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`
`Ericsson Ex. 1017.001
`
`Ericsson Ex. 1017.001
`
`

`

`Mobile Radio
`Communications
`
`Raymond Steele (Ed).
`Professor of Communications in the Electronics and Computer
`Science Department, University of Southampton,
`and
`Managing Director of Multiple Access Communications Ltd.,
`Southampton
`
`@3
`
`PENTECH PRESS
`Publishers - London
`
`©
`
`IEEE PRESS
`New York
`
`Ericsson Ex. 1017.002
`
`Ericsson Ex. 1017.002
`
`

`

`First published 1992
`by Pentech Press Limited
`Graham Lodge, Graham Road
`London NW4 3DG
`
`North, South and Central America rights assigned
`exclusively to IEEE Press, 445 Hoes Lane,
`Piscatavvay, NJ 08855
`
`ISBN 0-7803-1102-7
`IEEE Order No. PC04572_
`
`© Raymond Steele, 1992
`
`All rights reserved. No part of this book may be reproduced
`in any form. nor may it be stored in a retrieval system or
`transmitted in any form without written permission from
`the publisher.
`
`Reprinted 1994, 1995
`
`British Library Cataloguing-in-Publication Data.
`A catalogue record for this book is available from the
`British Library.
`‘
`
`ISBN 0—7273-1406-8
`
`First printed and reprinted (1994) in Great Britain by BPC Wheatons Ltd. Exeter
`
`Reprinted (1995) in the United States of America
`
`Ericsson Ex. 1017.003
`
`Ericsson Ex. 1017.003
`
`

`

`74 CHAPTER 1.
`
`INTRODUCTION TO DIGITAL CELLULAR RADIO
`
`the power level on a per frame basis, and the 42 bit mask used to generate
`the long code contains different data.
`
`All the 64 CDMA channels are combined to give single I and Q channels.
`These signals are applied to quadrature modulators and the resulting signals
`summed to form a CDMA/QPSK signal. The resulting CDMA signal is
`linearly amplified.
`
`The pilot CDMA signal transmitted by a BS provides a coherent carrier
`reference for all MSs to use in their demodulation process. The transmitted
`pilot signal level for all 335 is some 4 to 6 dB higher than a traffic channel
`and is of constant value. The pilot signals are quadrature PRBS signals with
`a period of 32768 chips. As the chip rate is 1.2288 Mchip/s(= 128 x 9600
`where 9600, is the maximum bit rate of the speech codec) the pilot PRBS
`corresponds to a period of 26.66 ms, equivalent to ’i’ 5 pilot channel code
`repetitions every two seconds. The pilot signals from all BSs use the same
`PRBS, but each BS is characterised by a unique time offset of its PRES.
`These ofi'sets are in increments of 64 chips providing 511 unique offsets rel-
`ative to the zero offset code. These large numbers of offsets ensure that
`unique BS identification can be performed, even in dense microcellular en-
`vironments.
`
`A MS processes the pilot channel and finds the strongest signal compo-
`nents. The processed pilot signal provides an accurate estimation of the
`time delay, phase and magnitude of three of the multipath components.
`These components are tracked in the presence of fast'fading, and coherent
`reception with combining is used. The chip rate on the pilot channel, and
`on all channels is locked to precise system time, e.g., by using the Global
`Positioning System (GPS). Once the MS identifies the strongest pilot offset
`by processing the multipath components from the pilot channel correlator,
`it examines the signal on its synchronisation channel which is locked to the
`PRBS signal on the pilot channel.
`
`All synchronisation channels use the same code W32 to spread their data.
`The information rate on the synchronisation channel is 1200 12/5 (although
`its chip rate is 1.2288 Mchips/sec). Because the synchronisation channel is
`time aligned with its BS’s pilot channel, the MS finds on the synchronisation
`channel the information pertinent to this particular BS. The synchronisa-
`tion channel message contains time-of—day and long code synchronisation
`to ensure that the long code generators at the BS and MS are aligned and
`identical.
`'
`
`The MS now attempts to access the paging channel, and listens for system
`information. The MS enters the idle state when it has completed acquisition
`and synchronisation. It listens to the assigned paging channel and is able
`to receive and initiate calls. When told by the paging channel that voice
`traffic is available on a particular channel, the MS recovers the speech data
`by applying the inverse of the scrambling procedures shown in Figure 1.42.
`
`Ericsson Ex. 1017.004
`
`Ericsson Ex. 1017.004
`
`

`

`698
`
`CHAPTER 8. THE GSM SYSTEM
`
`-
`
`.
`
`will be the timing advance to be signalled, rounded to the nearest integer
`bit period, to the MS. As the timing advance is encoded by 6 hits, it is hard;-
`limited to 64-3.69=236 us and it is kept constant for higher propagation
`delays. This timing advance is continuously updated and the adjustment
`error is less than half of a bit period.
`
`8.3.4 Frequency Hopping
`
`Frequency hopping combined with interleaving is known to be very efficient
`in combating channel fading, and it results in near—Gaussian performance
`even over hostile Rayleigh-fading channels. The principle of Frequency
`Hopping (FH) is that each TDMA burst is transmitted via a different RF
`CHannel (RFCH). If the present TDMA burst happened to be in a deep
`fade, then the next burst most probably will not be, as long as hopping is
`carried out to a frequency sufficiently different from the present one, hav—
`ing a differently fading envelope. However, this is not easily ensured due to
`the limited bandwidth available for GSM, since, for example, uplink trans—
`missions arc carried out in the 890-915 MHz band, where the maximum
`relative hopping frequency is ~25 MHz/900 MHzm2.8%. Nevertheless,
`FH reduces the amount of time spent by the MS in a fade to 4.615 ms,
`the duration of a TDMA burst, which brings substantial gains in case of.
`slowly moving MSs, such as pedestrians. The GSM frequency hopping al-
`gorithm is shown in Figure 8.9. The algorithm’s input parameters include
`the TDMA Frame Number (FN) specified in terms of the indices FN(T1),
`FN(T2) and FN(T3), as received in the synchronisation burst (SB) via
`the Synchronisation Channel (SCH). A further parameter is the set of RF
`channels called mobile allocation(MA) assigned. for use in the MS hopping
`sequence, which is limited to 1§N564 channels out of the legitimate 124
`GSM channels. The Mobile Allocation Index Offset (MAID) determines
`the minimum value of the Mobile Allocation Index (MAI), which is the
`output variable of the FE algorithm determining the next RF channel to
`which frequency hopping is required. Lastly, the Hopping Sequence gen-
`erator Number OEHSNSGZS is a further control parameter, which results
`in cyclic hopping if HSNzfi, as seen in Figure 8.9, and in pseudo-random
`hopping patterns if 1 _<_
`.H SN _<_ 63. This is, because for HSN=0 the mobile
`allocation index is computed as:
`
`MAI = ((FN + MAIO) mod N),
`
`(8.8)
`
`where (mod N) is taken to ensure that MAI remains an element of the set
`MA.
`
`For 1 5 H SN 3 63 somewhat more complex Operations have to be com—
`puted, using a number of intermediate internal variables, as demonstrated
`by Figure 8.9. The only undefined variable in the figure is NB, represent-
`ing the number of bits required for the binary encoding of N, the number
`of RF channels in the set MA. The function RNTABLE simply assigns
`
`Ericsson Ex. 1017.005
`
`Ericsson Ex. 1017.005
`
`

`

`3.3. MAPPING LOGICAL CHANNELS
`
`’
`
`699
`
`MAI:=<FN+MAID> mod N
`
`M==(T8+RNTABLE([HSN XURle mod 64334-13)
`
`_
`
`Ericsson Ex. 1017.006
`
`Y
`
`M'==(M mod 2 “3)
`
`T'I=(T3 mod 2"“ )
`
`S:=(M’+T’)mod N
`
` MAI=[(MAIU + 8) mod N]
`
`MAI
`
`GI MA
`
`Figure 8.9: The GSM frequency hopping algorithm
`
`Ericsson Ex. 1017.006
`
`

`

`700
`
`.
`
`CHAPTER 8. THE GSM SYSTEM
`
`one out of 114 pseudo-random numbers'specified by GSM according to its
`argument, the XOR operator means bit-wise exclusive OR, while the re-
`maining operations are self-explanatory. The result of the process is the
`mobile allocation index (MAI) specifying the next RF channel to be used
`by the MS. Note that frequency hopping is not allowed on timeslot zero of
`the BCCH carrier, which is ensured by using a single RFCH, i.e., setting
`N21 and MAIO=0. In this case the PH sequence generation is unefi'ected
`by the value of HSN.
`
`'
`
`8.4 Speech Coding
`
`The selection of the most appropriate speech codec for the GSM system
`from the set of candidate codecs was based on extensive comparative tests
`among various operating conditions. The rigorous comparisons published
`in {7] are interesting and offer deep insights for system designers as regards
`to the pertinent trade-oil's in terms of speech quality, robustness against
`channel errors, complexity, system delay, etc.
`
`8.4.1 Candidate codecs
`
`Originally the participating countries have proposed six difi'erent codecs
`with an overall channel coding and speech coding rate of 16kbps for comm
`parison At a preliminary test the codecs were compared to the presently
`used companded FM system, and then two of the codecs were withdrawn.
`The remaining codecs were two different sub—band codecs and two pulse—
`excited codecs, which are detailedin Chapter 3.
`SBC- APCM: Subband codec with block adaptive PCM. This codec
`used quadrature mirror filters (QMF) to split the input signal into 16 sub-
`bands of 250 Hz bandwidth, out of which the two highest bands were not
`transmitted. Adaptive bit allocation was used in the subbands on the basis
`of the power ratios of the various subbands, which constituted the side-
`information to be transmitted. The gross transmission rate of the subband
`signals was 10 kbit/s, the side-information was 3 kbit/s, which was pro—
`tected by 3 lcbit/s forward error correction coding (FEC) redundancy.
`SBC—ADPCM: Subband codec with adaptive delta POM. In this schc~
`me the speech input signal was split into 8 subbands, out of which only 6
`Were transmitted. The subband signals were encoded by differential coding
`with backward estimation and adaptation, as opposed to the SBC—APCM
`candidate, where fOIWard estimation and adaptation were used. The bit 31»
`location of the subbands was fixed, hence no side—information was transmit-
`ted, which made the scheme more noise resilient, hence no FEC protection
`was required, and the bitrate was 15 khit/s only.
`MPE-L‘I‘P: Multi~pulse excited LPG codec with long term predictor.
`The particular speech codec implementation used in the cornparisons rc—
`
`Ericsson Ex. 1017.007
`
`Ericsson Ex. 1017.007
`
`