14 research outputs found
Timely Estimation Using Coded Quantized Samples
The effects of quantization and coding on the estimation quality of a
Gauss-Markov, namely Ornstein-Uhlenbeck, process are considered. Samples are
acquired from the process, quantized, and then encoded for transmission using
either infinite incremental redundancy or fixed redundancy coding schemes. A
fixed processing time is consumed at the receiver for decoding and sending
feedback to the transmitter. Decoded messages are used to construct a minimum
mean square error (MMSE) estimate of the process as a function of time. This is
shown to be an increasing functional of the age-of-information, defined as the
time elapsed since the sampling time pertaining to the latest successfully
decoded message. Such (age-penalty) functional depends on the quantization
bits, codeword lengths and receiver processing time. The goal, for each coding
scheme, is to optimize sampling times such that the long term average MMSE is
minimized. This is then characterized in the setting of general increasing
age-penalty functionals, not necessarily corresponding to MMSE, which may be of
independent interest in other contexts.Comment: To appear in ISIT 202
Age of Information in Downlink Systems: Broadcast or Unicast Transmission?
We analytically decide whether the broadcast transmission scheme or the
unicast transmission scheme achieves the optimal age of information (AoI)
performance of a multiuser system where a base station (BS) generates and
transmits status updates to multiple user equipments (UEs). In the broadcast
transmission scheme, the status update for all UEs is jointly encoded into a
packet for transmission, while in the unicast transmission scheme, the status
update for each UE is encoded individually and transmitted by following the
round robin policy. For both transmission schemes, we examine three packet
management strategies, namely the non-preemption strategy, the preemption in
buffer strategy, and the preemption in serving strategy. We first derive new
closed-form expressions for the average AoI achieved by two transmission
schemes with three packet management strategies. Based on them, we compare the
AoI performance of two transmission schemes in two systems, namely, the remote
control system and the dynamic system. Aided by simulation results, we verify
our analysis and investigate the impact of system parameters on the average
AoI. For example, the unicast transmission scheme is more appropriate for the
system with a large number UEs. Otherwise, the broadcast transmission scheme is
more appropriate