Spectrum sharing improves the network efficiency for cellular operators

Abstract

The article describes the potential gain by spectrum sharing between cellular operators in terms of network efficiency. The focus of the study is on a specific resource sharing scenario: spectrum sharing between two operators in cellular downlink transmission. If frequency bands are allocated dynamically and exclusively to one operator - a case called orthogonal spectrum sharing - significant gains in terms of achievable throughput (spectrum sharing gains between 50 percent and 100 percent) and user satisfaction are reported for asymmetric scenarios at link and system level as well as from two hardware demonstrators. Additionally, if frequency bands are allocated simultaneously to two operators - a case called non-orthogonal spectrum sharing - further gains are reported. In order to achieve these, different enablers from hardware technologies and base station capabilities are required. However, we argue that all requirements are fulfilled in 3GPP and newer mobile standards. Therefore, the results and conclusions of this overview article encourage to seriously consider the inter-operator spectrum sharing technologies

Licensed Spectrum Sharing Schemes for Mobile Operators: A Survey and Outlook

“…In general, inter-cell interference coordination in multi-operator deployment scenarios requires further investigations, as these techniques in the curren t LTE systems are only applicable for single operator scenarios over the physical X2 interface among the BSs, and it might not be possible to extend such connection among BSs of two different MNOs [75]. In fact, efficient spectrum sharing schemes are required, which conform to the various deployment scenarios such as shared RAN (whether collocated or not).…”

“…The information, which can range from slowly varying/static data (such as average propagation conditions ), up to realtime/dynamically varying data (such as CSI or traffic load of the cell), has to be transferred between networks/systems through a specific media such as wired backhaul, X2 interface, etc. The inter-site control data rate has been estimated to be approximately 96Mb/s in the case of negotiation among two operators, whereas the practical backhaul rate for one cell in a dense urban scenario and also one site is almost 100 Mb/s and 300 Mb/s respectively [75]. This shows that the amount of control information which is required to be exchanged is large and is almost equal to the effective backhaul capacity of one cell.…”

“…The BSs require further enhancements in order to be able to support increased spectrum bandwidth, increased number of end users, additional processing power, and enhanced backbone capacity. Increasing spectrum bandwidth requires increased processing power, especially for the PHY layer processing and the complexity is known to increase linearly with the spectrum size in this layer [75].…”

“…However, in the second type which is known as joint transmission/processing, both CSI and UE data is exchanged between BSs due to the reason that both BS transmit to the user at the same time [165]. Thus, it is reasonable to expect that the BSs which support CoMP technologies could be able to support interoperator spectrum sharing as well since it has the same requirements on synchronisation as in CoMP [75]. However, CoMP is now only applicable for intra-operator scenarios, and also requires the exchange of CSI and also user data with specific reference signals to perform joint precoding over a fast backbone connection (e.g., X2).…”

“…However, CoMP is now only applicable for intra-operator scenarios, and also requires the exchange of CSI and also user data with specific reference signals to perform joint precoding over a fast backbone connection (e.g., X2). Thus, the deployment of inter-operator CoMP technique, to manage the coexistence of the MNOs on the shared bands, requires that all the adjacent BSs (of the different MNOs) to be connected through, e.g., X2 interface to each other as well as sharing of some control and user data between them [75].…”