New CDMA/PCS Library Supports IS-95-A and J-STD-008 Communications Standards
"This library was developed in response to overwhelming demand from our customers worldwide," said Geoffrey Chatfield, Vice President of Marketing and Sales for <%=company%>. "Our largest customer segment is in the communications area. This segment has been well served by SystemView tools since 1993. The new CDMA/PCS library enhances the core capabilities with tools specific to IS-95-A and J-STD-008 system design. It is the first of many application-specific products <%=company%> will offer to support standards in wireless and other segments of the communications market".
This library features all of the baseband models required to implement both the forward and reverse link. Individual models are provided for the various elements making up the channel such as the interleaver, frame quality indicator, Walsh codes, long code, PN spreading codes and more. Other models represent the entire channel such as the traffic, pilot, sync, paging, access, or reverse channel in one functional block. The user can optimize his simulation by mixing and matching these elements.
Propagation models include a basic Jakes multipath as well as the specific models called out in the IS-97-A specification. The CDMA/PCS library complements the comprehensive array of communications design tools already provided in SystemView by <%=company%>. The SystemView Communications library contains modulators/demodulators, channel models, encoders/decoders, and BER analysis functions. The SystemView filter design package allows users to create standard and custom FIR and IIR filters. APG allows users to accelerate simulation run times, reducing BER analysis times from hours to minutes.
The Dynamic System Probe provides a mechanism for rapid design debug in real time during system execution. In addition to the library, <%=company%> ships example files intended as starting points for customer designs. These designs include traffic channel designs, as well as forward, reverse, and paging channel designs. Two of these examples are described below.
Example: traffic_channel.svu: This example compares two IS-95-A forward traffic channels generated by two methods. The first method is a complete stand alone IS-95-A token, with all functions included. The second is a block by block implementation, which employs several individual IS-95-A blocks such as the interleaver. The complete token has the ability to add impairments such as relative delay and amplitude between the I and Q channels as well as an overall phase rotation which might be different from channel to channel. The I channel output from the two implementations are compared on a sample by sample basis.
Example: IS95_sim.svu: This simulation combines a forward pilot, a sync, a paging, and a traffic channel. A simple receiver recovers the traffic channel. It is assumed that synchronization has already occurred. First, the I and Q spreading codes are removed, and then the Walsh 55 code is removed. A PLL acts on the pilot channel to recover the relative phase of 30 degrees entered into the transmit tokens. The output of the demodulator is compared with the actual data. The slight variation of the (undetected) recovered signal is due to the ISI introduced in the receive matched filter. This filter is the same as the one in the transmitter, and the cascaded result is not a zero ISI combination at the data sampling times.