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Carrier sensing method for multi-point access system
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A technology of carrier sensing and multi-point access, which is applied in the direction of transmission system, digital transmission system, modulated carrier system, etc., can solve the problems of reducing system efficiency, system efficiency reduction, unpredictable channel recovery and idleness, etc., and achieves improving system efficiency Effect
Active Publication Date: 2009-02-11
SPREADTRUM COMM (SHANGHAI) CO LTD
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[0003] In the existing carrier sense technology, it is generally judged by detecting energy. In the case of interference, especially in wireless systems, this detection method is easy to misjudgment (judging idle as busy) and causing system failure. Efficiency is reduced. At the same time, when the channel is detected to be busy, this detection method cannot predict when the channel will return to idle. It can only listen all the time or wait for a random time to listen again, which brings power consumption to the terminal. also reduces the efficiency of the system
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Embodiment 1
[0032] Embodiment 1: Public channel access signal A
[0033] See figure 2 , is a frame structure diagram of the common control channel access signal A in Embodiment 1 of the present invention. figure 2 Each grid in the first layer represents a GSMwirelesssubframe, that is, 120 / 26ms.
[0034] F stands for GSMfrequency correction burst, that is, GSMFrequency Correction Burst, S stands for GSM synchronization burst, that is, GSM Synchronize Burst, and P stands for GSM regular burst, that is, GSM Normal Burst.
[0035] The time for the user to send a data frame to access the public channel for one access is M*18*120 / 26ms, and M can be adjusted according to needs. For example, if M=26, the time for one access to occupy the public channel is 2160MS.
[0036] The S subframe uses the synchronized burst (SB) of the GSM system and carries 25 bits. Some or all of the bits can be defined as SFN (SubFrame Number). The first S subframe SFN=1.
[0047] Embodiment 2: Common channel access signal B
[0048] see Figure 4~6 . Figure 4 It is a frame structure diagram of the common control channel access signal B in Embodiment 2 of the present invention. Figure 5 It is a TD-SCDMA system burst structure diagram of Embodiment 2 of the present invention. Image 6 It is a diagram of the DwPTS burst structure in Embodiment 2 of the present invention.
[0049] Figure 4 In the third layer, TS0-TS6 represent 7 time slots, all of which adopt the system burst structure in TD-SCDMA, with a length of 864chips. DwPTS represents the downlink pilot time slot, which adopts the DwPTS burst structure in TDS-CDMA, with a length of 96chips , GP stands for idle, length 256chips.
[0050] Figure 4 In the second layer, each grid represents a subframe with a duration of 5 ms.
[0051] The time for one access to occupy the public channel is M*4*5ms, and M can be adjusted according to needs
[0052]DwPTS and TS0 are always sent, TS1-TS6...
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Abstract
A carrier sensing method of a multi-point access system comprises the following steps: (1) transmitting a data transmission request to a media access layer; (2) packing data to be transmitted to a data frame consisting of N sub-frames with a given signal sub-frame inserted therein; (3) checking to determine whether the given signal sub-frame is present in public control channel access signals and, if so, turning to step (4), or else, turning to step (6); (4) decoding the given signal sub-frame to obtain the sub-frame number of the signal; (5) waiting for (N-SFN)*t, and retuning to step (2) for further sensing when the detected data frame is ended; and (6) transmitting the data frame by the user. The method can accurately sense carrier, and can predict when a channel is idle if the channel is busy. The method has the advantages of improved system efficiency and power saving.
Description
technical field [0001] The invention relates to a carrier sensing technology, in particular to a carrier sensing method of a multipoint access system. Background technique [0002] In a multi-point access system, multiple users may send data frames at the same time. In order to avoid conflicts, the access layer must perform carrier sense before occupying the channel to confirm that the channel is idle. [0003] In the existing carrier sense technology, it is generally judged by detecting energy. In the case of interference, especially in wireless systems, this detection method is easy to misjudgment (judging idle as busy) and causing system failure. Efficiency is reduced. At the same time, when the channel is detected to be busy, this detection method cannot predict when the channel will return to idle. It can only listen all the time or wait for a random time to listen again, which brings power consumption to the terminal. It also reduces the efficiency of the system. Co...
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