Cost-Efficient Wireless Friendly Jamming and Interference Mitigation: No Pains, No Gains

In this article, we investigate a friendly jamming and mutual interference mitigation problem, where a friendly jammer equipped with a directional antenna is deployed to exert adversarial interference to the hostile user in a confrontational scenario. However, the side lobe of the signal of friendly jammer may cause unintended interference to ally users. Power control and jammer position are jointly designed to significantly impede the hostile users' radio communication at the cost of self-inflicted performance loss. The friendly jammer-to-hostile users channel is assumed to be a flat Rayleigh fading channel, while the friendly jammer-to-ally users channel gain is of finite states governed by the probability mass function (PMF). Cost-efficiency is defined to characterize the trade-off between the expected sum-capacity of the ally users, the outage-capacity loss of the hostile users, and the friendly jammer risk costs. We formulate the cost-efficiency maximization problem under ally users' transmission rate constraints. The block coordinate descent (BCD) and successive convex approximation (SCA) methods are applied to effectively solve the problem by optimizing: 1) coordination of the internal interference among the ally users; 2) the friendly jammer jamming power; and 3) the jammer position. The convergence of the proposed algorithm is illustrated. The impacts of power/risk costs and rate threshold of ally users on the utility have been demonstrated. Numerical results verify that the proposed scheme rapidly converges to a near-optimal solution and outperforms uniform power allocation or fixed jamming position policies.