State features of IS 95 B and IS-136.
1 Answer

The features of IS - 95B are:

The interim data solution of CDMA is called IS-95B. Like GPRS, IS-95B is already being deployed worldwide, and provides high speed packet and circuit switched data access on a common CDMA radio channel by dedicating multiple orthogonal user channels (Walsh functions) for specific users and specific purposes -

  1. Each IS-95 CDMA radio channel supports up to 64 different user channels.

  2. The original IS-95 throughput rate specification of 9.6 kbps was not implemented in practice but was improved to the current rate of 14.4 kbps as specified in IS-95A.

  3. The 2.5G CDMA solution, IS-95B supports medium data rate (MDR) service by allowing a dedicated user to command up to 8 different user Walsh codes simultaneously and in parallel for an instantaneous throughput of 115.2 kbps per user (8*14.4 kbps)

  4. However, only about 64 kbps of practical throughput is available to a single user in IS-95B due to the slotting techniques of the air interface.

  5. IS-95B also specifies hard hand-off procedures that allow subscriber units to record different radio channels in the network without instructions from the switch so that the subscriber.

Features of IS-136: (2 Marks for four correct)

1) Time Slots per Channel: 6

2) Users per Channel: 3 (full rate), 6 (half rate), 9 (future)

3) Modulation: Digital: Pi/4 DQPSK, Nyquist Filter factor = 0.35

4) Analog: FM

5) Data Structure: TDMA

6) Speech Coding: VSELP (vector sum excited linear predictive) 8 kbps

7) Modulation Data Rate: 24,300 symbols per second (1 symbol = 2 bits)

8) EIA/TIA Standards: IS-136.1 and IS-136.2 for system

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