White Paper Simplifying Simultaneous Multimode RRH Design
RRH technology with support for simultaneous operation of multiple air-interface protocols is an emerging end-product requirement. The diverse modulation formats and sampling rates between standards such as MC-GSM, WCDMA, and LTE make designing common building blocks, including DUCs and DDCs, challenging. This white paper explores potential filter-chain architectures to simplify simultaneous multimode digital IF processing design, and highlights the productivity and resource utilization tradeoffs between a modular DUC approach and a duplicated DUC approach for a multimode MC-GSM/WCDMA/LTE design.
Introduction
Multimode basestations capable of supporting multiple standards such as MC-GSM, WCDMA, WiMAX, and LTE offer numerous benefits for both operators and infrastructure OEMs. The benefits to operators include:
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Flexible use of available spectrum via inlay deployment of new networks such as LTE Reduction of capital expenses by reusing existing basestation equipment and making only software or board level upgrades for deploying new networks Reduction of operating expenses by reusing cell sites (saves on rental costs), reusing remote radio heads (RRHs) (saves on installation costs), and reusing backhaul Ability to future-proof networks and reduction of long-term total cost of ownership
The benefits to infrastructure OEMs include:
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Reduction of R&D expenses via universal basestation approach for multiple standards Simplification of product line management Ability to quickly adapt to evolving standards and bug fixes via programmable hardware Ability to differentiate from competition and charge a premium for future-proof equipment
While separate cost-optimized channel cards can be added to the basestation cabinet to deploy the modem functionality for various standards, upgrading tower-mounted RRHs with corresponding standard-specific cards is not a desirable solution for operators from an operating expense standpoint. Hence, a universal RRH capable of supporting multiple standards via only software upgrades is an emerging market requirement. The emergence of MC-GSM deployment using multicarrier-power amplifier (MC-PA) technology also enables the multimode RRH trend. Recent changes in spectrum regulations make it possible to use MC-PAs and digital intermediate frequency (IF) processing to deploy multiple GSM carriers, as shown in Figure 1. Figure 1. MC-GSM Digital IF Processing With MC-PA Technology

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