Koteswararao Kondepu

Energy-saving framework for passive optical networks with ONU sleep/doze mode

This paper proposes an energy-saving passive optical network framework (ESPON) that aims to incorporate optical network unit (ONU) sleep/doze mode into dynamic bandwidth allocation (DBA) algorithms to reduce ONU energy consumption. In the ESPON, the optical line terminal (OLT) schedules both downstream (DS) and upstream (US) transmissions in the same slot in an online and dynamic fashion whereas the ONU enters sleep mode outside the slot. The ONU sleep time is maximized based on both DS and US traffic. Moreover, during the slot, the ONU might enter doze mode when only its transmitter is idle to further improve energy efficiency. The scheduling order of data transmission, control message exchange, sleep period, and doze period defines an energy-efficient scheme under the ESPON. Three schemes are designed and evaluated in an extensive FPGA-based evaluation. Results show that whilst all the schemes significantly save ONU energy for different evaluation scenarios, the scheduling order has great impact on their performance. In addition, the ESPON allows for a scheduling order that saves ONU energy independently of the network reach.

5G fronthaul-latency and jitter studies of CPRI over ethernet

Common Public Radio Interface (CPRI) is a successful industry cooperation defining the publicly available specification for the key internal interface of radio base stations between the radio equipment control (REC) and the radio equipment (RE) in the fronthaul of mobile networks. However, CPRI is expensive to deploy, consumes large bandwidth, and currently is statically configured. On the other hand, an Ethernet-based mobile fronthaul will be cost-efficient and more easily reconfigurable. Encapsulating CPRI over Ethernet (CoE) is an attractive solution, but stringent CPRI requirements such as delay and jitter are major challenges that need to be met to make CoE a reality. This study investigates whether CoE can meet delay and jitter requirements by performing FPGA-based Verilog experiments and simulations. Verilog experiments show that CoE encapsulation with fixed Ethernet frame size requires about tens of microseconds. Numerical experiments show that the proposed scheduling policy of CoE flows on Ethernet can reduce jitter when redundant Ethernet capacity is provided. The reduction in jitter can be as large as 1 μs, hence making Ethernet-based mobile fronthaul a credible technology.

Trading energy savings and network performance in reconfigurable TWDM-PONS

In time and wavelength division multiplexed (TWDM) passive optical networks (PONs), energy savings at the optical line termination (OLT) are achievable by dynamically allocating the number of active wavelengths in the network and by turning off unutilized OLT transceivers. However, optical network unit (ONU) and PON parameters might impact network performance. This paper evaluates the impact of ONU parameters (e.g., transceiver tuning time) and other PON parameters (e.g., reconfiguration period) on OLT energy savings and average frame delay when dynamic wavelength allocation is performed periodically. Results show that the average frame delay is mainly affected by tuning time and reconfiguration period with lower absolute values if only one ONU buffers traffic during tuning. Increased tuning time trades increased delay with increased energy savings while increased reconfiguration period trades decreased delay with decreased energy savings.

Dual-Beacon mobile-node discovery in sparse wireless sensor networks

In sparse wireless sensor networks data collection is typically accomplished through specialized mobile nodes. One of the main challenges to be faced in this kind of networks is the energy-efficient and timely discovery of mobile nodes. In this paper we propose a simple yet effective discovery protocol based on two different Beacon messages emitted by the mobile node (i.e., Long-Range Beacons and Short-Range Beacons). Our simulation results show that, although very simple, the proposed scheme can provide a significant energy reduction with respect to the commonly used scheme based on a single Beacon, especially if the discovery phase is long.

A hybrid and flexible discovery algorithm for wireless sensor networks with mobile elements

In sparse wireless sensor networks, data collection is carried out through specialized mobile nodes that visit sensor nodes, gather data, and transport them to the sink node. Since visit times are typically unpredictable, one of the main challenges to be faced in this kind of networks is the energy-efficient discovery of mobile collector nodes by sensor nodes. In this paper, we propose an adaptive discovery algorithm that combines a learning-based approach with a hierarchical scheme. Thanks to its hybrid nature, the proposed algorithm is very flexible, as it can adapt to very different mobility patterns of the mobile collector node(s), ranging from deterministic to completely random mobility. We have investigated the performance of the proposed approach, through simulation, and we have compared it with existing adaptive algorithms that only leverage either a learning-based or a hierarchical approach. Our results show that the proposed hybrid algorithm outperforms the considered adaptive approaches in all the analyzed scenarios.

An effective pointer-based HLR location registration scheme in location management for PCS networks

In this paper, a pointer based HLR (Home Location Register) scheme for location management in PCS (Personal Communication Service) network is presented. The proposed scheme maintained cache information at each HLR database. Whenever the Mobile Terminal (MT) moves from old service area to new service area, its entry will enter in to the cache that is maintained by the old service area. This entry tells about information of MT, i.e., to which SA (Service Area) it has gone. An analytical model is developed for studying the performance of the proposed scheme.

Experimenting the integration of green optical access and metro networks based on SDN

This paper outlines the issues in providing a seamless integration between energy-efficient optical access networks and metro networks that preserves the overall latency balance. A solution based on SDN is proposed and detailed. The proposed solution allows to trade the increased delay in the access section, due the utilization of energy efficient schemes, with a reduced delay in the metro section. Experiments in a geographically distributed testbed evaluate the different delay contributions.

Partially Overlapping Super Location Area (POSLA): An Efficient Scheme for Location Management in PCS Networks

A partially overlapping super location area (POSLA) Scheme is suggested to overcome the varying updation problem of Overlapping Super Location Area (OSLA) Scheme. In this scheme, the LA is partially overlapped by its surrounding LAs and the location updates will be done based on the minimum distance from the center cell. The suggested scheme, POSLA, shows the reduction in the location update cost as compared to OSLA scheme.

Analytical and experimental evaluation of CPRI over Ethernet dynamic rate reconfiguration

The utilization of Ethernet in the cellular terrestrial cloud radio access network (C-RAN) fronthaul is considered as a way for improving C-RAN network reconfigurability and efficiency in terms of both capital and operational expenditures. Moreover CPRI line bit rate dynamic reconfiguration may spare further capital expenditures by avoiding a peak traffic capacity allocation. A possible solution for introducing Ethernet in the fronthaul is the encapsulation of Common Packet Radio Interface (CPRI) over Ethernet. However, it must be assured that CPRI strict requirements on delay and jitter are still met. In this work the combined impact of encapsulating CPRI on Ethernet and of the dynamic CPRI line bit rate reconfiguration on delay and jitter is evaluated. The evaluation is both analytical and based on the pre-synthesis emulation of dynamic CPRI line bit rate reconfiguration. Results show that dynamic CPRI line bit rate reconfiguration can be achieved within about one millisecond. However, if a size-based encapsulation of CPRI over Ethernet is utilized, dynamic CPRI line bit rate reconfiguration might cause delay variations (i.e., jitter) up to few microseconds.

Time-versus size-based CPRI in ethernet encapsulation for next generation reconfigurable fronthaul

The utilization of Ethernet in the cellular terrestrial cloud radio access network (C-RAN) fronthaul will potentially improve C-RAN reconfigurability and cost efficiency in terms of both capital and operational expenditures. Moreover, Common Public Radio Interface (CPRI) line bit rate dynamic reconfiguration may spare further capital expenditures by avoiding peak traffic capacity allocation. A possible solution for introducing Ethernet in the fronthaul is the encapsulation of CPRI in Ethernet. This solution is now part of the radio over Ethernet interface specified by the IEEE P1914 working group. However, it must be assured that fronthaul strict requirements on delay and jitter are still met. In this study, the combined impact of encapsulating CPRI in Ethernet and of the dynamic CPRI line bit rate reconfiguration on delay and jitter of the communication between radio equipment and a radio equipment controller is evaluated. The evaluation is both analytical and based on the presynthesis emulation of dynamic CPRI line bit rate reconfiguration. Both a size-based and a time-based encapsulation are considered. Results show that dynamic CPRI line bit rate reconfiguration can be achieved within about 1 ms. However, if a size-based encapsulation of CPRI in Ethernet is utilized, dynamic CPRI line bit rate reconfiguration might cause delay variations (i.e., jitter) up to few microseconds. Thus, to avoid jitter upon CPRI line bit rate reconfiguration, time-based encapsulation is preferable.