The Mobile User Objective System (MUOS) adapts a commercial third generation (3G) WCDMA cellular architecture to military UHF geostationary satellites to serve several terminal types including handhelds (HHT). The satellites also serve Legacy narrowband (NB) nets. The WCDMA uplink (terminal-to-base) waveform, or Common Air Interface (CAI), is a secondary user of its 5 MHz channel, sharing the bandwidth with other services. Uplink CAI spectrum modifications to 3G WCDMA use spectrally adapted (SA) "notching" designed to prevent interference with primary NB users. The new SA-WCDMA signal has increased amplitude modulation quantified here as peak-to-average power ratio (PAPR). To preserve the SA capabilities, as well as low bit energyto-noise density capability, adequate fidelity is needed from a terminal power amplifier (PA). The HHT has an additional regulatory radiated power limit imposed for users' safety. Despite these constraints, the HHT must provide a minimum uplink availability under channel fading and interference, as well as acceptable battery life and thermal behavior We present simulations of SA-WCDMA PAPR and its effect on PA operation. Pre-PA processing, PA backoff and efficiency, and other RF issues are considered with the goal of improving the terminal designer s understanding of practical MUOS HHT implementation.BACKGROUND ON MUOS SA-WCDMA CAI
The Mobile User Objective System (MUOS) is DoD's next generation military UHF SA TCOM system. MUOS is an integrated system that includes an advanced satellite constellation as well as all supporting ground radio access and switchingfacilities to support the worldwide transport of voice and data (including access to the Global Information Grid). For the last thirty years UHF SATCOM has operated over individual 5-kHz and 25-kHz bandwidth transponders, but MUOS departs from this by adapting a commercial third generation (3G) Wideband Code Division Multiple Access (WCDMA) cellular phone architecture using geosynchronous satellites in place of cell towers. Use of WCDMA allows MUOS to increase UHF communication capacity and availability to a level far in excess of what is currently achievable using the existing UHFSATCOMsystem.The U.S. Navy utilizes several tactical data networking systems, commonly referred to as Information Exchange Subsystems or "IXS. " Each IXS has a unique over-the-air protocol tailored for a specific data networking system. These systems will need to eventually transition from the use of UHF 5-kHz and 25-kHz channel waveforms to the new MUOS WCDMA waveform. The MUOS architecture provides a broad range of voice and data communication services, including a very efficient IP data transport capability, which have the potential to greatly increase the performance ofthese Navy tactical networks.In this paper the authors briefly explain the MUOS architecture, service and transport classes, QoS, and explore several options for the support of Navy tactical network applications on MUOS.
The Operational Requirements Document (ORD) for the Mobile User Objective System (MUOS), the replacement for the current UHF MILSATCOM, requires a great increase in communication capacity and Quality ofService (QoS). To achieve these objectives, MUOS is moving away from operation over individual 5-kHz and 25-kHz bandwidth transponders and adapting a commercial third generation (3G) Wideband Code Division Multiple Access (WCDMA) cellular phone architecture using geosynchronous satellites in place of cell towers. Because the WCDMA waveform will not be interoperable with the current UHF waveforms, each MUOS satellite carries a legacy payload, similar to that flown on the currently deployed UFO 11 satellite, to allow for a gradual transition to the MUOS WCDMA waveform.While the current narrowband UHF MILSATCOM system provides reliable service to many users, it provides unacceptable service to many other users, and worse, there is insufficient capacity to provide any service at all to many potential users. The MUOS constellation offour satellites provides greater than 10 times the capacity ofthe current UHF constellation, but because the MUOS waveform will eliminate the needfor dedicating resources to individual services, its ability to fulfill user communication requirements will actually be much greater than this. The current UHF waveforms are unable to provide efficient transport for Internet Protocol (IP) packets which has prevented the migration to modern net centric IP communication services. MUOS implements an all packet core networking infrastructure that supports both net centric IP communication services as well as traditional circuit-switched services.In this paper the authors briefly explain the MUOS architecture, service and transport classes, and QoS, and compare this to what is available using the current UHF system. The paper also discusses what MUOS users will need to do to prepare for transition to the new MUOS WCDMA waveform. SYSTEMS IMPROVEMENTS REQUIRED BY THE MUOS ORDThe operational requirements for the Mobile User Objective System (MUOS) demand a considerable increase in total communication capacity over the current UHF Follow-on (UFO) narrowband SATCOM system, as well as improved availability, improved Quality of Service (QoS), and the ability to serve handheld terminals.Within the MUOS program the current UHF waveforms, defined by MIL-STD-188-181, 182 and 183, are referred to as the legacy waveforms, and that is the way this paper will refer to them. The legacy waveforms (introduced back in 1992) do not always meet user needs, can be complex to use, and often require link margins that users can't reliably achieve. The biggest failing of the legacy system is that it has insufficient capacity to provide service to a large percentage of its potential users. All potential users with MUOS compatible radios will be able to use MUOS. MUOS WAVEFORMOVERVIEW MUOS adapts a commercial third generation (3G) Wideband Code Division Multiple Access (WCDMA) cellular phone architecture for use in a military UHF...
The Mobile User Objective System (MUOS) is being developed to nieet a continuing Department of Defense (DoD) reguirenzent for mobile unprotected narrowband beyond line-of-sight communications. The A4UOS will replace the current UHF Follow-On (UFO) satellite constellation as those satellites reach end-of life. As part of this efort a new Common Air Inteirface (CAI) will be developed to standardize the waveform used behveen MUOS user terminals and the satellite. This paper describes a protocol capable of satis&ing the MUOS Operational Requirements Document ( O D ) directive to provide a higher guality of service than the current UFO system is capable of providing. This protocol captures key features j+om the Integrated Wavefornz, a waveform being developed as a possible future replacement for the two current Demand-Assigned Multiple Access ( D A M ) waveforms now required for operation over 5-kHz and 25-kHz UHF military satellite channels. The new CAI would greatly simplifi the use of UHF satellite communications by automatically locating a control channel, capturing the list o f available services, and passively connecting to these services. The new CAI should include a standard medium access control (MAC) protocol layer to allow use of modern communication protocols, and provide standardized protocols for voice and messaging that could be easily extended to systems outside of the MUOS network.
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