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All figures (11)
Fig. 1. State-transition diagram modeling the number of active interfering users with the aid of a Markov chain havingK states.
Fig. 5. Spreading factor versus the number of active users required for achieving the target BER of P = 0:01.
Fig. 6. BER performance versus the number of interfering users when the number of users obeys the distribution of (4), while employing the spreading factors according to Fig. 5.
Fig. 3. BER performance versus the number of active users for the parameters of = 0 dB and spreading factors of N = 8, 16, 24, 40, 56, 80, 112, and 120 computed from (2).
Fig. 2. Markov characteristics of the number of active interfering users.
Fig. 8. Throughput performance comparison of the constant spreading factor assisted nonadaptive DS-CDMA scheme and the VSF-assisted adaptive DS-CDMA arrangement.
Fig. 7. Throughput density and throughput cumulative functions versus the number of users when the number of interfering users obeys the distribution of (4), while employing the variable spreading factors according to Fig. 5 for the target BER of P = 0:01.
Fig. 4. Data structure of the transmitted signal in adaptive rate DS-CDMA systems using VSF-assisted adaptive rate transmissions.
Fig. 9. BER performance comparison between the constant spreading factor assisted nonadaptive DS-CDMA and the VSF-assisted adaptive DS-CDMA schemes when they achieve the effective throughputs of Fig. 8.
TABLE II NUMBER OF BITS TRANSMITTED IN A FRAME BY ASSUMING THAT THE TOTAL NUMBER OF CHIPS PER FRAME IS N = 1680 = 4 2 3 5 7 WHEN THE VARIOUS SPREADING FACTORS SEEN IN THE RIGHT COLUMN ARE EMPLOYED. ORTHOGONAL WALSH–HADAMARD SPREADING CODES WERE ASSUMED
TABLE I NUMBER OF BITS TRANSMITTED IN A FRAME BY ASSUMING THAT THE TOTAL NUMBER OF CHIPS PER FRAME IS
Journal Article
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DOI
•
Adaptive rate DS-CDMA systems using variable spreading factors
[...]
Lie-Liang Yang
1
,
Lajos Hanzo
1
•
Institutions (1)
University of Southampton
1
30 Jan 2004
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IEEE Transactions on Vehicular Technology