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Diffstat (limited to 'assignments')
| -rw-r--r-- | assignments/3/README.md | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/assignments/3/README.md b/assignments/3/README.md index 27d9c4c..544aabc 100644 --- a/assignments/3/README.md +++ b/assignments/3/README.md @@ -128,6 +128,7 @@ Wi-Fi 6/6E (802.11ax): - Divides channels into smaller pieces (OFDMA) for better efficiency with many devices - Improved performance in crowded areas like offices and apartments - Speeds several Gbps +- Introduced Target Wake Time (TWT) for IoT battery efficiency. Wi-Fi 7 (802.11be, emerging): @@ -142,19 +143,20 @@ Wi-Fi 7 (802.11be, emerging): > (15%) Begin with reading about the simple CDMA protocol... choose one CDMA scheme and explain how it works. Describe the advantages that CDMA has over other coding schemes, such as TDM and FDM. Include in your answer the titles and sources of the articles/documents you consulted. -Direct-Sequence CDMA (DS-CDMA) assigns each user a unique spreading code -and multiplies their data bits by this code at a high chip rate, spreading -each bit across many chips so all users can transmit simultaneously -over the same frequency band. The receiver uses the intended user's -code to despread and isolate their signal while treating others as -noise. - -Compared to TDM and FDM, DS-CDMA offers flexible "soft capacity" with -graceful degradation rather than hard user limits, natural resistance -to narrowband interference, the ability to exploit multipath signals, -less need for precise synchronization or complex frequency planning, -frequency reuse factor near 1 in adjacent cells, and security benefits -from low probability of intercept. +In DS-CDMA, each user has a unique code that changes much faster than +their data transmission rate. When sending data, each bit is multiplied +by this code, spreading it across many "chips". All users transmit +simultaneously on the same frequency, but receivers can extract their +intended signal by multiplying the received signal by the sender's +code. + +Unlike TDM (which divides time) and FDM (which divides frequency), CDMA +divides the codespace. This provides several advantages like that the +system gracefully handles varying numbers of users without hard capacity +limits, resists interference, requires less timing coordination, and +allows adjacent cells to reuse the same frequencies. + +Citation: Kurose, J. F., & Ross, K. W. (2020). Computer Networking: A Top-Down Approach (8th ed.). Section 7.2.1, pp. 563-566. ## 2.2 Two-Dimensional Checksum (15%) |