Smart Grid Technology Discussions 2010

1. Smart Grid Technology Discussions 2010 Date: 2010-October-18 Abstract: NIST PAP#2 Report r6 recommended changes Bruce Kraemer, Marvell

2. NIST PAP#2 Report Commentsthat complement text in Section 6 & 7 of r6 Bruce Kraemer, Marvell

3. Comment #01 • Section 4.2.1.3 talks about Coverage Area. It is important to discuss coverage in conjunction with data rates and link margin for example, in order to avoid associations between inconsistent pieces of information, e.g., citing the largest coverage area achievable by a given technology along with the highest data rate achievable by the technology is incorrect – generally the two have a reverse relationship and the highest coverage is achievable at the lowest data rate. • Agreed to text change: • Add the following text at the end of Section 4.2.1.3: When comparing coverage areas between different technologies, it is important to take into account the link budgets used in the coverage computation. Note that the largest coverage area achievable by a specific technology typically requires transmission at the lowest data rate used by that technology. Bruce Kraemer, Marvell

4. Comment #02a • Section 4.2.1.4 talks about Mobility. It would be useful to mention the data rates achievable at various mobility levels to avoid assumptions that mobile devices can communicate at the highest data rates used by a specific technology. • Agreed to text change: • Add the following text at the end of Section 4.2.1.4: Comparisons between the capabilities of different mobile technologies have to take into account the maximum data rate achievable at each mobility level -- mobile devices may not be able to communicate at the highest available data rates when moving at high speeds. Bruce Kraemer, Marvell

5. Comment #03 • Section 4.2.1.5 talks about Data Rates. • Agreed text change: • Add the following text at the end of Section 4.2.1.5: Additional factors to consider when discussing data rates: • Throughput must be considered in conjunction with packet size, coverage range and rate of mobility (if any). • It is important to distinguish between unicast, multicast and broadcast rates, as they may not be the same for a given wireless technology. • Throughput depends on medium access scheduling, including the capability to provide block transmissions (whereby multiple data packets can be sent in succession with minimum or no individual medium access operations per packet except before the first packet is sent), and/or block acknowledgements (whereby a single acknowledgement packet can acknowledge multiple preceding data packets). The capability and flexibility to optimize block transmissions and acknowledgements can have a significant effect on GoodPut. • The use of rate adaptation mechanisms, where the data rate on a link is modified when the quality of the link changes. Bruce Kraemer, Marvell

6. Add these definitions to Section 2.2 Broadcast • Broadcast is a form of message transmission where a message is sent from a single source to all potential receiving nodes. Multicast • Multicast is a form of message transmission where a message is sent from a single source to a subset of all potential receiving nodes. (The mechanism for selecting the members of the subset is not part of this definition.) Unicast • Unicast is a form of message transmission where a message is sent from a single source is sent to a single receiving node. Bruce Kraemer, Marvell

7. Comment #04 • Section 4.2.1.6 talks about RF utilization. • Agreed text change: • Add the following text at the end of Section 4.2.1.6: • Consider the power level regulations for the different channels used by a particular technology. • Consider the impact of Dynamic Frequency Selection (DFS) regulations on the channels used by a particular technology, e.g., certain UNII channels are subject to DFS regulation which requires wireless devices to change channel when they detect the use of radar on their current channel. Bruce Kraemer, Marvell

8. Comment #05 • Section 4.2.1.7 talks about Data Frames and Packets. It is important to consider frame duration in conjunction with data rate and size of the frame. Also, we need to consider multicast and broadcast frames in addition to unicast frames. • Agreed text change: • Modify item “a)” in Section 4.2.1.7 as follows: • What is the maximum frame duration for a unicast, multicast and broadcast frame respectively, and what are the corresponding frame size and data rate at which each type of frame was sent? • Modify item “b)” in Section 4.2.1.7 as follows: • What is the maximum packet size that can be sent in one unicast, multicast and broadcast radio frame respectively? • Modify item “c)” in Section 4.2.1.7 as follows: • Does the radio system support segmentation of unicast, multicast and broadcast packets respectively, when the payload size exceeds the capacity of one radio frame? Bruce Kraemer, Marvell

9. Comment #06 • Section 4.2.2.4 talks about Connection Topologies. The Bus and Ring topology need to be removed, they are not wireless topologies. One way to characterize wireless topologies is as single hop and multi-hop (statically configured or mesh), and wireless links as point-to-point, point-to-multipoint, and omnidirectional. We need to add figures that correspond to the text we end up with. • Agreed text change: • Remove the Bus and Ring figures • Replace the current text in Section 4.2.2.4 with the following: Wireless network topologies can be divided into single hop and multi-hop, where a multi-hop topology can be statically configured, or can be dynamic and self-forming, e.g., a mesh. A wireless link can be point-to-point, point-to-multipoint, or broadcast. • Add the definitions on the following 4 slides to Section 2.2 Bruce Kraemer, Marvell

10. Hop Definitions • Proposed PAP2 Guidelines Document Definitions • Hop: The term hop is used to signify a link between a pair of devices that a frame or packet needs to traverse to reach one device from the other. • Single-Hop Network: A single-hop network is one in which devices can only communicate with each other directly, e.g., over a single link (hop), and do not have the capability to forward traffic on each other’s behalf. • Multi-Hop Network: A multi-hop network is one in which devices have the capability to forward traffic on each other’s behalf and can thus communicate along paths composed of multiple links (hops). Bruce Kraemer, Marvell

11. Configuring Definition • Statically Configured Multi-Hop Network: A multi-hop network can be statically configured, such that each node’s forwarding decisions are dictated by configuration. • Dynamic and Self-Configuring Multi-Hop Network: A multi-hop network can be dynamic and self-configuring, such that network devices have the ability to discover (multi-hop) forwarding paths in the network and make their own forwarding decisions based on various pre-configured constraints and requirements, e.g., lowest delay or highest throughput. Bruce Kraemer, Marvell

12. MESH Definition • Mesh Network: A mesh network is a dynamic self-configuring network composed of devices that can forward traffic on each other’s behalf, have the ability to discover (multi-hop) forwarding paths in the network and make their own forwarding decisions based on various pre-configured constraints and requirements, e.g., lowest delay or highest throughput. Bruce Kraemer, Marvell

13. Comment #07 • Section 4.2.2.5 talks about Connection Management. The section needs to mention what aspects of “connection management” can be used to compare different wireless technologies. For example, we can evaluate the latency to join a network, available security mechanisms employed when joining a network, and overhead to join the network (number of control packets exchanged). Perhaps section titles such as “Network Participation Mechanisms” or “Joining the Network” are more descriptive of the content of this section. Bruce Kraemer, Marvell

14. Comment 07b Add the following text at the end of Section 4.2.2.5: • It is important to evaluate: • the time it takes for a device to join a particular network, and the overhead required to do so • the time and overhead required to rejoin the network when a device becomes disconnected from the network • the overhead required to maintain membership in the network after the initial admission into the network • the overhead associated with optimizing connectivity, e.g., in mesh-based topologies. Bruce Kraemer, Marvell

15. Comment #08 • Section 4.2.3.2 talks about Location Characterization. It seems like many of the techniques applicable to this section are not technology-specific but implementation-specific and as such can be incorporated across different wireless technologies even if they are not currently incorporated into the products of a specific wireless technology. It would be helpful to make the distinction between technology-specific properties and product-specific properties in the text. • Agreed text change: • Add the following text at the end of Section 4.2.3.2: • It is important to distinguish between technology-specific mechanisms for location characterization and mechanisms that are applicable across technologies or communication topologies, which can easily be added to products that may not currently support them. Bruce Kraemer, Marvell

16. Comment #09 • A category that is missing from Section 4 is one that characterizes the deployment complexity of each technology. I have some initial proposed text below but I would like to solicit the group’s input on how to characterize deployment complexity in a measurable way. • Agreed text change: Add the following text after Section 4.2.4.1: • 4.2.5 Group 22: Deployment Complexity • It is important to evaluate the complexity of: • installation and maintenance of a given wireless system • integration with other, possibly existing, networks • expansion of the wireless network coverage over time. Bruce Kraemer, Marvell

17. General Comment #10 • It would be helpful to have some tables and text summarizing the information in Section 5, and to move a lot of the discussions/derivations to an appendix. Otherwise, the message/conclusions/recommendations get lost in the text. Bruce Kraemer, Marvell

18. General Comment #11 Section 4.2.1.2 (p. 24) talks about voice and video traffic over the smart grid. We need more use cases motivating why we would want to have voice and video traffic over the smart grid network. The current set of use cases supplied by OpenSG does not currently contain this service. The only video example given in the text is one of surveillance of affected outage areas. It would seem that voice and video might be of lower priority during outages, e.g., caused by disasters or weather-related events, since the network would require a high degree of availability for its regular functions. In addition, surveillance is generally part of the public safety infrastructure and there is spectrum allocated for such use so I am not convinced that we should be discussing this kind of application in the context of the smart grid. • Applications such as voice and video have requirements that even broadband network providers are struggling with (wireless and landline) and making them part of the smart grid infrastructure requires significant justification. Bruce Kraemer, Marvell

19. General Comment #12 • Link Availability in Section 4.2.1.1 does not appear to be consistently calculated for the various candidate various radio technologies, nor did majority of the technology candidates describe the method used to calculate availability. • The current description of the characteristic does not match the calculation. • Both of these issues need to be resolved before progressing to completion of Sections 6 & 7. Bruce Kraemer, Marvell

20. Comment #13 Para 2 Recommended change • Reword the preface to incorporate the idea that SG application requirements evolve over time, yielding to experience rather than remain locked in 1989 or 1999 or 2009 economics. • Smart Grid application requirements must be defined with enough specificity to quantitatively define communications traffic and levels of performance over the lifetime of the applications.  Applications requirements must be combined with as complete a set of management and security requirements for the life-cycle of the equipment.  The decisions to apply wireless for any given set of applications can then be based on expected performance and costs over the projected useful lifetimes of the spectrum and equipment.  Bruce Kraemer, Marvell