Wireless Systems Communications

Wireless Systems Communications

Introduction

Wireless Systems Communications is the process of fully transforming how individuals and institutions across various sectors (that are not physically connected) communicate - and how they receive and exchange information. Wireless systems are rapidly rendering a wide range of personalized communications services as portable as cellular phones. Many of today’s most promising new wireless technologies involve Wireless Local Area Networks (WLANs), which enable a wide range of communications devices to stay connected to more conventional wired networks without requiring users to be physically connected through wires or cables. Through widely spaced access points, WLANs receive and transmit radio signals to and from Network Interface Cards (NIC) that contain small radio receivers and transmitters attached to users’ computers or other communications apparatuses.

Wireless Communications – down the lane

Wireless Communications are one of the most rapidly developing segments of the information industry. With the mass proliferation and expansion of the wireless industry, many experts believe that wireless communications will eventually replace wired ones. While some maintain that this transformation is several decades down the road, others contend that it is just around the corner.

Over the past two decade, mass-offering of mobile broadband access to the Internet has been the dominating theme of wireless communications. Also, given the dramatic changes in wireless technology in just the past five years, it is reasonable to predict that wireless networks will replace all wired network communications within the next few years.

Security and Privacy

It is well known that wireless networks are inherently more vulnerable than their wired counter-parts. Also on the other hand, At the same time, node resource constraints — due to battery operation (power), weak transceivers (bandwidth), and small memory/storage — make direct adoption of existing security solutions difficult.

Wireless communication systems are carrying a growing amount of confidential information. It is in in deed changing the way in which people communicate. The broadcasting nature of wireless transmissions, however, makes the transmitted information vulnerable to eavesdropping. To effectively support various highly-secrecy-sensitive applications, novel transmission technologies should apply to facilitate or even enhance the information secrecy. Innovative transmission solutions to secrecy and privacy enhancement are of great continuing interests to the wireless community.

The attacks on network availability are also known as the Denial of Service (DoS) attacks. In stealthy attacks, an attacker compromises a sensor node and injects false data. DoS attacks, if launched successfully, can severely degrade the performance of WSNs. Hence security measures such as Application of cryptographic mechanisms, key management protocols, defense mechanisms against the DoS attacks and on the attacks on the routing protocols should be implemented effectively.

Communication Infrastructure

The real challenge in the Communication Infrastructure is how to realize the potential performance gains with acceptable system complexity and implementation cost, associated with real-time channel estimation, synchronization in time and frequency domains, and joint processing at fully-connected base stations. In order to provide heterogeneous global connectivity envisaged to future wireless systems, the integration of satellite, aerial, terrestrial, and underwater networks has become an emerging trend of communication infrastructure and will attract significant attention and studies along the next few years.

Resource and Spectrum Utilizations

The spectrum suitable for wireless communications is becoming increasingly scarce, which motivate the exploration of new spectrum bands, including millimeter-wave and tera-Hertz (THz). While enjoying larger bandwidth, the coverage area over these higher RF bands are generally much smaller due to their higher propagation loss. The most popular mitigation solution is to apply directional beamforming transmission technology. Also, one another best solution to address spectrum scarcity is to improve the utilization of existing spectrum through cognitive radio transmission.

Spectrum scarcity can also be addressed from many different perspectives. For instance, from the point of view of signal processing, we can look for higher spectral efficiency in modulations by enhancing multicarrier modulation based on discrete cosine transform (DCT-MCM), proposing two new blind algorithms to perform tight timing offset and coarse frequency synchronization, which addresses the problem of symbol timing offset in these modulations.

Wireless access techniques

Effective wireless access techniques are essential to future generations of wireless communication systems to fundamentally meet the stringent requirements, which include very high spectral efficiency, very low latency, massive device connectivity, very high achievable data rate, ultrahigh reliability, excellent user fairness, high throughput, support to diverse quality-of-service (QoS), energy efficiency, and a dramatic reduction in the cost. The recent advancements such as 5G (fifth generation) mobile networks refers to the next wave of wireless communication designed to improve the speed and reliability of wireless networks.

The 5G system intends to improve performance parameters such as coverage, peak rate, spectral efficiency, and latency. Multiple radio access technologies are projected to be supported by the 5G network (RATs). The radio frequency of 5G networks ranges from 30 GHz to 300 GHz whereas the earlier generation – 4G can range up to 6 GHz only. Due to this massive upgrade, 5G mobile networks can reach up to a speed of around 1 to 20 Gbps. Also the latency of 5G is extremely low as it’s less than 10 milliseconds, whereas the latency of 4G LTE is slightly longer, coming in at around 50 milliseconds.

Blockchain-enabled wireless communications

With the successful deployment of fifth-generation - 5G wireless networks worldwide, research on sixth-generation (6G) wireless communications has started. It is highly expected that 6G networks can accommodate numerous heterogeneous devices and infrastructures with enhanced efficiency and security over diverse, e.g. spectrum, computing and storage, resources. Due to the success of its use in cryptocurrency, blockchain technology has been studied in wireless networks, allowing unknown individuals to interact with each other in a verifiable manner. For example, blockchain can be used for secure data sharing in a wireless body area network. Building on its nature of decentralization, transparency, anonymity, immutability, traceability and resiliency, blockchain can establish cooperative trust among separate network entities and facilitate efficient resource sharing, trusted data interaction, secure access control, privacy protection, and tracing, certification and supervision functionalities for wireless networks.

Blockchain would be the most promising technology to meet these new security requirements for the upcoming wireless communications systems such as IoT data collection, driverless cars, Unmanned Aerial Vehicles (UAVs), Federated Learning (FL), etc. The concept of blockchain is based on a peer-to-peer network architecture in which transaction information is managed flexibly by all network participants and not controlled by any single centralized authority.

Satellite Communication and GPS

Satellite Communication System is an important type of Wireless Communication. Satellite Communication Networks provide worldwide coverage independent to population density. It offers telecommunication (Satellite Phones), Global positioning and navigation (GPS), broadcasting, internet, etc. Other wireless services like mobile, television broadcasting and other radio systems are also heavily dependent of Satellite Communication Systems.

In satellite communication systems, FEC (Forward Error Correction) technique is often employed to effectively improve the transmission quality which is degraded due to the interference and the power limitation of the system. Also, since there is a considerable amount of propagation delay (250–300 msec) in satellite communication systems, FEC technique tends to be more widely used than the ARQ (Automatic Repeat Request) technology, which requires retransmission of the data.

GPS which is an U.S.- owned utility provides different wireless services like navigation, positioning, location, speed and timing etc. with the help of dedicated GPS receivers and satellites. The GPS space segment is formed by a satellite constellation with enough satellites to ensure that the users will have, at least, 4 simultaneous satellites in view from any point at the Earth’s surface at any time. In between the GPS space segment and user end, there is a control segment which comprises a master control station and five monitor stations outfitted with atomic clocks that are spread around the globe. The five monitor stations monitor the GPS satellite signals and then send that qualified information to the master control station where abnormalities are revised and sent back to the GPS satellites through ground antennas. In the user end, there will be a GPS receiver, which receives the signals from the GPS satellites and determines how far away it is from each satellite.

Integration of Wireless Information and Power Transfer

Due to enormous energy consumption expected by the massive number of connected nodes in future wireless networks, several strategies have been proposed to implement self-sustainable communication systems. Specifically, an emerging paradigm - Simultaneous Wireless Information and Power Transfer (SWIPT) that transfers information and power to wireless devices simultaneously also enables proactive energy replenishment of wireless devices and becomes a promising solution to power energy-constrained wireless networks which will be particularly important for future wireless networks.

SWIPT aided Cooperative Relaying (CoR) has emerged as a new trend for fifth generation (5G) and Beyond 5G (B5G) systems owing to the rapidly increasing challenges faced by these networks. Cooperative relaying combined with SWIPT can be helpful in overcoming the rising demands of next generation wireless networks by providing an enhanced data rate, low latency, shorter coverage, wide spread connectivity of massive number of devices along with energy-efficiency.

Resource and Interference management

The current generation wireless communications technologies such as Cognitive radio network, small cell network, wireless local area network, wireless sensor system, WiMAX, and LTE network will promote the next generation network communication technology to achieve greater development. In order to support various emerging applications, new resource and interference management schemes are expected in future wireless networks. Under this perspective, machine learning (ML) based techniques have attracted huge interest due to their ability to improve system performance and reduce the computational cost. The resource involves strategies and algorithms for controlling parameters such as transmit power, user allocation, beamforming, data rates, handover criteria, modulation scheme, error coding scheme, etc. The objective is to utilize the limited radio-frequency spectrum resources and radio network infrastructure as efficiently as possible.

Energy efficiency enhancement

Most of the IoT applications involve a huge number of resource-limited sensors, which are expected to autonomously operate over 10 years. Although transmitting in a sporadic fashion, these sensor nodes demand transmission schemes with very high energy efficiency. Hence, improving the channel condition during transmission will naturally help reduce transmission energy consumption. In order to have an efficient data transmission to the final destination, the traffic must be relayed using intermediate nodes, creating a multi-hop route – hence the total energy consumption associated with an end-to-end transmission over such a route can be significantly reduced if the nodes are correctly configured.

To achieve this, a cross layer design methodology can be adopted to design an energy efficient routing protocol known as Position Responsive Routing Protocol (PRRP). PRRP is designed to minimize energy consumed in each node by (1) reducing the amount of time in which a sensor node is in an idle listening state and (2) reducing the average communication distance over the network. The performance of PRRP can be critically evaluated in the context of network lifetime, throughput, and energy consumption of the network per individual basis and per data packet basis and should be correlated and benchmarked against the well-known protocols such as LEACH (Low-Energy Adaptive Clustering Hierarchy) and CELRP (Cluster based Energy Efficient Location Routing Protocol).

Conclusion

The field of wireless communications will witness many exciting technological breakthroughs in the foreseeable future. Many technical challenges are to be addressed to satisfying stringent and conflicting requirements for future wireless systems, including very high spectral efficiency, very low latency, massive device connectivity, very high achievable data rate, ultra-high reliability, excellent user fairness, high throughput, diverse quality-of-service, energy efficiency, and a dramatic cost reduction.