Bikramjit Singh

Coordination protocol for inter-operator spectrum sharing in co-primary 5G small cell networks

We consider spectrum sharing between a limited set of operators having similar rights for accessing spectrum. A coordination protocol acting on the level of the RAN is designed. The protocol is non-cooperative, but assumes an agreement to a set of negotiation rules. The signaling overhead is low, and knowledge of a competitors channel state information is not assumed. No monetary transactions are involved; instead, spectrum sharing is based on a RAN-internal virtual currency. The protocol is applicable both in a scenario of mutual renting and when the operators form a spectrum pool. The protocol reacts to variations in interference and load of operators, and shows gains in a simulated small cell scenario.

Ultra-reliable communication in a factory environment for 5G wireless networks: Link level and deployment study

The focus of this paper on mission-critical communications in a 5G cellular communication system. Technologies to provide ultra-reliable communication, with 99.999 % availability in a factory environment are studied. We have analysed the feasibility requirements for ultra-reliable communication and obtained the loss margins against path loss, shadow and fast fading. We also study the effect of increased interference due to higher deployment density on offered reliable rates and packet delays. Resource allocation schemes based on full and orthogonal resource sharing, as well as power control are compared. Last, the importance of multi-hop communication and multi-point coordination schemes are highlighted to improve the reliable communication in presence of interference and clutter.

Co-primary inter-operator spectrum sharing using repeated games

Currently mobile network operators are allocated spectrum bands on an exclusive basis. While this approach facilitates interference control, it may also result in low spectrum utilization efficiency. Inter-operator spectrum sharing is a potential method to enhance spectrum utilization. In order to realize it, a protocol to coordinate the actions of operators is needed. In this paper, we propose a spectrum sharing protocol which is distributed in nature, does not require operator-specific information exchange, and incurs minimal communication overhead between the operators. Operators are free to decide whether they share spectrum or not as the protocol is based on a book keeping of spectrum usage favors asked and received by the operators. We show that operators can enhance their QoS in comparison with a scheme where no spectrum sharing is allowed while also maintaining reciprocity i.e. no operator benefits over the other in the long run. We demonstrate the usability of the proposed protocol in an indoor deployment scenario with frequent network load variations which are expected in small cell deployments.

Co-primary inter-operator spectrum sharing over a limited spectrum pool using repeated games

We consider two small cell operators deployed in the same geographical area, sharing spectrum resources from a common pool. A method is investigated to coordinate the utilization of the spectrum pool without monetary transactions and without revealing operator-specific information to other parties. For this, we construct a protocol based on asking and receiving spectrum usage favors by the operators, and keeping a book of the favors. A spectrum usage favor is exchanged between the operators if one is asking for a permission to use some of the resources from the pool on an exclusive basis, and the other is willing to accept that. As a result, the proposed method does not force an operator to take action. An operator with a high load may take spectrum usage favors from an operator that has few users to serve, and it is likely to return these favors in the future to show a cooperative spirit and maintain reciprocity. We formulate the interactions between the operators as a repeated game and determine rules to decide whether to ask or grant a favor at each stage game. We illustrate that under frequent network load variations, which are expected to be prominent in small cell deployments, both operators can attain higher user rates as compared to the case of no coordination of the resource utilization.

Selective multi-hop relaying for ultra-reliable communication in a factory environment

Evolving 5G cellular communication is envisioned to enable connectivity for a wide range of new use cases. The focus on mission-critical communications, such as factory automation, public safety and vehicular safety applications presses the demand for ultra-reliable communication. In this paper, we investigate by various means of multi-hop relaying schemes to improve the reliable communication in a factory environment. Impacts due to half- and full-duplex operation at relay nodes are studied together with resource allocation. No retransmissions are considered and the relaying schemes are limited to two hops to meet the low latency constraint. Performance evaluations in a factory scenario are shown. We illustrate that in a network of uncoordinated cells one can exploit the varying fading profiles and can improve the offered reliable rate using multi-hop communication.

Contention-Based Access for Ultra-Reliable Low Latency Uplink Transmissions

We consider a sporadic ultra-reliable and low latency communications in the uplink 5G cellular systems. Reliable low latency access for randomly emerging packet transmission cannot be guaranteed in current wireless systems. To achieve the goal of low latency and high reliability simultaneously, we propose a contention-based transmission scheme aimed at users with small payloads. We seek to reduce collision probability by considering multiple transmissions for the same packet for reliable reception. We find the optimal number of consecutive multiple transmissions that reduces collisions and achieves target reliability within the latency window. Performance is analyzed with a frame structure planned for 5G cellular systems. Results are compared with default multi-channel slotted ALOHA access scheme.

Repeated spectrum sharing games in multi-operator heterogeneous networks

When femto cells of different network operators do not generate harmful interference to each other, they may agree to aggregate their spectral resources and share spectrum. While this approach would enhance the femto cell performance of both operators, it may introduce harmful inter-operator cross-tier interference, for instance, between the femto cells of one operator and the micro or the macro cells of the other. In this paper, we design a scheme in which two operators construct a spectrum pool and coordinate spectrum sharing in the downlink using repeated games between femto cells and micro cells of different network operators. The scheme does not require operator-specific information exchange. It is based on book keeping of asking and receiving spectrum usage favors. When the micro cells of an operator are exposed to high inter-operator interference, they ask for spectrum usage favors from the femto cells of the opponent operator. A spectrum usage favor is exchanged if the micro cells of an operator ask for the permission to use some of the resources of the spectrum pool exclusively, and the femto cells of the opponent operator allow it. Micro cells with a high load may take spectrum usage favors from femto cells that have few users to serve. We illustrate that two heterogeneous network operators can exploit varying network traffic and interference profiles in space and time and both achieves benefits from spectrum sharing.