Post on 08-May-2020
DC Lab.
Assembly Coding for Implementing in DSP
❏ Procedure for assembly coding
● Special instructions for modem
floating pointsimulation
fixed pointsimulation
assemblyprogramming
debugging performanceverification
�� �� �� instruction � instruction � ������ �� �
� ��� �� ��6 instructions 2 instructions 8 MIPS
��� minimum ��� condition �� ��
6 instructions 2 instructions 3 MIPS
� ���� squaredistance �
7 instructions 3 instructions 5 MIPS
�� ! "#$ %&'bits () shift
2 instructions 1 instruction 2 MIPS
*+, -.� memory/0 data $ cyclic &1
234' ��
4 instructions 1 instruction 1 MIPS
Hamming distance � 7 instructions 1 instruction 2 MIPS
DC Lab.
❏ IS-136 modem �������� �������� ������������
● modulation/demodulation : 0.5MIPS
● pulse shaping filter : 2MIPS
● channel coding/decoding : 4MIPS
● timing recovery : 1.5MIPS
● MLSE equalizer : 5MIPS
● total 13MIPS
DC Lab.
Introduction to IS-95 CDMA system (1)
❏ Multiple access: DS-CDMA/FDD
❏ Frequency band (USA): 869-894MHz (Reverse), 824-849MHz (Forward)
❏ Channel spacing: 1.25MHz
❏ Modulation● Q-Spread BPSK (Forward)
● Orthogonal modulation with noncoherent detection (Reverse)
❏ Speech coding: QCELP (Qualcomm Code-Excited Linear Prediction)
❏ Data rate: 9.6k, 4.8k, 2.4k, 1.2kbps (Use different transmit power level)
❏ Channel coding● K=9, R=1/2 conv. Coding (Forward), 1/3 conv. Coding(Reverse)
● CRC (9.6kbps, 4.8kbps)
❏ Frame duration: 20ms
❏ Chip rate: 1.2288 Mcps
DC Lab.
Introduction to IS-95 CDMA system (2)
❏ Single long PN code : 242-1 chips● Forward link : Data scrambling● Reverse link : Spreading, Different long PN code for different user and channel
❏ Single pair of short PN code : 215 chips● Quadrature spreading● Base station is distinguished by the phase of short PN sequence.● 256 different phases (spacing: 64 chip)
❏ 64 orthogonal Walsh codes● Forward link : 64 channels , W0: Pilot channel, W32: Sync channel
◆ W1-W7: Paging channel (7), W8-W63:Traffic channel (55)
● Reverse link : Orthogonal modulation (Noncoherent demodulation)
DC Lab.
Introduction to IS-95 CDMA system (3)
❏ Forward link channels● Pilot channel
◆ Synchronization (Especially, short PN code acquisition and tracking)◆ Phase recovery for coherent demodulation
◆ Channel estimation for RAKE receiver● Sync channel
◆ Synchronization (Long PN code), System information.● Paging channel - Used for paging message● Traffic channel - Transmit data
❏ Reverse link channels● Access channel
◆ Used by mobile to initiate communication with the base station and to respondto paging channel messages.
● Traffic channel - Transmit data
DC Lab.
IS-95 Transmitter structure (Forward link) (1)
Pilot Channel
W0 (All 0’s)
All 0’s
DecimatorLong code
Generator
1.2288 Mcps
Long Code
Mask forPaging Channel p
19.2 kbps
19.2 kbps
Wp
1.2288 McpsConv. Encoder
r=1/2, K=9
Symbol
Repetition9.6 kbps
4.8 kbps
19.2 kbps
9.6 kbps Block
Interleaver
19.2 kbps
Paging Channel
X
XX
DC Lab.
IS-95 Transmitter structure (Forward link) (2)
Add
CRCAdd 8 bit
Encoder Tail
Conv. Encoder
r=1/2, K=9
Symbol
Repetition8.6 kbps
4.0 kbps
2.0 kbps
0.8 kbps
9.2 kbps
4.4 kbps
2.0 kbps
0.8 kbps
9.6 kbps
4.8 kbps
2.4 kbps
1.2 kbps
19.2 kbps
9.6 kbps
4.8 kbps
2.4 kbps
Block
Interleaver
19.2 kbps
DecimatorLong code
Generator
1.2288 Mcps
Long Code
Mask forUser m
19.2 kbps 19.2 kbps
Decimator
MUX
Power control bits800 bps
800 bps
Wn
1.2288 Mcps
Traffic Channel
XX
DC Lab.
IS-95 Transmitter structure (Forward link) (3)
I-Channel short PN sequence
1.2288Mcps
Q-Channel short PN sequence
1.2288Mcps
Baseband
Filter
Baseband
Filter
X
X
cos (2πf0t)
sin (2πf0t)
+ S(t)
Conv. Encoder
r=1/2, K=9
Symbol
Repetition1.2 kbps 2.4 kbps
Block
Interleaver4.8 kbps
W32
1.2288 Mcps4.8 kbps
Sync Channel
Σ
X
X
X
DC Lab.
IS-95 Transmitter structure (Reverse link) (1)
Add
CRCAdd 8 bit
Encoder Tail
Conv. Encoder
r=1/3, K=9
Symbol
Repetition8.6 kbps
4.0 kbps
2.0 kbps
0.8 kbps
9.2 kbps
4.4 kbps
2.0 kbps
0.8 kbps
9.6 kbps
4.8 kbps
2.4 kbps
1.2 kbps
28.8 kbps
14.4 kbps
7.2 kbps
3.6 kbps
Block
Interleaver
28.8 kbps
Long code
Generator
1.2288 Mcps
Long CodeMask
1.2288 Mcps64-ary
OrthogonalModulator
Data Burst
Randomizer
307.2 kcps
Traffic Channel
X #
DC Lab.
Add 8 bitEncoder Tail
Conv.
Encoder
r=1/3, K=9
Symbol
Repetition
4.4 kbps 4.8 kbps 14.4 kbps
Block
Interleaver
28.8 kbps
Long code
GeneratorLong Code
Mask
1.2288 Mcps
64-ary
Orthogonal
Modulator
307.2 kcps28.8 kbps1.2288 Mcps
Access Channel
I-Channel short PN sequence
1.2288Mcps
Q-Channel short PN sequence
1.2288Mcps
Baseband
Filter
Baseband
Filter
X
X
cos (2πf0t)
sin (2πf0t)
+ S(t)
D
1/2 PN chip (406.9 ns)
X
X
X
Σ
#
#
DC Lab.
IS-95 receiver structure
RF/IF A/D Searcher
FingersCombining Deinterleaver
ViterbiDecoder
Rx Data
Packet
Code Acquisition
RAKE receiver
DC Lab.
Modem chip structure of IS-95 receiver (Qualcomm MSM2300)
DFM : Digital FM
UART : Universal Asynchronous
Receiver/Transmitter
DC Lab.
● Waveform-Encoded Orthogonal Modulation (Sklar Sect. 5.1)
◆ Used for IS-95 (Hadamard Sequence)
DC Lab.
Spread-Spectrum Communication (1)
z Many users simultaneously transmit signals over a single frequency band.
z Ec/N0 is very low. (< 0)
z Individual chip timing can’t be recovered by traditional timing recovery methods.
z Timing is recovered by partial cross-correlation between received signals and local PN codes. Thisis called the code acquisition and tracking.
z Chip-level equalization is neither possible nor required. Symbol values are recovered by evaluatingcorrelations.
Fig.1. Waveform when there exist 4 users. Fig.2. Cross-correlation (length=256 chip, user: 4)
−100 −50 0 50 100−100
−50
0
50
100
150
200
250
Timing offset
cros
s co
rrela
tion
user 1+2+3+4user 1
0 20 40 60 80 100 120 140 160 180 200−4
−3
−2
−1
0
1
2
3
4
5
DC Lab.
User 1
User 2
X
PN1
X
PN2
+
s1(n)
s2(n)
X
PN1
X
PN2
r1(n)
r2(n)
∑PG
∑PG
User 1
User 2
1 -1
-1 1
X
X
PN1 = (-1 1 1 -1 1 -1 -1 -1)
PN2 = (-1 1 -1 1 1 1 -1 1) +
sc=(0 0 2 -2 0 2 0 2)
sc(n)
sc=(0 0 2 -2 0 2 0 2) X
X
PN1 = (-1 1 1 -1 1 -1 -1 -1)
PN2 = (-1 1 -1 1 1 1 -1 1)
r1=(0 0 2 2 0 -2 0 -2)
∑PG
∑PG
r2=(0 0 -2 -2 0 2 0 2)
(4 -4)
(-4 4)
DC Lab.
User 1 X
PN1
+s1(n)
X
PN1
X
PN1’ (Delayed)
r1(n)
r2(n)
∑PG
∑PG
sc(n)
Z-1
1
Multipath channel
User 11 -1
X
PN1 = (-1, -1 1 1 -1 1 1 -1 1, -1)
+ sc(n)
sc=(… -2 0 2 0 -2 -2 0 0 -2 ...)X
X
PN1 = (-1, -1 1 1 -1 1 1 -1 1 )
PN1’ = ( -1 1 1 -1 1 1 -1 1, -1)
r1=(… 2, 0 2 0 2 -2 0 0 -2 ...)
r2=(… 2 0 2 0 -2 -2 0 0, 2 ...)
∑PG
∑PG
(4 -4)
(4 -4)
DC Lab.
Code Acquisition and Tracking
r a(t)
2 e-j ω0t
L P Fg[ l ]
| |2
t = k∆ TC
H t1 η0 H t0
r [ k] LP
/ ∆
Σn = 1 (H t1)
(H t0)Ma jo r i t y
Log i c
l L P /∆
C o d eGene ra to r
V C O
| |2
| |2
-
+
L o o pFi l ter
ε[k]
(H 1) (H 0)
H 0 / H1
D e s p r e a d e ra n d
Da taDe tec to r
c [ k]c [ k+ ∆T C]
c[ k-∆TC]
Code Acquis i t ion Block
Code Track ing Block
DC Lab.
Active and Passive Correlator
❏ Active Correlator - Simple but slow acquisition (Decision every LPTC)
❏ Passive Correlartor - Complex but fast acquisition (Decision every ∆∆∆∆TC)
g [ l ]| |2
H t1 η0 H t0
r [ k] LP
/ ∆
Σn= 1
C o d eGenera to r Reset i f (H t0) o r (H 0)
(H t1)
(H t0)Major i ty
Log ic
H 0 / H1
l L P /∆
g [ k]| |2
( H t1 )
( H t0 )
Ht1 η0H t0
r [ k]∆ TC ∆ TC ∆ TC
Code Weigh t ing
Summat ion (H t1)
(H t0)Major i ty
Log ic
H 0 / H1
C o d eGenera to r
DC Lab.
Rake Receiver
X
X
cos(2πf0t)
sin(2πf0t)
LPF
LPF
L Parallel
Demodulation
Fingers
+
X1(k)
X2(k)
XL(k)
X(k)
x(t) [PN_Icos(2 πf0t+θ)+PN_Qsin (2 πf0t +θ)]
Short PN
sequence
despreading
W64,m
X
X
X
X
Σ
ΣChannel
Amplitude &
Phase
+
Code Tracking
loop (Early-late)
Initial timing fromsearcher finger
1 Finger
Xi(k)
DC Lab.
α[A+xkW64,m][PN_Icos(θ)
+PN_Qsin (θ)] +
+
+
+
Short PN_Q
Σ
Σ
+
+
W64,m
X
X
ΣΣ
Initial timingfrom
searcher finger
+
+
Avg.
Avg.
+
Code Tracking loop (Early-late)
Short PN_I
Code Tracking
loop (Early-late)
Initial timingfrom
searcher finger
α[A+xkW64,m] [-PN_Isin(θ) +PN_Qcos (θ)]
-
[A+xkW64,m] αcos(θ)
[A+xkW64,m] αsin(θ)
xk αcos(θ)
xk αsin(θ)
Channel Amplitude & Phase Estimationfrom Pilot Channel
α: Channel amplitude
A: Pilot channel value
θ: Phase offset
xk: Transmitted symbol
)ˆcos(ˆA θα
)ˆsin(ˆA θα
)ˆcos(ˆAx k θ−θαα
DC Lab.
References
[1] Electronic Industries Association, EIA/TIA IS-136: dual-mode mobile station-basestation compatibility standard, TIA, Washington D.C., 1994.
[2] Kamilo Feher, “Wireless digital communications,” Prentice Hall, 1995.
[3] Samueli, H., “On the design of FIR digital data transmission filters with arbitrarymagnitude specifications,” IEEE Trans. Circuits and Systems, vol. 38, pp. 1563-1567, Dec. 1991.
[4] Ging-Shing Liu and Che-Ho Wei, “Timing recovery techniques for digital cellularradio with ππππ/4 DQPSK modulation,” ICC’92, vol.1, pp.319-323, 1992.
[5] M. J. Omidi, S. Pasupathy, and P. G. Gulak, “Joint data and kalman estimation offading channel using a generalized viterbi algorithm,” ICC’96, vol. 2, pp.1198-1203, May 1996.
[6] M. Luise and R. Reggiannini, “Carrier frequency recovery in all-digital modemsfor burst-mode transmissions,” IEEE Trans. Commun., vol. 39, pp.1169-1178,Feb./Mar./Apr. 1994.
DC Lab.
❏ Adaptive PRML Detection
�������� � � � � ������������ �������� ��������
● Adaptive PR Equalizer followed by Viterbi Detector (PRML)● Feed-Forward Filter shapes the target Partial-Response P(D)● We select those P(D) that matches channel characteristics
◆ HDD : 1-D^2(PR4), 1+D-D^2-D^3 (EPR4)◆ MOD, DVD : 1+D(PR!), 1+2D^2+D^3(PR2), etc.
● Ref : John M. Cioffi et al, “Adaptive Equalization in Magnetic-Disk Storage Channels” IEEE Comm. Magazine Feb. 1990.
Xn*hn
Xn : B it Information
hn : Channel Impulse Resp.
Pn : PR Impulse Resp.
P(D) : z-T r. Of Pn
PRML Receivers
DC Lab.
Software Defined Radio (SDR)
ParametersAccess Tech.
(Feature)Freq. Band
RF channelspacing (kHz)
Basebandsampling
GSMTDMA/FDMA
(GMSK)890-915MHz Forward935-960MHz Reverse
200 270.833kbps
Cdma2000CDMA/FDMA(OCQPSK)
1885-2025MHz2110-2200MHz
N �1250N=1,3,6,9,12
N �1.2288McpsN=1,3,6,9,12
W-CDMACDMA/FDMA(OCQPSK)
1885-2025MHz2110-2200MHz
1250/5000/10000/20000
1.024/4.096/8.192/16.384
Mcps
Wireless LANCSMA/FDMA
(OFDM)
Lower: 5.15-5.25GHzMiddle: 5.25-5.35GHzUpper: 5.725-5.825GHz
20000 20Msps
�� DVB (OFDM) UHF 7000/8000 9.14Msps
�� DVB (8VSB) VHF, UHF 6000 10.76Msps
Some Rescent Wireless Communication Systems.
DC Lab.
SDR Concept
SOFTWARE INSTALLATION:
z IN MANUFACTURING
z IN STORE (SIM CARD, MEMORY MODULE)
z VIA AIR
Common
Programmable
RF
Hardware
Common
Programmable
Baseband
Hardware
Software
DC Lab.
SDR Systems
Multibeam Antenna Array
Multiband RF Conversion
Wideband A/D & D/A Conversion
Digital IFProcessing
BasebandProcessing
Digital IFProcessing
BasebandProcessing
Network
Transmit Receive
ProgrammableHardware,
DSP &Software Design
DC Lab.
● Decimation filter with very narrow passbande.g. IS-95 : 1.25M / 50M = 1/40
GSM : 200k / 50M = 1/250
e.g.fc=37.5MHzBW=15MHz
e.g.fc=12.5MHzBW=15MHz
ADC50Msps12bits
DecimationFilter
DecimationFilter
ComplexSinusoid
Generator
ωmcos( n)
ωm-sin( n)
Programmable Downconverter (PDC)
RFDSP for
Baseband
Bandpass Sampling
ωm−ωm
5 20
Programmable Downconverter
DC Lab.
PDC with CIC and ISOP (Proposed)
ISOP (Interpolated Second Order Poly.)
)1(|2|
1)( 2kMkM zcz
czP −− ++
+=
Magnitude response of P(z)
(1-z )-1 (1-z )-RML
L1(1+cz +z )-k -2k MHBFs PFIR2
m
CIC filter ISOPMultistageHalfbandDecimationFilter
Fs
F /Ms
F /Ms
F /2s
m M
Q FIR
InterpolationFilter
(1-z )-1 (1-z )-RML
L1(1+cz +z )-k -2k
CIC filter ISOP
k=1k=2k=3
0 1/8M 1/4M 3/8M 1/2M0
1
2
3
4
5
6
Normalized frequency
Mag
nitu
de
c=−3
c=−4
c=−5
c=−6
DC Lab.
SDR References
[1] Special issue on Software Radios, IEEE Commun. Mag., vol.33, no.5, May1995, pp.24-68.
[2] Special issue on Software Radio, IEEE Commun. Mag., vol.37, no.2, Feb.1999, pp.82-131.
[3] Special issue on Software Radio, IEEE Jour. on Selected Areas inCommun. , May 1999.
[4] ACTS program, http://www.infowin.org/ACTS
[5] FIRST, http://www.era.co.uk/first/first.htm
[6] SDR forum, http://www.sdrforum.org
[7] Abstract of SDR Market Demand Forecast Series on Software DefinedRadio, Issue #1 Nov. 1, 1998, http://www.sdrforum.org
DC Lab.
SDR References
[8] H. J. Oh, S. Kim, G. Choi, Y. H. Lee, "On the Use of Interpolated Second
Order Polynomials for Efficient Design in Programmable Downconversion,"IEEE Jour. on Selected Areas in Commun. , vol.17, pp.551-560, May 1999.
[9] J. E. Russel, "Wireless Communications: Past, Present & Future," ICUPCTutorial , Boston, MA, Sep. 30, 1996.
[10] J. D. Silva, "Why 3rd Generation?," Workshop on RTT's for IMT-2000,http://www.itu.int/imt/2-radio-dev/Workshop-97/2a.ppt, 10-11 Nov. 1998.
[11] J. Spicer, "Configuring the Terminal - Software Downloads and SoftwareRadios," Workshop on RTT's for IMT-2000, http://www.itu.int/imt/2-radio-dev/Workshop-97/3a1.ppt, 10-11 Nov. 1998.