TBF (Temporary Block flow) is the start and end of a session on behalf of the user, we are in the statistics of GPRS traffic, is often concerned about PDCH traffic and tch and PDCH conversion (if the device supports conversion), To assess whether the community is busy or busy, macro analysis, so that it can characterize a community of busy and busy, but does not represent the user in the use of the real feeling of GPRS, for example, 1 users using laptop Internet, occupy 4 PDCH channel, at this time for users of this Sessoin Only the only TBF, at this time the PDCH channel should be high traffic, but the user feel good, because a user exclusive 4 channels, at this time the RLC layer bandwidth roughly calculated also has 50kb/s, if the application CS3, 4, the bandwidth is higher. If 100 users use these 4 channels, the same PDCH channel is busy, but there are 100 sessions running, it can be considered that there are 100 TBF (in fact, because of the number of TBF per PDCH limit, so not 100), That's only 0.5 of the bandwidth per user, and it's not going to work at all. So simple to PDCH is busy or idle can not reflect the user's true feelings. Therefore, we need to pay attention to the relationship between TBF and PDCH, to analyze the occupied bandwidth of each TBF, and in fact, many manufacturers of statistics on the TBF statistical items are very few, can not be analyzed from the data. This is a need for us to conduct in-depth analysis.
Another problem is that the number of TBF concurrency on a single PDCH is limited, for example, the upper and lower TBF on 1 PDCH channels can only be up to 4 at the same time, so there is a problem here, is how the user's TBF is assigned to the PDCH channel, some manufacturers are using parallel algorithm, That is, 4 channel users are all occupied, each PDCH on the allocation of a user's TBF, so that 4 users at the same time Occupy 4 pdch, the new user is unable to access, need to adjust the configuration of PDCH channel, this process needs a certain time and algorithm, which will also have a certain impact on the user's perception. Another is the vertical algorithm, that is, to set aside a certain pdch, for the new access to the user reservation, but the user can not get the best bandwidth. This is also in the GPRS network optimization needs to pay close attention.
GPRS system wireless resources refers to the PDCH,PDCH is all GPRS attached mobile phone sharing and dynamic distribution in the community, in the form of TBF (temporary Block Flow) to divide, on demand, when the data (specifically, rlc/ Mac block) needs to be transferred when the TBF is assigned, TBF will be released after the transmission is complete. TBF is represented as TFI (the upper and lower lines TBF are independent). TBF uses 5-bit encoding, so there are up to 32 TBF on a single pdtch, meaning 32 phones can transmit data simultaneously (but not every manufacturer can support so many users to share a physical channel).
TBF (Temporary Block Flow) is a physical connection used by two wireless resource entities to support one-way delivery of LLC PDUs on PDCH. The network can assign one or more PDCH channels to the TBF. A TBF contains many Rlc/mac blocks that are used to host one or more LLC PDUs. The network arranges a TFI (temporary Flow Indicator) for each TBF to uniquely identify a TBF.
