An adaptive delayed acknowledgment strategy to improve TCP performance in multi-hop wireless networks.

In multi-hop wireless networks, transmission control protocol (TCP) suffers from performance deterioration due to poor wireless channel characteristics. Earlier studies have shown that the small TCP acknowledgments consume as much wireless resources as the long TCP data packets. Moreover, generating an acknowledgment (ACK) for each incoming data packet reduces the performance of TCP. The main factor affecting TCP performance in multi-hop wireless networks is the contention and collision between ACK and data packets that share the same path. Thus, lowering the number of ACKs using the delayed acknowledgment option defined in IETF RFC 1122 will improve TCP performance. However, large cumulative ACKs will induce packet loss due to retransmission time-out at the sender side of TCP. Motivated by this understanding, we propose a new TCP receiver with an adaptive delayed ACK strategy to improve TCP performance in multi-hop wireless networks. Extensive simulations have been done to prove and evaluate our strategy over different topologies. The simulation results demonstrate that our strategy can improve TCP performance significantly

New fossil remains of Homo naledi from the Lesedi Chamber, South Africa

The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species

New fossil remains of Homo naledi from the Lesedi Chamber, South Africa

The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species.SP201

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa.

Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa

Fast transmission mechanism for secure VPLS architectures

Abstract Ethernet based secure VPLS (Virtual Private LAN Services) networks require to establish full mesh of VPLS tunnels between the customer sites. However, the tunnel establishment between geographically distant customer sites introduces a significantly high delay to the user traffic transportation. In this article, we propose a novel fast transmission mechanism for secure VPLS architectures to reduce the waiting time before transmitting the data and the average data transmission delay between geographically distant customer sites. The performance of proposed mechanism is analyzed by using a simulation model and a testbed implementation

Enhancing security, scalability and flexibility of virtual private LAN services

Abstract Ethernet based VPLS (Virtual Private LAN Service) networks are now becoming attractive in many enterprise applications due to simple, protocol-independent and cost efficient operation. However, new VPLS applications demand additional requirements, such as elevated security, enhanced scalability and improved flexibility. This paper summarized the results of a thesis which focused to increase the scalability, flexibility and compatibility of secure VPLS networks. First, we propose a scalable secure flat-VPLS architecture based on Host Identity Protocol (HIP) to increase the forwarding and security plane scalability. Then, a secure hierarchical-VPLS architecture has been proposed by extending the previous proposal to achieve control plane scalability as well. To solve the compatibility issues of Spanning Tree Protocol (STP) in VPLS networks, a novel Distributed STP (DSTP) is proposed. Lastly, we propose a novel SDN (Software Defined Networking) based VPLS (SoftVPLS) architecture to overcome tunnel management limitations in legacy secure VPLS architectures. Simulation models and testbed implementations are used to verify the performance of proposed solutions

Software defined VPLS architectures:opportunities and challenges

Abstract Virtual Private LAN Services (VPLS) is an Ethernet based VPN (Virtual Private Network) service which provides protocol independent and high speed multipoint-to-multipoint connectivity. In this article, we discuss the possibility to use emerging networks concepts such as Software Defined Networking (SDN) and Network Function Virtualization (NFV) to improve the performance, flexibility and adaptability of VPLS networks. SDN and NFV based VPLS (SoftVPLS) architectures offer new features such as centralized control, network programmability and abstraction to improve the performance, flexibility and automation of traffic, security and network management functions for future VPLS networks