Optimizing Receiver Performance Using Interference Limits

More and more systems need to be squeezed together in frequency, space and time in order to satisfy the growth in demand for radio services. However, greater proximity increases the risk of service breakdowns due to harmful interference, caused both by poor interference tolerance in receivers and by inappropriate signals radiated by transmitters. In order to maximize the social value of radio operation, a system view that facilitates trade-off between receiver and transmitter performance is required. However, radio operation has traditionally been regulated using limits on transmitters, with few if any explicit constraints on receivers. This paper proposes bringing receivers into the regulatory picture by using interference limits, a specification of the interfering signal levels that receivers need to be able to tolerate before being able to claim harmful interference. The paper explains how receiver interference limits would be defined in terms of both radio engineering and regulatory process, and suggests parameter values for a number of typical allocations such as television reception and cellular service in the adjacent band. It also discusses those cases where interference limits may not be sufficient to ensure adequate receiver performance, and proposes a series of progressively more prescriptive device performance requirements, culminating in receiver standards. It argues that interference limits are both necessary and sufficient for exclusive licensees, except when the allocation is next to a quiet band; and that self-certification requirements, and sometimes mandatory performance standards, need to be added for unlicensed devices and decoupled receivers. Interference limits provide benefits to both radio system operators and regulators by providing greater clarity about the entitlements that are, and are not, entailed in assignments. They reduce business risk, and allow regulators to delegate both system design and entitlement adjustment decisions to operators. These attributes will be particularly useful in bands with many, diverse and frequently emerging new services and devices