QoS in Integrated 3G Networks Robert Lloyd Evans (2)

Podobne

Cytat

Do celu tam się wysiada. Lec Stanisław Jerzy (pierw. de Tusch-Letz, 1909-1966)
A bogowie grają w kości i nie pytają wcale czy chcesz przyłączyć się do gry (. . . ) Bogowie kpią sobie z twojego poukładanego życia (. . . ) nie przejmują się zbytnio ani naszymi planami na przyszłość ani oczekiwaniami. Gdzieś we wszechświecie rzucają kości i przypadkiem wypada twoja kolej. I odtąd zwyciężyć lub przegrać - to tylko kwestia szczęścia. Borys Pasternak
Idąc po kurzych jajach nie podskakuj. Przysłowie szkockie
I Herkules nie poradzi przeciwko wielu.
Dialog półinteligentów równa się monologowi ćwierćinteligenta. Stanisław Jerzy Lec (pierw. de Tusch - Letz, 1909-1966)

[ Pobierz całość w formacie PDF ]
.GPRS109In GPRS the window size WS is 64, and the SNS is 128.For EGPRSthese values are extended, with SNS rising to 2,048 and WS ranging from 64up to a maximum depending on the number of slots used (from 1 to 8) witha peak of 1,024 for eight slots.There are also minimum window sizesfor EGPRS.Table 5.1 shows the maxima and minima in relation to themultislot capabilities of the mobile.In all cases the receiver and transmitter have to maintain a largenumber of timers to control retransmissions and request/release of temporaryblock flows.Logical ChannelsLogical channels comprise both CS traffic channels and packet data trafficchannels (PDTCH).Traffic channels [16] carry either voice or data in CSmode and consist of three basic types:1.Full-rate traffic channel (TCH/F) with gross information rate of22.8 Kbps;2.Half-rate traffic channel (TCH/H) with gross information rate of11.4 Kbps;3.Enhanced full-rate traffic channel (E-TCH/F) with gross informa-tion rate of 69.6 Kbps.The distinction between E-TCH/F and theothers is that the modulation scheme used in EDGE is 8-PSKinstead of GMSK.Table 5.1EGPRS Window SizesMultislot CapabilityMinimumMaximum1641,1922961,25631601,38441601,51252241,64063201,76873521,89685121,024110QoS in Integrated 3G NetworksWhen used for data, the actual data rates and channel acronyms are as givenin Table 5.2.The difference between these data rates and the three possible grossinformation rates is primarily due to the need for channel coding to provideerror correction together with some small overheads.Layer 2 uses a wide range of distinct logical channels to carry out its PS needs.These are as follows:• Common packet control channels (PCCCH and CPCCCH), whichinclude packet random access channels (PRACH and CPRACH),packet paging channels (PPCH and CPCCH), packet access grantchannels (PAGCH and CPAGCH), and packet notification chan-nels (PNCH and CPNCH);• Packet broadcast control channels (PBCCH and CPBCCH);• Packet data traffic channels (PDTCH);• Packet associated control channel (PACCH);• Packet timing advance control channels (PTCCH).Common packet control channels are a generic term for the four subtypesPRACH, PPCH, PAGCH, and PNCH together with their compact versionsfor mobiles able to support that mode.PRACH and CPRACH are used by the MS to initiate UL data transferor signaling, while the paging channels are used by the network to do thison the DL.PAGCH and CPAGCH are used in the packet transferTable 5.2Data RatesChannel Name Data Rate (Kbps)TCH/F14.4≤14.4TCH/F9.6≤ 9.6TCH/F4.8≤ 4.8TCH/F2.4≤ 2.4TCH/H4.8≤ 4.8TCH/H2.4≤ 2.4E-TCH/F28.8≤28.8E-TCH/F32.0≤32.0E-TCH/F43.2≤43.2GPRS111establishment phase to grant resources to the MS.PNCH and CPNCHnotify the MS of a point-to-multipoint packet transfer, while the broadcastchannels are used to transmit system information.The PDTCH are allocated to either a single MS or to a group of MSsfor the purpose of packet data transfer.In multislot operation a single MSmay be allocated several PDTCH for use in parallel to achieve a higher datathroughput.PDTCH are unidirectional for either UL or DL and can beeither full-rate or half-rate depending on the physical data channel to which they are mapped in layer 1.The remaining two control types are dedicated to a specific MS.PACCH carries signaling, power control information, and resource assign-ments to a specific MS, while PTCCH is for timing control information.5.3.2 MAC-MODEThe MAC layer controls the allocation of channels and timeslots.The GPRSMAC function is responsible for providing:1.Efficient multiplexing of data and control signaling on both ULand DL, the control of which resides on the network side.On theDL, multiplexing is controlled by a scheduling mechanism.On theUL, multiplexing is controlled by medium allocation to individualusers (e.g., in response to service request);2.Mobile originated channel access and contention resolution betweenchannel access attempts, including collision detection and recovery;3.Mobile terminated channel access and scheduling of accessattempts, including queuing of packet accesses;4.Priority handling.This is performed through the exchange of control messages between thenetwork and mobile.The messages most directly associated with user traf-fic are channel, packet channel, and resource reallocation messages from themobile, and packet UL/DL assignment messages from the network.There are five modes of operation of the MAC layer, and these areselected by the network and passed to the mobile in the packet assignmentmessages:1.Dynamic;2.Extended dynamic;112QoS in Integrated 3G Networks3.Fixed full-duplex;4.Fixed half-duplex;5.Exclusive.Dynamic assigns a single packet dedicated channel (PDCH) to a mobile thatis already in either packet transfer or dual transfer mode.Extended dynamicassigns up to eight PDCHs to a mobile in either of these modes accordingto the mobiles multislot capability.These two allocation modes provide forsharing of resources based on the USF field at the start of each radio block [ Pobierz całość w formacie PDF ]

zanotowane.pl

doc.pisz.pl

pdf.pisz.pl

trendy-girls.htw.pl