Vývoj standardu digitální mobilní sítě pro hlasovou komunikaci začal v první polovině 80. let minulého století společnostmi Nordic Telecom (severské státy využívající Nordic Mobile Telephony 450 MHz (NMT-450))a holandským Postal, Telegraph and Telephone (PTT) (národní regulátor). Evropská komise navrhla použití pásma 900 MHz a vydala nařízení pro vyhrazení tohoto pásma v jednotlivých státech pro zajištění roamingu. V roce 1987 byla založena skupina Group Speciale Mobile. Zahrnovala ...
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Inefficient usage!
Dedicated DCH
UNTS
R99
Shared HS-DSCH
HSDPA
Time
multiplexingFast user scheduling Node based
on reported conditions
2ms
10ms
code
multiplexing
“Big shared pipe”
wasted bandwidth!
Figure Time multiplexing downlink channel with HSDPA
The HS-DPCCH, signaling channel paramount importance provides
Channel Quality Indicator (CQI), ACK and NACK.
Based this CQI, the UMTS BTS may change every the modulation, the coding
and the number codes during all the communication.59: Princip multiplexování kód˚u pro uživatele sdíleném kanálu [internet]
Pˇrehled sdílení kanálu multiplexování kódu ukazuje obr. The
numbers indicate the number bits after the different stages using the example case the text.
Obrázek 3. Thanks the real time
knowledge (every ms) the radio conditions for each user, HSDPA matches the exact
throughput the radio bandwidth available for every user during the communication,
which means higher average throughput and higher spectrum efficiency. obrázku jsou znázornˇeny další vy-
lepšení standardu rádiové ˇcásti, jako zkrácení TTI pˇresun ˇrízení schedulingu Node B. 3.60: Incremental redudancy HSDPA sítích [17]
. should noted that chang-
ing the number channel bits changing the modulation scheme the
number channelization codes also affects which coded bits that are trans-
mitted even the and parameters are unchanged between the transmission
attempts.
same set information bits can generated.59.
3. Princip HARQ vidˇet obr.
Hybrid Automatic Repeat Request (HARQ) Dalším inovativním krokem HSDPA HARQ rádiovém
rozhraní.Fakulta elektrotechniky komunikaˇcních technologií VUT Brnˇe 111
11
during the TTI, may split among several HSDPA users.
Obrázek 3.61.16 example the generation different redundancy versions the case IR. There more power
control with HSDPA and the High Speed Downlink Shared Channel transmitted a
constant power while the modulation, the coding and the number codes are changed
to adapt the variations radio conditions. The CQI based the
measurement the CPICH power reflects the Signal Interference Ratio (SIR).60 paralelní zpracování jednotlivých HARQ proces˚u obr. 3.
High-Speed Downlink Packet Access 167
2432
704
704
0
1920
1920
Initialtransmission
To Turbo
decoder
Multiple received copies the same
coded bits are added prior decoding
(as the case for Chase combining)
2404
CRC insertion, scrambling, rate-1/3
Turbo coding, tail inclusion
2432
2432
2432
Systematic bits
Parity bits
First rate matching
2432
2284
2284
Second rate matching,
initial transmission
Second rate matching,
retransmission
Retransmission
Soft combining the UE
Transport block
Virtual buffer
Figure 9
