Link-State Based Decode-Forward Schemes for Two-way Relaying

In this paper, we analyze a composite decode-and-forward scheme for the two-way relay channel with a direct link. During transmission, our scheme combines both block Markov coding and an independent coding scheme similar to network coding at the relay. The main contribution of this work is to examine how link state impacts the allocation of power between these two distinct techniques, which in turn governs the necessity of each technique in achieving the largest transmission rate region. We analytically determine the link-state regimes and associated relaying techniques. Our results illustrate an interesting trend: when the user-to-relay link is marginally stronger than the direct link, it is optimal to use only independent coding. In this case, the relay need not use full power. However, for larger user-to-relay link gains, the relay must supplement independent coding with block Markov coding to achieve the largest rate region. These link-state regimes are important for the application of two-way relaying in 5G networks, such as in D2D mode or relay-aided transmission.Comment: To be presented at Globecom 2014, Emerging Technologies for 5G Wireless Cellular Networks (Wi5G

H2-ARQ-relaying: spectrum and energy efficiency perspectives

In this paper, we propose novel Hybrid Automatic Repeat re-Quest (HARQ) strategies used in conjunction with hybrid relaying schemes, named as H2-ARQ-Relaying. The strategies allow the relay to dynamically switch between amplify-and-forward/compress-and-forward and decode-and-forward schemes according to its decoding status. The performance analysis is conducted from both the spectrum and energy efficiency perspectives. The spectrum efficiency of the proposed strategies, in terms of the maximum throughput, is significantly improved compared with their non-hybrid counterparts under the same constraints. The consumed energy per bit is optimized by manipulating the node activation time, the transmission energy and the power allocation between the source and the relay. The circuitry energy consumption of all involved nodes is taken into consideration. Numerical results shed light on how and when the energy efficiency can be improved in cooperative HARQ. For instance, cooperative HARQ is shown to be energy efficient in long distance transmission only. Furthermore, we consider the fact that the compress-and-forward scheme requires instantaneous signal to noise ratios of all three constituent links. However, this requirement can be impractical in some cases. In this regard, we introduce an improved strategy where only partial and affordable channel state information feedback is needed

Telemetry problems with pacemakers in a noisy environment

This report covers the investigation of problems relating to the telemetry of pacemakers in a noisy environment. An attempt was made to suggest schemes that improve system performance. We define system performance to be improved noise immunity with high reliability and increased message throughput. Three aspects were considered, with implementation schemes that incur minimal protocol changes over systems in existence. 1. The present scheme is writing to the pacemaker and echoing each bit back within a 2ms frame. If any echoed bit is not in agreement with that sent, the message is re-transmitted from the start of the block. Because the return link is poor in terms of signal to noise ratio, echoing bits up this link degrades system performance, particularly as the noise power increases. An ARQ (autamatic repeat request) scheme is suggested as a solution to this problem. 2. When data is to be read from the pacemaker, reply is via two 4ms frames each of 6 bits. A CRC (cyclic redundancy check) is performed on the returned data (8 bits) which checks for three or less errors, and the redundancy bits are appended to the end of the 9 bits. If any errors are detected, a retransmission is required. Using a FEC (forward error correction) scheme to correct errors, together with a CRC to check the integrity of data, throughput can be significantly improved especially in a noisy environment. The scheme we suggest is to encode data bits plus CRC with a 23,12 Golay code, and send the data using four by 4ms frames. The Golay code suggested is a perfect code, triple error correcting. 3. The final aspect we considered is the possible system performance improvement using soft decision quantization at the programmer of received data. This system gives gains of the order of 1.75 dB over current practice

A Mobile Satellite Experiment (MSAT-X) network definition

The network architecture development of the Mobile Satellite Experiment (MSAT-X) project for the past few years is described. The results and findings of the network research activities carried out under the MSAT-X project are summarized. A framework is presented upon which the Mobile Satellite Systems (MSSs) operator can design a commercial network. A sample network configuration and its capability are also included under the projected scenario. The Communication Interconnection aspect of the MSAT-X network is discussed. In the MSAT-X network structure two basic protocols are presented: the channel access protocol, and the link connection protocol. The error-control techniques used in the MSAT-X project and the packet structure are also discussed. A description of two testbeds developed for experimentally simulating the channel access protocol and link control protocol, respectively, is presented. A sample network configuration and some future network activities of the MSAT-X project are also presented

SELECTIVE FORWARD ERROR CORRECTION WITH FULL DUPLEX FEEDBACK LOOP

Numerous techniques exist for detecting and correcting errors that are introduced during the transmission of information (e.g., a data frame) between two pieces of network equipment, including, for example, forward error correction (FEC), cyclic redundancy check (CRC), hybrid automatic repeat request (HARQ), etc. Use of such techniques carries a cost, often shared between the transmitter and the receiver, comprising increased latency, consumption of bandwidth, the use of computational resources for verification and correction, etc. Techniques are presented herein that support a new method for detecting and correcting errors that leverages a return channel of a bidirectional radio environment to provide a feedback loop through which FEC may be focused just on the areas of a frame that are poorly received, thereby avoiding the latency, bandwidth, etc. costs that would be associated with retransmission of areas of the frame that are well received. The techniques presented herein build on new capabilities of full duplex radios and apply to, for example, Wi-Fi® 6 and 7 and Third Generation Partnership Project (3GPP) Fifth Generation (5G) networks

Survey of unified approaches to integrated-service networks

The increasing demand for communication services, coupled with recent technological advances in communication media and switching techniques, has resulted in a proliferation of new and expanded services. Currently, networks are needed which can transmit voice, data, and video services in an application-independent fashion. Unified approaches employ a single switching technique across the entire network bandwidth, thus, allowing services to be switched in an application-independent manner. This paper presents a taxonomy of integrated-service networks including a look at N-ISDN, while focusing on unified approaches to integrated-service networks.The two most promising unified approaches are burst and fast packet switching. Burst switching is a circuit switching-based approach which allocates channel bandwidth to a connection only during the transmission of "bursts" of information. Fast packet switching is a packet switching-based approach which can be characterized by very high transmission rates on network links and simple, hardwired protocols which match the rapid channel speed of the network. Both approaches are being proposed as possible implementations for integrated-service networks. We survey these two approaches, and also examine the key performance issues found in fast packet switching. We then present the results of a simulation study of a fast packet switching network