Wireless communicationpe-3855140


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Wireless communicationpe-3855140

  1. 1.  3rd generation system Proposed by Bellcore in 1992 It supports voice, data, and videoimages Coverage is within 500 meter range Provides wireless connectivity forLECs
  2. 2. o PACs concept with LECs is calledWireless Access CommunicationSystemo Use of time slot, channels, frameswere proposed for PACso Changes were made in channel B.W,data rate, no. of. Slot per frame andQPSK were chosen
  3. 3.  Universal wireless access system forwidespread applications Used in private and public telephonesystem which operate in either licensedor unlicensed PCS bands It is served by a central office inresidential application
  4. 4. 1. Subscriber unit (SU) : fixed / portable2. Radio ports (RP)3. Radio port control unit (RPCU)4. Access manager (AM)
  5. 5. Air interface provides a connectionbetween the SU and RP SU connects through the RPs to theRPCU
  6. 6. RPCU is connected with its RPs byusing an Embedded OperationsChannel (EOC) provided within theinterface Standard contains a fixeddistribution network and networkintelligence Only at 500m of the distributionnetwork is designed to be wireless
  7. 7.  Designed for operation in US PCS band Uses a large number of channels Channels are., 1. frequency division multiplexed 2. time division multiplexed PACS and WACS channel bandwidth is300 khz
  8. 8.  Uses TDMA with frequency divisionduplexing (FDD) Uses 8 time slots provided in 2msframe on each radio channel The reverse link time slot is offset,from its paired forward link time slot byexactly 1 time slot + 62.5 us
  9. 9.  FORWARD LINK : 1850 MHz – 1910 MHz REVERSE LINK : 1930 MHz – 1990 MHz UNLICENSED US PCS : 1920 MHz – 1930 MHz
  10. 10.  ∏ / 4 – DQPSK modulation 99% of transmitted signal power is contained in channel channel bandwidth is of 288 kHz 8 time slots, each contains 120 bits and are sent in a 2.5 ms frame With TDD, 2 time slots apart for each user
  11. 11. WACS uses 32 kbps for digitalspeech encoding Provides, 1. low complexity 2. minimum cost 3. radio link privacy
  12. 12.  Provides system broadcasting channels (SBCs) – used in paging messages 32 kbps SBC provides alerting and system information for upto 80,000 users forward link to synchronize, 1. synchronization channel 2. slow channel
  13. 13.  Technology uses FDD or TDD Many portable handsets and data terminals can be served The radio links can be shared Provides a wide range of user transmission rates within a common architecture
  14. 14. The PACS subscriber unit usesadaptive power control to minimizebattery drain during transmissionUsed to reduce the co-channelinterference on the reverse path