As a result of the constant efforts to improve mobile system performance and spectral efficiency, the 3GPP standardization forum is currently defining new architectural and functional requirements that hope to ensure long-term evolution (specifically defined as the “Long-Term Evolution (LTE) concept”) and general future competitiveness of the 2G and 3G radio access technologies. Previous discussions on LTE efficiency have been focused on general assumptions on signaling overhead and overall system capacity, based on experience from existing mobile systems. However, as 3GPP standardization has become more mature (although not yet settled), there is a need to investigate how different potential LTE services will be affected by the use of available overhead information and basic scheduling algorithms. This thesis investigates the lower protocol layers’ overhead impacts on the downlink for different packet switched services, in an LTE radio access network (RAN). Results show that the use of RTP/TCP/IP header compression (ROHC) is the single most important factor to reduce payload overhead, for packet sizes of ~1kB or smaller. However, for packets larger than ~1 kB, the use of ROHC becomes insignificant. Protocol headers – including the AMR frame header, RLC/MAC headers, and CRC where applicable – remain the largest part of payload overhead regardless of packet size and header compression (ROHC). For VoIP over the UDP protocol (with ROHC), RLC/MAC headers constitute the largest part of protocol headers. For TCP/IP applications (without ROHC), TCP/IP headers are predominant. Services that require packet sizes beyond ~1 kB will require about the same power per payload bit regardless of percentage of payload overhead. / Som ett resultat av ständiga ansträngningar att förbättra såväl prestanda som spektrumeffektivitet för mobila system, definierar 3GPPs standardiseringsforum nya krav på arkitektur och funktionalitet. Dessa är avsedda att säkerställa långsiktig utveckling (explicit definierat som konceptet “Long-Term Evolution (LTE)”, samt framtida konkurrenskraft för både 2G och 3G som radioaccess-teknologier. Tidigare diskussioner rörande effektivitet inom LTE har fokuserat på allmänna antaganden vad gäller kontrolldata för signallering och övergripande systemprestanda. Dessa har i sin tur baserats på erfarenheter från existerande mobilsystem. När standardiseringen inom 3GPP mognar uppstår nu ett behov av att undersöka hur olika tjänster inom LTE påverkas, av såväl hur man använder den kontrollinformation som finns tillgänglig, som av basala algoritmer for schemaläggning av resurser. Denna rapport undersöker påverkan från lägre protokoll-lagers kontrollinformation på nerlänken hos olika paket-kopplade tjänster inom ett radioaccessnät för LTE. Resultaten visar att användandet av ROHC (som packar kontrollinformation för protokollen RTP/TCP/IP), är det ensamt viktigaste bidraget till minskad kontrollinformation i relation till informationsbitar för paketstorlekar upp till c:a 1kB. För större paket är vinsten med ROHC dock försumbar. Kontrollinformation för protokoll – inkluderat data avsett för AMR-tal-ramen, RLC/MAC-protokollen, samt CRC – utgör för övrigt en stor del av kontrollinformationen relativt informationsbitar, oavsett paketstorlek och packning av kontrolldata. Tjänster som kräver paketstorlekar på över c:a 1 kB kräver uppskattningsvis samma mängd energi per informationsbit, oavsett andelen kontrollinformation.

In this dissertation we have studied nearield phenomena in dipole radiation. We have studied first the energy flow patterns of the radiation emitted by an electric dipole located in between parallel mirrors. The field lines of the Poynting vector have intricate structures, including many singularities and vortices. For a dipole parallel to the mirror surfaces, vortices appear close to the dipole. Vortices are located where the magnetic field vanishes. Also, a radiating electric dipole near the joint of two orthogonal mirrors is considered, and also here we find numerous singularities and vortices in the energy flow patterns. We have also studied the current density in the mirrors. Next we have studied the reflection of radiation by and the transmission of radiation through an interface with an  -near-zero (ENZ) material. For p polarization, we find that the reflection coefficient is -1, and the transmission coefficient is zero for all angles of incidence. The transmitted electric field is evanescent and circularly polarized. The transmitted magnetic field is identically zero. For s polarization, the transmitted electric field is s polarized and the transmitted magnetic field is circularly polarized. The next topic was the study of the force exerted on the dipole by its own reflected field near an ENZ interface. We found that, under certain circumstances, it could be possible that the dipole would levitate in its reflected field. This levitation is brought about by evanescent reflected waves. Finally, power emission by an electric dipole near an interface was considered. We have derived expressions for the emitted power crossing an interface. The power splits in contributions from traveling and evanescent incident waves. We found that for an ENZ interface, only evanescent dipole waves penetrate the material, but there is no net power flow into the material.