Network control (NC) MR

Network carries relative network control parameters carried in PSI5 broadcast on PBCCH, SI13 on BCCH, and PSI13 on PACCH to control MS.

Under NC1 or NC2 mode, MS should carry out NC measurement and indicate MR period in PSI5.

II. Extended MR

Network can order MS to send extended MR. MS sending extended MR is controlled by XT Measurement Order parameter. This parameter is contained in PSI5 or order packet measurement message. Network broadcasts PSI5 on PBCCH, or sends order packet measurement message on PCCCH or PACCH to address a specified MS. The value of parameter EXT Measurement Order should be EM0, EM1.

When MS is under EM1 mode, it should carry out EM measurement. MR period is specified in field EXT Reporting Period in PSI5 or in order packet measurement message. After MS receives order of EM MR, it starts timer T3178 according to the instructed report period. When T3178 is active, MS can reselect a new cell which is in EM1 mode. If T3178 timeout duration is greater than the report period indicated in the new cell, MS should immediately use this period to restart T3178. If timer timeout duration is less than this period, then T3178 continues working.

Uplink MR is supported. The priority and quality of uplink transmission signal from MS to site calculated by BTS is sent to PCU through inband signaling of Abis interface TRAU frame and is used to generate MR.

2.3.12 Supported Flow Control

Gb interface and Um interface have different physical mediums and transfer protocols, which leads to their different transfer rates. The data transfer rate of Gb interface is greater than that of Um interface. Moreover, in downlink data transfer, the data transfer through Um interface is restricted by MS multislot capacity, radio quality, whether there is radio channel available in the cell. Thus the transfer rate is not constant and it is necessary to implement flow control for downlink data.

When cell is in normal state, PCU starts flow control procedure: PCU periodically reports the cell bucket size and the cell bucket rate according to the state of radio packet channel in the cell, and reports MS bucket size and bucket rate according radio resource occupation state of MS.

SGSN adjusts the downlink data rate of this cell/MS according to the reported parameters, which is the purpose of downlink data flow control.

Note:

z Cell bucket refers to the maximum packet data quantity that allowed being stored. It varies from the number of packet channels in the cell.

z MS bucket refers to the maximum packet data quantity that allowed being stored. It varies from the number of packet channels assigned to MS.

z Bucket rate is data transfer rater. Huawei PCU system can implement downlink data flow control, report the bucket size and bucket rate of the current cell/MS to SGSN, and adjust the reported parameters according to the changes of cell packet resource and MS resource occupation.

z Uplink flow control supports refusal of immediate assignment on CCCH.

z For downlink flow control, BVC downlink flow control and MS downlink flow control are supported.

2.3.13 Supported Dynamic Handover between TCH and PDCH

At the early stage of GPRS service, GSM network is usually updated to support GPRS service due to the shortage of radio frequencies. In order to reduce the effect on original GSM circuit switched speech services caused by GPRS service, Huawei GPRS BSS supports the dynamic handover between TCH and PDCH.

1) Supporting the handover from TCH to PDCH during the establishment of TBF.

Huawei GPRS BSS classifies channel attribute into fixed packet service channel, voice service channel and dynamic channel. Fixed packet service channel is dedicated for packet data service, such as PBCCH, PCCCH, and PDCH; voice traffic channel is dedicated for voice service, such as TCH, BCCH, SDCCH; and the dynamic channel is voice TCH at its initialization stage. It can be converted between TCH and PDCH.

When there is more packet traffic and the speech channels are relatively idle, PCU will request the BSC to convert the dynamic channel into the dynamic packet data channel.

Whereas when BSC determines the speech channels are busy, it can also request PCU to return the converted dynamic channel and use it again as speech channel. In this process, the speech service is given the priority over the packet service to guarantee the original speech services.

2) Supporting inter-cell PDCH sharing on the same RPPU

2.3.14 Supported Packet Access Function

When MS upper layers have data to be transferred, MS RLC/MAC will initiate packet access. MS packet access types are as follows: Short access, phase I access, phase II access, single block not establishing TBF access, paging response, cell update, mobility management.

z If the data to be transferred is less than 8 RLC blocks, the MS channel request type is short access. The number of data packets is calculated according to CS-1.

z If the data to be transferred is more than 8 RLC blocks and RLC mode is required to be acknowledged mode, then MS channel request type is phase I access or phase II access.

z If MS MR is to be transferred, then the channel request type is monolith not establishing TBF access.

z For channel request type of paging response, cell update, and mobility management, they are usually processed as phase I or phase II access.

For short access and phase I access, radio resource is assigned for MS in the first time (such as TFI, dynamic assignment of USF or list of fixed assignment of radio block position list)

For two-phase access channel request, the first request is for assigning a radio block for MS. MS sends packet resource request message on assigned sigle radio block for second resource assignment (including TFI, USF or radio block position list). Then MS begins to transfer data on assigned resource. The packet channel request is an access burst with 8 bit or 11 bit, so it carries a little of information. While the packet resource request is an RLC/MAC signaling packet with CS-1, it can carry relatively more information (including MS TLLI, MS multislot capacity, radio priority). These kinds of information are helpful in assigning appropriate resource for MS.

M900/M1800 PCU supports all these access types. For access types such as paging response, cell update, and mobility management, it processes them by regarding them as two-phase ones.