ADAPTIVE TONE MAP REQUEST CONTROL IN POWER LINE COMMUNICATION MESH NETWORK

Techniques are provided herein for a sliding window mechanism to adjust the macMaxAgeTime dynamically to adapt to different environmental conditions. This solution can greatly reduce issues caused by a fixed macMaxAgeTime, such as communication failure due to tone map parameters not being updated, or valuable bandwidth being wasted due to needless tone map request/response. Consequently, this improves data throughput and network robustness of the whole system. DETAILED DESCRIPTION The Institute of Electrical and Electronics Engineers (IEEE) P1901.2 working group is actively standardizing the PHY / Media Access Control (MAC) address of a Power Line Communication (PLC) link-layer targeted at Smart Utility Networks (SUNs). To help achieve greater throughput and robustness in a noisy environment, IEEE P1901.2 relies on Orthogonal Frequency Division Multiplexing (OFDM). OFDM utilizes additional bandwidth by allowing transmission of multiple data streams across orthogonal subcarriers simultaneously to increase throughput. Adaptive Tone Mapping (ATM) is a process that dynamically selects which subcarriers and coding parameters to use when transmitting a frame. The goal of ATM is to maximize overall throughput by choosing a modulation and identifying subcarriers that offer an acceptable Signal-to-Noise Ratio (SNR). Adjusting the modulation, code-rate, and number of subcarriers can vastly change the effective throughput of the link. IEEE P1901.2 currently specifies the ATM process as follows. First, when sending a frame to a neighboring node, the neighbor’s entry is found in the neighbor table and the ATM parameters (i.e., modulation, code-rate, and subcarriers) are obtained. Second, if no neighbor table entry exists or the neighbor’s age parameter exceeds a threshold, the ATM 2 Zhang et al.: ADAPTIVE TONE MAP REQUEST CONTROL IN POWER LINE COMMUNICATION MES Published by Technical Disclosure Commons, 2018 2 5718 parameters are initialized to ROBO mode (i.e., the slowest data rate possible using all subcarriers). Also, the Tone Map Request (TMREQ) bit in the frame’s header is set. Third, when receiving a frame with the TMREQ bit set, the SNR is evaluated across all subcarriers. The modulation, code-rate, and subcarrier set are chosen to maximize the overall throughput. The parameters are provided back to the source in a Tone Map Response (TMRES) frame. Fourth, when receiving a TMRES frame, the ATM parameters are stored in the neighbor table and the age value is reset. Nodes in PLC or dual-PHY (Radio Frequency (RF) and PLC) mesh networks need to start the ATM process at regular intervals. IEEE P1901.2 requires any frame with the TMREQ bit set to be sent utilizing ROBO or Super ROBO mode (e.g., Binary Frequency Shift Keying (2-FSK) modulation with Reed-Solomon with repetition coding across all sub-carriers) which offers the slowest data rate (2.4 kbps in the European Committee for Electrotechnical Standardization (CENELEC) A band). The benefit of using ROBO mode is it (1) maximizes the effective range and (2) allows the receiver to evaluate the SNR across all subcarriers. However, this is done at the cost of minimizing overall throughput. The interval to start the ATM process usually depends on the age parameters (e.g., macMaxAgeTime as defined in IEEE 1901.2-2013). Figure 1 below illustrates an example system.