50 lines
3.7 KiB
Plaintext
50 lines
3.7 KiB
Plaintext
There are fundamental changes to the L2 emulation mechanism; these changes allow the
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user to run multiple UEs in separate Linux processes/machines/VMs/etc. They use a separate
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entity between the UE(s) and eNB. The UEs use nFAPI to communicate with the eNB. The
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nFAPI interface allows us to run in an emulated layer 2 mode, meaning that we are bypassing
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the layer 1 (PHY) functionality. Because we are bypassing the PHY layer,
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channel modeling capabilties have been added in the LTE UE phy_stub_ue.c file. To understand
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the interfaces between the different components associated with LTE mode, the image
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functional_diagram_proxy_lte.png has been provided.
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This functionality allows the user to plug in their own channel model and emulate the packet dropping procedure
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in real time. The channel modeling has not been provided by EpiSci, but the OAI code
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base already has some BLER curves available for use. The channel modeling functionality
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that is included in the phy_stub_ue.c file only includes the downlink channel modeling.
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Any uplink channel modeling must be conducted in some sort of proxy, which would sit
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between the UEs and eNB. (A description of the downlink channel modeling is shown in the
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Channel_Abstraction_UE_Handling_LTE.PNG image).
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The updates to the OAI code base removed some latent bugs, added multi-UE scalability,
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and were tested with a standard bypass proxy between the UE(s) and eNB. The bypass proxy is
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publicly available on GitHub (https://github.com/EpiSci/oai-lte-multi-ue-proxy). With this package,
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various multi-UE scenarios can be tested without the overhead of PHY-layer features
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of underlying radios. The features added in the L2 Emulator Mode for LTE are:
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- Ease of use of gprof and address sanitizer for debugging purposes
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- Updated json files to allow for GDB, real-time debugging capabilities
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- Updated logging features to minimally log only key connection milestones. This improves scalability of multiple UEs.
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The logging mechanism described here is located in the log.c and log.h files. The LOG_MINIMAL
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function allows us to remove most OAI logging and includes LOG_A(...) logs and above. The LOG_A
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logs were chosen as analysis logs to meet EpiSci's internal testing procedure. The LOG_As
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only include logs that are considered to be milestones in a given test. For example, a
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log indicating that the RACH procedure has been completed for LTE. To select full logging,
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set LOG_MINIMAL = 0 in the log.h file.
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- Updated logging to include time stamp for timing analysis
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- Updated memory allocation procedures to correct size requirements
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- Added debugging features to handle signal terminations
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- nfapi.c pullarray8 fix invalid pointer math
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- Overlapping destination and source memory in memcpy, so updated to memmove to check for this bug
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- Advanced error checking mechanisms in critical pack and unpack functions
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- Created option for CPU assignment to UE to improve scalability
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- Added EPC integration to allow multiple individual UE entities to each have their USIM information parsed by the executables
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- Updated random value seeds to minimize probability of error in generation of random values
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- Enables capability round robin scheduler if desired
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- Enables capability real time scheduler if desired
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- Added new standalone functions to the UE phy-layer (phy_stub_ue.c) to incorporate individual UE entities
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- Updated sending and packing functions in UE (lte_ue.c) to incorporate new standalone changes
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- Incorporated semaphores to control timing of incoming downlink packets
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- Implemented new queuing system to handle message exchange from UE to eNB and vice versa
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- Updated global value in nFAPI for size of subframe
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- Updated global value to increase scalability in system
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