A Method for Reducing Carrier Sense Multiple Access Resource Conflict
A technology of multiple access and resource conflict, which is applied in the field of carrier sense multiple access transmission resource usage, can solve the problems of increasing the probability of conflict, the system cannot be used normally, and the utilization rate of system transmission resources is reduced, so as to achieve a reduced probability. Effect
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specific example 1
[0054] Broadband power carrier communication (abbreviation: PLC) is a power communication system that uses transmission lines as the transmission medium of carrier signals. Since the power transmission line has a very strong support structure and more than 3 conductors (generally there are three-phase good conductors and one or two overhead ground wires), it is economical to use the power frequency current to transmit the carrier signal at the same time as the transmission line And very reliable. This kind of comprehensive utilization has already become the unique communication means adopted by all electric power departments in the world. In order to promote the application of power carrier communication, the State Grid has also released the enterprise standard agreement "Communication Protocol for Power User Information Collection System".
[0055] In the agreement, the OFDMA method is clearly adopted for signal modulation, and the use of transmission resources is divided in...
specific Embodiment 2
[0066] In the specific embodiment 1, the method of grouping by site identification is adopted. In practical engineering applications, site priority or service priority can also be used for grouping. The following uses the method of priority for grouping.
[0067] In the PLC system, the transmitted data messages can be divided into two categories, one is the application message, and the other is the network management sub-layer message.
[0068] When competing for channels, packets or devices with higher priority should have higher channel competition capability than those with lower priority, that is, they should occupy the collision detection time slice first. There is a link identifier field in the variable area of the start of frame (abbreviation: SOF), which is used to indicate different priorities or different services. The priority of the message is determined by the classification rules, see Table 1.
[0069] Table 1 Packet classification rule table
[0070]
[0...
specific Embodiment 3
[0086] In addition to the way of grouping in the above two examples, according to the present invention, the amount of data cached in the site can also be used for grouping.
[0087] In this embodiment, it is assumed that the maximum amount of data to be sent is K bytes, and the stations are divided into L groups, and the specific groups are shown in Table 4.
[0088] Table 4 is grouped according to the amount of data to be sent
[0089] Data volume (M) group (K / L)(L-1)=
1 (K / L)(L-2)=
2 ... ... 0=
L
[0090] The parameters K bytes and L packet numbers are involved, which can be fixed in the design of the site equipment, or can be broadcast in the central beacon of the central control site.
[0091] In practice, it is assumed that the amount of data to be transmitted by the two stations STA1 and STA2 is K1 and K2 bytes respectively, calculated according to Table 4, it is assumed that STA1 falls into the first gr...
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