresses are partitioned into a 5-bit dwell group number and a 6-bit member number within that dwell group.
Four additional unassignable addresses in each group xx are available for temporary use by stations calling into the network. HF Links are also used for voice communication.
A transmitting ACP application needs to control the rate at which it sends out packets, and when using IP there is not protocol mechanism to achieve this.
In situations of low packet loss, a UDP based approach is in practice reasonably reliable. This includes for instance frequency compensation and gain control. Unit data may be unacknowledged best effort or acknowledged reliable.