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In this paper, we describe possible interactions between UMTS Layer 2 and Layer 1 protocols to gain throughput performance improvements. The effect of transmission errors in Hybrid ARQ (HARQ) control signalling is shown along with the improvements that are possible by tighter coupling of Medium Access Control (MAC) layer HARQ and Radio link layer Control (RLC) layer ARQ level retransmissions. It is shown how the number of RLC segments in the MAC SDU affects the design of the required reliability of the ACK and signalling. MAC HARQ "NACK to ACK" errors can cause considerable throughput reductions, which can be substantially alleviated by the use of HARQ error recovery techniques.

The Internet of Things (IoT) will see the connection of tens of billions of objects to the Internet over the next 10 years and will lead to improvements in the quality of life for everyone. The density of all the radio-connected IoT objects will place increasing pressure on the available limited spectrum resources. These radio-connected IoT objects will, in addition, often use different radio access technologies (RATs), making service advertising and discovery as well as coordination of radio resources extremely challenging, due to the potentially vast numbers of connected devices. These problems can be addressed both by using centralised co-ordination of radio resources and by distributed intelligent devices that actively manage their own radio resource usage. This paper addresses solutions for centralised co-ordination of the wireless connected IoT devices through a new approach which relies on a shared service-level platform to provide flexible radio spectrum usage. New algorithms for interference mitigation and device co-existence are described which use device management made possible by such a platform, and avoid potential conflicts across heterogeneous systems. Under the assumption that geographically co-located devices are all using a common service platform, the centralised algorithms proposed here have the potential for more efficient solutions than existing inter-RAT interference mitigation solutions. An implementation of our algorithms using the emerging ETSI M2M standard is outlined.Keywords-Internet of Things (IoT); machine-to-machine (M2M) communication; device co-existence; spectrum management for IoT; radio interference mitigation; heterogeneous networks; service platforms for IoT/M2M; crosslayer design; ETSI M2M standard

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