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Energy efficiency and renewable energy are the main pillars of sustainability and environmental compatibility. This study presents an overview of sustainable and green cellular base stations (BSs), which account for most of the energy consumed in cellular networks. We review the architecture of the BS and the power consumption model, and then summarize the trends in green cellular network research over the past decade. As its major contribution, this study highlights the uses of renewable energy in cellular communication by: (i) investigating the system model and the potential of renewable energy solutions for cellular BSs; (ii) identifying the potential geographical locations for renewable-energy-powered BSs; (iii) performing case studies on renewable-energy-powered cellular BSs and suggesting future research directions based on our findings; (iv) examining the present deployment of sustainable and green BSs; and (v) studying the barriers that prevent the widespread use of renewable-energy-powered BSs and providing recommendations for future work.

The explosive development of Information and Communication Technology (ICT) has significantly enlarged both the energy demands and the CO 2 emissions, and consequently contributes to make the energy crisis and global warming problems worse. However, as the main force of the ICT field, the mobile networks, are currently focusing on the capacity, variety and stability of the communication services, without paying too much severe concerns on the energy efficiency. The escalating energy costs and environmental concerns have already created an urgent need for more energy-efficient “green” wireless communications. In this paper, we survey and discuss various remarkable techniques toward green mobile networks to date, mainly targeting mobile cellular networks. We also summarize the current research projects related to green mobile networks, along with the taxonomy of energy-efficiency metrics. We finally discuss and elaborate future research opportunities and design challenges for green mobile networks.

Following FCC pressure to end bill shock, cellular carriers now alert customers when they exceed usage allowances. We estimate a model of plan choice, usage, and learning using a 2002-2004 panel of cellular bills. Accounting for firm price adjustment, we predict that implementing alerts in 2002-2004 would have lowered average annual consumer welfare by $33. We show that consumers are inattentive to past usage, meaning that bill-shock alerts are informative. Additionally, our estimates imply that consumers are overconfident, underestimating the variance of future calling. Overconfidence costs consumers $76 annually at 2002-2004 prices. Absent overconfidence, alerts would have little to no effect.

We study the contagious switching behavior related to a consumer’s choice of wireless carriers, that is, that a consumer is more likely to switch wireless carriers if more of their contacts from the same carrier have switched. Contagious switching (or a positive network effect) can be driven by information-based social learning, as well as other mechanisms related to network size. Although previous marketing literature has documented the social-learning effect, most of the applications studied involve products in which consumers usually do not enjoy any direct benefits from a large network other than from information-based social learning. We explore the importance of the social-learning effect relative to other mechanisms that may also lead to the network effect. We propose a dynamic structural model with interpersonal interactions. To model the social-learning effect, a consumer uses feedback from his or her contacts who have switched from a focal carrier to update his or her quality expectations of alternative carriers. Our model further accounts for two unique aspects of consumer strategic learning: (i) the individual’s perception on the signal of alternative carriers from contacts who switch is systematically different according to whether the signal comes from a loyal contact; and (ii) that the perceived noisiness of the signal on alternative carriers from a contact who has switched depends on the strength of the relationship between the individual and the contact. The remaining network effect not captured through social learning is modeled as a function of the size of the network. We solve the model with a two-step dynamic programming algorithm, with the assumption that a consumer is forward-looking and decides whether to stay with the same service carrier in each period by maximizing the total utility received from that day onward. We apply the proposed model to the data set of a mobile network operator in a European country. We find that churning/switching behavior is contagious in the network context and that one-third of general network effects can be attributed to social learning. We also detect strategic learning by consumers from their contacts in two ways: the experience signal on alternative carriers from a more loyal contact who has switched from the focal carrier is perceived to be more positive than that from a less loyal contact; and the social-learning effect is stronger from an individual’s closest contacts. The simulation analysis demonstrates the value of our model in helping a company prioritize its customer relationship management effort. This paper was accepted by Matthew Shum, marketing.

We examine how entrepreneurial entry by diversifying and de novo firms in new industries leads to different levels of performance. We propose that these types of firms differ in dynamic capabilities, which help them overcome growth impediments and transition to incumbency in the industry. Growth impediments arise at larger size, older tenure levels in industry, and after technological discontinuities. Because of their prior experience, diversifying firms are better equipped to handle the challenges of impediments to growth. Meanwhile, de novo firms, ostensibly tailor-made for the targeted industry, are more likely to stumble over these growth challenges, and eventually lag behind diversifying firms. We find support for our hypotheses using a near census of firms in the U.S. wireless telecommunications industry over the 1983-2004 period.

The movement of personnel between firms has been shown to have important implications for firms, yet there has been little direct investigation of the underlying mechanisms. We propose that in addition to their human capital, mobile individuals carry social capital, affecting the outcomes of the firms they join and leave by altering the patterns of interaction between firms. In this study, we examine how job mobility affects firm influence in a technical standards setting committee for U.S. wireless telecommunications. We hypothesize and find that hiring individuals who are richer in social capital increases firm influence in technical standards setting committees by increasing the hiring firm's social capital. We also find the benefits of hiring social capital are attenuated when an interfirm relationship is maintained by multiple individuals. In contrast, we find that the loss of personnel does not affect a firm's social capital or influence over standards directly but that it does have an effect on firm social capital and influence contingent on changes in the firm's business strategy. In advancing these arguments, we address the broader question of individuals as carriers of social capital and the conditions under which interpersonal connections are appropriable by firms.

Recent advancements in hybrid photonic integrated circuits (PICs) for wireless communications are reviewed, with a focus on innovations developed at Fraunhofer HHI. This work leverages hybrid integration technology, which combines indium phosphide (InP) active elements, silicon nitride (Si3N4) low-loss waveguides, and high-efficient thermal-optical tunable polymers with micro-optical functions to achieve fully integrated wireless transceivers. Key contributions include (1) On-chip optical injection locking for generating phase-locked optical beat notes at 45 GHz, enabled by cascaded InP phase modulators and hybrid InP/polymer tunable lasers with a 3.8 GHz locking range. (2) Waveguide-integrated THz emitters and receivers, featuring photoconductive antennas (PCAs) with a 22× improved photoresponse compared to top-illuminated designs, alongside scalable 1 × 4 PIN-PD and PCA arrays for enhanced power and directivity. (3) Beam steering at 300 GHz using a polymer-based optical phased array (OPA) integrated with an InP antenna array, achieving continuous steering across 20° and a 10.6 dB increase in output power. (4) Demonstration of fully integrated hybrid wireless transceiver PICs combining InP, Si3N4, and polymer material platforms, validated through key component characterization, on-chip optical frequency comb generation, and coherent beat note generation at 45 GHz. These advancements result in compact form factors, reduced power consumption, and enhanced scalability, positioning PICs as an enabling technology for future high-speed wireless networks.

Text4baby is the first free national health text messaging service in the United States that aims to provide timely information to pregnant women and new mothers to help them improve their health and the health of their babies. Here we describe the development of the text messages and the large public–private partnership that led to the national launch of the service in 2010. Promotion at the local, state, and national levels produced rapid uptake across the United States. More than 320 000 people enrolled with text4baby between February 2010 and March 2012. Further evaluations of the effectiveness of the service are ongoing; however, important lessons can be learned from its development and uptake.

Spectrum auctions are used by governments to assign and price licenses for wireless communications. The standard approach is the simultaneous ascending auction, in which many related lots are auctioned simultaneously in a sequence of rounds. I analyze the strengths and weaknesses of the approach with examples from US spectrum auctions. I then present a variation-the combinatorial clock auctionwhich has been adopted by the UK and many other countries, which addresses many of the problems of the simultaneous ascending auction while building on its strengths. The combinatorial clock auction is a simple dynamic auction in which bidders bid on packages of lots. Most importantly, the auction allows alternative technologies that require the spectrum to be organized in different ways to compete in a technologyneutral auction. In addition, the pricing rule and information policy are carefully tailored to mitigate gaming behavior. An activity rule based on revealed preference promotes price and assignment discovery throughout the clock stage of the auction. Truthful bidding is encouraged, which simplifies bidding and improves efficiency. Experimental tests and early auctions confirm the advantages of the approach.

Based on the narratives of environmental munificence perspective, RBV and contingency theory, this study investigates how management innovation capability influence the functional relationship between environmental munificence and service firm performance. Employing a cross-sectional survey-based sample of 162 employees of four mobile telecommunication firms in Lagos State, Nigeria. A moderated regression analysis to test two-way interaction hypotheses was conducted, and the results show that environmental munificence has a significant positive effect on market share (R2 =0.273, F(1,160) = 60.060, p <0.05). However, it failed to significantly influence profitability (R2 =0.008, F(1,160) = 1.250, p > 0.05). Further analysis shows that environmental munificence explained the variation in service firm performance for both market share (? R2 =0.154, p <0.05) and profitability (?R2 =0.159, p < 0.05) with the introduction of management innovation capability as a moderator. This finding suggests that managers of service firms should invest in developing an innovative high-level capability that would help their firms to identify and take advantage of the opportunities for growth in a dynamic environment. This study contributes to innovation and environmental munificence literature. First, contrary to prior studies which position environmental munificence as a moderator, this study employs environmental munificence as a first-order predictor variable of firm performance and suggest under which condition firm performance can be enhanced. Finally, this study further corroborates the position of the RBV which posit that firm can achieve superior performance in a fast-changing environment as long as it can deploy its core resource and unique competencies.