mm-wave Satellite Links – Satellite Communications as Inherent Part of 5G Systems?
The vision of 5G mobile communications is driven by the predictions of up to 1000 times data requirement by 2020 and the fact that all traffic could be video embedded. If one compares this with the mobile spectrum available now (about 500 MHz) there is, what is referred to as the
‘spectrum crunch’—there is not enough bandwidth to satisfy the demands. Thus the conclusion is to move to a more dense networks and increase the area spectral efficiency by orders of magnitude. This leads to a network of much smaller cells, all of which will not be solely homogeneous but a flexible heterogeneous network where the resources can be adapted dynamically (on demand) as the users demand in space, time and spectral resources and even between operators varies.
Mobile satellites today provide services to air, sea and remote land areas via GEO operators (e.g., Inmarsat, Thuraya) and non GEO operators (e.g. Iridium, Globalstar, O3b). These operate in L, S and more recently Ka bands, to both handheld and vehicle mounted as well as some fixed terminals. Air interfaces and network functions have tended to be proprietary although some integration with MSS and 3GPP network interfaces exist. Fixed satellites today provide backhaul services to cellular in C, Ku and Ka bands, and also services to moving fixed terminals on vehicles in C-, Ku-, X- and Ka-bands. Satellite has been an overlay, rather than integrated system except in S band where an integrated satellite and terrestrial MSS standard has been adopted. 3GPP like services exist via satellite to individual users, but as yet these have not been extended to 4G. Satellite services to ships, aircraft and fast trains using FSS satellites provide a full range of mobile and broadcast services to passenger vehicles. A growing area of interest is in the transport sector where safety services and V2V (Vehicle To Vehicle) are seen as ideal for satellite delivery.
Since research into V2V systems proposes use of higher frequencies such as 76 GHz radar and communication integrated systems, the objective of this project is to investigate feasibility of using satellite links for V2V communications.
The objective of this project is to develop and validate communication link models over the 71 – 76 GHz and 81 – 86 GHz frequency bandwidths. This technical objective necessitates a higher level of sophistication as bi-directional, modulated data signal measurements are required. Key measurements include bit-error-rate, link margin, Doppler shift, and availability. The approach to meet this objective is to operate a transponder at a geostationary orbit over the continental United States. The transponder will receive (uplink) signals from a ground transceiver in the 81 – 86 GHz frequency band and retransmit (downlink) signals to the ground transceiver in the 71 – 76 GHz frequency band.
To accomplish meaningful research and experimental data collection, the system design criteria listed in Table 1 should be considered as a starting point for the beacon payload and companion ground data collection instruments. Clear-day link margins are suggested so as to provide ample signal strength to facilitate rain-fade measurements. Table 2 lists additional information and assumptions that should be considered in the design.
In addition to above constraints, additional the system design criteria listed in Table 3 should be considered as a starting point for the transponder payload and companion ground transceiver instruments. Given the increased difficulty of the transponder experiment, clear-day only operation may be the only feasible design approach. Information and assumptions given for the beacon are applicable to the transponder. To insure interoperability and to reduce technical risk, it can be assumed that the ground receivers (and / or transceivers) would be designed in parallel with the space segment.
I will assign ~7 teams with 4-5 members. I expect everyone to contribute to the final design and documentation and will solicit internal rankings of team-member efforts.
Due to the multiplicity of talents within each group and the “systems”-nature of the class, all aspects of the mission design should be explored in the final proposal. Communication systems should receive the most design focus, but the final project should address all of the following systems:
- Communication Systems – antennas, RF hardware, modulation, spectral usage, peak data output, bit rate, coding, etc. A key aspect will be demonstrating that the proposed transmission can make it through the atmosphere of Venus for reliable communications.
- Propulsion System – engine type, trajectory, and voyage time, single craft system or additional (and more expensive) relay orbiter
- Power Systems – power source, peak power output, estimated lifetime, etc. Thermalproofing the power system is critical.
- Resiliency of Electronics – Discuss strategies for space-hardening and heat-hardening the electronics for the duration of the mission. Identify the likely points of failure.
- Budget and Timeline – total research and development costs broken into materials, equipment, supplies, people costs, space resources, and other miscellaneous costs.
This list is not necessarily exhaustive. The level of detail for each system is left up to the groups. However, increased descriptions will enhance the competitiveness of your design. Verbose descriptions will degrade the competitiveness of your design.